src/sqlite.h.in

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.  If a C-function, structure, datatype,
** or constant definition does not appear in this file, then it is
** not a published API of SQLite, is subject to change without
** notice, and should not be referenced by programs that use SQLite.
**
** Some of the definitions that are in this file are marked as
** "experimental".  Experimental interfaces are normally new
** features recently added to SQLite.  We do not anticipate changes
** to experimental interfaces but reserve to make minor changes if
** experience from use "in the wild" suggest such changes are prudent.
**
** The official C-language API documentation for SQLite is derived
** from comments in this file.  This file is the authoritative source
** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.431 2009/02/11 15:23:35 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
*/
#ifdef __cplusplus
extern "C" {
#endif


/*
** Add the ability to override 'extern'
*/
#ifndef SQLITE_EXTERN
# define SQLITE_EXTERN extern
#endif

/*
** These no-op macros are used in front of interfaces to mark those
** interfaces as either deprecated or experimental.  New applications
** should not use deprecated intrfaces - they are support for backwards
** compatibility only.  Application writers should be aware that
** experimental interfaces are subject to change in point releases.
**
** These macros used to resolve to various kinds of compiler magic that
** would generate warning messages when they were used.  But that
** compiler magic ended up generating such a flurry of bug reports
** that we have taken it all out and gone back to using simple
** noop macros.
*/
#define SQLITE_DEPRECATED
#define SQLITE_EXPERIMENTAL

/*
** Ensure these symbols were not defined by some previous header file.
*/
#ifdef SQLITE_VERSION
# undef SQLITE_VERSION
#endif
#ifdef SQLITE_VERSION_NUMBER
# undef SQLITE_VERSION_NUMBER
#endif

/*
** CAPI3REF: Compile-Time Library Version Numbers {H10010} <S60100>
**
** The SQLITE_VERSION and SQLITE_VERSION_NUMBER #defines in
** the sqlite3.h file specify the version of SQLite with which
** that header file is associated.
**
** The "version" of SQLite is a string of the form "X.Y.Z".
** The phrase "alpha" or "beta" might be appended after the Z.
** The X value is major version number always 3 in SQLite3.
** The X value only changes when backwards compatibility is
** broken and we intend to never break backwards compatibility.
** The Y value is the minor version number and only changes when
** there are major feature enhancements that are forwards compatible
** but not backwards compatible.
** The Z value is the release number and is incremented with
** each release but resets back to 0 whenever Y is incremented.
**
** See also: [sqlite3_libversion()] and [sqlite3_libversion_number()].
**
** INVARIANTS:
**
** {H10011} The SQLITE_VERSION #define in the sqlite3.h header file shall
**          evaluate to a string literal that is the SQLite version
**          with which the header file is associated.
**
** {H10014} The SQLITE_VERSION_NUMBER #define shall resolve to an integer
**          with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z
**          are the major version, minor version, and release number.
*/
#define SQLITE_VERSION         "--VERS--"
#define SQLITE_VERSION_NUMBER  --VERSION-NUMBER--

/*
** CAPI3REF: Run-Time Library Version Numbers {H10020} <S60100>
** KEYWORDS: sqlite3_version
**
** These features provide the same information as the [SQLITE_VERSION]
** and [SQLITE_VERSION_NUMBER] #defines in the header, but are associated
** with the library instead of the header file.  Cautious programmers might
** include a check in their application to verify that
** sqlite3_libversion_number() always returns the value
** [SQLITE_VERSION_NUMBER].
**
** The sqlite3_libversion() function returns the same information as is
** in the sqlite3_version[] string constant.  The function is provided
** for use in DLLs since DLL users usually do not have direct access to string
** constants within the DLL.
**
** INVARIANTS:
**
** {H10021} The [sqlite3_libversion_number()] interface shall return
**          an integer equal to [SQLITE_VERSION_NUMBER].
**
** {H10022} The [sqlite3_version] string constant shall contain
**          the text of the [SQLITE_VERSION] string.
**
** {H10023} The [sqlite3_libversion()] function shall return
**          a pointer to the [sqlite3_version] string constant.
*/
SQLITE_EXTERN const char sqlite3_version[];
const char *sqlite3_libversion(void);
int sqlite3_libversion_number(void);

/*
** CAPI3REF: Test To See If The Library Is Threadsafe {H10100} <S60100>
**
** SQLite can be compiled with or without mutexes.  When
** the [SQLITE_THREADSAFE] C preprocessor macro 1 or 2, mutexes
** are enabled and SQLite is threadsafe.  When the
** [SQLITE_THREADSAFE] macro is 0, 
** the mutexes are omitted.  Without the mutexes, it is not safe
** to use SQLite concurrently from more than one thread.
**
** Enabling mutexes incurs a measurable performance penalty.
** So if speed is of utmost importance, it makes sense to disable
** the mutexes.  But for maximum safety, mutexes should be enabled.
** The default behavior is for mutexes to be enabled.
**
** This interface can be used by a program to make sure that the
** version of SQLite that it is linking against was compiled with
** the desired setting of the [SQLITE_THREADSAFE] macro.
**
** This interface only reports on the compile-time mutex setting
** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
** SQLITE_THREADSAFE=1 then mutexes are enabled by default but
** can be fully or partially disabled using a call to [sqlite3_config()]
** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
** or [SQLITE_CONFIG_MUTEX].  The return value of this function shows
** only the default compile-time setting, not any run-time changes
** to that setting.
**
** See the [threading mode] documentation for additional information.
**
** INVARIANTS:
**
** {H10101} The [sqlite3_threadsafe()] function shall return zero if
**          and only if SQLite was compiled with mutexing code omitted.
**
** {H10102} The value returned by the [sqlite3_threadsafe()] function
**          shall remain the same across calls to [sqlite3_config()].
*/
int sqlite3_threadsafe(void);

/*
** CAPI3REF: Database Connection Handle {H12000} <S40200>
** KEYWORDS: {database connection} {database connections}
**
** Each open SQLite database is represented by a pointer to an instance of
** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
** is its destructor.  There are many other interfaces (such as
** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
** [sqlite3_busy_timeout()] to name but three) that are methods on an
** sqlite3 object.
*/
typedef struct sqlite3 sqlite3;

/*
** CAPI3REF: 64-Bit Integer Types {H10200} <S10110>
** KEYWORDS: sqlite_int64 sqlite_uint64
**
** Because there is no cross-platform way to specify 64-bit integer types
** SQLite includes typedefs for 64-bit signed and unsigned integers.
**
** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
** The sqlite_int64 and sqlite_uint64 types are supported for backwards
** compatibility only.
**
** INVARIANTS:
**
** {H10201} The [sqlite_int64] and [sqlite3_int64] type shall specify
**          a 64-bit signed integer.
**
** {H10202} The [sqlite_uint64] and [sqlite3_uint64] type shall specify
**          a 64-bit unsigned integer.
*/
#ifdef SQLITE_INT64_TYPE
  typedef SQLITE_INT64_TYPE sqlite_int64;
  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
#elif defined(_MSC_VER) || defined(__BORLANDC__)
  typedef __int64 sqlite_int64;
  typedef unsigned __int64 sqlite_uint64;
#else
  typedef long long int sqlite_int64;
  typedef unsigned long long int sqlite_uint64;
#endif
typedef sqlite_int64 sqlite3_int64;
typedef sqlite_uint64 sqlite3_uint64;

/*
** If compiling for a processor that lacks floating point support,
** substitute integer for floating-point.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# define double sqlite3_int64
#endif

/*
** CAPI3REF: Closing A Database Connection {H12010} <S30100><S40200>
**
** This routine is the destructor for the [sqlite3] object.
**
** Applications should [sqlite3_finalize | finalize] all [prepared statements]
** and [sqlite3_blob_close | close] all [BLOB handles] associated with
** the [sqlite3] object prior to attempting to close the object.
** The [sqlite3_next_stmt()] interface can be used to locate all
** [prepared statements] associated with a [database connection] if desired.
** Typical code might look like this:
**
** <blockquote><pre>
** sqlite3_stmt *pStmt;
** while( (pStmt = sqlite3_next_stmt(db, 0))!=0 ){
** &nbsp;   sqlite3_finalize(pStmt);
** }
** </pre></blockquote>
**
** If [sqlite3_close()] is invoked while a transaction is open,
** the transaction is automatically rolled back.
**
** INVARIANTS:
**
** {H12011} A successful call to [sqlite3_close(C)] shall destroy the
**          [database connection] object C.
**
** {H12012} A successful call to [sqlite3_close(C)] shall return SQLITE_OK.
**
** {H12013} A successful call to [sqlite3_close(C)] shall release all
**          memory and system resources associated with [database connection]
**          C.
**
** {H12014} A call to [sqlite3_close(C)] on a [database connection] C that
**          has one or more open [prepared statements] shall fail with
**          an [SQLITE_BUSY] error code.
**
** {H12015} A call to [sqlite3_close(C)] where C is a NULL pointer shall
**          be a harmless no-op returning SQLITE_OK.
**
** {H12019} When [sqlite3_close(C)] is invoked on a [database connection] C
**          that has a pending transaction, the transaction shall be
**          rolled back.
**
** ASSUMPTIONS:
**
** {A12016} The C parameter to [sqlite3_close(C)] must be either a NULL
**          pointer or an [sqlite3] object pointer obtained
**          from [sqlite3_open()], [sqlite3_open16()], or
**          [sqlite3_open_v2()], and not previously closed.
*/
int sqlite3_close(sqlite3 *);

/*
** The type for a callback function.
** This is legacy and deprecated.  It is included for historical
** compatibility and is not documented.
*/
typedef int (*sqlite3_callback)(void*,int,char**, char**);

/*
** CAPI3REF: One-Step Query Execution Interface {H12100} <S10000>
**
** The sqlite3_exec() interface is a convenient way of running one or more
** SQL statements without having to write a lot of C code.  The UTF-8 encoded
** SQL statements are passed in as the second parameter to sqlite3_exec().
** The statements are evaluated one by one until either an error or
** an interrupt is encountered, or until they are all done.  The 3rd parameter
** is an optional callback that is invoked once for each row of any query
** results produced by the SQL statements.  The 5th parameter tells where
** to write any error messages.
**
** The error message passed back through the 5th parameter is held
** in memory obtained from [sqlite3_malloc()].  To avoid a memory leak,
** the calling application should call [sqlite3_free()] on any error
** message returned through the 5th parameter when it has finished using
** the error message.
**
** If the SQL statement in the 2nd parameter is NULL or an empty string
** or a string containing only whitespace and comments, then no SQL
** statements are evaluated and the database is not changed.
**
** The sqlite3_exec() interface is implemented in terms of
** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()].
** The sqlite3_exec() routine does nothing to the database that cannot be done
** by [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()].
**
** INVARIANTS:
**
** {H12101} A successful invocation of [sqlite3_exec(D,S,C,A,E)]
**          shall sequentially evaluate all of the UTF-8 encoded,
**          semicolon-separated SQL statements in the zero-terminated
**          string S within the context of the [database connection] D.
**
** {H12102} If the S parameter to [sqlite3_exec(D,S,C,A,E)] is NULL then
**          the actions of the interface shall be the same as if the
**          S parameter were an empty string.
**
** {H12104} The return value of [sqlite3_exec()] shall be [SQLITE_OK] if all
**          SQL statements run successfully and to completion.
**
** {H12105} The return value of [sqlite3_exec()] shall be an appropriate
**          non-zero [error code] if any SQL statement fails.
**
** {H12107} If one or more of the SQL statements handed to [sqlite3_exec()]
**          return results and the 3rd parameter is not NULL, then
**          the callback function specified by the 3rd parameter shall be
**          invoked once for each row of result.
**
** {H12110} If the callback returns a non-zero value then [sqlite3_exec()]
**          shall abort the SQL statement it is currently evaluating,
**          skip all subsequent SQL statements, and return [SQLITE_ABORT].
**
** {H12113} The [sqlite3_exec()] routine shall pass its 4th parameter through
**          as the 1st parameter of the callback.
**
** {H12116} The [sqlite3_exec()] routine shall set the 2nd parameter of its
**          callback to be the number of columns in the current row of
**          result.
**
** {H12119} The [sqlite3_exec()] routine shall set the 3rd parameter of its
**          callback to be an array of pointers to strings holding the
**          values for each column in the current result set row as
**          obtained from [sqlite3_column_text()].
**
** {H12122} The [sqlite3_exec()] routine shall set the 4th parameter of its
**          callback to be an array of pointers to strings holding the
**          names of result columns as obtained from [sqlite3_column_name()].
**
** {H12125} If the 3rd parameter to [sqlite3_exec()] is NULL then
**          [sqlite3_exec()] shall silently discard query results.
**
** {H12131} If an error occurs while parsing or evaluating any of the SQL
**          statements in the S parameter of [sqlite3_exec(D,S,C,A,E)] and if
**          the E parameter is not NULL, then [sqlite3_exec()] shall store
**          in *E an appropriate error message written into memory obtained
**          from [sqlite3_malloc()].
**
** {H12134} The [sqlite3_exec(D,S,C,A,E)] routine shall set the value of
**          *E to NULL if E is not NULL and there are no errors.
**
** {H12137} The [sqlite3_exec(D,S,C,A,E)] function shall set the [error code]
**          and message accessible via [sqlite3_errcode()], 
**          [sqlite3_extended_errcode()],
**          [sqlite3_errmsg()], and [sqlite3_errmsg16()].
**
** {H12138} If the S parameter to [sqlite3_exec(D,S,C,A,E)] is NULL or an
**          empty string or contains nothing other than whitespace, comments,
**          and/or semicolons, then results of [sqlite3_errcode()],
**          [sqlite3_extended_errcode()],
**          [sqlite3_errmsg()], and [sqlite3_errmsg16()]
**          shall reset to indicate no errors.
**
** ASSUMPTIONS:
**
** {A12141} The first parameter to [sqlite3_exec()] must be an valid and open
**          [database connection].
**
** {A12142} The database connection must not be closed while
**          [sqlite3_exec()] is running.
**
** {A12143} The calling function should use [sqlite3_free()] to free
**          the memory that *errmsg is left pointing at once the error
**          message is no longer needed.
**
** {A12145} The SQL statement text in the 2nd parameter to [sqlite3_exec()]
**          must remain unchanged while [sqlite3_exec()] is running.
*/
int sqlite3_exec(
  sqlite3*,                                  /* An open database */
  const char *sql,                           /* SQL to be evaluated */
  int (*callback)(void*,int,char**,char**),  /* Callback function */
  void *,                                    /* 1st argument to callback */
  char **errmsg                              /* Error msg written here */
);

/*
** CAPI3REF: Result Codes {H10210} <S10700>
** KEYWORDS: SQLITE_OK {error code} {error codes}
** KEYWORDS: {result code} {result codes}
**
** Many SQLite functions return an integer result code from the set shown
** here in order to indicates success or failure.
**
** New error codes may be added in future versions of SQLite.
**
** See also: [SQLITE_IOERR_READ | extended result codes]
*/
#define SQLITE_OK           0   /* Successful result */
/* beginning-of-error-codes */
#define SQLITE_ERROR        1   /* SQL error or missing database */
#define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
#define SQLITE_PERM         3   /* Access permission denied */
#define SQLITE_ABORT        4   /* Callback routine requested an abort */
#define SQLITE_BUSY         5   /* The database file is locked */
#define SQLITE_LOCKED       6   /* A table in the database is locked */
#define SQLITE_NOMEM        7   /* A malloc() failed */
#define SQLITE_READONLY     8   /* Attempt to write a readonly database */
#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
#define SQLITE_NOTFOUND    12   /* NOT USED. Table or record not found */
#define SQLITE_FULL        13   /* Insertion failed because database is full */
#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
#define SQLITE_PROTOCOL    15   /* NOT USED. Database lock protocol error */
#define SQLITE_EMPTY       16   /* Database is empty */
#define SQLITE_SCHEMA      17   /* The database schema changed */
#define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
#define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
#define SQLITE_MISMATCH    20   /* Data type mismatch */
#define SQLITE_MISUSE      21   /* Library used incorrectly */
#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
#define SQLITE_AUTH        23   /* Authorization denied */
#define SQLITE_FORMAT      24   /* Auxiliary database format error */
#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
#define SQLITE_NOTADB      26   /* File opened that is not a database file */
#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
/* end-of-error-codes */

/*
** CAPI3REF: Extended Result Codes {H10220} <S10700>
** KEYWORDS: {extended error code} {extended error codes}
** KEYWORDS: {extended result code} {extended result codes}
**
** In its default configuration, SQLite API routines return one of 26 integer
** [SQLITE_OK | result codes].  However, experience has shown that many of
** these result codes are too coarse-grained.  They do not provide as
** much information about problems as programmers might like.  In an effort to
** address this, newer versions of SQLite (version 3.3.8 and later) include
** support for additional result codes that provide more detailed information
** about errors. The extended result codes are enabled or disabled
** on a per database connection basis using the
** [sqlite3_extended_result_codes()] API.
**
** Some of the available extended result codes are listed here.
** One may expect the number of extended result codes will be expand
** over time.  Software that uses extended result codes should expect
** to see new result codes in future releases of SQLite.
**
** The SQLITE_OK result code will never be extended.  It will always
** be exactly zero.
**
** INVARIANTS:
**
** {H10223} The symbolic name for an extended result code shall contains
**          a related primary result code as a prefix.
**
** {H10224} Primary result code names shall contain a single "_" character.
**
** {H10225} Extended result code names shall contain two or more "_" characters.
**
** {H10226} The numeric value of an extended result code shall contain the
**          numeric value of its corresponding primary result code in
**          its least significant 8 bits.
*/
#define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
#define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
#define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
#define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
#define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
#define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
#define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
#define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
#define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
#define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))

/*
** CAPI3REF: Flags For File Open Operations {H10230} <H11120> <H12700>
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the xOpen method of the
** [sqlite3_vfs] object.
*/
#define SQLITE_OPEN_READONLY         0x00000001
#define SQLITE_OPEN_READWRITE        0x00000002
#define SQLITE_OPEN_CREATE           0x00000004
#define SQLITE_OPEN_DELETEONCLOSE    0x00000008
#define SQLITE_OPEN_EXCLUSIVE        0x00000010
#define SQLITE_OPEN_MAIN_DB          0x00000100
#define SQLITE_OPEN_TEMP_DB          0x00000200
#define SQLITE_OPEN_TRANSIENT_DB     0x00000400
#define SQLITE_OPEN_MAIN_JOURNAL     0x00000800
#define SQLITE_OPEN_TEMP_JOURNAL     0x00001000
#define SQLITE_OPEN_SUBJOURNAL       0x00002000
#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000
#define SQLITE_OPEN_NOMUTEX          0x00008000
#define SQLITE_OPEN_FULLMUTEX        0x00010000

/*
** CAPI3REF: Device Characteristics {H10240} <H11120>
**
** The xDeviceCapabilities method of the [sqlite3_io_methods]
** object returns an integer which is a vector of the these
** bit values expressing I/O characteristics of the mass storage
** device that holds the file that the [sqlite3_io_methods]
** refers to.
**
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite().
*/
#define SQLITE_IOCAP_ATOMIC          0x00000001
#define SQLITE_IOCAP_ATOMIC512       0x00000002
#define SQLITE_IOCAP_ATOMIC1K        0x00000004
#define SQLITE_IOCAP_ATOMIC2K        0x00000008
#define SQLITE_IOCAP_ATOMIC4K        0x00000010
#define SQLITE_IOCAP_ATOMIC8K        0x00000020
#define SQLITE_IOCAP_ATOMIC16K       0x00000040
#define SQLITE_IOCAP_ATOMIC32K       0x00000080
#define SQLITE_IOCAP_ATOMIC64K       0x00000100
#define SQLITE_IOCAP_SAFE_APPEND     0x00000200
#define SQLITE_IOCAP_SEQUENTIAL      0x00000400

/*
** CAPI3REF: File Locking Levels {H10250} <H11120> <H11310>
**
** SQLite uses one of these integer values as the second
** argument to calls it makes to the xLock() and xUnlock() methods
** of an [sqlite3_io_methods] object.
*/
#define SQLITE_LOCK_NONE          0
#define SQLITE_LOCK_SHARED        1
#define SQLITE_LOCK_RESERVED      2
#define SQLITE_LOCK_PENDING       3
#define SQLITE_LOCK_EXCLUSIVE     4

/*
** CAPI3REF: Synchronization Type Flags {H10260} <H11120>
**
** When SQLite invokes the xSync() method of an
** [sqlite3_io_methods] object it uses a combination of
** these integer values as the second argument.
**
** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
** sync operation only needs to flush data to mass storage.  Inode
** information need not be flushed. The SQLITE_SYNC_NORMAL flag means
** to use normal fsync() semantics. The SQLITE_SYNC_FULL flag means
** to use Mac OS X style fullsync instead of fsync().
*/
#define SQLITE_SYNC_NORMAL        0x00002
#define SQLITE_SYNC_FULL          0x00003
#define SQLITE_SYNC_DATAONLY      0x00010

/*
** CAPI3REF: OS Interface Open File Handle {H11110} <S20110>
**
** An [sqlite3_file] object represents an open file in the OS
** interface layer.  Individual OS interface implementations will
** want to subclass this object by appending additional fields
** for their own use.  The pMethods entry is a pointer to an
** [sqlite3_io_methods] object that defines methods for performing
** I/O operations on the open file.
*/
typedef struct sqlite3_file sqlite3_file;
struct sqlite3_file {
  const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
};

/*
** CAPI3REF: OS Interface File Virtual Methods Object {H11120} <S20110>
**
** Every file opened by the [sqlite3_vfs] xOpen method populates an
** [sqlite3_file] object (or, more commonly, a subclass of the
** [sqlite3_file] object) with a pointer to an instance of this object.
** This object defines the methods used to perform various operations
** against the open file represented by the [sqlite3_file] object.
**
** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
** flag may be ORed in to indicate that only the data of the file
** and not its inode needs to be synced.
**
** The integer values to xLock() and xUnlock() are one of
** <ul>
** <li> [SQLITE_LOCK_NONE],
** <li> [SQLITE_LOCK_SHARED],
** <li> [SQLITE_LOCK_RESERVED],
** <li> [SQLITE_LOCK_PENDING], or
** <li> [SQLITE_LOCK_EXCLUSIVE].
** </ul>
** xLock() increases the lock. xUnlock() decreases the lock.
** The xCheckReservedLock() method checks whether any database connection,
** either in this process or in some other process, is holding a RESERVED,
** PENDING, or EXCLUSIVE lock on the file.  It returns true
** if such a lock exists and false otherwise.
**
** The xFileControl() method is a generic interface that allows custom
** VFS implementations to directly control an open file using the
** [sqlite3_file_control()] interface.  The second "op" argument is an
** integer opcode.  The third argument is a generic pointer intended to
** point to a structure that may contain arguments or space in which to
** write return values.  Potential uses for xFileControl() might be
** functions to enable blocking locks with timeouts, to change the
** locking strategy (for example to use dot-file locks), to inquire
** about the status of a lock, or to break stale locks.  The SQLite
** core reserves all opcodes less than 100 for its own use.
** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
** Applications that define a custom xFileControl method should use opcodes
** greater than 100 to avoid conflicts.
**
** The xSectorSize() method returns the sector size of the
** device that underlies the file.  The sector size is the
** minimum write that can be performed without disturbing
** other bytes in the file.  The xDeviceCharacteristics()
** method returns a bit vector describing behaviors of the
** underlying device:
**
** <ul>
** <li> [SQLITE_IOCAP_ATOMIC]
** <li> [SQLITE_IOCAP_ATOMIC512]
** <li> [SQLITE_IOCAP_ATOMIC1K]
** <li> [SQLITE_IOCAP_ATOMIC2K]
** <li> [SQLITE_IOCAP_ATOMIC4K]
** <li> [SQLITE_IOCAP_ATOMIC8K]
** <li> [SQLITE_IOCAP_ATOMIC16K]
** <li> [SQLITE_IOCAP_ATOMIC32K]
** <li> [SQLITE_IOCAP_ATOMIC64K]
** <li> [SQLITE_IOCAP_SAFE_APPEND]
** <li> [SQLITE_IOCAP_SEQUENTIAL]
** </ul>
**
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite().
**
** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
** in the unread portions of the buffer with zeros.  A VFS that
** fails to zero-fill short reads might seem to work.  However,
** failure to zero-fill short reads will eventually lead to
** database corruption.
*/
typedef struct sqlite3_io_methods sqlite3_io_methods;
struct sqlite3_io_methods {
  int iVersion;
  int (*xClose)(sqlite3_file*);
  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
  int (*xSync)(sqlite3_file*, int flags);
  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
  int (*xLock)(sqlite3_file*, int);
  int (*xUnlock)(sqlite3_file*, int);
  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
  int (*xSectorSize)(sqlite3_file*);
  int (*xDeviceCharacteristics)(sqlite3_file*);
  /* Additional methods may be added in future releases */
};

/*
** CAPI3REF: Standard File Control Opcodes {H11310} <S30800>
**
** These integer constants are opcodes for the xFileControl method
** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
** interface.
**
** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
** opcode causes the xFileControl method to write the current state of
** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
** into an integer that the pArg argument points to. This capability
** is used during testing and only needs to be supported when SQLITE_TEST
** is defined.
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4

/*
** CAPI3REF: Mutex Handle {H17110} <S20130>
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
** deals with pointers to the [sqlite3_mutex] object.
**
** Mutexes are created using [sqlite3_mutex_alloc()].
*/
typedef struct sqlite3_mutex sqlite3_mutex;

/*
** CAPI3REF: OS Interface Object {H11140} <S20100>
**
** An instance of the sqlite3_vfs object defines the interface between
** the SQLite core and the underlying operating system.  The "vfs"
** in the name of the object stands for "virtual file system".
**
** The value of the iVersion field is initially 1 but may be larger in
** future versions of SQLite.  Additional fields may be appended to this
** object when the iVersion value is increased.  Note that the structure
** of the sqlite3_vfs object changes in the transaction between
** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
** modified.
**
** The szOsFile field is the size of the subclassed [sqlite3_file]
** structure used by this VFS.  mxPathname is the maximum length of
** a pathname in this VFS.
**
** Registered sqlite3_vfs objects are kept on a linked list formed by
** the pNext pointer.  The [sqlite3_vfs_register()]
** and [sqlite3_vfs_unregister()] interfaces manage this list
** in a thread-safe way.  The [sqlite3_vfs_find()] interface
** searches the list.  Neither the application code nor the VFS
** implementation should use the pNext pointer.
**
** The pNext field is the only field in the sqlite3_vfs
** structure that SQLite will ever modify.  SQLite will only access
** or modify this field while holding a particular static mutex.
** The application should never modify anything within the sqlite3_vfs
** object once the object has been registered.
**
** The zName field holds the name of the VFS module.  The name must
** be unique across all VFS modules.
**
** SQLite will guarantee that the zFilename parameter to xOpen
** is either a NULL pointer or string obtained
** from xFullPathname().  SQLite further guarantees that
** the string will be valid and unchanged until xClose() is
** called. Because of the previous sentense,
** the [sqlite3_file] can safely store a pointer to the
** filename if it needs to remember the filename for some reason.
** If the zFilename parameter is xOpen is a NULL pointer then xOpen
** must invite its own temporary name for the file.  Whenever the 
** xFilename parameter is NULL it will also be the case that the
** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
**
** The flags argument to xOpen() includes all bits set in
** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
** or [sqlite3_open16()] is used, then flags includes at least
** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
** If xOpen() opens a file read-only then it sets *pOutFlags to
** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
**
** SQLite will also add one of the following flags to the xOpen()
** call, depending on the object being opened:
**
** <ul>
** <li>  [SQLITE_OPEN_MAIN_DB]
** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
** <li>  [SQLITE_OPEN_TEMP_DB]
** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
** <li>  [SQLITE_OPEN_TRANSIENT_DB]
** <li>  [SQLITE_OPEN_SUBJOURNAL]
** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
** </ul>
**
** The file I/O implementation can use the object type flags to
** change the way it deals with files.  For example, an application
** that does not care about crash recovery or rollback might make
** the open of a journal file a no-op.  Writes to this journal would
** also be no-ops, and any attempt to read the journal would return
** SQLITE_IOERR.  Or the implementation might recognize that a database
** file will be doing page-aligned sector reads and writes in a random
** order and set up its I/O subsystem accordingly.
**
** SQLite might also add one of the following flags to the xOpen method:
**
** <ul>
** <li> [SQLITE_OPEN_DELETEONCLOSE]
** <li> [SQLITE_OPEN_EXCLUSIVE]
** </ul>
**
** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
** deleted when it is closed.  The [SQLITE_OPEN_DELETEONCLOSE]
** will be set for TEMP  databases, journals and for subjournals.
**
** The [SQLITE_OPEN_EXCLUSIVE] flag means the file should be opened
** for exclusive access.  This flag is set for all files except
** for the main database file.
**
** At least szOsFile bytes of memory are allocated by SQLite
** to hold the  [sqlite3_file] structure passed as the third
** argument to xOpen.  The xOpen method does not have to
** allocate the structure; it should just fill it in.
**
** The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
** to test whether a file is at least readable.   The file can be a
** directory.
**
** SQLite will always allocate at least mxPathname+1 bytes for the
** output buffer xFullPathname.  The exact size of the output buffer
** is also passed as a parameter to both  methods. If the output buffer
** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
** handled as a fatal error by SQLite, vfs implementations should endeavor
** to prevent this by setting mxPathname to a sufficiently large value.
**
** The xRandomness(), xSleep(), and xCurrentTime() interfaces
** are not strictly a part of the filesystem, but they are
** included in the VFS structure for completeness.
** The xRandomness() function attempts to return nBytes bytes
** of good-quality randomness into zOut.  The return value is
** the actual number of bytes of randomness obtained.
** The xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given.  The xCurrentTime()
** method returns a Julian Day Number for the current date and time.
**
*/
typedef struct sqlite3_vfs sqlite3_vfs;
struct sqlite3_vfs {
  int iVersion;            /* Structure version number */
  int szOsFile;            /* Size of subclassed sqlite3_file */
  int mxPathname;          /* Maximum file pathname length */
  sqlite3_vfs *pNext;      /* Next registered VFS */
  const char *zName;       /* Name of this virtual file system */
  void *pAppData;          /* Pointer to application-specific data */
  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  void (*xDlClose)(sqlite3_vfs*, void*);
  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  int (*xSleep)(sqlite3_vfs*, int microseconds);
  int (*xCurrentTime)(sqlite3_vfs*, double*);
  int (*xGetLastError)(sqlite3_vfs*, int, char *);
  /* New fields may be appended in figure versions.  The iVersion
  ** value will increment whenever this happens. */
};

/*
** CAPI3REF: Flags for the xAccess VFS method {H11190} <H11140>
**
** These integer constants can be used as the third parameter to
** the xAccess method of an [sqlite3_vfs] object. {END}  They determine
** what kind of permissions the xAccess method is looking for.
** With SQLITE_ACCESS_EXISTS, the xAccess method
** simply checks whether the file exists.
** With SQLITE_ACCESS_READWRITE, the xAccess method
** checks whether the file is both readable and writable.
** With SQLITE_ACCESS_READ, the xAccess method
** checks whether the file is readable.
*/
#define SQLITE_ACCESS_EXISTS    0
#define SQLITE_ACCESS_READWRITE 1
#define SQLITE_ACCESS_READ      2

/*
** CAPI3REF: Initialize The SQLite Library {H10130} <S20000><S30100>
**
** The sqlite3_initialize() routine initializes the
** SQLite library.  The sqlite3_shutdown() routine
** deallocates any resources that were allocated by sqlite3_initialize().
**
** A call to sqlite3_initialize() is an "effective" call if it is
** the first time sqlite3_initialize() is invoked during the lifetime of
** the process, or if it is the first time sqlite3_initialize() is invoked
** following a call to sqlite3_shutdown().  Only an effective call
** of sqlite3_initialize() does any initialization.  All other calls
** are harmless no-ops.
**
** Among other things, sqlite3_initialize() shall invoke
** sqlite3_os_init().  Similarly, sqlite3_shutdown()
** shall invoke sqlite3_os_end().
**
** The sqlite3_initialize() routine returns [SQLITE_OK] on success.
** If for some reason, sqlite3_initialize() is unable to initialize
** the library (perhaps it is unable to allocate a needed resource such
** as a mutex) it returns an [error code] other than [SQLITE_OK].
**
** The sqlite3_initialize() routine is called internally by many other
** SQLite interfaces so that an application usually does not need to
** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
** calls sqlite3_initialize() so the SQLite library will be automatically
** initialized when [sqlite3_open()] is called if it has not be initialized
** already.  However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
** compile-time option, then the automatic calls to sqlite3_initialize()
** are omitted and the application must call sqlite3_initialize() directly
** prior to using any other SQLite interface.  For maximum portability,
** it is recommended that applications always invoke sqlite3_initialize()
** directly prior to using any other SQLite interface.  Future releases
** of SQLite may require this.  In other words, the behavior exhibited
** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
** default behavior in some future release of SQLite.
**
** The sqlite3_os_init() routine does operating-system specific
** initialization of the SQLite library.  The sqlite3_os_end()
** routine undoes the effect of sqlite3_os_init().  Typical tasks
** performed by these routines include allocation or deallocation
** of static resources, initialization of global variables,
** setting up a default [sqlite3_vfs] module, or setting up
** a default configuration using [sqlite3_config()].
**
** The application should never invoke either sqlite3_os_init()
** or sqlite3_os_end() directly.  The application should only invoke
** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
** interface is called automatically by sqlite3_initialize() and
** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
** implementations for sqlite3_os_init() and sqlite3_os_end()
** are built into SQLite when it is compiled for unix, windows, or os/2.
** When built for other platforms (using the [SQLITE_OS_OTHER=1] compile-time
** option) the application must supply a suitable implementation for
** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
** implementation of sqlite3_os_init() or sqlite3_os_end()
** must return [SQLITE_OK] on success and some other [error code] upon
** failure.
*/
int sqlite3_initialize(void);
int sqlite3_shutdown(void);
int sqlite3_os_init(void);
int sqlite3_os_end(void);

/*
** CAPI3REF: Configuring The SQLite Library {H14100} <S20000><S30200>
** EXPERIMENTAL
**
** The sqlite3_config() interface is used to make global configuration
** changes to SQLite in order to tune SQLite to the specific needs of
** the application.  The default configuration is recommended for most
** applications and so this routine is usually not necessary.  It is
** provided to support rare applications with unusual needs.
**
** The sqlite3_config() interface is not threadsafe.  The application
** must insure that no other SQLite interfaces are invoked by other
** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
** may only be invoked prior to library initialization using
** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
** Note, however, that sqlite3_config() can be called as part of the
** implementation of an application-defined [sqlite3_os_init()].
**
** The first argument to sqlite3_config() is an integer
** [SQLITE_CONFIG_SINGLETHREAD | configuration option] that determines
** what property of SQLite is to be configured.  Subsequent arguments
** vary depending on the [SQLITE_CONFIG_SINGLETHREAD | configuration option]
** in the first argument.
**
** When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
** If the option is unknown or SQLite is unable to set the option
** then this routine returns a non-zero [error code].
**
** INVARIANTS:
**
** {H14103} A successful invocation of [sqlite3_config()] shall return
**          [SQLITE_OK].
**
** {H14106} The [sqlite3_config()] interface shall return [SQLITE_MISUSE]
**          if it is invoked in between calls to [sqlite3_initialize()] and
**          [sqlite3_shutdown()].
**
** {H14120} A successful call to [sqlite3_config]([SQLITE_CONFIG_SINGLETHREAD])
**          shall set the default [threading mode] to Single-thread.
**
** {H14123} A successful call to [sqlite3_config]([SQLITE_CONFIG_MULTITHREAD])
**          shall set the default [threading mode] to Multi-thread.
**
** {H14126} A successful call to [sqlite3_config]([SQLITE_CONFIG_SERIALIZED])
**          shall set the default [threading mode] to Serialized.
**
** {H14129} A successful call to [sqlite3_config]([SQLITE_CONFIG_MUTEX],X)
**          where X is a pointer to an initialized [sqlite3_mutex_methods]
**          object shall cause all subsequent mutex operations performed
**          by SQLite to use the mutex methods that were present in X
**          during the call to [sqlite3_config()].
**
** {H14132} A successful call to [sqlite3_config]([SQLITE_CONFIG_GETMUTEX],X)
**          where X is a pointer to an [sqlite3_mutex_methods] object 
**          shall overwrite the content of [sqlite3_mutex_methods] object
**          with the mutex methods currently in use by SQLite.
**
** {H14135} A successful call to [sqlite3_config]([SQLITE_CONFIG_MALLOC],M)
**          where M is a pointer to an initialized [sqlite3_mem_methods]
**          object shall cause all subsequent memory allocation operations
**          performed by SQLite to use the methods that were present in 
**          M during the call to [sqlite3_config()].
**
** {H14138} A successful call to [sqlite3_config]([SQLITE_CONFIG_GETMALLOC],M)
**          where M is a pointer to an [sqlite3_mem_methods] object shall
**          overwrite the content of [sqlite3_mem_methods] object with 
**          the memory allocation methods currently in use by
**          SQLite.
**
** {H14141} A successful call to [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],1)
**          shall enable the memory allocation status collection logic.
**
** {H14144} A successful call to [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],0)
**          shall disable the memory allocation status collection logic.
**
** {H14147} The memory allocation status collection logic shall be
**          enabled by default.
**
** {H14150} A successful call to [sqlite3_config]([SQLITE_CONFIG_SCRATCH],S,Z,N)
**          where Z and N are non-negative integers and 
**          S is a pointer to an aligned memory buffer not less than
**          Z*N bytes in size shall cause S to be used by the
**          [scratch memory allocator] for as many as N simulataneous
**          allocations each of size (Z & ~7).
**
** {H14153} A successful call to [sqlite3_config]([SQLITE_CONFIG_SCRATCH],S,Z,N)
**          where S is a NULL pointer shall disable the
**          [scratch memory allocator].
**
** {H14156} A successful call to
**          [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],S,Z,N)
**          where Z and N are non-negative integers and 
**          S is a pointer to an aligned memory buffer not less than
**          Z*N bytes in size shall cause S to be used by the
**          [pagecache memory allocator] for as many as N simulataneous
**          allocations each of size (Z & ~7).
**
** {H14159} A successful call to
**          [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],S,Z,N)
**          where S is a NULL pointer shall disable the
**          [pagecache memory allocator].
**
** {H14162} A successful call to [sqlite3_config]([SQLITE_CONFIG_HEAP],H,Z,N)
**          where Z and N are non-negative integers and 
**          H is a pointer to an aligned memory buffer not less than
**          Z bytes in size shall enable the [memsys5] memory allocator
**          and cause it to use buffer S as its memory source and to use
**          a minimum allocation size of N.
**
** {H14165} A successful call to [sqlite3_config]([SQLITE_CONFIG_HEAP],H,Z,N)
**          where H is a NULL pointer shall disable the
**          [memsys5] memory allocator.
**
** {H14168} A successful call to [sqlite3_config]([SQLITE_CONFIG_LOOKASIDE],Z,N)
**          shall cause the default [lookaside memory allocator] configuration
**          for new [database connections] to be N slots of Z bytes each.
*/
SQLITE_EXPERIMENTAL int sqlite3_config(int, ...);

/*
** CAPI3REF: Configure database connections  {H14200} <S20000>
** EXPERIMENTAL
**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).  The
** sqlite3_db_config() interface can only be used immediately after
** the database connection is created using [sqlite3_open()],
** [sqlite3_open16()], or [sqlite3_open_v2()].  
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** configuration verb - an integer code that indicates what
** aspect of the [database connection] is being configured.
** The only choice for this value is [SQLITE_DBCONFIG_LOOKASIDE].
** New verbs are likely to be added in future releases of SQLite.
** Additional arguments depend on the verb.
**
** INVARIANTS:
**
** {H14203} A call to [sqlite3_db_config(D,V,...)] shall return [SQLITE_OK]
**          if and only if the call is successful.
**
** {H14206} If one or more slots of the [lookaside memory allocator] for
**          [database connection] D are in use, then a call to
**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],...) shall
**          fail with an [SQLITE_BUSY] return code.
**
** {H14209} A successful call to 
**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],B,Z,N) where
**          D is an open [database connection] and Z and N are positive
**          integers and B is an aligned buffer at least Z*N bytes in size
**          shall cause the [lookaside memory allocator] for D to use buffer B 
**          with N slots of Z bytes each.
**
** {H14212} A successful call to 
**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],B,Z,N) where
**          D is an open [database connection] and Z and N are positive
**          integers and B is NULL pointer shall cause the
**          [lookaside memory allocator] for D to a obtain Z*N byte buffer
**          from the primary memory allocator and use that buffer
**          with N lookaside slots of Z bytes each.
**
** {H14215} A successful call to 
**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],B,Z,N) where
**          D is an open [database connection] and Z and N are zero shall
**          disable the [lookaside memory allocator] for D.
**
**
*/
SQLITE_EXPERIMENTAL int sqlite3_db_config(sqlite3*, int op, ...);

/*
** CAPI3REF: Memory Allocation Routines {H10155} <S20120>
** EXPERIMENTAL
**
** An instance of this object defines the interface between SQLite
** and low-level memory allocation routines.
**
** This object is used in only one place in the SQLite interface.
** A pointer to an instance of this object is the argument to
** [sqlite3_config()] when the configuration option is
** [SQLITE_CONFIG_MALLOC].  By creating an instance of this object
** and passing it to [sqlite3_config()] during configuration, an
** application can specify an alternative memory allocation subsystem
** for SQLite to use for all of its dynamic memory needs.
**
** Note that SQLite comes with a built-in memory allocator that is
** perfectly adequate for the overwhelming majority of applications
** and that this object is only useful to a tiny minority of applications
** with specialized memory allocation requirements.  This object is
** also used during testing of SQLite in order to specify an alternative
** memory allocator that simulates memory out-of-memory conditions in
** order to verify that SQLite recovers gracefully from such
** conditions.
**
** The xMalloc, xFree, and xRealloc methods must work like the
** malloc(), free(), and realloc() functions from the standard library.
**
** xSize should return the allocated size of a memory allocation
** previously obtained from xMalloc or xRealloc.  The allocated size
** is always at least as big as the requested size but may be larger.
**
** The xRoundup method returns what would be the allocated size of
** a memory allocation given a particular requested size.  Most memory
** allocators round up memory allocations at least to the next multiple
** of 8.  Some allocators round up to a larger multiple or to a power of 2.
**
** The xInit method initializes the memory allocator.  (For example,
** it might allocate any require mutexes or initialize internal data
** structures.  The xShutdown method is invoked (indirectly) by
** [sqlite3_shutdown()] and should deallocate any resources acquired
** by xInit.  The pAppData pointer is used as the only parameter to
** xInit and xShutdown.
*/
typedef struct sqlite3_mem_methods sqlite3_mem_methods;
struct sqlite3_mem_methods {
  void *(*xMalloc)(int);         /* Memory allocation function */
  void (*xFree)(void*);          /* Free a prior allocation */
  void *(*xRealloc)(void*,int);  /* Resize an allocation */
  int (*xSize)(void*);           /* Return the size of an allocation */
  int (*xRoundup)(int);          /* Round up request size to allocation size */
  int (*xInit)(void*);           /* Initialize the memory allocator */
  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  void *pAppData;                /* Argument to xInit() and xShutdown() */
};

/*
** CAPI3REF: Configuration Options {H10160} <S20000>
** EXPERIMENTAL
**
** These constants are the available integer configuration options that
** can be passed as the first argument to the [sqlite3_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_config()] to make sure that
** the call worked.  The [sqlite3_config()] interface will return a
** non-zero [error code] if a discontinued or unsupported configuration option
** is invoked.
**
** <dl>
** <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
** <dd>There are no arguments to this option.  This option disables
** all mutexing and puts SQLite into a mode where it can only be used
** by a single thread.</dd>
**
** <dt>SQLITE_CONFIG_MULTITHREAD</dt>
** <dd>There are no arguments to this option.  This option disables
** mutexing on [database connection] and [prepared statement] objects.
** The application is responsible for serializing access to
** [database connections] and [prepared statements].  But other mutexes
** are enabled so that SQLite will be safe to use in a multi-threaded
** environment as long as no two threads attempt to use the same
** [database connection] at the same time.  See the [threading mode]
** documentation for additional information.</dd>
**
** <dt>SQLITE_CONFIG_SERIALIZED</dt>
** <dd>There are no arguments to this option.  This option enables
** all mutexes including the recursive
** mutexes on [database connection] and [prepared statement] objects.
** In this mode (which is the default when SQLite is compiled with
** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
** to [database connections] and [prepared statements] so that the
** application is free to use the same [database connection] or the
** same [prepared statement] in different threads at the same time.
** See the [threading mode] documentation for additional information.</dd>
**
** <dt>SQLITE_CONFIG_MALLOC</dt>
** <dd>This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mem_methods] structure.  The argument specifies
** alternative low-level memory allocation routines to be used in place of
** the memory allocation routines built into SQLite.</dd>
**
** <dt>SQLITE_CONFIG_GETMALLOC</dt>
** <dd>This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mem_methods] structure.  The [sqlite3_mem_methods]
** structure is filled with the currently defined memory allocation routines.
** This option can be used to overload the default memory allocation
** routines with a wrapper that simulations memory allocation failure or
** tracks memory usage, for example.</dd>
**
** <dt>SQLITE_CONFIG_MEMSTATUS</dt>
** <dd>This option takes single argument of type int, interpreted as a 
** boolean, which enables or disables the collection of memory allocation 
** statistics. When disabled, the following SQLite interfaces become 
** non-operational:
**   <ul>
**   <li> [sqlite3_memory_used()]
**   <li> [sqlite3_memory_highwater()]
**   <li> [sqlite3_soft_heap_limit()]
**   <li> [sqlite3_status()]
**   </ul>
** </dd>
**
** <dt>SQLITE_CONFIG_SCRATCH</dt>
** <dd>This option specifies a static memory buffer that SQLite can use for
** scratch memory.  There are three arguments:  A pointer to the memory, the
** size of each scratch buffer (sz), and the number of buffers (N).  The sz
** argument must be a multiple of 16. The sz parameter should be a few bytes
** larger than the actual scratch space required due internal overhead.
** The first
** argument should point to an allocation of at least sz*N bytes of memory.
** SQLite will use no more than one scratch buffer at once per thread, so
** N should be set to the expected maximum number of threads.  The sz
** parameter should be 6 times the size of the largest database page size.
** Scratch buffers are used as part of the btree balance operation.  If
** The btree balancer needs additional memory beyond what is provided by
** scratch buffers or if no scratch buffer space is specified, then SQLite
** goes to [sqlite3_malloc()] to obtain the memory it needs.</dd>
**
** <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd>This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implemenation.  
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
** There are three arguments to this option: A pointer to the
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument must be a power of two between 512 and 32768.  The first
** argument should point to an allocation of at least sz*N bytes of memory.
** SQLite will use the memory provided by the first argument to satisfy its
** memory needs for the first N pages that it adds to cache.  If additional
** page cache memory is needed beyond what is provided by this option, then
** SQLite goes to [sqlite3_malloc()] for the additional storage space.
** The implementation might use one or more of the N buffers to hold 
** memory accounting information. </dd>
**
** <dt>SQLITE_CONFIG_HEAP</dt>
** <dd>This option specifies a static memory buffer that SQLite will use
** for all of its dynamic memory allocation needs beyond those provided
** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
** There are three arguments: A pointer to the memory, the number of
** bytes in the memory buffer, and the minimum allocation size.  If
** the first pointer (the memory pointer) is NULL, then SQLite reverts
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.</dd>
**
** <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd>This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.</dd>
**
** <dt>SQLITE_CONFIG_GETMUTEX</dt>
** <dd>This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The
** [sqlite3_mutex_methods]
** structure is filled with the currently defined mutex routines.
** This option can be used to overload the default mutex allocation
** routines with a wrapper used to track mutex usage for performance
** profiling or testing, for example.</dd>
**
** <dt>SQLITE_CONFIG_LOOKASIDE</dt>
** <dd>This option takes two arguments that determine the default
** memory allcation lookaside optimization.  The first argument is the
** size of each lookaside buffer slot and the second is the number of
** slots allocated to each database connection.</dd>
**
** <dt>SQLITE_CONFIG_PCACHE</dt>
** <dd>This option takes a single argument which is a pointer to
** an [sqlite3_pcache_methods] object.  This object specifies the interface
** to a custom page cache implementation.  SQLite makes a copy of the
** object and uses it for page cache memory allocations.</dd>
**
** <dt>SQLITE_CONFIG_GETPCACHE</dt>
** <dd>This option takes a single argument which is a pointer to an
** [sqlite3_pcache_methods] object.  SQLite copies of the current
** page cache implementation into that object.</dd>
**
** </dl>
*/
#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
#define SQLITE_CONFIG_PCACHE       14  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_GETPCACHE    15  /* sqlite3_pcache_methods* */

/*
** CAPI3REF: Configuration Options {H10170} <S20000>
** EXPERIMENTAL
**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_db_config()] to make sure that
** the call worked.  The [sqlite3_db_config()] interface will return a
** non-zero [error code] if a discontinued or unsupported configuration option
** is invoked.
**
** <dl>
** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
** <dd>This option takes three additional arguments that determine the 
** [lookaside memory allocator] configuration for the [database connection].
** The first argument (the third parameter to [sqlite3_db_config()] is a
** pointer to a memory buffer to use for lookaside memory.  The first
** argument may be NULL in which case SQLite will allocate the lookaside
** buffer itself using [sqlite3_malloc()].  The second argument is the
** size of each lookaside buffer slot and the third argument is the number of
** slots.  The size of the buffer in the first argument must be greater than
** or equal to the product of the second and third arguments.</dd>
**
** </dl>
*/
#define SQLITE_DBCONFIG_LOOKASIDE    1001  /* void* int int */


/*
** CAPI3REF: Enable Or Disable Extended Result Codes {H12200} <S10700>
**
** The sqlite3_extended_result_codes() routine enables or disables the
** [extended result codes] feature of SQLite. The extended result
** codes are disabled by default for historical compatibility considerations.
**
** INVARIANTS:
**
** {H12201} Each new [database connection] shall have the
**          [extended result codes] feature disabled by default.
**
** {H12202} The [sqlite3_extended_result_codes(D,F)] interface shall enable
**          [extended result codes] for the  [database connection] D
**          if the F parameter is true, or disable them if F is false.
*/
int sqlite3_extended_result_codes(sqlite3*, int onoff);

/*
** CAPI3REF: Last Insert Rowid {H12220} <S10700>
**
** Each entry in an SQLite table has a unique 64-bit signed
** integer key called the [ROWID | "rowid"]. The rowid is always available
** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
** names are not also used by explicitly declared columns. If
** the table has a column of type [INTEGER PRIMARY KEY] then that column
** is another alias for the rowid.
**
** This routine returns the [rowid] of the most recent
** successful [INSERT] into the database from the [database connection]
** in the first argument.  If no successful [INSERT]s
** have ever occurred on that database connection, zero is returned.
**
** If an [INSERT] occurs within a trigger, then the [rowid] of the inserted
** row is returned by this routine as long as the trigger is running.
** But once the trigger terminates, the value returned by this routine
** reverts to the last value inserted before the trigger fired.
**
** An [INSERT] that fails due to a constraint violation is not a
** successful [INSERT] and does not change the value returned by this
** routine.  Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
** and INSERT OR ABORT make no changes to the return value of this
** routine when their insertion fails.  When INSERT OR REPLACE
** encounters a constraint violation, it does not fail.  The
** INSERT continues to completion after deleting rows that caused
** the constraint problem so INSERT OR REPLACE will always change
** the return value of this interface.
**
** For the purposes of this routine, an [INSERT] is considered to
** be successful even if it is subsequently rolled back.
**
** INVARIANTS:
**
** {H12221} The [sqlite3_last_insert_rowid()] function shall return
**          the [rowid]
**          of the most recent successful [INSERT] performed on the same
**          [database connection] and within the same or higher level
**          trigger context, or zero if there have been no qualifying
**          [INSERT] statements.
**
** {H12223} The [sqlite3_last_insert_rowid()] function shall return the
**          same value when called from the same trigger context
**          immediately before and after a [ROLLBACK].
**
** ASSUMPTIONS:
**
** {A12232} If a separate thread performs a new [INSERT] on the same
**          database connection while the [sqlite3_last_insert_rowid()]
**          function is running and thus changes the last insert [rowid],
**          then the value returned by [sqlite3_last_insert_rowid()] is
**          unpredictable and might not equal either the old or the new
**          last insert [rowid].
*/
sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);

/*
** CAPI3REF: Count The Number Of Rows Modified {H12240} <S10600>
**
** This function returns the number of database rows that were changed
** or inserted or deleted by the most recently completed SQL statement
** on the [database connection] specified by the first parameter.
** Only changes that are directly specified by the [INSERT], [UPDATE],
** or [DELETE] statement are counted.  Auxiliary changes caused by
** triggers are not counted. Use the [sqlite3_total_changes()] function
** to find the total number of changes including changes caused by triggers.
**
** A "row change" is a change to a single row of a single table
** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
** are changed as side effects of REPLACE constraint resolution,
** rollback, ABORT processing, DROP TABLE, or by any other
** mechanisms do not count as direct row changes.
**
** A "trigger context" is a scope of execution that begins and
** ends with the script of a trigger.  Most SQL statements are
** evaluated outside of any trigger.  This is the "top level"
** trigger context.  If a trigger fires from the top level, a
** new trigger context is entered for the duration of that one
** trigger.  Subtriggers create subcontexts for their duration.
**
** Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
** not create a new trigger context.
**
** This function returns the number of direct row changes in the
** most recent INSERT, UPDATE, or DELETE statement within the same
** trigger context.
**
** Thus, when called from the top level, this function returns the
** number of changes in the most recent INSERT, UPDATE, or DELETE
** that also occurred at the top level.  Within the body of a trigger,
** the sqlite3_changes() interface can be called to find the number of
** changes in the most recently completed INSERT, UPDATE, or DELETE
** statement within the body of the same trigger.
** However, the number returned does not include changes
** caused by subtriggers since those have their own context.
**
** SQLite implements the command "DELETE FROM table" without a WHERE clause
** by dropping and recreating the table.  Doing so is much faster than going
** through and deleting individual elements from the table.  Because of this
** optimization, the deletions in "DELETE FROM table" are not row changes and
** will not be counted by the sqlite3_changes() or [sqlite3_total_changes()]
** functions, regardless of the number of elements that were originally
** in the table.  To get an accurate count of the number of rows deleted, use
** "DELETE FROM table WHERE 1" instead.  Or recompile using the
** [SQLITE_OMIT_TRUNCATE_OPTIMIZATION] compile-time option to disable the
** optimization on all queries.
**
** INVARIANTS:
**
** {H12241} The [sqlite3_changes()] function shall return the number of
**          row changes caused by the most recent INSERT, UPDATE,
**          or DELETE statement on the same database connection and
**          within the same or higher trigger context, or zero if there have
**          not been any qualifying row changes.
**
** {H12243} Statements of the form "DELETE FROM tablename" with no
**          WHERE clause shall cause subsequent calls to
**          [sqlite3_changes()] to return zero, regardless of the
**          number of rows originally in the table.
**
** ASSUMPTIONS:
**
** {A12252} If a separate thread makes changes on the same database connection
**          while [sqlite3_changes()] is running then the value returned
**          is unpredictable and not meaningful.
*/
int sqlite3_changes(sqlite3*);

/*
** CAPI3REF: Total Number Of Rows Modified {H12260} <S10600>
**
** This function returns the number of row changes caused by INSERT,
** UPDATE or DELETE statements since the [database connection] was opened.
** The count includes all changes from all trigger contexts.  However,
** the count does not include changes used to implement REPLACE constraints,
** do rollbacks or ABORT processing, or DROP table processing.
** The changes are counted as soon as the statement that makes them is
** completed (when the statement handle is passed to [sqlite3_reset()] or
** [sqlite3_finalize()]).
**
** SQLite implements the command "DELETE FROM table" without a WHERE clause
** by dropping and recreating the table.  (This is much faster than going
** through and deleting individual elements from the table.)  Because of this
** optimization, the deletions in "DELETE FROM table" are not row changes and
** will not be counted by the sqlite3_changes() or [sqlite3_total_changes()]
** functions, regardless of the number of elements that were originally
** in the table.  To get an accurate count of the number of rows deleted, use
** "DELETE FROM table WHERE 1" instead.   Or recompile using the
** [SQLITE_OMIT_TRUNCATE_OPTIMIZATION] compile-time option to disable the
** optimization on all queries.
**
** See also the [sqlite3_changes()] interface.
**
** INVARIANTS:
**
** {H12261} The [sqlite3_total_changes()] returns the total number
**          of row changes caused by INSERT, UPDATE, and/or DELETE
**          statements on the same [database connection], in any
**          trigger context, since the database connection was created.
**
** {H12263} Statements of the form "DELETE FROM tablename" with no
**          WHERE clause shall not change the value returned
**          by [sqlite3_total_changes()].
**
** ASSUMPTIONS:
**
** {A12264} If a separate thread makes changes on the same database connection
**          while [sqlite3_total_changes()] is running then the value
**          returned is unpredictable and not meaningful.
*/
int sqlite3_total_changes(sqlite3*);

/*
** CAPI3REF: Interrupt A Long-Running Query {H12270} <S30500>
**
** This function causes any pending database operation to abort and
** return at its earliest opportunity. This routine is typically
** called in response to a user action such as pressing "Cancel"
** or Ctrl-C where the user wants a long query operation to halt
** immediately.
**
** It is safe to call this routine from a thread different from the
** thread that is currently running the database operation.  But it
** is not safe to call this routine with a [database connection] that
** is closed or might close before sqlite3_interrupt() returns.
**
** If an SQL operation is very nearly finished at the time when
** sqlite3_interrupt() is called, then it might not have an opportunity
** to be interrupted and might continue to completion.
**
** An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
** If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
** that is inside an explicit transaction, then the entire transaction
** will be rolled back automatically.
**
** A call to sqlite3_interrupt() has no effect on SQL statements
** that are started after sqlite3_interrupt() returns.
**
** INVARIANTS:
**
** {H12271} The [sqlite3_interrupt()] interface will force all running
**          SQL statements associated with the same database connection
**          to halt after processing at most one additional row of data.
**
** {H12272} Any SQL statement that is interrupted by [sqlite3_interrupt()]
**          will return [SQLITE_INTERRUPT].
**
** ASSUMPTIONS:
**
** {A12279} If the database connection closes while [sqlite3_interrupt()]
**          is running then bad things will likely happen.
*/
void sqlite3_interrupt(sqlite3*);

/*
** CAPI3REF: Determine If An SQL Statement Is Complete {H10510} <S70200>
**
** These routines are useful for command-line input to determine if the
** currently entered text seems to form complete a SQL statement or
** if additional input is needed before sending the text into
** SQLite for parsing.  These routines return true if the input string
** appears to be a complete SQL statement.  A statement is judged to be
** complete if it ends with a semicolon token and is not a fragment of a
** CREATE TRIGGER statement.  Semicolons that are embedded within
** string literals or quoted identifier names or comments are not
** independent tokens (they are part of the token in which they are
** embedded) and thus do not count as a statement terminator.
**
** These routines do not parse the SQL statements thus
** will not detect syntactically incorrect SQL.
**
** INVARIANTS:
**
** {H10511} A successful evaluation of [sqlite3_complete()] or
**          [sqlite3_complete16()] functions shall
**          return a numeric 1 if and only if the last non-whitespace
**          token in their input is a semicolon that is not in between
**          the BEGIN and END of a CREATE TRIGGER statement.
**
** {H10512} If a memory allocation error occurs during an invocation
**          of [sqlite3_complete()] or [sqlite3_complete16()] then the
**          routine shall return [SQLITE_NOMEM].
**
** ASSUMPTIONS:
**
** {A10512} The input to [sqlite3_complete()] must be a zero-terminated
**          UTF-8 string.
**
** {A10513} The input to [sqlite3_complete16()] must be a zero-terminated
**          UTF-16 string in native byte order.
*/
int sqlite3_complete(const char *sql);
int sqlite3_complete16(const void *sql);

/*
** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors {H12310} <S40400>
**
** This routine sets a callback function that might be invoked whenever
** an attempt is made to open a database table that another thread
** or process has locked.
**
** If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
** is returned immediately upon encountering the lock. If the busy callback
** is not NULL, then the callback will be invoked with two arguments.
**
** The first argument to the handler is a copy of the void* pointer which
** is the third argument to sqlite3_busy_handler().  The second argument to
** the handler callback is the number of times that the busy handler has
** been invoked for this locking event.  If the
** busy callback returns 0, then no additional attempts are made to
** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
** If the callback returns non-zero, then another attempt
** is made to open the database for reading and the cycle repeats.
**
** The presence of a busy handler does not guarantee that it will be invoked
** when there is lock contention. If SQLite determines that invoking the busy
** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
** Consider a scenario where one process is holding a read lock that
** it is trying to promote to a reserved lock and
** a second process is holding a reserved lock that it is trying
** to promote to an exclusive lock.  The first process cannot proceed
** because it is blocked by the second and the second process cannot
** proceed because it is blocked by the first.  If both processes
** invoke the busy handlers, neither will make any progress.  Therefore,
** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
** will induce the first process to release its read lock and allow
** the second process to proceed.
**
** The default busy callback is NULL.
**
** The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
** when SQLite is in the middle of a large transaction where all the
** changes will not fit into the in-memory cache.  SQLite will
** already hold a RESERVED lock on the database file, but it needs
** to promote this lock to EXCLUSIVE so that it can spill cache
** pages into the database file without harm to concurrent
** readers.  If it is unable to promote the lock, then the in-memory
** cache will be left in an inconsistent state and so the error
** code is promoted from the relatively benign [SQLITE_BUSY] to
** the more severe [SQLITE_IOERR_BLOCKED].  This error code promotion
** forces an automatic rollback of the changes.  See the
** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
** CorruptionFollowingBusyError</a> wiki page for a discussion of why
** this is important.
**
** There can only be a single busy handler defined for each
** [database connection].  Setting a new busy handler clears any
** previously set handler.  Note that calling [sqlite3_busy_timeout()]
** will also set or clear the busy handler.
**
** The busy callback should not take any actions which modify the
** database connection that invoked the busy handler.  Any such actions
** result in undefined behavior.
** 
** INVARIANTS:
**
** {H12311} The [sqlite3_busy_handler(D,C,A)] function shall replace
**          busy callback in the [database connection] D with a new
**          a new busy handler C and application data pointer A.
**
** {H12312} Newly created [database connections] shall have a busy
**          handler of NULL.
**
** {H12314} When two or more [database connections] share a
**          [sqlite3_enable_shared_cache | common cache],
**          the busy handler for the database connection currently using
**          the cache shall be invoked when the cache encounters a lock.
**
** {H12316} If a busy handler callback returns zero, then the SQLite interface
**          that provoked the locking event shall return [SQLITE_BUSY].
**
** {H12318} SQLite shall invokes the busy handler with two arguments which
**          are a copy of the pointer supplied by the 3rd parameter to
**          [sqlite3_busy_handler()] and a count of the number of prior
**          invocations of the busy handler for the same locking event.
**
** ASSUMPTIONS:
**
** {A12319} A busy handler must not close the database connection
**          or [prepared statement] that invoked the busy handler.
*/
int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);

/*
** CAPI3REF: Set A Busy Timeout {H12340} <S40410>
**
** This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
** for a specified amount of time when a table is locked.  The handler
** will sleep multiple times until at least "ms" milliseconds of sleeping
** have accumulated. {H12343} After "ms" milliseconds of sleeping,
** the handler returns 0 which causes [sqlite3_step()] to return
** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
**
** Calling this routine with an argument less than or equal to zero
** turns off all busy handlers.
**
** There can only be a single busy handler for a particular
** [database connection] any any given moment.  If another busy handler
** was defined  (using [sqlite3_busy_handler()]) prior to calling
** this routine, that other busy handler is cleared.
**
** INVARIANTS:
**
** {H12341} The [sqlite3_busy_timeout()] function shall override any prior
**          [sqlite3_busy_timeout()] or [sqlite3_busy_handler()] setting
**          on the same [database connection].
**
** {H12343} If the 2nd parameter to [sqlite3_busy_timeout()] is less than
**          or equal to zero, then the busy handler shall be cleared so that
**          all subsequent locking events immediately return [SQLITE_BUSY].
**
** {H12344} If the 2nd parameter to [sqlite3_busy_timeout()] is a positive
**          number N, then a busy handler shall be set that repeatedly calls
**          the xSleep() method in the [sqlite3_vfs | VFS interface] until
**          either the lock clears or until the cumulative sleep time
**          reported back by xSleep() exceeds N milliseconds.
*/
int sqlite3_busy_timeout(sqlite3*, int ms);

/*
** CAPI3REF: Convenience Routines For Running Queries {H12370} <S10000>
**
** Definition: A <b>result table</b> is memory data structure created by the
** [sqlite3_get_table()] interface.  A result table records the
** complete query results from one or more queries.
**
** The table conceptually has a number of rows and columns.  But
** these numbers are not part of the result table itself.  These
** numbers are obtained separately.  Let N be the number of rows
** and M be the number of columns.
**
** A result table is an array of pointers to zero-terminated UTF-8 strings.
** There are (N+1)*M elements in the array.  The first M pointers point
** to zero-terminated strings that  contain the names of the columns.
** The remaining entries all point to query results.  NULL values result
** in NULL pointers.  All other values are in their UTF-8 zero-terminated
** string representation as returned by [sqlite3_column_text()].
**
** A result table might consist of one or more memory allocations.
** It is not safe to pass a result table directly to [sqlite3_free()].
** A result table should be deallocated using [sqlite3_free_table()].
**
** As an example of the result table format, suppose a query result
** is as follows:
**
** <blockquote><pre>
**        Name        | Age
**        -----------------------
**        Alice       | 43
**        Bob         | 28
**        Cindy       | 21
** </pre></blockquote>
**
** There are two column (M==2) and three rows (N==3).  Thus the
** result table has 8 entries.  Suppose the result table is stored
** in an array names azResult.  Then azResult holds this content:
**
** <blockquote><pre>
**        azResult&#91;0] = "Name";
**        azResult&#91;1] = "Age";
**        azResult&#91;2] = "Alice";
**        azResult&#91;3] = "43";
**        azResult&#91;4] = "Bob";
**        azResult&#91;5] = "28";
**        azResult&#91;6] = "Cindy";
**        azResult&#91;7] = "21";
** </pre></blockquote>
**
** The sqlite3_get_table() function evaluates one or more
** semicolon-separated SQL statements in the zero-terminated UTF-8
** string of its 2nd parameter.  It returns a result table to the
** pointer given in its 3rd parameter.
**
** After the calling function has finished using the result, it should
** pass the pointer to the result table to sqlite3_free_table() in order to
** release the memory that was malloced.  Because of the way the
** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
** function must not try to call [sqlite3_free()] directly.  Only
** [sqlite3_free_table()] is able to release the memory properly and safely.
**
** The sqlite3_get_table() interface is implemented as a wrapper around
** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
** to any internal data structures of SQLite.  It uses only the public
** interface defined here.  As a consequence, errors that occur in the
** wrapper layer outside of the internal [sqlite3_exec()] call are not
** reflected in subsequent calls to [sqlite3_errcode()] or [sqlite3_errmsg()].
**
** INVARIANTS:
**
** {H12371} If a [sqlite3_get_table()] fails a memory allocation, then
**          it shall free the result table under construction, abort the
**          query in process, skip any subsequent queries, set the
**          *pazResult output pointer to NULL and return [SQLITE_NOMEM].
**
** {H12373} If the pnColumn parameter to [sqlite3_get_table()] is not NULL
**          then a successful invocation of [sqlite3_get_table()] shall
**          write the number of columns in the
**          result set of the query into *pnColumn.
**
** {H12374} If the pnRow parameter to [sqlite3_get_table()] is not NULL
**          then a successful invocation of [sqlite3_get_table()] shall
**          writes the number of rows in the
**          result set of the query into *pnRow.
**
** {H12376} A successful invocation of [sqlite3_get_table()] that computes
**          N rows of result with C columns per row shall make *pazResult
**          point to an array of pointers to (N+1)*C strings where the first
**          C strings are column names as obtained from
**          [sqlite3_column_name()] and the rest are column result values
**          obtained from [sqlite3_column_text()].
**
** {H12379} The values in the pazResult array returned by [sqlite3_get_table()]
**          shall remain valid until cleared by [sqlite3_free_table()].
**
** {H12382} When an error occurs during evaluation of [sqlite3_get_table()]
**          the function shall set *pazResult to NULL, write an error message
**          into memory obtained from [sqlite3_malloc()], make
**          **pzErrmsg point to that error message, and return a
**          appropriate [error code].
*/
int sqlite3_get_table(
  sqlite3 *db,          /* An open database */
  const char *zSql,     /* SQL to be evaluated */
  char ***pazResult,    /* Results of the query */
  int *pnRow,           /* Number of result rows written here */
  int *pnColumn,        /* Number of result columns written here */
  char **pzErrmsg       /* Error msg written here */
);
void sqlite3_free_table(char **result);

/*
** CAPI3REF: Formatted String Printing Functions {H17400} <S70000><S20000>
**
** These routines are workalikes of the "printf()" family of functions
** from the standard C library.
**
** The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
** results into memory obtained from [sqlite3_malloc()].
** The strings returned by these two routines should be
** released by [sqlite3_free()].  Both routines return a
** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
** memory to hold the resulting string.
**
** In sqlite3_snprintf() routine is similar to "snprintf()" from
** the standard C library.  The result is written into the
** buffer supplied as the second parameter whose size is given by
** the first parameter. Note that the order of the
** first two parameters is reversed from snprintf().  This is an
** historical accident that cannot be fixed without breaking
** backwards compatibility.  Note also that sqlite3_snprintf()
** returns a pointer to its buffer instead of the number of
** characters actually written into the buffer.  We admit that
** the number of characters written would be a more useful return
** value but we cannot change the implementation of sqlite3_snprintf()
** now without breaking compatibility.
**
** As long as the buffer size is greater than zero, sqlite3_snprintf()
** guarantees that the buffer is always zero-terminated.  The first
** parameter "n" is the total size of the buffer, including space for
** the zero terminator.  So the longest string that can be completely
** written will be n-1 characters.
**
** These routines all implement some additional formatting
** options that are useful for constructing SQL statements.
** All of the usual printf() formatting options apply.  In addition, there
** is are "%q", "%Q", and "%z" options.
**
** The %q option works like %s in that it substitutes a null-terminated
** string from the argument list.  But %q also doubles every '\'' character.
** %q is designed for use inside a string literal.  By doubling each '\''
** character it escapes that character and allows it to be inserted into
** the string.
**
** For example, assume the string variable zText contains text as follows:
**
** <blockquote><pre>
**  char *zText = "It's a happy day!";
** </pre></blockquote>
**
** One can use this text in an SQL statement as follows:
**
** <blockquote><pre>
**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
**  sqlite3_exec(db, zSQL, 0, 0, 0);
**  sqlite3_free(zSQL);
** </pre></blockquote>
**
** Because the %q format string is used, the '\'' character in zText
** is escaped and the SQL generated is as follows:
**
** <blockquote><pre>
**  INSERT INTO table1 VALUES('It''s a happy day!')
** </pre></blockquote>
**
** This is correct.  Had we used %s instead of %q, the generated SQL
** would have looked like this:
**
** <blockquote><pre>
**  INSERT INTO table1 VALUES('It's a happy day!');
** </pre></blockquote>
**
** This second example is an SQL syntax error.  As a general rule you should
** always use %q instead of %s when inserting text into a string literal.
**
** The %Q option works like %q except it also adds single quotes around
** the outside of the total string.  Additionally, if the parameter in the
** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
** single quotes) in place of the %Q option.  So, for example, one could say:
**
** <blockquote><pre>
**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
**  sqlite3_exec(db, zSQL, 0, 0, 0);
**  sqlite3_free(zSQL);
** </pre></blockquote>
**
** The code above will render a correct SQL statement in the zSQL
** variable even if the zText variable is a NULL pointer.
**
** The "%z" formatting option works exactly like "%s" with the
** addition that after the string has been read and copied into
** the result, [sqlite3_free()] is called on the input string. {END}
**
** INVARIANTS:
**
** {H17403}  The [sqlite3_mprintf()] and [sqlite3_vmprintf()] interfaces
**           return either pointers to zero-terminated UTF-8 strings held in
**           memory obtained from [sqlite3_malloc()] or NULL pointers if
**           a call to [sqlite3_malloc()] fails.
**
** {H17406}  The [sqlite3_snprintf()] interface writes a zero-terminated
**           UTF-8 string into the buffer pointed to by the second parameter
**           provided that the first parameter is greater than zero.
**
** {H17407}  The [sqlite3_snprintf()] interface does not write slots of
**           its output buffer (the second parameter) outside the range
**           of 0 through N-1 (where N is the first parameter)
**           regardless of the length of the string
**           requested by the format specification.
*/
char *sqlite3_mprintf(const char*,...);
char *sqlite3_vmprintf(const char*, va_list);
char *sqlite3_snprintf(int,char*,const char*, ...);

/*
** CAPI3REF: Memory Allocation Subsystem {H17300} <S20000>
**
** The SQLite core  uses these three routines for all of its own
** internal memory allocation needs. "Core" in the previous sentence
** does not include operating-system specific VFS implementation.  The
** Windows VFS uses native malloc() and free() for some operations.
**
** The sqlite3_malloc() routine returns a pointer to a block
** of memory at least N bytes in length, where N is the parameter.
** If sqlite3_malloc() is unable to obtain sufficient free
** memory, it returns a NULL pointer.  If the parameter N to
** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
** a NULL pointer.
**
** Calling sqlite3_free() with a pointer previously returned
** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
** that it might be reused.  The sqlite3_free() routine is
** a no-op if is called with a NULL pointer.  Passing a NULL pointer
** to sqlite3_free() is harmless.  After being freed, memory
** should neither be read nor written.  Even reading previously freed
** memory might result in a segmentation fault or other severe error.
** Memory corruption, a segmentation fault, or other severe error
** might result if sqlite3_free() is called with a non-NULL pointer that
** was not obtained from sqlite3_malloc() or sqlite3_realloc().
**
** The sqlite3_realloc() interface attempts to resize a
** prior memory allocation to be at least N bytes, where N is the
** second parameter.  The memory allocation to be resized is the first
** parameter.  If the first parameter to sqlite3_realloc()
** is a NULL pointer then its behavior is identical to calling
** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
** If the second parameter to sqlite3_realloc() is zero or
** negative then the behavior is exactly the same as calling
** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
** sqlite3_realloc() returns a pointer to a memory allocation
** of at least N bytes in size or NULL if sufficient memory is unavailable.
** If M is the size of the prior allocation, then min(N,M) bytes
** of the prior allocation are copied into the beginning of buffer returned
** by sqlite3_realloc() and the prior allocation is freed.
** If sqlite3_realloc() returns NULL, then the prior allocation
** is not freed.
**
** The memory returned by sqlite3_malloc() and sqlite3_realloc()
** is always aligned to at least an 8 byte boundary. {END}
**
** The default implementation of the memory allocation subsystem uses
** the malloc(), realloc() and free() provided by the standard C library.
** {H17382} However, if SQLite is compiled with the
** SQLITE_MEMORY_SIZE=<i>NNN</i> C preprocessor macro (where <i>NNN</i>
** is an integer), then SQLite create a static array of at least
** <i>NNN</i> bytes in size and uses that array for all of its dynamic
** memory allocation needs. {END}  Additional memory allocator options
** may be added in future releases.
**
** In SQLite version 3.5.0 and 3.5.1, it was possible to define
** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
** implementation of these routines to be omitted.  That capability
** is no longer provided.  Only built-in memory allocators can be used.
**
** The Windows OS interface layer calls
** the system malloc() and free() directly when converting
** filenames between the UTF-8 encoding used by SQLite
** and whatever filename encoding is used by the particular Windows
** installation.  Memory allocation errors are detected, but
** they are reported back as [SQLITE_CANTOPEN] or
** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
**
** INVARIANTS:
**
** {H17303}  The [sqlite3_malloc(N)] interface returns either a pointer to
**           a newly checked-out block of at least N bytes of memory
**           that is 8-byte aligned, or it returns NULL if it is unable
**           to fulfill the request.
**
** {H17304}  The [sqlite3_malloc(N)] interface returns a NULL pointer if
**           N is less than or equal to zero.
**
** {H17305}  The [sqlite3_free(P)] interface releases memory previously
**           returned from [sqlite3_malloc()] or [sqlite3_realloc()],
**           making it available for reuse.
**
** {H17306}  A call to [sqlite3_free(NULL)] is a harmless no-op.
**
** {H17310}  A call to [sqlite3_realloc(0,N)] is equivalent to a call
**           to [sqlite3_malloc(N)].
**
** {H17312}  A call to [sqlite3_realloc(P,0)] is equivalent to a call
**           to [sqlite3_free(P)].
**
** {H17315}  The SQLite core uses [sqlite3_malloc()], [sqlite3_realloc()],
**           and [sqlite3_free()] for all of its memory allocation and
**           deallocation needs.
**
** {H17318}  The [sqlite3_realloc(P,N)] interface returns either a pointer
**           to a block of checked-out memory of at least N bytes in size
**           that is 8-byte aligned, or a NULL pointer.
**
** {H17321}  When [sqlite3_realloc(P,N)] returns a non-NULL pointer, it first
**           copies the first K bytes of content from P into the newly
**           allocated block, where K is the lesser of N and the size of
**           the buffer P.
**
** {H17322}  When [sqlite3_realloc(P,N)] returns a non-NULL pointer, it first
**           releases the buffer P.
**
** {H17323}  When [sqlite3_realloc(P,N)] returns NULL, the buffer P is
**           not modified or released.
**
** ASSUMPTIONS:
**
** {A17350}  The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
**           must be either NULL or else pointers obtained from a prior
**           invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
**           not yet been released.
**
** {A17351}  The application must not read or write any part of
**           a block of memory after it has been released using
**           [sqlite3_free()] or [sqlite3_realloc()].
*/
void *sqlite3_malloc(int);
void *sqlite3_realloc(void*, int);
void sqlite3_free(void*);

/*
** CAPI3REF: Memory Allocator Statistics {H17370} <S30210>
**
** SQLite provides these two interfaces for reporting on the status
** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
** routines, which form the built-in memory allocation subsystem.
**
** INVARIANTS:
**
** {H17371} The [sqlite3_memory_used()] routine returns the number of bytes
**          of memory currently outstanding (malloced but not freed).
**
** {H17373} The [sqlite3_memory_highwater()] routine returns the maximum
**          value of [sqlite3_memory_used()] since the high-water mark
**          was last reset.
**
** {H17374} The values returned by [sqlite3_memory_used()] and
**          [sqlite3_memory_highwater()] include any overhead
**          added by SQLite in its implementation of [sqlite3_malloc()],
**          but not overhead added by the any underlying system library
**          routines that [sqlite3_malloc()] may call.
**
** {H17375} The memory high-water mark is reset to the current value of
**          [sqlite3_memory_used()] if and only if the parameter to
**          [sqlite3_memory_highwater()] is true.  The value returned
**          by [sqlite3_memory_highwater(1)] is the high-water mark
**          prior to the reset.
*/
sqlite3_int64 sqlite3_memory_used(void);
sqlite3_int64 sqlite3_memory_highwater(int resetFlag);

/*
** CAPI3REF: Pseudo-Random Number Generator {H17390} <S20000>
**
** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
** select random [ROWID | ROWIDs] when inserting new records into a table that
** already uses the largest possible [ROWID].  The PRNG is also used for
** the build-in random() and randomblob() SQL functions.  This interface allows
** applications to access the same PRNG for other purposes.
**
** A call to this routine stores N bytes of randomness into buffer P.
**
** The first time this routine is invoked (either internally or by
** the application) the PRNG is seeded using randomness obtained
** from the xRandomness method of the default [sqlite3_vfs] object.
** On all subsequent invocations, the pseudo-randomness is generated
** internally and without recourse to the [sqlite3_vfs] xRandomness
** method.
**
** INVARIANTS:
**
** {H17392} The [sqlite3_randomness(N,P)] interface writes N bytes of
**          high-quality pseudo-randomness into buffer P.
*/
void sqlite3_randomness(int N, void *P);

/*
** CAPI3REF: Compile-Time Authorization Callbacks {H12500} <S70100>
**
** This routine registers a authorizer callback with a particular
** [database connection], supplied in the first argument.
** The authorizer callback is invoked as SQL statements are being compiled
** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  At various
** points during the compilation process, as logic is being created
** to perform various actions, the authorizer callback is invoked to
** see if those actions are allowed.  The authorizer callback should
** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
** specific action but allow the SQL statement to continue to be
** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
** rejected with an error.  If the authorizer callback returns
** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
** then the [sqlite3_prepare_v2()] or equivalent call that triggered
** the authorizer will fail with an error message.
**
** When the callback returns [SQLITE_OK], that means the operation
** requested is ok.  When the callback returns [SQLITE_DENY], the
** [sqlite3_prepare_v2()] or equivalent call that triggered the
** authorizer will fail with an error message explaining that
** access is denied.  If the authorizer code is [SQLITE_READ]
** and the callback returns [SQLITE_IGNORE] then the
** [prepared statement] statement is constructed to substitute
** a NULL value in place of the table column that would have
** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
** return can be used to deny an untrusted user access to individual
** columns of a table.
**
** The first parameter to the authorizer callback is a copy of the third
** parameter to the sqlite3_set_authorizer() interface. The second parameter
** to the callback is an integer [SQLITE_COPY | action code] that specifies
** the particular action to be authorized. The third through sixth parameters
** to the callback are zero-terminated strings that contain additional
** details about the action to be authorized.
**
** An authorizer is used when [sqlite3_prepare | preparing]
** SQL statements from an untrusted source, to ensure that the SQL statements
** do not try to access data they are not allowed to see, or that they do not
** try to execute malicious statements that damage the database.  For
** example, an application may allow a user to enter arbitrary
** SQL queries for evaluation by a database.  But the application does
** not want the user to be able to make arbitrary changes to the
** database.  An authorizer could then be put in place while the
** user-entered SQL is being [sqlite3_prepare | prepared] that
** disallows everything except [SELECT] statements.
**
** Applications that need to process SQL from untrusted sources
** might also consider lowering resource limits using [sqlite3_limit()]
** and limiting database size using the [max_page_count] [PRAGMA]
** in addition to using an authorizer.
**
** Only a single authorizer can be in place on a database connection
** at a time.  Each call to sqlite3_set_authorizer overrides the
** previous call.  Disable the authorizer by installing a NULL callback.
** The authorizer is disabled by default.
**
** The authorizer callback must not do anything that will modify
** the database connection that invoked the authorizer callback.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** When [sqlite3_prepare_v2()] is used to prepare a statement, the
** statement might be reprepared during [sqlite3_step()] due to a 
** schema change.  Hence, the application should ensure that the
** correct authorizer callback remains in place during the [sqlite3_step()].
**
** Note that the authorizer callback is invoked only during
** [sqlite3_prepare()] or its variants.  Authorization is not
** performed during statement evaluation in [sqlite3_step()].
**
** INVARIANTS:
**
** {H12501} The [sqlite3_set_authorizer(D,...)] interface registers a
**          authorizer callback with database connection D.
**
** {H12502} The authorizer callback is invoked as SQL statements are
**          being parseed and compiled.
**
** {H12503} If the authorizer callback returns any value other than
**          [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY], then
**          the application interface call that caused
**          the authorizer callback to run shall fail with an
**          [SQLITE_ERROR] error code and an appropriate error message.
**
** {H12504} When the authorizer callback returns [SQLITE_OK], the operation
**          described is processed normally.
**
** {H12505} When the authorizer callback returns [SQLITE_DENY], the
**          application interface call that caused the
**          authorizer callback to run shall fail
**          with an [SQLITE_ERROR] error code and an error message
**          explaining that access is denied.
**
** {H12506} If the authorizer code (the 2nd parameter to the authorizer
**          callback) is [SQLITE_READ] and the authorizer callback returns
**          [SQLITE_IGNORE], then the prepared statement is constructed to
**          insert a NULL value in place of the table column that would have
**          been read if [SQLITE_OK] had been returned.
**
** {H12507} If the authorizer code (the 2nd parameter to the authorizer
**          callback) is anything other than [SQLITE_READ], then
**          a return of [SQLITE_IGNORE] has the same effect as [SQLITE_DENY].
**
** {H12510} The first parameter to the authorizer callback is a copy of
**          the third parameter to the [sqlite3_set_authorizer()] interface.
**
** {H12511} The second parameter to the callback is an integer
**          [SQLITE_COPY | action code] that specifies the particular action
**          to be authorized.
**
** {H12512} The third through sixth parameters to the callback are
**          zero-terminated strings that contain
**          additional details about the action to be authorized.
**
** {H12520} Each call to [sqlite3_set_authorizer()] overrides
**          any previously installed authorizer.
**
** {H12521} A NULL authorizer means that no authorization
**          callback is invoked.
**
** {H12522} The default authorizer is NULL.
*/
int sqlite3_set_authorizer(
  sqlite3*,
  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  void *pUserData
);

/*
** CAPI3REF: Authorizer Return Codes {H12590} <H12500>
**
** The [sqlite3_set_authorizer | authorizer callback function] must
** return either [SQLITE_OK] or one of these two constants in order
** to signal SQLite whether or not the action is permitted.  See the
** [sqlite3_set_authorizer | authorizer documentation] for additional
** information.
*/
#define SQLITE_DENY   1   /* Abort the SQL statement with an error */
#define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */

/*
** CAPI3REF: Authorizer Action Codes {H12550} <H12500>
**
** The [sqlite3_set_authorizer()] interface registers a callback function
** that is invoked to authorize certain SQL statement actions.  The
** second parameter to the callback is an integer code that specifies
** what action is being authorized.  These are the integer action codes that
** the authorizer callback may be passed.
**
** These action code values signify what kind of operation is to be
** authorized.  The 3rd and 4th parameters to the authorization
** callback function will be parameters or NULL depending on which of these
** codes is used as the second parameter.  The 5th parameter to the
** authorizer callback is the name of the database ("main", "temp",
** etc.) if applicable.  The 6th parameter to the authorizer callback
** is the name of the inner-most trigger or view that is responsible for
** the access attempt or NULL if this access attempt is directly from
** top-level SQL code.
**
** INVARIANTS:
**
** {H12551} The second parameter to an
**          [sqlite3_set_authorizer | authorizer callback] shall be an integer
**          [SQLITE_COPY | authorizer code] that specifies what action
**          is being authorized.
**
** {H12552} The 3rd and 4th parameters to the
**          [sqlite3_set_authorizer | authorization callback]
**          shall be parameters or NULL depending on which
**          [SQLITE_COPY | authorizer code] is used as the second parameter.
**
** {H12553} The 5th parameter to the
**          [sqlite3_set_authorizer | authorizer callback] shall be the name
**          of the database (example: "main", "temp", etc.) if applicable.
**
** {H12554} The 6th parameter to the
**          [sqlite3_set_authorizer | authorizer callback] shall be the name
**          of the inner-most trigger or view that is responsible for
**          the access attempt or NULL if this access attempt is directly from
**          top-level SQL code.
*/
/******************************************* 3rd ************ 4th ***********/
#define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
#define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
#define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
#define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
#define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
#define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
#define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
#define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
#define SQLITE_DELETE                9   /* Table Name      NULL            */
#define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
#define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
#define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
#define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
#define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
#define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
#define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
#define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
#define SQLITE_INSERT               18   /* Table Name      NULL            */
#define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
#define SQLITE_READ                 20   /* Table Name      Column Name     */
#define SQLITE_SELECT               21   /* NULL            NULL            */
#define SQLITE_TRANSACTION          22   /* Operation       NULL            */
#define SQLITE_UPDATE               23   /* Table Name      Column Name     */
#define SQLITE_ATTACH               24   /* Filename        NULL            */
#define SQLITE_DETACH               25   /* Database Name   NULL            */
#define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
#define SQLITE_REINDEX              27   /* Index Name      NULL            */
#define SQLITE_ANALYZE              28   /* Table Name      NULL            */
#define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
#define SQLITE_COPY                  0   /* No longer used */

/*
** CAPI3REF: Tracing And Profiling Functions {H12280} <S60400>
** EXPERIMENTAL
**
** These routines register callback functions that can be used for
** tracing and profiling the execution of SQL statements.
**
** The callback function registered by sqlite3_trace() is invoked at
** various times when an SQL statement is being run by [sqlite3_step()].
** The callback returns a UTF-8 rendering of the SQL statement text
** as the statement first begins executing.  Additional callbacks occur
** as each triggered subprogram is entered.  The callbacks for triggers
** contain a UTF-8 SQL comment that identifies the trigger.
**
** The callback function registered by sqlite3_profile() is invoked
** as each SQL statement finishes.  The profile callback contains
** the original statement text and an estimate of wall-clock time
** of how long that statement took to run.
**
** INVARIANTS:
**
** {H12281} The callback function registered by [sqlite3_trace()] 
**          shall be invoked
**          whenever an SQL statement first begins to execute and
**          whenever a trigger subprogram first begins to run.
**
** {H12282} Each call to [sqlite3_trace()] shall override the previously
**          registered trace callback.
**
** {H12283} A NULL trace callback shall disable tracing.
**
** {H12284} The first argument to the trace callback shall be a copy of
**          the pointer which was the 3rd argument to [sqlite3_trace()].
**
** {H12285} The second argument to the trace callback is a
**          zero-terminated UTF-8 string containing the original text
**          of the SQL statement as it was passed into [sqlite3_prepare_v2()]
**          or the equivalent, or an SQL comment indicating the beginning
**          of a trigger subprogram.
**
** {H12287} The callback function registered by [sqlite3_profile()] is invoked
**          as each SQL statement finishes.
**
** {H12288} The first parameter to the profile callback is a copy of
**          the 3rd parameter to [sqlite3_profile()].
**
** {H12289} The second parameter to the profile callback is a
**          zero-terminated UTF-8 string that contains the complete text of
**          the SQL statement as it was processed by [sqlite3_prepare_v2()]
**          or the equivalent.
**
** {H12290} The third parameter to the profile callback is an estimate
**          of the number of nanoseconds of wall-clock time required to
**          run the SQL statement from start to finish.
*/
SQLITE_EXPERIMENTAL void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);

/*
** CAPI3REF: Query Progress Callbacks {H12910} <S60400>
**
** This routine configures a callback function - the
** progress callback - that is invoked periodically during long
** running calls to [sqlite3_exec()], [sqlite3_step()] and
** [sqlite3_get_table()].  An example use for this
** interface is to keep a GUI updated during a large query.
**
** If the progress callback returns non-zero, the operation is
** interrupted.  This feature can be used to implement a
** "Cancel" button on a GUI progress dialog box.
**
** The progress handler must not do anything that will modify
** the database connection that invoked the progress handler.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** INVARIANTS:
**
** {H12911} The callback function registered by sqlite3_progress_handler()
**          is invoked periodically during long running calls to
**          [sqlite3_step()].
**
** {H12912} The progress callback is invoked once for every N virtual
**          machine opcodes, where N is the second argument to
**          the [sqlite3_progress_handler()] call that registered
**          the callback.  If N is less than 1, sqlite3_progress_handler()
**          acts as if a NULL progress handler had been specified.
**
** {H12913} The progress callback itself is identified by the third
**          argument to sqlite3_progress_handler().
**
** {H12914} The fourth argument to sqlite3_progress_handler() is a
**          void pointer passed to the progress callback
**          function each time it is invoked.
**
** {H12915} If a call to [sqlite3_step()] results in fewer than N opcodes
**          being executed, then the progress callback is never invoked.
**
** {H12916} Every call to [sqlite3_progress_handler()]
**          overwrites any previously registered progress handler.
**
** {H12917} If the progress handler callback is NULL then no progress
**          handler is invoked.
**
** {H12918} If the progress callback returns a result other than 0, then
**          the behavior is a if [sqlite3_interrupt()] had been called.
**          <S30500>
*/
void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);

/*
** CAPI3REF: Opening A New Database Connection {H12700} <S40200>
**
** These routines open an SQLite database file whose name is given by the
** filename argument. The filename argument is interpreted as UTF-8 for
** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
** order for sqlite3_open16(). A [database connection] handle is usually
** returned in *ppDb, even if an error occurs.  The only exception is that
** if SQLite is unable to allocate memory to hold the [sqlite3] object,
** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
** object. If the database is opened (and/or created) successfully, then
** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.  The
** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
** an English language description of the error.
**
** The default encoding for the database will be UTF-8 if
** sqlite3_open() or sqlite3_open_v2() is called and
** UTF-16 in the native byte order if sqlite3_open16() is used.
**
** Whether or not an error occurs when it is opened, resources
** associated with the [database connection] handle should be released by
** passing it to [sqlite3_close()] when it is no longer required.
**
** The sqlite3_open_v2() interface works like sqlite3_open()
** except that it accepts two additional parameters for additional control
** over the new database connection.  The flags parameter can take one of
** the following three values, optionally combined with the 
** [SQLITE_OPEN_NOMUTEX] or [SQLITE_OPEN_FULLMUTEX] flags:
**
** <dl>
** <dt>[SQLITE_OPEN_READONLY]</dt>
** <dd>The database is opened in read-only mode.  If the database does not
** already exist, an error is returned.</dd>
**
** <dt>[SQLITE_OPEN_READWRITE]</dt>
** <dd>The database is opened for reading and writing if possible, or reading
** only if the file is write protected by the operating system.  In either
** case the database must already exist, otherwise an error is returned.</dd>
**
** <dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
** <dd>The database is opened for reading and writing, and is creates it if
** it does not already exist. This is the behavior that is always used for
** sqlite3_open() and sqlite3_open16().</dd>
** </dl>
**
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** combinations shown above or one of the combinations shown above combined
** with the [SQLITE_OPEN_NOMUTEX] or [SQLITE_OPEN_FULLMUTEX] flags,
** then the behavior is undefined.
**
** If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
** opens in the multi-thread [threading mode] as long as the single-thread
** mode has not been set at compile-time or start-time.  If the
** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
** in the serialized [threading mode] unless single-thread was
** previously selected at compile-time or start-time.
**
** If the filename is ":memory:", then a private, temporary in-memory database
** is created for the connection.  This in-memory database will vanish when
** the database connection is closed.  Future versions of SQLite might
** make use of additional special filenames that begin with the ":" character.
** It is recommended that when a database filename actually does begin with
** a ":" character you should prefix the filename with a pathname such as
** "./" to avoid ambiguity.
**
** If the filename is an empty string, then a private, temporary
** on-disk database will be created.  This private database will be
** automatically deleted as soon as the database connection is closed.
**
** The fourth parameter to sqlite3_open_v2() is the name of the
** [sqlite3_vfs] object that defines the operating system interface that
** the new database connection should use.  If the fourth parameter is
** a NULL pointer then the default [sqlite3_vfs] object is used.
**
** <b>Note to Windows users:</b>  The encoding used for the filename argument
** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
** codepage is currently defined.  Filenames containing international
** characters must be converted to UTF-8 prior to passing them into
** sqlite3_open() or sqlite3_open_v2().
**
** INVARIANTS:
**
** {H12701} The [sqlite3_open()], [sqlite3_open16()], and
**          [sqlite3_open_v2()] interfaces create a new
**          [database connection] associated with
**          the database file given in their first parameter.
**
** {H12702} The filename argument is interpreted as UTF-8
**          for [sqlite3_open()] and [sqlite3_open_v2()] and as UTF-16
**          in the native byte order for [sqlite3_open16()].
**
** {H12703} A successful invocation of [sqlite3_open()], [sqlite3_open16()],
**          or [sqlite3_open_v2()] writes a pointer to a new
**          [database connection] into *ppDb.
**
** {H12704} The [sqlite3_open()], [sqlite3_open16()], and
**          [sqlite3_open_v2()] interfaces return [SQLITE_OK] upon success,
**          or an appropriate [error code] on failure.
**
** {H12706} The default text encoding for a new database created using
**          [sqlite3_open()] or [sqlite3_open_v2()] will be UTF-8.
**
** {H12707} The default text encoding for a new database created using
**          [sqlite3_open16()] will be UTF-16.
**
** {H12709} The [sqlite3_open(F,D)] interface is equivalent to
**          [sqlite3_open_v2(F,D,G,0)] where the G parameter is
**          [SQLITE_OPEN_READWRITE]|[SQLITE_OPEN_CREATE].
**
** {H12711} If the G parameter to [sqlite3_open_v2(F,D,G,V)] contains the
**          bit value [SQLITE_OPEN_READONLY] then the database is opened
**          for reading only.
**
** {H12712} If the G parameter to [sqlite3_open_v2(F,D,G,V)] contains the
**          bit value [SQLITE_OPEN_READWRITE] then the database is opened
**          reading and writing if possible, or for reading only if the
**          file is write protected by the operating system.
**
** {H12713} If the G parameter to [sqlite3_open_v2(F,D,G,V)] omits the
**          bit value [SQLITE_OPEN_CREATE] and the database does not
**          previously exist, an error is returned.
**
** {H12714} If the G parameter to [sqlite3_open_v2(F,D,G,V)] contains the
**          bit value [SQLITE_OPEN_CREATE] and the database does not
**          previously exist, then an attempt is made to create and
**          initialize the database.
**
** {H12717} If the filename argument to [sqlite3_open()], [sqlite3_open16()],
**          or [sqlite3_open_v2()] is ":memory:", then an private,
**          ephemeral, in-memory database is created for the connection.
**          <todo>Is SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE required
**          in sqlite3_open_v2()?</todo>
**
** {H12719} If the filename is NULL or an empty string, then a private,
**          ephemeral on-disk database will be created.
**          <todo>Is SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE required
**          in sqlite3_open_v2()?</todo>
**
** {H12721} The [database connection] created by [sqlite3_open_v2(F,D,G,V)]
**          will use the [sqlite3_vfs] object identified by the V parameter,
**          or the default [sqlite3_vfs] object if V is a NULL pointer.
**
** {H12723} Two [database connections] will share a common cache if both were
**          opened with the same VFS while [shared cache mode] was enabled and
**          if both filenames compare equal using memcmp() after having been
**          processed by the [sqlite3_vfs | xFullPathname] method of the VFS.
*/
int sqlite3_open(
  const char *filename,   /* Database filename (UTF-8) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);
int sqlite3_open16(
  const void *filename,   /* Database filename (UTF-16) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);
int sqlite3_open_v2(
  const char *filename,   /* Database filename (UTF-8) */
  sqlite3 **ppDb,         /* OUT: SQLite db handle */
  int flags,              /* Flags */
  const char *zVfs        /* Name of VFS module to use */
);

/*
** CAPI3REF: Error Codes And Messages {H12800} <S60200>
**
** The sqlite3_errcode() interface returns the numeric [result code] or
** [extended result code] for the most recent failed sqlite3_* API call
** associated with a [database connection]. If a prior API call failed
** but the most recent API call succeeded, the return value from
** sqlite3_errcode() is undefined.  The sqlite3_extended_errcode()
** interface is the same except that it always returns the 
** [extended result code] even when extended result codes are
** disabled.
**
** The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
** text that describes the error, as either UTF-8 or UTF-16 respectively.
** Memory to hold the error message string is managed internally.
** The application does not need to worry about freeing the result.
** However, the error string might be overwritten or deallocated by
** subsequent calls to other SQLite interface functions.
**
** When the serialized [threading mode] is in use, it might be the
** case that a second error occurs on a separate thread in between
** the time of the first error and the call to these interfaces.
** When that happens, the second error will be reported since these
** interfaces always report the most recent result.  To avoid
** this, each thread can obtain exclusive use of the [database connection] D
** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
** all calls to the interfaces listed here are completed.
**
** If an interface fails with SQLITE_MISUSE, that means the interface
** was invoked incorrectly by the application.  In that case, the
** error code and message may or may not be set.
**
** INVARIANTS:
**
** {H12801} The [sqlite3_errcode(D)] interface returns the numeric
**          [result code] or [extended result code] for the most recently
**          failed interface call associated with the [database connection] D.
**
** {H12802} The [sqlite3_extended_errcode(D)] interface returns the numeric
**          [extended result code] for the most recently
**          failed interface call associated with the [database connection] D.
**
** {H12803} The [sqlite3_errmsg(D)] and [sqlite3_errmsg16(D)]
**          interfaces return English-language text that describes
**          the error in the mostly recently failed interface call,
**          encoded as either UTF-8 or UTF-16 respectively.
**
** {H12807} The strings returned by [sqlite3_errmsg()] and [sqlite3_errmsg16()]
**          are valid until the next SQLite interface call.
**
** {H12808} Calls to API routines that do not return an error code
**          (example: [sqlite3_data_count()]) do not
**          change the error code or message returned by
**          [sqlite3_errcode()], [sqlite3_extended_errcode()],
**          [sqlite3_errmsg()], or [sqlite3_errmsg16()].
**
** {H12809} Interfaces that are not associated with a specific
**          [database connection] (examples:
**          [sqlite3_mprintf()] or [sqlite3_enable_shared_cache()]
**          do not change the values returned by
**          [sqlite3_errcode()], [sqlite3_extended_errcode()],
**          [sqlite3_errmsg()], or [sqlite3_errmsg16()].
*/
int sqlite3_errcode(sqlite3 *db);
int sqlite3_extended_errcode(sqlite3 *db);
const char *sqlite3_errmsg(sqlite3*);
const void *sqlite3_errmsg16(sqlite3*);

/*
** CAPI3REF: SQL Statement Object {H13000} <H13010>
** KEYWORDS: {prepared statement} {prepared statements}
**
** An instance of this object represents a single SQL statement.
** This object is variously known as a "prepared statement" or a
** "compiled SQL statement" or simply as a "statement".
**
** The life of a statement object goes something like this:
**
** <ol>
** <li> Create the object using [sqlite3_prepare_v2()] or a related
**      function.
** <li> Bind values to [host parameters] using the sqlite3_bind_*()
**      interfaces.
** <li> Run the SQL by calling [sqlite3_step()] one or more times.
** <li> Reset the statement using [sqlite3_reset()] then go back
**      to step 2.  Do this zero or more times.
** <li> Destroy the object using [sqlite3_finalize()].
** </ol>
**
** Refer to documentation on individual methods above for additional
** information.
*/
typedef struct sqlite3_stmt sqlite3_stmt;

/*
** CAPI3REF: Run-time Limits {H12760} <S20600>
**
** This interface allows the size of various constructs to be limited
** on a connection by connection basis.  The first parameter is the
** [database connection] whose limit is to be set or queried.  The
** second parameter is one of the [limit categories] that define a
** class of constructs to be size limited.  The third parameter is the
** new limit for that construct.  The function returns the old limit.
**
** If the new limit is a negative number, the limit is unchanged.
** For the limit category of SQLITE_LIMIT_XYZ there is a 
** [limits | hard upper bound]
** set by a compile-time C preprocessor macro named 
** [limits | SQLITE_MAX_XYZ].
** (The "_LIMIT_" in the name is changed to "_MAX_".)
** Attempts to increase a limit above its hard upper bound are
** silently truncated to the hard upper limit.
**
** Run time limits are intended for use in applications that manage
** both their own internal database and also databases that are controlled
** by untrusted external sources.  An example application might be a
** web browser that has its own databases for storing history and
** separate databases controlled by JavaScript applications downloaded
** off the Internet.  The internal databases can be given the
** large, default limits.  Databases managed by external sources can
** be given much smaller limits designed to prevent a denial of service
** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
** interface to further control untrusted SQL.  The size of the database
** created by an untrusted script can be contained using the
** [max_page_count] [PRAGMA].
**
** New run-time limit categories may be added in future releases.
**
** INVARIANTS:
**
** {H12762} A successful call to [sqlite3_limit(D,C,V)] where V is
**          positive changes the limit on the size of construct C in the
**          [database connection] D to the lesser of V and the hard upper
**          bound on the size of C that is set at compile-time.
**
** {H12766} A successful call to [sqlite3_limit(D,C,V)] where V is negative
**          leaves the state of the [database connection] D unchanged.
**
** {H12769} A successful call to [sqlite3_limit(D,C,V)] returns the
**          value of the limit on the size of construct C in the
**          [database connection] D as it was prior to the call.
*/
int sqlite3_limit(sqlite3*, int id, int newVal);

/*
** CAPI3REF: Run-Time Limit Categories {H12790} <H12760>
** KEYWORDS: {limit category} {limit categories}
**
** These constants define various performance limits
** that can be lowered at run-time using [sqlite3_limit()].
** The synopsis of the meanings of the various limits is shown below.
** Additional information is available at [limits | Limits in SQLite].
**
** <dl>
** <dt>SQLITE_LIMIT_LENGTH</dt>
** <dd>The maximum size of any string or BLOB or table row.<dd>
**
** <dt>SQLITE_LIMIT_SQL_LENGTH</dt>
** <dd>The maximum length of an SQL statement.</dd>
**
** <dt>SQLITE_LIMIT_COLUMN</dt>
** <dd>The maximum number of columns in a table definition or in the
** result set of a [SELECT] or the maximum number of columns in an index
** or in an ORDER BY or GROUP BY clause.</dd>
**
** <dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
** <dd>The maximum depth of the parse tree on any expression.</dd>
**
** <dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
** <dd>The maximum number of terms in a compound SELECT statement.</dd>
**
** <dt>SQLITE_LIMIT_VDBE_OP</dt>
** <dd>The maximum number of instructions in a virtual machine program
** used to implement an SQL statement.</dd>
**
** <dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
** <dd>The maximum number of arguments on a function.</dd>
**
** <dt>SQLITE_LIMIT_ATTACHED</dt>
** <dd>The maximum number of [ATTACH | attached databases].</dd>
**
** <dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
** <dd>The maximum length of the pattern argument to the [LIKE] or
** [GLOB] operators.</dd>
**
** <dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
** <dd>The maximum number of variables in an SQL statement that can
** be bound.</dd>
** </dl>
*/
#define SQLITE_LIMIT_LENGTH                    0
#define SQLITE_LIMIT_SQL_LENGTH                1
#define SQLITE_LIMIT_COLUMN                    2
#define SQLITE_LIMIT_EXPR_DEPTH                3
#define SQLITE_LIMIT_COMPOUND_SELECT           4
#define SQLITE_LIMIT_VDBE_OP                   5
#define SQLITE_LIMIT_FUNCTION_ARG              6
#define SQLITE_LIMIT_ATTACHED                  7
#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
#define SQLITE_LIMIT_VARIABLE_NUMBER           9

/*
** CAPI3REF: Compiling An SQL Statement {H13010} <S10000>
** KEYWORDS: {SQL statement compiler}
**
** To execute an SQL query, it must first be compiled into a byte-code
** program using one of these routines.
**
** The first argument, "db", is a [database connection] obtained from a
** prior call to [sqlite3_open()], [sqlite3_open_v2()] or [sqlite3_open16()].
**
** The second argument, "zSql", is the statement to be compiled, encoded
** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
** use UTF-16.
**
** If the nByte argument is less than zero, then zSql is read up to the
** first zero terminator. If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes.
**
** *pzTail is made to point to the first byte past the end of the
** first SQL statement in zSql.  These routines only compile the first
** statement in zSql, so *pzTail is left pointing to what remains
** uncompiled.
**
** *ppStmt is left pointing to a compiled [prepared statement] that can be
** executed using [sqlite3_step()].  If there is an error, *ppStmt is set
** to NULL.  If the input text contains no SQL (if the input is an empty
** string or a comment) then *ppStmt is set to NULL.
** {A13018} The calling procedure is responsible for deleting the compiled
** SQL statement using [sqlite3_finalize()] after it has finished with it.
**
** On success, [SQLITE_OK] is returned, otherwise an [error code] is returned.
**
** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
** recommended for all new programs. The two older interfaces are retained
** for backwards compatibility, but their use is discouraged.
** In the "v2" interfaces, the prepared statement
** that is returned (the [sqlite3_stmt] object) contains a copy of the
** original SQL text. This causes the [sqlite3_step()] interface to
** behave a differently in two ways:
**
** <ol>
** <li>
** If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
** always used to do, [sqlite3_step()] will automatically recompile the SQL
** statement and try to run it again.  If the schema has changed in
** a way that makes the statement no longer valid, [sqlite3_step()] will still
** return [SQLITE_SCHEMA].  But unlike the legacy behavior, [SQLITE_SCHEMA] is
** now a fatal error.  Calling [sqlite3_prepare_v2()] again will not make the
** error go away.  Note: use [sqlite3_errmsg()] to find the text
** of the parsing error that results in an [SQLITE_SCHEMA] return.
** </li>
**
** <li>
** When an error occurs, [sqlite3_step()] will return one of the detailed
** [error codes] or [extended error codes].  The legacy behavior was that
** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
** and you would have to make a second call to [sqlite3_reset()] in order
** to find the underlying cause of the problem. With the "v2" prepare
** interfaces, the underlying reason for the error is returned immediately.
** </li>
** </ol>
**
** INVARIANTS:
**
** {H13011} The [sqlite3_prepare(db,zSql,...)] and
**          [sqlite3_prepare_v2(db,zSql,...)] interfaces interpret the
**          text in their zSql parameter as UTF-8.
**
** {H13012} The [sqlite3_prepare16(db,zSql,...)] and
**          [sqlite3_prepare16_v2(db,zSql,...)] interfaces interpret the
**          text in their zSql parameter as UTF-16 in the native byte order.
**
** {H13013} If the nByte argument to [sqlite3_prepare_v2(db,zSql,nByte,...)]
**          and its variants is less than zero, the SQL text is
**          read from zSql is read up to the first zero terminator.
**
** {H13014} If the nByte argument to [sqlite3_prepare_v2(db,zSql,nByte,...)]
**          and its variants is non-negative, then at most nBytes bytes of
**          SQL text is read from zSql.
**
** {H13015} In [sqlite3_prepare_v2(db,zSql,N,P,pzTail)] and its variants
**          if the zSql input text contains more than one SQL statement
**          and pzTail is not NULL, then *pzTail is made to point to the
**          first byte past the end of the first SQL statement in zSql.
**          <todo>What does *pzTail point to if there is one statement?</todo>
**
** {H13016} A successful call to [sqlite3_prepare_v2(db,zSql,N,ppStmt,...)]
**          or one of its variants writes into *ppStmt a pointer to a new
**          [prepared statement] or a pointer to NULL if zSql contains
**          nothing other than whitespace or comments.
**
** {H13019} The [sqlite3_prepare_v2()] interface and its variants return
**          [SQLITE_OK] or an appropriate [error code] upon failure.
**
** {H13021} Before [sqlite3_prepare(db,zSql,nByte,ppStmt,pzTail)] or its
**          variants returns an error (any value other than [SQLITE_OK]),
**          they first set *ppStmt to NULL.
*/
int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
);
int sqlite3_prepare_v2(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
);
int sqlite3_prepare16(
  sqlite3 *db,            /* Database handle */
  const void *zSql,       /* SQL statement, UTF-16 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
);
int sqlite3_prepare16_v2(
  sqlite3 *db,            /* Database handle */
  const void *zSql,       /* SQL statement, UTF-16 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
);

/*
** CAPI3REF: Retrieving Statement SQL {H13100} <H13000>
**
** This interface can be used to retrieve a saved copy of the original
** SQL text used to create a [prepared statement] if that statement was
** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
**
** INVARIANTS:
**
** {H13101} If the [prepared statement] passed as the argument to
**          [sqlite3_sql()] was compiled using either [sqlite3_prepare_v2()] or
**          [sqlite3_prepare16_v2()], then [sqlite3_sql()] returns
**          a pointer to a zero-terminated string containing a UTF-8 rendering
**          of the original SQL statement.
**
** {H13102} If the [prepared statement] passed as the argument to
**          [sqlite3_sql()] was compiled using either [sqlite3_prepare()] or
**          [sqlite3_prepare16()], then [sqlite3_sql()] returns a NULL pointer.
**
** {H13103} The string returned by [sqlite3_sql(S)] is valid until the
**          [prepared statement] S is deleted using [sqlite3_finalize(S)].
*/
const char *sqlite3_sql(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Dynamically Typed Value Object {H15000} <S20200>
** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
**
** SQLite uses the sqlite3_value object to represent all values
** that can be stored in a database table. SQLite uses dynamic typing
** for the values it stores. Values stored in sqlite3_value objects
** can be integers, floating point values, strings, BLOBs, or NULL.
**
** An sqlite3_value object may be either "protected" or "unprotected".
** Some interfaces require a protected sqlite3_value.  Other interfaces
** will accept either a protected or an unprotected sqlite3_value.
** Every interface that accepts sqlite3_value arguments specifies
** whether or not it requires a protected sqlite3_value.
**
** The terms "protected" and "unprotected" refer to whether or not
** a mutex is held.  A internal mutex is held for a protected
** sqlite3_value object but no mutex is held for an unprotected
** sqlite3_value object.  If SQLite is compiled to be single-threaded
** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
** or if SQLite is run in one of reduced mutex modes 
** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
** then there is no distinction between protected and unprotected
** sqlite3_value objects and they can be used interchangeably.  However,
** for maximum code portability it is recommended that applications
** still make the distinction between between protected and unprotected
** sqlite3_value objects even when not strictly required.
**
** The sqlite3_value objects that are passed as parameters into the
** implementation of [application-defined SQL functions] are protected.
** The sqlite3_value object returned by
** [sqlite3_column_value()] is unprotected.
** Unprotected sqlite3_value objects may only be used with
** [sqlite3_result_value()] and [sqlite3_bind_value()].
** The [sqlite3_value_blob | sqlite3_value_type()] family of
** interfaces require protected sqlite3_value objects.
*/
typedef struct Mem sqlite3_value;

/*
** CAPI3REF: SQL Function Context Object {H16001} <S20200>
**
** The context in which an SQL function executes is stored in an
** sqlite3_context object.  A pointer to an sqlite3_context object
** is always first parameter to [application-defined SQL functions].
** The application-defined SQL function implementation will pass this
** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
** [sqlite3_aggregate_context()], [sqlite3_user_data()],
** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
** and/or [sqlite3_set_auxdata()].
*/
typedef struct sqlite3_context sqlite3_context;

/*
** CAPI3REF: Binding Values To Prepared Statements {H13500} <S70300>
** KEYWORDS: {host parameter} {host parameters} {host parameter name}
** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
**
** In the SQL strings input to [sqlite3_prepare_v2()] and its variants,
** literals may be replaced by a parameter in one of these forms:
**
** <ul>
** <li>  ?
** <li>  ?NNN
** <li>  :VVV
** <li>  @VVV
** <li>  $VVV
** </ul>
**
** In the parameter forms shown above NNN is an integer literal,
** and VVV is an alpha-numeric parameter name. The values of these
** parameters (also called "host parameter names" or "SQL parameters")
** can be set using the sqlite3_bind_*() routines defined here.
**
** The first argument to the sqlite3_bind_*() routines is always
** a pointer to the [sqlite3_stmt] object returned from
** [sqlite3_prepare_v2()] or its variants.
**
** The second argument is the index of the SQL parameter to be set.
** The leftmost SQL parameter has an index of 1.  When the same named
** SQL parameter is used more than once, second and subsequent
** occurrences have the same index as the first occurrence.
** The index for named parameters can be looked up using the
** [sqlite3_bind_parameter_index()] API if desired.  The index
** for "?NNN" parameters is the value of NNN.
** The NNN value must be between 1 and the [sqlite3_limit()]
** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
**
** The third argument is the value to bind to the parameter.
**
** In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.
** If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.
**
** The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it. If the fifth argument is
** the special value [SQLITE_STATIC], then SQLite assumes that the
** information is in static, unmanaged space and does not need to be freed.
** If the fifth argument has the value [SQLITE_TRANSIENT], then
** SQLite makes its own private copy of the data immediately, before
** the sqlite3_bind_*() routine returns.
**
** The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
** is filled with zeroes.  A zeroblob uses a fixed amount of memory
** (just an integer to hold its size) while it is being processed.
** Zeroblobs are intended to serve as placeholders for BLOBs whose
** content is later written using
** [sqlite3_blob_open | incremental BLOB I/O] routines.
** A negative value for the zeroblob results in a zero-length BLOB.
**
** The sqlite3_bind_*() routines must be called after
** [sqlite3_prepare_v2()] (and its variants) or [sqlite3_reset()] and
** before [sqlite3_step()].
** Bindings are not cleared by the [sqlite3_reset()] routine.
** Unbound parameters are interpreted as NULL.
**
** These routines return [SQLITE_OK] on success or an error code if
** anything goes wrong.  [SQLITE_RANGE] is returned if the parameter
** index is out of range.  [SQLITE_NOMEM] is returned if malloc() fails.
** [SQLITE_MISUSE] might be returned if these routines are called on a
** virtual machine that is the wrong state or which has already been finalized.
** Detection of misuse is unreliable.  Applications should not depend
** on SQLITE_MISUSE returns.  SQLITE_MISUSE is intended to indicate a
** a logic error in the application.  Future versions of SQLite might
** panic rather than return SQLITE_MISUSE.
**
** See also: [sqlite3_bind_parameter_count()],
** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
**
** INVARIANTS:
**
** {H13506} The [SQL statement compiler] recognizes tokens of the forms
**          "?", "?NNN", "$VVV", ":VVV", and "@VVV" as SQL parameters,
**          where NNN is any sequence of one or more digits
**          and where VVV is any sequence of one or more alphanumeric
**          characters or "::" optionally followed by a string containing
**          no spaces and contained within parentheses.
**
** {H13509} The initial value of an SQL parameter is NULL.
**
** {H13512} The index of an "?" SQL parameter is one larger than the
**          largest index of SQL parameter to the left, or 1 if
**          the "?" is the leftmost SQL parameter.
**
** {H13515} The index of an "?NNN" SQL parameter is the integer NNN.
**
** {H13518} The index of an ":VVV", "$VVV", or "@VVV" SQL parameter is
**          the same as the index of leftmost occurrences of the same
**          parameter, or one more than the largest index over all
**          parameters to the left if this is the first occurrence
**          of this parameter, or 1 if this is the leftmost parameter.
**
** {H13521} The [SQL statement compiler] fails with an [SQLITE_RANGE]
**          error if the index of an SQL parameter is less than 1
**          or greater than the compile-time SQLITE_MAX_VARIABLE_NUMBER
**          parameter.
**
** {H13524} Calls to [sqlite3_bind_text | sqlite3_bind(S,N,V,...)]
**          associate the value V with all SQL parameters having an
**          index of N in the [prepared statement] S.
**
** {H13527} Calls to [sqlite3_bind_text | sqlite3_bind(S,N,...)]
**          override prior calls with the same values of S and N.
**
** {H13530} Bindings established by [sqlite3_bind_text | sqlite3_bind(S,...)]
**          persist across calls to [sqlite3_reset(S)].
**
** {H13533} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
**          [sqlite3_bind_text(S,N,V,L,D)], or
**          [sqlite3_bind_text16(S,N,V,L,D)] SQLite binds the first L
**          bytes of the BLOB or string pointed to by V, when L
**          is non-negative.
**
** {H13536} In calls to [sqlite3_bind_text(S,N,V,L,D)] or
**          [sqlite3_bind_text16(S,N,V,L,D)] SQLite binds characters
**          from V through the first zero character when L is negative.
**
** {H13539} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
**          [sqlite3_bind_text(S,N,V,L,D)], or
**          [sqlite3_bind_text16(S,N,V,L,D)] when D is the special
**          constant [SQLITE_STATIC], SQLite assumes that the value V
**          is held in static unmanaged space that will not change
**          during the lifetime of the binding.
**
** {H13542} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
**          [sqlite3_bind_text(S,N,V,L,D)], or
**          [sqlite3_bind_text16(S,N,V,L,D)] when D is the special
**          constant [SQLITE_TRANSIENT], the routine makes a
**          private copy of the value V before it returns.
**
** {H13545} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
**          [sqlite3_bind_text(S,N,V,L,D)], or
**          [sqlite3_bind_text16(S,N,V,L,D)] when D is a pointer to
**          a function, SQLite invokes that function to destroy the
**          value V after it has finished using the value V.
**
** {H13548} In calls to [sqlite3_bind_zeroblob(S,N,V,L)] the value bound
**          is a BLOB of L bytes, or a zero-length BLOB if L is negative.
**
** {H13551} In calls to [sqlite3_bind_value(S,N,V)] the V argument may
**          be either a [protected sqlite3_value] object or an
**          [unprotected sqlite3_value] object.
*/
int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
int sqlite3_bind_double(sqlite3_stmt*, int, double);
int sqlite3_bind_int(sqlite3_stmt*, int, int);
int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
int sqlite3_bind_null(sqlite3_stmt*, int);
int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);

/*
** CAPI3REF: Number Of SQL Parameters {H13600} <S70300>
**
** This routine can be used to find the number of [SQL parameters]
** in a [prepared statement].  SQL parameters are tokens of the
** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
** placeholders for values that are [sqlite3_bind_blob | bound]
** to the parameters at a later time.
**
** This routine actually returns the index of the largest (rightmost)
** parameter. For all forms except ?NNN, this will correspond to the
** number of unique parameters.  If parameters of the ?NNN are used,
** there may be gaps in the list.
**
** See also: [sqlite3_bind_blob|sqlite3_bind()],
** [sqlite3_bind_parameter_name()], and
** [sqlite3_bind_parameter_index()].
**
** INVARIANTS:
**
** {H13601} The [sqlite3_bind_parameter_count(S)] interface returns
**          the largest index of all SQL parameters in the
**          [prepared statement] S, or 0 if S contains no SQL parameters.
*/
int sqlite3_bind_parameter_count(sqlite3_stmt*);

/*
** CAPI3REF: Name Of A Host Parameter {H13620} <S70300>
**
** This routine returns a pointer to the name of the n-th
** [SQL parameter] in a [prepared statement].
** SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
** respectively.
** In other words, the initial ":" or "$" or "@" or "?"
** is included as part of the name.
** Parameters of the form "?" without a following integer have no name
** and are also referred to as "anonymous parameters".
**
** The first host parameter has an index of 1, not 0.
**
** If the value n is out of range or if the n-th parameter is
** nameless, then NULL is returned.  The returned string is
** always in UTF-8 encoding even if the named parameter was
** originally specified as UTF-16 in [sqlite3_prepare16()] or
** [sqlite3_prepare16_v2()].
**
** See also: [sqlite3_bind_blob|sqlite3_bind()],
** [sqlite3_bind_parameter_count()], and
** [sqlite3_bind_parameter_index()].
**
** INVARIANTS:
**
** {H13621} The [sqlite3_bind_parameter_name(S,N)] interface returns
**          a UTF-8 rendering of the name of the SQL parameter in
**          the [prepared statement] S having index N, or
**          NULL if there is no SQL parameter with index N or if the
**          parameter with index N is an anonymous parameter "?".
*/
const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);

/*
** CAPI3REF: Index Of A Parameter With A Given Name {H13640} <S70300>
**
** Return the index of an SQL parameter given its name.  The
** index value returned is suitable for use as the second
** parameter to [sqlite3_bind_blob|sqlite3_bind()].  A zero
** is returned if no matching parameter is found.  The parameter
** name must be given in UTF-8 even if the original statement
** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
**
** See also: [sqlite3_bind_blob|sqlite3_bind()],
** [sqlite3_bind_parameter_count()], and
** [sqlite3_bind_parameter_index()].
**
** INVARIANTS:
**
** {H13641} The [sqlite3_bind_parameter_index(S,N)] interface returns
**          the index of SQL parameter in the [prepared statement]
**          S whose name matches the UTF-8 string N, or 0 if there is
**          no match.
*/
int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);

/*
** CAPI3REF: Reset All Bindings On A Prepared Statement {H13660} <S70300>
**
** Contrary to the intuition of many, [sqlite3_reset()] does not reset
** the [sqlite3_bind_blob | bindings] on a [prepared statement].
** Use this routine to reset all host parameters to NULL.
**
** INVARIANTS:
**
** {H13661} The [sqlite3_clear_bindings(S)] interface resets all SQL
**          parameter bindings in the [prepared statement] S back to NULL.
*/
int sqlite3_clear_bindings(sqlite3_stmt*);

/*
** CAPI3REF: Number Of Columns In A Result Set {H13710} <S10700>
**
** Return the number of columns in the result set returned by the
** [prepared statement]. This routine returns 0 if pStmt is an SQL
** statement that does not return data (for example an [UPDATE]).
**
** INVARIANTS:
**
** {H13711} The [sqlite3_column_count(S)] interface returns the number of
**          columns in the result set generated by the [prepared statement] S,
**          or 0 if S does not generate a result set.
*/
int sqlite3_column_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Column Names In A Result Set {H13720} <S10700>
**
** These routines return the name assigned to a particular column
** in the result set of a [SELECT] statement.  The sqlite3_column_name()
** interface returns a pointer to a zero-terminated UTF-8 string
** and sqlite3_column_name16() returns a pointer to a zero-terminated
** UTF-16 string.  The first parameter is the [prepared statement]
** that implements the [SELECT] statement. The second parameter is the
** column number.  The leftmost column is number 0.
**
** The returned string pointer is valid until either the [prepared statement]
** is destroyed by [sqlite3_finalize()] or until the next call to
** sqlite3_column_name() or sqlite3_column_name16() on the same column.
**
** If sqlite3_malloc() fails during the processing of either routine
** (for example during a conversion from UTF-8 to UTF-16) then a
** NULL pointer is returned.
**
** The name of a result column is the value of the "AS" clause for
** that column, if there is an AS clause.  If there is no AS clause
** then the name of the column is unspecified and may change from
** one release of SQLite to the next.
**
** INVARIANTS:
**
** {H13721} A successful invocation of the [sqlite3_column_name(S,N)]
**          interface returns the name of the Nth column (where 0 is
**          the leftmost column) for the result set of the
**          [prepared statement] S as a zero-terminated UTF-8 string.
**
** {H13723} A successful invocation of the [sqlite3_column_name16(S,N)]
**          interface returns the name of the Nth column (where 0 is
**          the leftmost column) for the result set of the
**          [prepared statement] S as a zero-terminated UTF-16 string
**          in the native byte order.
**
** {H13724} The [sqlite3_column_name()] and [sqlite3_column_name16()]
**          interfaces return a NULL pointer if they are unable to
**          allocate memory to hold their normal return strings.
**
** {H13725} If the N parameter to [sqlite3_column_name(S,N)] or
**          [sqlite3_column_name16(S,N)] is out of range, then the
**          interfaces return a NULL pointer.
**
** {H13726} The strings returned by [sqlite3_column_name(S,N)] and
**          [sqlite3_column_name16(S,N)] are valid until the next
**          call to either routine with the same S and N parameters
**          or until [sqlite3_finalize(S)] is called.
**
** {H13727} When a result column of a [SELECT] statement contains
**          an AS clause, the name of that column is the identifier
**          to the right of the AS keyword.
*/
const char *sqlite3_column_name(sqlite3_stmt*, int N);
const void *sqlite3_column_name16(sqlite3_stmt*, int N);

/*
** CAPI3REF: Source Of Data In A Query Result {H13740} <S10700>
**
** These routines provide a means to determine what column of what
** table in which database a result of a [SELECT] statement comes from.
** The name of the database or table or column can be returned as
** either a UTF-8 or UTF-16 string.  The _database_ routines return
** the database name, the _table_ routines return the table name, and
** the origin_ routines return the column name.
** The returned string is valid until the [prepared statement] is destroyed
** using [sqlite3_finalize()] or until the same information is requested
** again in a different encoding.
**
** The names returned are the original un-aliased names of the
** database, table, and column.
**
** The first argument to the following calls is a [prepared statement].
** These functions return information about the Nth column returned by
** the statement, where N is the second function argument.
**
** If the Nth column returned by the statement is an expression or
** subquery and is not a column value, then all of these functions return
** NULL.  These routine might also return NULL if a memory allocation error
** occurs.  Otherwise, they return the name of the attached database, table
** and column that query result column was extracted from.
**
** As with all other SQLite APIs, those postfixed with "16" return
** UTF-16 encoded strings, the other functions return UTF-8. {END}
**
** These APIs are only available if the library was compiled with the
** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
**
** {A13751}
** If two or more threads call one or more of these routines against the same
** prepared statement and column at the same time then the results are
** undefined.
**
** INVARIANTS:
**
** {H13741} The [sqlite3_column_database_name(S,N)] interface returns either
**          the UTF-8 zero-terminated name of the database from which the
**          Nth result column of the [prepared statement] S is extracted,
**          or NULL if the Nth column of S is a general expression
**          or if unable to allocate memory to store the name.
**
** {H13742} The [sqlite3_column_database_name16(S,N)] interface returns either
**          the UTF-16 native byte order zero-terminated name of the database
**          from which the Nth result column of the [prepared statement] S is
**          extracted, or NULL if the Nth column of S is a general expression
**          or if unable to allocate memory to store the name.
**
** {H13743} The [sqlite3_column_table_name(S,N)] interface returns either
**          the UTF-8 zero-terminated name of the table from which the
**          Nth result column of the [prepared statement] S is extracted,
**          or NULL if the Nth column of S is a general expression
**          or if unable to allocate memory to store the name.
**
** {H13744} The [sqlite3_column_table_name16(S,N)] interface returns either
**          the UTF-16 native byte order zero-terminated name of the table
**          from which the Nth result column of the [prepared statement] S is
**          extracted, or NULL if the Nth column of S is a general expression
**          or if unable to allocate memory to store the name.
**
** {H13745} The [sqlite3_column_origin_name(S,N)] interface returns either
**          the UTF-8 zero-terminated name of the table column from which the
**          Nth result column of the [prepared statement] S is extracted,
**          or NULL if the Nth column of S is a general expression
**          or if unable to allocate memory to store the name.
**
** {H13746} The [sqlite3_column_origin_name16(S,N)] interface returns either
**          the UTF-16 native byte order zero-terminated name of the table
**          column from which the Nth result column of the
**          [prepared statement] S is extracted, or NULL if the Nth column
**          of S is a general expression or if unable to allocate memory
**          to store the name.
**
** {H13748} The return values from
**          [sqlite3_column_database_name | column metadata interfaces]
**          are valid for the lifetime of the [prepared statement]
**          or until the encoding is changed by another metadata
**          interface call for the same prepared statement and column.
**
** ASSUMPTIONS:
**
** {A13751} If two or more threads call one or more
**          [sqlite3_column_database_name | column metadata interfaces]
**          for the same [prepared statement] and result column
**          at the same time then the results are undefined.
*/
const char *sqlite3_column_database_name(sqlite3_stmt*,int);
const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
const char *sqlite3_column_table_name(sqlite3_stmt*,int);
const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);

/*
** CAPI3REF: Declared Datatype Of A Query Result {H13760} <S10700>
**
** The first parameter is a [prepared statement].
** If this statement is a [SELECT] statement and the Nth column of the
** returned result set of that [SELECT] is a table column (not an
** expression or subquery) then the declared type of the table
** column is returned.  If the Nth column of the result set is an
** expression or subquery, then a NULL pointer is returned.
** The returned string is always UTF-8 encoded. {END}
**
** For example, given the database schema:
**
** CREATE TABLE t1(c1 VARIANT);
**
** and the following statement to be compiled:
**
** SELECT c1 + 1, c1 FROM t1;
**
** this routine would return the string "VARIANT" for the second result
** column (i==1), and a NULL pointer for the first result column (i==0).
**
** SQLite uses dynamic run-time typing.  So just because a column
** is declared to contain a particular type does not mean that the
** data stored in that column is of the declared type.  SQLite is
** strongly typed, but the typing is dynamic not static.  Type
** is associated with individual values, not with the containers
** used to hold those values.
**
** INVARIANTS:
**
** {H13761}  A successful call to [sqlite3_column_decltype(S,N)] returns a
**           zero-terminated UTF-8 string containing the declared datatype
**           of the table column that appears as the Nth column (numbered
**           from 0) of the result set to the [prepared statement] S.
**
** {H13762}  A successful call to [sqlite3_column_decltype16(S,N)]
**           returns a zero-terminated UTF-16 native byte order string
**           containing the declared datatype of the table column that appears
**           as the Nth column (numbered from 0) of the result set to the
**           [prepared statement] S.
**
** {H13763}  If N is less than 0 or N is greater than or equal to
**           the number of columns in the [prepared statement] S,
**           or if the Nth column of S is an expression or subquery rather
**           than a table column, or if a memory allocation failure
**           occurs during encoding conversions, then
**           calls to [sqlite3_column_decltype(S,N)] or
**           [sqlite3_column_decltype16(S,N)] return NULL.
*/
const char *sqlite3_column_decltype(sqlite3_stmt*,int);
const void *sqlite3_column_decltype16(sqlite3_stmt*,int);

/*
** CAPI3REF: Evaluate An SQL Statement {H13200} <S10000>
**
** After a [prepared statement] has been prepared using either
** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
** must be called one or more times to evaluate the statement.
**
** The details of the behavior of the sqlite3_step() interface depend
** on whether the statement was prepared using the newer "v2" interface
** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
** new "v2" interface is recommended for new applications but the legacy
** interface will continue to be supported.
**
** In the legacy interface, the return value will be either [SQLITE_BUSY],
** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
** With the "v2" interface, any of the other [result codes] or
** [extended result codes] might be returned as well.
**
** [SQLITE_BUSY] means that the database engine was unable to acquire the
** database locks it needs to do its job.  If the statement is a [COMMIT]
** or occurs outside of an explicit transaction, then you can retry the
** statement.  If the statement is not a [COMMIT] and occurs within a
** explicit transaction then you should rollback the transaction before
** continuing.
**
** [SQLITE_DONE] means that the statement has finished executing
** successfully.  sqlite3_step() should not be called again on this virtual
** machine without first calling [sqlite3_reset()] to reset the virtual
** machine back to its initial state.
**
** If the SQL statement being executed returns any data, then [SQLITE_ROW]
** is returned each time a new row of data is ready for processing by the
** caller. The values may be accessed using the [column access functions].
** sqlite3_step() is called again to retrieve the next row of data.
**
** [SQLITE_ERROR] means that a run-time error (such as a constraint
** violation) has occurred.  sqlite3_step() should not be called again on
** the VM. More information may be found by calling [sqlite3_errmsg()].
** With the legacy interface, a more specific error code (for example,
** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
** can be obtained by calling [sqlite3_reset()] on the
** [prepared statement].  In the "v2" interface,
** the more specific error code is returned directly by sqlite3_step().
**
** [SQLITE_MISUSE] means that the this routine was called inappropriately.
** Perhaps it was called on a [prepared statement] that has
** already been [sqlite3_finalize | finalized] or on one that had
** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
** be the case that the same database connection is being used by two or
** more threads at the same moment in time.
**
** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
** API always returns a generic error code, [SQLITE_ERROR], following any
** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
** specific [error codes] that better describes the error.
** We admit that this is a goofy design.  The problem has been fixed
** with the "v2" interface.  If you prepare all of your SQL statements
** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
** then the more specific [error codes] are returned directly
** by sqlite3_step().  The use of the "v2" interface is recommended.
**
** INVARIANTS:
**
** {H13202}  If the [prepared statement] S is ready to be run, then
**           [sqlite3_step(S)] advances that prepared statement until
**           completion or until it is ready to return another row of the
**           result set, or until an [sqlite3_interrupt | interrupt]
**           or a run-time error occurs.
**
** {H15304}  When a call to [sqlite3_step(S)] causes the [prepared statement]
**           S to run to completion, the function returns [SQLITE_DONE].
**
** {H15306}  When a call to [sqlite3_step(S)] stops because it is ready to
**           return another row of the result set, it returns [SQLITE_ROW].
**
** {H15308}  If a call to [sqlite3_step(S)] encounters an
**           [sqlite3_interrupt | interrupt] or a run-time error,
**           it returns an appropriate error code that is not one of
**           [SQLITE_OK], [SQLITE_ROW], or [SQLITE_DONE].
**
** {H15310}  If an [sqlite3_interrupt | interrupt] or a run-time error
**           occurs during a call to [sqlite3_step(S)]
**           for a [prepared statement] S created using
**           legacy interfaces [sqlite3_prepare()] or
**           [sqlite3_prepare16()], then the function returns either
**           [SQLITE_ERROR], [SQLITE_BUSY], or [SQLITE_MISUSE].
*/
int sqlite3_step(sqlite3_stmt*);

/*
** CAPI3REF: Number of columns in a result set {H13770} <S10700>
**
** Returns the number of values in the current row of the result set.
**
** INVARIANTS:
**
** {H13771}  After a call to [sqlite3_step(S)] that returns [SQLITE_ROW],
**           the [sqlite3_data_count(S)] routine will return the same value
**           as the [sqlite3_column_count(S)] function.
**
** {H13772}  After [sqlite3_step(S)] has returned any value other than
**           [SQLITE_ROW] or before [sqlite3_step(S)] has been called on the
**           [prepared statement] for the first time since it was
**           [sqlite3_prepare | prepared] or [sqlite3_reset | reset],
**           the [sqlite3_data_count(S)] routine returns zero.
*/
int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Fundamental Datatypes {H10265} <S10110><S10120>
** KEYWORDS: SQLITE_TEXT
**
** {H10266} Every value in SQLite has one of five fundamental datatypes:
**
** <ul>
** <li> 64-bit signed integer
** <li> 64-bit IEEE floating point number
** <li> string
** <li> BLOB
** <li> NULL
** </ul> {END}
**
** These constants are codes for each of those types.
**
** Note that the SQLITE_TEXT constant was also used in SQLite version 2
** for a completely different meaning.  Software that links against both
** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
** SQLITE_TEXT.
*/
#define SQLITE_INTEGER  1
#define SQLITE_FLOAT    2
#define SQLITE_BLOB     4
#define SQLITE_NULL     5
#ifdef SQLITE_TEXT
# undef SQLITE_TEXT
#else
# define SQLITE_TEXT     3
#endif
#define SQLITE3_TEXT     3

/*
** CAPI3REF: Result Values From A Query {H13800} <S10700>
** KEYWORDS: {column access functions}
**
** These routines form the "result set query" interface.
**
** These routines return information about a single column of the current
** result row of a query.  In every case the first argument is a pointer
** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
** that was returned from [sqlite3_prepare_v2()] or one of its variants)
** and the second argument is the index of the column for which information
** should be returned.  The leftmost column of the result set has the index 0.
**
** If the SQL statement does not currently point to a valid row, or if the
** column index is out of range, the result is undefined.
** These routines may only be called when the most recent call to
** [sqlite3_step()] has returned [SQLITE_ROW] and neither
** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
** If any of these routines are called after [sqlite3_reset()] or
** [sqlite3_finalize()] or after [sqlite3_step()] has returned
** something other than [SQLITE_ROW], the results are undefined.
** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
** are called from a different thread while any of these routines
** are pending, then the results are undefined.
**
** The sqlite3_column_type() routine returns the
** [SQLITE_INTEGER | datatype code] for the initial data type
** of the result column.  The returned value is one of [SQLITE_INTEGER],
** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
** returned by sqlite3_column_type() is only meaningful if no type
** conversions have occurred as described below.  After a type conversion,
** the value returned by sqlite3_column_type() is undefined.  Future
** versions of SQLite may change the behavior of sqlite3_column_type()
** following a type conversion.
**
** If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
** routine returns the number of bytes in that BLOB or string.
** If the result is a UTF-16 string, then sqlite3_column_bytes() converts
** the string to UTF-8 and then returns the number of bytes.
** If the result is a numeric value then sqlite3_column_bytes() uses
** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
** the number of bytes in that string.
** The value returned does not include the zero terminator at the end
** of the string.  For clarity: the value returned is the number of
** bytes in the string, not the number of characters.
**
** Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
** even empty strings, are always zero terminated.  The return
** value from sqlite3_column_blob() for a zero-length BLOB is an arbitrary
** pointer, possibly even a NULL pointer.
**
** The sqlite3_column_bytes16() routine is similar to sqlite3_column_bytes()
** but leaves the result in UTF-16 in native byte order instead of UTF-8.
** The zero terminator is not included in this count.
**
** The object returned by [sqlite3_column_value()] is an
** [unprotected sqlite3_value] object.  An unprotected sqlite3_value object
** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
** If the [unprotected sqlite3_value] object returned by
** [sqlite3_column_value()] is used in any other way, including calls
** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
** or [sqlite3_value_bytes()], then the behavior is undefined.
**
** These routines attempt to convert the value where appropriate.  For
** example, if the internal representation is FLOAT and a text result
** is requested, [sqlite3_snprintf()] is used internally to perform the
** conversion automatically.  The following table details the conversions
** that are applied:
**
** <blockquote>
** <table border="1">
** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
**
** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
** <tr><td>  NULL    <td>   TEXT    <td> Result is NULL pointer
** <tr><td>  NULL    <td>   BLOB    <td> Result is NULL pointer
** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
** <tr><td>  FLOAT   <td> INTEGER   <td> Convert from float to integer
** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
** <tr><td>  FLOAT   <td>   BLOB    <td> Same as FLOAT->TEXT
** <tr><td>  TEXT    <td> INTEGER   <td> Use atoi()
** <tr><td>  TEXT    <td>  FLOAT    <td> Use atof()
** <tr><td>  TEXT    <td>   BLOB    <td> No change
** <tr><td>  BLOB    <td> INTEGER   <td> Convert to TEXT then use atoi()
** <tr><td>  BLOB    <td>  FLOAT    <td> Convert to TEXT then use atof()
** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
** </table>
** </blockquote>
**
** The table above makes reference to standard C library functions atoi()
** and atof().  SQLite does not really use these functions.  It has its
** own equivalent internal routines.  The atoi() and atof() names are
** used in the table for brevity and because they are familiar to most
** C programmers.
**
** Note that when type conversions occur, pointers returned by prior
** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
** sqlite3_column_text16() may be invalidated.
** Type conversions and pointer invalidations might occur
** in the following cases:
**
** <ul>
** <li> The initial content is a BLOB and sqlite3_column_text() or
**      sqlite3_column_text16() is called.  A zero-terminator might
**      need to be added to the string.</li>
** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
**      sqlite3_column_text16() is called.  The content must be converted
**      to UTF-16.</li>
** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
**      sqlite3_column_text() is called.  The content must be converted
**      to UTF-8.</li>
** </ul>
**
** Conversions between UTF-16be and UTF-16le are always done in place and do
** not invalidate a prior pointer, though of course the content of the buffer
** that the prior pointer points to will have been modified.  Other kinds
** of conversion are done in place when it is possible, but sometimes they
** are not possible and in those cases prior pointers are invalidated.
**
** The safest and easiest to remember policy is to invoke these routines
** in one of the following ways:
**
** <ul>
**  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
**  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
**  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
** </ul>
**
** In other words, you should call sqlite3_column_text(),
** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
** into the desired format, then invoke sqlite3_column_bytes() or
** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
** to sqlite3_column_text() or sqlite3_column_blob() with calls to
** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
** with calls to sqlite3_column_bytes().
**
** The pointers returned are valid until a type conversion occurs as
** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
** [sqlite3_finalize()] is called.  The memory space used to hold strings
** and BLOBs is freed automatically.  Do <b>not</b> pass the pointers returned
** [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
** [sqlite3_free()].
**
** If a memory allocation error occurs during the evaluation of any
** of these routines, a default value is returned.  The default value
** is either the integer 0, the floating point number 0.0, or a NULL
** pointer.  Subsequent calls to [sqlite3_errcode()] will return
** [SQLITE_NOMEM].
**
** INVARIANTS:
**
** {H13803} The [sqlite3_column_blob(S,N)] interface converts the
**          Nth column in the current row of the result set for
**          the [prepared statement] S into a BLOB and then returns a
**          pointer to the converted value.
**
** {H13806} The [sqlite3_column_bytes(S,N)] interface returns the
**          number of bytes in the BLOB or string (exclusive of the
**          zero terminator on the string) that was returned by the
**          most recent call to [sqlite3_column_blob(S,N)] or
**          [sqlite3_column_text(S,N)].
**
** {H13809} The [sqlite3_column_bytes16(S,N)] interface returns the
**          number of bytes in the string (exclusive of the
**          zero terminator on the string) that was returned by the
**          most recent call to [sqlite3_column_text16(S,N)].
**
** {H13812} The [sqlite3_column_double(S,N)] interface converts the
**          Nth column in the current row of the result set for the
**          [prepared statement] S into a floating point value and
**          returns a copy of that value.
**
** {H13815} The [sqlite3_column_int(S,N)] interface converts the
**          Nth column in the current row of the result set for the
**          [prepared statement] S into a 64-bit signed integer and
**          returns the lower 32 bits of that integer.
**
** {H13818} The [sqlite3_column_int64(S,N)] interface converts the
**          Nth column in the current row of the result set for the
**          [prepared statement] S into a 64-bit signed integer and
**          returns a copy of that integer.
**
** {H13821} The [sqlite3_column_text(S,N)] interface converts the
**          Nth column in the current row of the result set for
**          the [prepared statement] S into a zero-terminated UTF-8
**          string and returns a pointer to that string.
**
** {H13824} The [sqlite3_column_text16(S,N)] interface converts the
**          Nth column in the current row of the result set for the
**          [prepared statement] S into a zero-terminated 2-byte
**          aligned UTF-16 native byte order string and returns
**          a pointer to that string.
**
** {H13827} The [sqlite3_column_type(S,N)] interface returns
**          one of [SQLITE_NULL], [SQLITE_INTEGER], [SQLITE_FLOAT],
**          [SQLITE_TEXT], or [SQLITE_BLOB] as appropriate for
**          the Nth column in the current row of the result set for
**          the [prepared statement] S.
**
** {H13830} The [sqlite3_column_value(S,N)] interface returns a
**          pointer to an [unprotected sqlite3_value] object for the
**          Nth column in the current row of the result set for
**          the [prepared statement] S.
*/
const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
double sqlite3_column_double(sqlite3_stmt*, int iCol);
int sqlite3_column_int(sqlite3_stmt*, int iCol);
sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
int sqlite3_column_type(sqlite3_stmt*, int iCol);
sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);

/*
** CAPI3REF: Destroy A Prepared Statement Object {H13300} <S70300><S30100>
**
** The sqlite3_finalize() function is called to delete a [prepared statement].
** If the statement was executed successfully or not executed at all, then
** SQLITE_OK is returned. If execution of the statement failed then an
** [error code] or [extended error code] is returned.
**
** This routine can be called at any point during the execution of the
** [prepared statement].  If the virtual machine has not
** completed execution when this routine is called, that is like
** encountering an error or an [sqlite3_interrupt | interrupt].
** Incomplete updates may be rolled back and transactions canceled,
** depending on the circumstances, and the
** [error code] returned will be [SQLITE_ABORT].
**
** INVARIANTS:
**
** {H11302} The [sqlite3_finalize(S)] interface destroys the
**          [prepared statement] S and releases all
**          memory and file resources held by that object.
**
** {H11304} If the most recent call to [sqlite3_step(S)] for the
**          [prepared statement] S returned an error,
**          then [sqlite3_finalize(S)] returns that same error.
*/
int sqlite3_finalize(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Reset A Prepared Statement Object {H13330} <S70300>
**
** The sqlite3_reset() function is called to reset a [prepared statement]
** object back to its initial state, ready to be re-executed.
** Any SQL statement variables that had values bound to them using
** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
** Use [sqlite3_clear_bindings()] to reset the bindings.
**
** {H11332} The [sqlite3_reset(S)] interface resets the [prepared statement] S
**          back to the beginning of its program.
**
** {H11334} If the most recent call to [sqlite3_step(S)] for the
**          [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
**          or if [sqlite3_step(S)] has never before been called on S,
**          then [sqlite3_reset(S)] returns [SQLITE_OK].
**
** {H11336} If the most recent call to [sqlite3_step(S)] for the
**          [prepared statement] S indicated an error, then
**          [sqlite3_reset(S)] returns an appropriate [error code].
**
** {H11338} The [sqlite3_reset(S)] interface does not change the values
**          of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
*/
int sqlite3_reset(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Create Or Redefine SQL Functions {H16100} <S20200>
** KEYWORDS: {function creation routines}
** KEYWORDS: {application-defined SQL function}
** KEYWORDS: {application-defined SQL functions}
**
** These two functions (collectively known as "function creation routines")
** are used to add SQL functions or aggregates or to redefine the behavior
** of existing SQL functions or aggregates.  The only difference between the
** two is that the second parameter, the name of the (scalar) function or
** aggregate, is encoded in UTF-8 for sqlite3_create_function() and UTF-16
** for sqlite3_create_function16().
**
** The first parameter is the [database connection] to which the SQL
** function is to be added.  If a single program uses more than one database
** connection internally, then SQL functions must be added individually to
** each database connection.
**
** The second parameter is the name of the SQL function to be created or
** redefined.  The length of the name is limited to 255 bytes, exclusive of
** the zero-terminator.  Note that the name length limit is in bytes, not
** characters.  Any attempt to create a function with a longer name
** will result in [SQLITE_ERROR] being returned.
**
** The third parameter (nArg)
** is the number of arguments that the SQL function or
** aggregate takes. If this parameter is negative, then the SQL function or
** aggregate may take any number of arguments.
**
** The fourth parameter, eTextRep, specifies what
** [SQLITE_UTF8 | text encoding] this SQL function prefers for
** its parameters.  Any SQL function implementation should be able to work
** work with UTF-8, UTF-16le, or UTF-16be.  But some implementations may be
** more efficient with one encoding than another.  It is allowed to
** invoke sqlite3_create_function() or sqlite3_create_function16() multiple
** times with the same function but with different values of eTextRep.
** When multiple implementations of the same function are available, SQLite
** will pick the one that involves the least amount of data conversion.
** If there is only a single implementation which does not care what text
** encoding is used, then the fourth argument should be [SQLITE_ANY].
**
** The fifth parameter is an arbitrary pointer.  The implementation of the
** function can gain access to this pointer using [sqlite3_user_data()].
**
** The seventh, eighth and ninth parameters, xFunc, xStep and xFinal, are
** pointers to C-language functions that implement the SQL function or
** aggregate. A scalar SQL function requires an implementation of the xFunc
** callback only, NULL pointers should be passed as the xStep and xFinal
** parameters. An aggregate SQL function requires an implementation of xStep
** and xFinal and NULL should be passed for xFunc. To delete an existing
** SQL function or aggregate, pass NULL for all three function callbacks.
**
** It is permitted to register multiple implementations of the same
** functions with the same name but with either differing numbers of
** arguments or differing preferred text encodings.  SQLite will use
** the implementation most closely matches the way in which the
** SQL function is used.  A function implementation with a non-negative
** nArg parameter is a better match than a function implementation with
** a negative nArg.  A function where the preferred text encoding
** matches the database encoding is a better
** match than a function where the encoding is different.  
** A function where the encoding difference is between UTF16le and UTF16be
** is a closer match than a function where the encoding difference is
** between UTF8 and UTF16.
**
** Built-in functions may be overloaded by new application-defined functions.
** The first application-defined function with a given name overrides all
** built-in functions in the same [database connection] with the same name.
** Subsequent application-defined functions of the same name only override 
** prior application-defined functions that are an exact match for the
** number of parameters and preferred encoding.
**
** An application-defined function is permitted to call other
** SQLite interfaces.  However, such calls must not
** close the database connection nor finalize or reset the prepared
** statement in which the function is running.
**
** INVARIANTS:
**
** {H16103} The [sqlite3_create_function16(D,X,...)] interface shall behave
**          as [sqlite3_create_function(D,X,...)] in every way except that it
**          interprets the X argument as zero-terminated UTF-16
**          native byte order instead of as zero-terminated UTF-8.
**
** {H16106} A successful invocation of the
**          [sqlite3_create_function(D,X,N,E,...)] interface shall register
**          or replaces callback functions in the [database connection] D
**          used to implement the SQL function named X with N parameters
**          and having a preferred text encoding of E.
**
** {H16109} A successful call to [sqlite3_create_function(D,X,N,E,P,F,S,L)]
**          shall replace the P, F, S, and L values from any prior calls with
**          the same D, X, N, and E values.
**
** {H16112} The [sqlite3_create_function(D,X,...)] interface shall fail
**          if the SQL function name X is
**          longer than 255 bytes exclusive of the zero terminator.
**
** {H16118} The [sqlite3_create_function(D,X,N,E,P,F,S,L)] interface
**          shall fail unless either F is NULL and S and L are non-NULL or
***         F is non-NULL and S and L are NULL.
**
** {H16121} The [sqlite3_create_function(D,...)] interface shall fails with an
**          error code of [SQLITE_BUSY] if there exist [prepared statements]
**          associated with the [database connection] D.
**
** {H16124} The [sqlite3_create_function(D,X,N,...)] interface shall fail with
**          an error code of [SQLITE_ERROR] if parameter N is less
**          than -1 or greater than 127.
**
** {H16127} When N is non-negative, the [sqlite3_create_function(D,X,N,...)]
**          interface shall register callbacks to be invoked for the
**          SQL function
**          named X when the number of arguments to the SQL function is
**          exactly N.
**
** {H16130} When N is -1, the [sqlite3_create_function(D,X,N,...)]
**          interface shall register callbacks to be invoked for the SQL
**          function named X with any number of arguments.
**
** {H16133} When calls to [sqlite3_create_function(D,X,N,...)]
**          specify multiple implementations of the same function X
**          and when one implementation has N>=0 and the other has N=(-1)
**          the implementation with a non-zero N shall be preferred.
**
** {H16136} When calls to [sqlite3_create_function(D,X,N,E,...)]
**          specify multiple implementations of the same function X with
**          the same number of arguments N but with different
**          encodings E, then the implementation where E matches the
**          database encoding shall preferred.
**
** {H16139} For an aggregate SQL function created using
**          [sqlite3_create_function(D,X,N,E,P,0,S,L)] the finalizer
**          function L shall always be invoked exactly once if the
**          step function S is called one or more times.
**
** {H16142} When SQLite invokes either the xFunc or xStep function of
**          an application-defined SQL function or aggregate created
**          by [sqlite3_create_function()] or [sqlite3_create_function16()],
**          then the array of [sqlite3_value] objects passed as the
**          third parameter shall be [protected sqlite3_value] objects.
*/
int sqlite3_create_function(
  sqlite3 *db,
  const char *zFunctionName,
  int nArg,
  int eTextRep,
  void *pApp,
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*)
);
int sqlite3_create_function16(
  sqlite3 *db,
  const void *zFunctionName,
  int nArg,
  int eTextRep,
  void *pApp,
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*)
);

/*
** CAPI3REF: Text Encodings {H10267} <S50200> <H16100>
**
** These constant define integer codes that represent the various
** text encodings supported by SQLite.
*/
#define SQLITE_UTF8           1
#define SQLITE_UTF16LE        2
#define SQLITE_UTF16BE        3
#define SQLITE_UTF16          4    /* Use native byte order */
#define SQLITE_ANY            5    /* sqlite3_create_function only */
#define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */

/*
** CAPI3REF: Deprecated Functions
** DEPRECATED
**
** These functions are [deprecated].  In order to maintain
** backwards compatibility with older code, these functions continue 
** to be supported.  However, new applications should avoid
** the use of these functions.  To help encourage people to avoid
** using these functions, we are not going to tell you what they do.
*/
#ifndef SQLITE_OMIT_DEPRECATED
SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
SQLITE_DEPRECATED int sqlite3_global_recover(void);
SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),void*,sqlite3_int64);
#endif

/*
** CAPI3REF: Obtaining SQL Function Parameter Values {H15100} <S20200>
**
** The C-language implementation of SQL functions and aggregates uses
** this set of interface routines to access the parameter values on
** the function or aggregate.
**
** The xFunc (for scalar functions) or xStep (for aggregates) parameters
** to [sqlite3_create_function()] and [sqlite3_create_function16()]
** define callbacks that implement the SQL functions and aggregates.
** The 4th parameter to these callbacks is an array of pointers to
** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
** each parameter to the SQL function.  These routines are used to
** extract values from the [sqlite3_value] objects.
**
** These routines work only with [protected sqlite3_value] objects.
** Any attempt to use these routines on an [unprotected sqlite3_value]
** object results in undefined behavior.
**
** These routines work just like the corresponding [column access functions]
** except that  these routines take a single [protected sqlite3_value] object
** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
**
** The sqlite3_value_text16() interface extracts a UTF-16 string
** in the native byte-order of the host machine.  The
** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
** extract UTF-16 strings as big-endian and little-endian respectively.
**
** The sqlite3_value_numeric_type() interface attempts to apply
** numeric affinity to the value.  This means that an attempt is
** made to convert the value to an integer or floating point.  If
** such a conversion is possible without loss of information (in other
** words, if the value is a string that looks like a number)
** then the conversion is performed.  Otherwise no conversion occurs.
** The [SQLITE_INTEGER | datatype] after conversion is returned.
**
** Please pay particular attention to the fact that the pointer returned
** from [sqlite3_value_blob()], [sqlite3_value_text()], or
** [sqlite3_value_text16()] can be invalidated by a subsequent call to
** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
** or [sqlite3_value_text16()].
**
** These routines must be called from the same thread as
** the SQL function that supplied the [sqlite3_value*] parameters.
**
** INVARIANTS:
**
** {H15103} The [sqlite3_value_blob(V)] interface converts the
**          [protected sqlite3_value] object V into a BLOB and then
**          returns a pointer to the converted value.
**
** {H15106} The [sqlite3_value_bytes(V)] interface returns the
**          number of bytes in the BLOB or string (exclusive of the
**          zero terminator on the string) that was returned by the
**          most recent call to [sqlite3_value_blob(V)] or
**          [sqlite3_value_text(V)].
**
** {H15109} The [sqlite3_value_bytes16(V)] interface returns the
**          number of bytes in the string (exclusive of the
**          zero terminator on the string) that was returned by the
**          most recent call to [sqlite3_value_text16(V)],
**          [sqlite3_value_text16be(V)], or [sqlite3_value_text16le(V)].
**
** {H15112} The [sqlite3_value_double(V)] interface converts the
**          [protected sqlite3_value] object V into a floating point value and
**          returns a copy of that value.
**
** {H15115} The [sqlite3_value_int(V)] interface converts the
**          [protected sqlite3_value] object V into a 64-bit signed integer and
**          returns the lower 32 bits of that integer.
**
** {H15118} The [sqlite3_value_int64(V)] interface converts the
**          [protected sqlite3_value] object V into a 64-bit signed integer and
**          returns a copy of that integer.
**
** {H15121} The [sqlite3_value_text(V)] interface converts the
**          [protected sqlite3_value] object V into a zero-terminated UTF-8
**          string and returns a pointer to that string.
**
** {H15124} The [sqlite3_value_text16(V)] interface converts the
**          [protected sqlite3_value] object V into a zero-terminated 2-byte
**          aligned UTF-16 native byte order
**          string and returns a pointer to that string.
**
** {H15127} The [sqlite3_value_text16be(V)] interface converts the
**          [protected sqlite3_value] object V into a zero-terminated 2-byte
**          aligned UTF-16 big-endian
**          string and returns a pointer to that string.
**
** {H15130} The [sqlite3_value_text16le(V)] interface converts the
**          [protected sqlite3_value] object V into a zero-terminated 2-byte
**          aligned UTF-16 little-endian
**          string and returns a pointer to that string.
**
** {H15133} The [sqlite3_value_type(V)] interface returns
**          one of [SQLITE_NULL], [SQLITE_INTEGER], [SQLITE_FLOAT],
**          [SQLITE_TEXT], or [SQLITE_BLOB] as appropriate for
**          the [sqlite3_value] object V.
**
** {H15136} The [sqlite3_value_numeric_type(V)] interface converts
**          the [protected sqlite3_value] object V into either an integer or
**          a floating point value if it can do so without loss of
**          information, and returns one of [SQLITE_NULL],
**          [SQLITE_INTEGER], [SQLITE_FLOAT], [SQLITE_TEXT], or
**          [SQLITE_BLOB] as appropriate for the
**          [protected sqlite3_value] object V after the conversion attempt.
*/
const void *sqlite3_value_blob(sqlite3_value*);
int sqlite3_value_bytes(sqlite3_value*);
int sqlite3_value_bytes16(sqlite3_value*);
double sqlite3_value_double(sqlite3_value*);
int sqlite3_value_int(sqlite3_value*);
sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
const unsigned char *sqlite3_value_text(sqlite3_value*);
const void *sqlite3_value_text16(sqlite3_value*);
const void *sqlite3_value_text16le(sqlite3_value*);
const void *sqlite3_value_text16be(sqlite3_value*);
int sqlite3_value_type(sqlite3_value*);
int sqlite3_value_numeric_type(sqlite3_value*);

/*
** CAPI3REF: Obtain Aggregate Function Context {H16210} <S20200>
**
** The implementation of aggregate SQL functions use this routine to allocate
** a structure for storing their state.
**
** The first time the sqlite3_aggregate_context() routine is called for a
** particular aggregate, SQLite allocates nBytes of memory, zeroes out that
** memory, and returns a pointer to it. On second and subsequent calls to
** sqlite3_aggregate_context() for the same aggregate function index,
** the same buffer is returned. The implementation of the aggregate can use
** the returned buffer to accumulate data.
**
** SQLite automatically frees the allocated buffer when the aggregate
** query concludes.
**
** The first parameter should be a copy of the
** [sqlite3_context | SQL function context] that is the first parameter
** to the callback routine that implements the aggregate function.
**
** This routine must be called from the same thread in which
** the aggregate SQL function is running.
**
** INVARIANTS:
**
** {H16211} The first invocation of [sqlite3_aggregate_context(C,N)] for
**          a particular instance of an aggregate function (for a particular
**          context C) causes SQLite to allocate N bytes of memory,
**          zero that memory, and return a pointer to the allocated memory.
**
** {H16213} If a memory allocation error occurs during
**          [sqlite3_aggregate_context(C,N)] then the function returns 0.
**
** {H16215} Second and subsequent invocations of
**          [sqlite3_aggregate_context(C,N)] for the same context pointer C
**          ignore the N parameter and return a pointer to the same
**          block of memory returned by the first invocation.
**
** {H16217} The memory allocated by [sqlite3_aggregate_context(C,N)] is
**          automatically freed on the next call to [sqlite3_reset()]
**          or [sqlite3_finalize()] for the [prepared statement] containing
**          the aggregate function associated with context C.
*/
void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);

/*
** CAPI3REF: User Data For Functions {H16240} <S20200>
**
** The sqlite3_user_data() interface returns a copy of
** the pointer that was the pUserData parameter (the 5th parameter)
** of the [sqlite3_create_function()]
** and [sqlite3_create_function16()] routines that originally
** registered the application defined function. {END}
**
** This routine must be called from the same thread in which
** the application-defined function is running.
**
** INVARIANTS:
**
** {H16243} The [sqlite3_user_data(C)] interface returns a copy of the
**          P pointer from the [sqlite3_create_function(D,X,N,E,P,F,S,L)]
**          or [sqlite3_create_function16(D,X,N,E,P,F,S,L)] call that
**          registered the SQL function associated with [sqlite3_context] C.
*/
void *sqlite3_user_data(sqlite3_context*);

/*
** CAPI3REF: Database Connection For Functions {H16250} <S60600><S20200>
**
** The sqlite3_context_db_handle() interface returns a copy of
** the pointer to the [database connection] (the 1st parameter)
** of the [sqlite3_create_function()]
** and [sqlite3_create_function16()] routines that originally
** registered the application defined function.
**
** INVARIANTS:
**
** {H16253} The [sqlite3_context_db_handle(C)] interface returns a copy of the
**          D pointer from the [sqlite3_create_function(D,X,N,E,P,F,S,L)]
**          or [sqlite3_create_function16(D,X,N,E,P,F,S,L)] call that
**          registered the SQL function associated with [sqlite3_context] C.
*/
sqlite3 *sqlite3_context_db_handle(sqlite3_context*);

/*
** CAPI3REF: Function Auxiliary Data {H16270} <S20200>
**
** The following two functions may be used by scalar SQL functions to
** associate metadata with argument values. If the same value is passed to
** multiple invocations of the same SQL function during query execution, under
** some circumstances the associated metadata may be preserved. This may
** be used, for example, to add a regular-expression matching scalar
** function. The compiled version of the regular expression is stored as
** metadata associated with the SQL value passed as the regular expression
** pattern.  The compiled regular expression can be reused on multiple
** invocations of the same function so that the original pattern string
** does not need to be recompiled on each invocation.
**
** The sqlite3_get_auxdata() interface returns a pointer to the metadata
** associated by the sqlite3_set_auxdata() function with the Nth argument
** value to the application-defined function. If no metadata has been ever
** been set for the Nth argument of the function, or if the corresponding
** function parameter has changed since the meta-data was set,
** then sqlite3_get_auxdata() returns a NULL pointer.
**
** The sqlite3_set_auxdata() interface saves the metadata
** pointed to by its 3rd parameter as the metadata for the N-th
** argument of the application-defined function.  Subsequent
** calls to sqlite3_get_auxdata() might return this data, if it has
** not been destroyed.
** If it is not NULL, SQLite will invoke the destructor
** function given by the 4th parameter to sqlite3_set_auxdata() on
** the metadata when the corresponding function parameter changes
** or when the SQL statement completes, whichever comes first.
**
** SQLite is free to call the destructor and drop metadata on any
** parameter of any function at any time.  The only guarantee is that
** the destructor will be called before the metadata is dropped.
**
** In practice, metadata is preserved between function calls for
** expressions that are constant at compile time. This includes literal
** values and SQL variables.
**
** These routines must be called from the same thread in which
** the SQL function is running.
**
** INVARIANTS:
**
** {H16272} The [sqlite3_get_auxdata(C,N)] interface returns a pointer
**          to metadata associated with the Nth parameter of the SQL function
**          whose context is C, or NULL if there is no metadata associated
**          with that parameter.
**
** {H16274} The [sqlite3_set_auxdata(C,N,P,D)] interface assigns a metadata
**          pointer P to the Nth parameter of the SQL function with context C.
**
** {H16276} SQLite will invoke the destructor D with a single argument
**          which is the metadata pointer P following a call to
**          [sqlite3_set_auxdata(C,N,P,D)] when SQLite ceases to hold
**          the metadata.
**
** {H16277} SQLite ceases to hold metadata for an SQL function parameter
**          when the value of that parameter changes.
**
** {H16278} When [sqlite3_set_auxdata(C,N,P,D)] is invoked, the destructor
**          is called for any prior metadata associated with the same function
**          context C and parameter N.
**
** {H16279} SQLite will call destructors for any metadata it is holding
**          in a particular [prepared statement] S when either
**          [sqlite3_reset(S)] or [sqlite3_finalize(S)] is called.
*/
void *sqlite3_get_auxdata(sqlite3_context*, int N);
void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));


/*
** CAPI3REF: Constants Defining Special Destructor Behavior {H10280} <S30100>
**
** These are special values for the destructor that is passed in as the
** final argument to routines like [sqlite3_result_blob()].  If the destructor
** argument is SQLITE_STATIC, it means that the content pointer is constant
** and will never change.  It does not need to be destroyed.  The
** SQLITE_TRANSIENT value means that the content will likely change in
** the near future and that SQLite should make its own private copy of
** the content before returning.
**
** The typedef is necessary to work around problems in certain
** C++ compilers.  See ticket #2191.
*/
typedef void (*sqlite3_destructor_type)(void*);
#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)

/*
** CAPI3REF: Setting The Result Of An SQL Function {H16400} <S20200>
**
** These routines are used by the xFunc or xFinal callbacks that
** implement SQL functions and aggregates.  See
** [sqlite3_create_function()] and [sqlite3_create_function16()]
** for additional information.
**
** These functions work very much like the [parameter binding] family of
** functions used to bind values to host parameters in prepared statements.
** Refer to the [SQL parameter] documentation for additional information.
**
** The sqlite3_result_blob() interface sets the result from
** an application-defined function to be the BLOB whose content is pointed
** to by the second parameter and which is N bytes long where N is the
** third parameter.
**
** The sqlite3_result_zeroblob() interfaces set the result of
** the application-defined function to be a BLOB containing all zero
** bytes and N bytes in size, where N is the value of the 2nd parameter.
**
** The sqlite3_result_double() interface sets the result from
** an application-defined function to be a floating point value specified
** by its 2nd argument.
**
** The sqlite3_result_error() and sqlite3_result_error16() functions
** cause the implemented SQL function to throw an exception.
** SQLite uses the string pointed to by the
** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
** as the text of an error message.  SQLite interprets the error
** message string from sqlite3_result_error() as UTF-8. SQLite
** interprets the string from sqlite3_result_error16() as UTF-16 in native
** byte order.  If the third parameter to sqlite3_result_error()
** or sqlite3_result_error16() is negative then SQLite takes as the error
** message all text up through the first zero character.
** If the third parameter to sqlite3_result_error() or
** sqlite3_result_error16() is non-negative then SQLite takes that many
** bytes (not characters) from the 2nd parameter as the error message.
** The sqlite3_result_error() and sqlite3_result_error16()
** routines make a private copy of the error message text before
** they return.  Hence, the calling function can deallocate or
** modify the text after they return without harm.
** The sqlite3_result_error_code() function changes the error code
** returned by SQLite as a result of an error in a function.  By default,
** the error code is SQLITE_ERROR.  A subsequent call to sqlite3_result_error()
** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
**
** The sqlite3_result_toobig() interface causes SQLite to throw an error
** indicating that a string or BLOB is to long to represent.
**
** The sqlite3_result_nomem() interface causes SQLite to throw an error
** indicating that a memory allocation failed.
**
** The sqlite3_result_int() interface sets the return value
** of the application-defined function to be the 32-bit signed integer
** value given in the 2nd argument.
** The sqlite3_result_int64() interface sets the return value
** of the application-defined function to be the 64-bit signed integer
** value given in the 2nd argument.
**
** The sqlite3_result_null() interface sets the return value
** of the application-defined function to be NULL.
**
** The sqlite3_result_text(), sqlite3_result_text16(),
** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
** set the return value of the application-defined function to be
** a text string which is represented as UTF-8, UTF-16 native byte order,
** UTF-16 little endian, or UTF-16 big endian, respectively.
** SQLite takes the text result from the application from
** the 2nd parameter of the sqlite3_result_text* interfaces.
** If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.
** If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** If the 4th parameter to the sqlite3_result_text* interfaces or
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not
** copy the it or call a destructor when it has finished using that result.
** If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
** then SQLite makes a copy of the result into space obtained from
** from [sqlite3_malloc()] before it returns.
**
** The sqlite3_result_value() interface sets the result of
** the application-defined function to be a copy the
** [unprotected sqlite3_value] object specified by the 2nd parameter.  The
** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
** so that the [sqlite3_value] specified in the parameter may change or
** be deallocated after sqlite3_result_value() returns without harm.
** A [protected sqlite3_value] object may always be used where an
** [unprotected sqlite3_value] object is required, so either
** kind of [sqlite3_value] object can be used with this interface.
**
** If these routines are called from within the different thread
** than the one containing the application-defined function that received
** the [sqlite3_context] pointer, the results are undefined.
**
** INVARIANTS:
**
** {H16403} The default return value from any SQL function is NULL.
**
** {H16406} The [sqlite3_result_blob(C,V,N,D)] interface changes the
**          return value of function C to be a BLOB that is N bytes
**          in length and with content pointed to by V.
**
** {H16409} The [sqlite3_result_double(C,V)] interface changes the
**          return value of function C to be the floating point value V.
**
** {H16412} The [sqlite3_result_error(C,V,N)] interface changes the return
**          value of function C to be an exception with error code
**          [SQLITE_ERROR] and a UTF-8 error message copied from V up to the
**          first zero byte or until N bytes are read if N is positive.
**
** {H16415} The [sqlite3_result_error16(C,V,N)] interface changes the return
**          value of function C to be an exception with error code
**          [SQLITE_ERROR] and a UTF-16 native byte order error message
**          copied from V up to the first zero terminator or until N bytes
**          are read if N is positive.
**
** {H16418} The [sqlite3_result_error_toobig(C)] interface changes the return
**          value of the function C to be an exception with error code
**          [SQLITE_TOOBIG] and an appropriate error message.
**
** {H16421} The [sqlite3_result_error_nomem(C)] interface changes the return
**          value of the function C to be an exception with error code
**          [SQLITE_NOMEM] and an appropriate error message.
**
** {H16424} The [sqlite3_result_error_code(C,E)] interface changes the return
**          value of the function C to be an exception with error code E.
**          The error message text is unchanged.
**
** {H16427} The [sqlite3_result_int(C,V)] interface changes the
**          return value of function C to be the 32-bit integer value V.
**
** {H16430} The [sqlite3_result_int64(C,V)] interface changes the
**          return value of function C to be the 64-bit integer value V.
**
** {H16433} The [sqlite3_result_null(C)] interface changes the
**          return value of function C to be NULL.
**
** {H16436} The [sqlite3_result_text(C,V,N,D)] interface changes the
**          return value of function C to be the UTF-8 string
**          V up to the first zero if N is negative
**          or the first N bytes of V if N is non-negative.
**
** {H16439} The [sqlite3_result_text16(C,V,N,D)] interface changes the
**          return value of function C to be the UTF-16 native byte order
**          string V up to the first zero if N is negative
**          or the first N bytes of V if N is non-negative.
**
** {H16442} The [sqlite3_result_text16be(C,V,N,D)] interface changes the
**          return value of function C to be the UTF-16 big-endian
**          string V up to the first zero if N is negative
**          or the first N bytes or V if N is non-negative.
**
** {H16445} The [sqlite3_result_text16le(C,V,N,D)] interface changes the
**          return value of function C to be the UTF-16 little-endian
**          string V up to the first zero if N is negative
**          or the first N bytes of V if N is non-negative.
**
** {H16448} The [sqlite3_result_value(C,V)] interface changes the
**          return value of function C to be the [unprotected sqlite3_value]
**          object V.
**
** {H16451} The [sqlite3_result_zeroblob(C,N)] interface changes the
**          return value of function C to be an N-byte BLOB of all zeros.
**
** {H16454} The [sqlite3_result_error()] and [sqlite3_result_error16()]
**          interfaces make a copy of their error message strings before
**          returning.
**
** {H16457} If the D destructor parameter to [sqlite3_result_blob(C,V,N,D)],
**          [sqlite3_result_text(C,V,N,D)], [sqlite3_result_text16(C,V,N,D)],
**          [sqlite3_result_text16be(C,V,N,D)], or
**          [sqlite3_result_text16le(C,V,N,D)] is the constant [SQLITE_STATIC]
**          then no destructor is ever called on the pointer V and SQLite
**          assumes that V is immutable.
**
** {H16460} If the D destructor parameter to [sqlite3_result_blob(C,V,N,D)],
**          [sqlite3_result_text(C,V,N,D)], [sqlite3_result_text16(C,V,N,D)],
**          [sqlite3_result_text16be(C,V,N,D)], or
**          [sqlite3_result_text16le(C,V,N,D)] is the constant
**          [SQLITE_TRANSIENT] then the interfaces makes a copy of the
**          content of V and retains the copy.
**
** {H16463} If the D destructor parameter to [sqlite3_result_blob(C,V,N,D)],
**          [sqlite3_result_text(C,V,N,D)], [sqlite3_result_text16(C,V,N,D)],
**          [sqlite3_result_text16be(C,V,N,D)], or
**          [sqlite3_result_text16le(C,V,N,D)] is some value other than
**          the constants [SQLITE_STATIC] and [SQLITE_TRANSIENT] then
**          SQLite will invoke the destructor D with V as its only argument
**          when it has finished with the V value.
*/
void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
void sqlite3_result_double(sqlite3_context*, double);
void sqlite3_result_error(sqlite3_context*, const char*, int);
void sqlite3_result_error16(sqlite3_context*, const void*, int);
void sqlite3_result_error_toobig(sqlite3_context*);
void sqlite3_result_error_nomem(sqlite3_context*);
void sqlite3_result_error_code(sqlite3_context*, int);
void sqlite3_result_int(sqlite3_context*, int);
void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
void sqlite3_result_null(sqlite3_context*);
void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
void sqlite3_result_zeroblob(sqlite3_context*, int n);

/*
** CAPI3REF: Define New Collating Sequences {H16600} <S20300>
**
** These functions are used to add new collation sequences to the
** [database connection] specified as the first argument.
**
** The name of the new collation sequence is specified as a UTF-8 string
** for sqlite3_create_collation() and sqlite3_create_collation_v2()
** and a UTF-16 string for sqlite3_create_collation16(). In all cases
** the name is passed as the second function argument.
**
** The third argument may be one of the constants [SQLITE_UTF8],
** [SQLITE_UTF16LE] or [SQLITE_UTF16BE], indicating that the user-supplied
** routine expects to be passed pointers to strings encoded using UTF-8,
** UTF-16 little-endian, or UTF-16 big-endian, respectively. The
** third argument might also be [SQLITE_UTF16_ALIGNED] to indicate that
** the routine expects pointers to 16-bit word aligned strings
** of UTF-16 in the native byte order of the host computer.
**
** A pointer to the user supplied routine must be passed as the fifth
** argument.  If it is NULL, this is the same as deleting the collation
** sequence (so that SQLite cannot call it anymore).
** Each time the application supplied function is invoked, it is passed
** as its first parameter a copy of the void* passed as the fourth argument
** to sqlite3_create_collation() or sqlite3_create_collation16().
**
** The remaining arguments to the application-supplied routine are two strings,
** each represented by a (length, data) pair and encoded in the encoding
** that was passed as the third argument when the collation sequence was
** registered. {END}  The application defined collation routine should
** return negative, zero or positive if the first string is less than,
** equal to, or greater than the second string. i.e. (STRING1 - STRING2).
**
** The sqlite3_create_collation_v2() works like sqlite3_create_collation()
** except that it takes an extra argument which is a destructor for
** the collation.  The destructor is called when the collation is
** destroyed and is passed a copy of the fourth parameter void* pointer
** of the sqlite3_create_collation_v2().
** Collations are destroyed when they are overridden by later calls to the
** collation creation functions or when the [database connection] is closed
** using [sqlite3_close()].
**
** INVARIANTS:
**
** {H16603} A successful call to the
**          [sqlite3_create_collation_v2(B,X,E,P,F,D)] interface
**          registers function F as the comparison function used to
**          implement collation X on the [database connection] B for
**          databases having encoding E.
**
** {H16604} SQLite understands the X parameter to
**          [sqlite3_create_collation_v2(B,X,E,P,F,D)] as a zero-terminated
**          UTF-8 string in which case is ignored for ASCII characters and
**          is significant for non-ASCII characters.
**
** {H16606} Successive calls to [sqlite3_create_collation_v2(B,X,E,P,F,D)]
**          with the same values for B, X, and E, override prior values
**          of P, F, and D.
**
** {H16609} If the destructor D in [sqlite3_create_collation_v2(B,X,E,P,F,D)]
**          is not NULL then it is called with argument P when the
**          collating function is dropped by SQLite.
**
** {H16612} A collating function is dropped when it is overloaded.
**
** {H16615} A collating function is dropped when the database connection
**          is closed using [sqlite3_close()].
**
** {H16618} The pointer P in [sqlite3_create_collation_v2(B,X,E,P,F,D)]
**          is passed through as the first parameter to the comparison
**          function F for all subsequent invocations of F.
**
** {H16621} A call to [sqlite3_create_collation(B,X,E,P,F)] is exactly
**          the same as a call to [sqlite3_create_collation_v2()] with
**          the same parameters and a NULL destructor.
**
** {H16624} Following a [sqlite3_create_collation_v2(B,X,E,P,F,D)],
**          SQLite uses the comparison function F for all text comparison
**          operations on the [database connection] B on text values that
**          use the collating sequence named X.
**
** {H16627} The [sqlite3_create_collation16(B,X,E,P,F)] works the same
**          as [sqlite3_create_collation(B,X,E,P,F)] except that the
**          collation name X is understood as UTF-16 in native byte order
**          instead of UTF-8.
**
** {H16630} When multiple comparison functions are available for the same
**          collating sequence, SQLite chooses the one whose text encoding
**          requires the least amount of conversion from the default
**          text encoding of the database.
*/
int sqlite3_create_collation(
  sqlite3*, 
  const char *zName, 
  int eTextRep, 
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*)
);
int sqlite3_create_collation_v2(
  sqlite3*, 
  const char *zName, 
  int eTextRep, 
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*),
  void(*xDestroy)(void*)
);
int sqlite3_create_collation16(
  sqlite3*, 
  const void *zName,
  int eTextRep, 
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*)
);

/*
** CAPI3REF: Collation Needed Callbacks {H16700} <S20300>
**
** To avoid having to register all collation sequences before a database
** can be used, a single callback function may be registered with the
** [database connection] to be called whenever an undefined collation
** sequence is required.
**
** If the function is registered using the sqlite3_collation_needed() API,
** then it is passed the names of undefined collation sequences as strings
** encoded in UTF-8. {H16703} If sqlite3_collation_needed16() is used,
** the names are passed as UTF-16 in machine native byte order.
** A call to either function replaces any existing callback.
**
** When the callback is invoked, the first argument passed is a copy
** of the second argument to sqlite3_collation_needed() or
** sqlite3_collation_needed16().  The second argument is the database
** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
** sequence function required.  The fourth parameter is the name of the
** required collation sequence.
**
** The callback function should register the desired collation using
** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
** [sqlite3_create_collation_v2()].
**
** INVARIANTS:
**
** {H16702} A successful call to [sqlite3_collation_needed(D,P,F)]
**          or [sqlite3_collation_needed16(D,P,F)] causes
**          the [database connection] D to invoke callback F with first
**          parameter P whenever it needs a comparison function for a
**          collating sequence that it does not know about.
**
** {H16704} Each successful call to [sqlite3_collation_needed()] or
**          [sqlite3_collation_needed16()] overrides the callback registered
**          on the same [database connection] by prior calls to either
**          interface.
**
** {H16706} The name of the requested collating function passed in the
**          4th parameter to the callback is in UTF-8 if the callback
**          was registered using [sqlite3_collation_needed()] and
**          is in UTF-16 native byte order if the callback was
**          registered using [sqlite3_collation_needed16()].
*/
int sqlite3_collation_needed(
  sqlite3*, 
  void*, 
  void(*)(void*,sqlite3*,int eTextRep,const char*)
);
int sqlite3_collation_needed16(
  sqlite3*, 
  void*,
  void(*)(void*,sqlite3*,int eTextRep,const void*)
);

/*
** Specify the key for an encrypted database.  This routine should be
** called right after sqlite3_open().
**
** The code to implement this API is not available in the public release
** of SQLite.
*/
int sqlite3_key(
  sqlite3 *db,                   /* Database to be rekeyed */
  const void *pKey, int nKey     /* The key */
);

/*
** Change the key on an open database.  If the current database is not
** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
** database is decrypted.
**
** The code to implement this API is not available in the public release
** of SQLite.
*/
int sqlite3_rekey(
  sqlite3 *db,                   /* Database to be rekeyed */
  const void *pKey, int nKey     /* The new key */
);

/*
** CAPI3REF: Suspend Execution For A Short Time {H10530} <S40410>
**
** The sqlite3_sleep() function causes the current thread to suspend execution
** for at least a number of milliseconds specified in its parameter.
**
** If the operating system does not support sleep requests with
** millisecond time resolution, then the time will be rounded up to
** the nearest second. The number of milliseconds of sleep actually
** requested from the operating system is returned.
**
** SQLite implements this interface by calling the xSleep()
** method of the default [sqlite3_vfs] object.
**
** INVARIANTS:
**
** {H10533} The [sqlite3_sleep(M)] interface invokes the xSleep
**          method of the default [sqlite3_vfs|VFS] in order to
**          suspend execution of the current thread for at least
**          M milliseconds.
**
** {H10536} The [sqlite3_sleep(M)] interface returns the number of
**          milliseconds of sleep actually requested of the operating
**          system, which might be larger than the parameter M.
*/
int sqlite3_sleep(int);

/*
** CAPI3REF: Name Of The Folder Holding Temporary Files {H10310} <S20000>
**
** If this global variable is made to point to a string which is
** the name of a folder (a.k.a. directory), then all temporary files
** created by SQLite will be placed in that directory.  If this variable
** is a NULL pointer, then SQLite performs a search for an appropriate
** temporary file directory.
**
** It is not safe to modify this variable once a [database connection]
** has been opened.  It is intended that this variable be set once
** as part of process initialization and before any SQLite interface
** routines have been call and remain unchanged thereafter.
*/
SQLITE_EXTERN char *sqlite3_temp_directory;

/*
** CAPI3REF: Test For Auto-Commit Mode {H12930} <S60200>
** KEYWORDS: {autocommit mode}
**
** The sqlite3_get_autocommit() interface returns non-zero or
** zero if the given database connection is or is not in autocommit mode,
** respectively.  Autocommit mode is on by default.
** Autocommit mode is disabled by a [BEGIN] statement.
** Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
**
** If certain kinds of errors occur on a statement within a multi-statement
** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
** transaction might be rolled back automatically.  The only way to
** find out whether SQLite automatically rolled back the transaction after
** an error is to use this function.
**
** INVARIANTS:
**
** {H12931} The [sqlite3_get_autocommit(D)] interface returns non-zero or
**          zero if the [database connection] D is or is not in autocommit
**          mode, respectively.
**
** {H12932} Autocommit mode is on by default.
**
** {H12933} Autocommit mode is disabled by a successful [BEGIN] statement.
**
** {H12934} Autocommit mode is enabled by a successful [COMMIT] or [ROLLBACK]
**          statement.
**
** ASSUMPTIONS:
**
** {A12936} If another thread changes the autocommit status of the database
**          connection while this routine is running, then the return value
**          is undefined.
*/
int sqlite3_get_autocommit(sqlite3*);

/*
** CAPI3REF: Find The Database Handle Of A Prepared Statement {H13120} <S60600>
**
** The sqlite3_db_handle interface returns the [database connection] handle
** to which a [prepared statement] belongs.  The [database connection]
** returned by sqlite3_db_handle is the same [database connection] that was the first argument
** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
** create the statement in the first place.
**
** INVARIANTS:
**
** {H13123} The [sqlite3_db_handle(S)] interface returns a pointer
**          to the [database connection] associated with the
**          [prepared statement] S.
*/
sqlite3 *sqlite3_db_handle(sqlite3_stmt*);

/*
** CAPI3REF: Find the next prepared statement {H13140} <S60600>
**
** This interface returns a pointer to the next [prepared statement] after
** pStmt associated with the [database connection] pDb.  If pStmt is NULL
** then this interface returns a pointer to the first prepared statement
** associated with the database connection pDb.  If no prepared statement
** satisfies the conditions of this routine, it returns NULL.
**
** INVARIANTS:
**
** {H13143} If D is a [database connection] that holds one or more
**          unfinalized [prepared statements] and S is a NULL pointer,
**          then [sqlite3_next_stmt(D, S)] routine shall return a pointer
**          to one of the prepared statements associated with D.
**
** {H13146} If D is a [database connection] that holds no unfinalized
**          [prepared statements] and S is a NULL pointer, then
**          [sqlite3_next_stmt(D, S)] routine shall return a NULL pointer.
**
** {H13149} If S is a [prepared statement] in the [database connection] D
**          and S is not the last prepared statement in D, then
**          [sqlite3_next_stmt(D, S)] routine shall return a pointer
**          to the next prepared statement in D after S.
**
** {H13152} If S is the last [prepared statement] in the
**          [database connection] D then the [sqlite3_next_stmt(D, S)]
**          routine shall return a NULL pointer.
**
** ASSUMPTIONS:
**
** {A13154} The [database connection] pointer D in a call to
**          [sqlite3_next_stmt(D,S)] must refer to an open database
**          connection and in particular must not be a NULL pointer.
*/
sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);

/*
** CAPI3REF: Commit And Rollback Notification Callbacks {H12950} <S60400>
**
** The sqlite3_commit_hook() interface registers a callback
** function to be invoked whenever a transaction is committed.
** Any callback set by a previous call to sqlite3_commit_hook()
** for the same database connection is overridden.
** The sqlite3_rollback_hook() interface registers a callback
** function to be invoked whenever a transaction is committed.
** Any callback set by a previous call to sqlite3_commit_hook()
** for the same database connection is overridden.
** The pArg argument is passed through to the callback.
** If the callback on a commit hook function returns non-zero,
** then the commit is converted into a rollback.
**
** If another function was previously registered, its
** pArg value is returned.  Otherwise NULL is returned.
**
** The callback implementation must not do anything that will modify
** the database connection that invoked the callback.  Any actions
** to modify the database connection must be deferred until after the
** completion of the [sqlite3_step()] call that triggered the commit
** or rollback hook in the first place.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** Registering a NULL function disables the callback.
**
** For the purposes of this API, a transaction is said to have been
** rolled back if an explicit "ROLLBACK" statement is executed, or
** an error or constraint causes an implicit rollback to occur.
** The rollback callback is not invoked if a transaction is
** automatically rolled back because the database connection is closed.
** The rollback callback is not invoked if a transaction is
** rolled back because a commit callback returned non-zero.
** <todo> Check on this </todo>
**
** INVARIANTS:
**
** {H12951} The [sqlite3_commit_hook(D,F,P)] interface registers the
**          callback function F to be invoked with argument P whenever
**          a transaction commits on the [database connection] D.
**
** {H12952} The [sqlite3_commit_hook(D,F,P)] interface returns the P argument
**          from the previous call with the same [database connection] D,
**          or NULL on the first call for a particular database connection D.
**
** {H12953} Each call to [sqlite3_commit_hook()] overwrites the callback
**          registered by prior calls.
**
** {H12954} If the F argument to [sqlite3_commit_hook(D,F,P)] is NULL
**          then the commit hook callback is canceled and no callback
**          is invoked when a transaction commits.
**
** {H12955} If the commit callback returns non-zero then the commit is
**          converted into a rollback.
**
** {H12961} The [sqlite3_rollback_hook(D,F,P)] interface registers the
**          callback function F to be invoked with argument P whenever
**          a transaction rolls back on the [database connection] D.
**
** {H12962} The [sqlite3_rollback_hook(D,F,P)] interface returns the P
**          argument from the previous call with the same
**          [database connection] D, or NULL on the first call
**          for a particular database connection D.
**
** {H12963} Each call to [sqlite3_rollback_hook()] overwrites the callback
**          registered by prior calls.
**
** {H12964} If the F argument to [sqlite3_rollback_hook(D,F,P)] is NULL
**          then the rollback hook callback is canceled and no callback
**          is invoked when a transaction rolls back.
*/
void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);

/*
** CAPI3REF: Data Change Notification Callbacks {H12970} <S60400>
**
** The sqlite3_update_hook() interface registers a callback function
** with the [database connection] identified by the first argument
** to be invoked whenever a row is updated, inserted or deleted.
** Any callback set by a previous call to this function
** for the same database connection is overridden.
**
** The second argument is a pointer to the function to invoke when a
** row is updated, inserted or deleted.
** The first argument to the callback is a copy of the third argument
** to sqlite3_update_hook().
** The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
** or [SQLITE_UPDATE], depending on the operation that caused the callback
** to be invoked.
** The third and fourth arguments to the callback contain pointers to the
** database and table name containing the affected row.
** The final callback parameter is the [rowid] of the row.
** In the case of an update, this is the [rowid] after the update takes place.
**
** The update hook is not invoked when internal system tables are
** modified (i.e. sqlite_master and sqlite_sequence).
**
** The update hook implementation must not do anything that will modify
** the database connection that invoked the update hook.  Any actions
** to modify the database connection must be deferred until after the
** completion of the [sqlite3_step()] call that triggered the update hook.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** If another function was previously registered, its pArg value
** is returned.  Otherwise NULL is returned.
**
** INVARIANTS:
**
** {H12971} The [sqlite3_update_hook(D,F,P)] interface causes the callback
**          function F to be invoked with first parameter P whenever
**          a table row is modified, inserted, or deleted on
**          the [database connection] D.
**
** {H12973} The [sqlite3_update_hook(D,F,P)] interface returns the value
**          of P for the previous call on the same [database connection] D,
**          or NULL for the first call.
**
** {H12975} If the update hook callback F in [sqlite3_update_hook(D,F,P)]
**          is NULL then the no update callbacks are made.
**
** {H12977} Each call to [sqlite3_update_hook(D,F,P)] overrides prior calls
**          to the same interface on the same [database connection] D.
**
** {H12979} The update hook callback is not invoked when internal system
**          tables such as sqlite_master and sqlite_sequence are modified.
**
** {H12981} The second parameter to the update callback
**          is one of [SQLITE_INSERT], [SQLITE_DELETE] or [SQLITE_UPDATE],
**          depending on the operation that caused the callback to be invoked.
**
** {H12983} The third and fourth arguments to the callback contain pointers
**          to zero-terminated UTF-8 strings which are the names of the
**          database and table that is being updated.

** {H12985} The final callback parameter is the [rowid] of the row after
**          the change occurs.
*/
void *sqlite3_update_hook(
  sqlite3*, 
  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  void*
);

/*
** CAPI3REF: Enable Or Disable Shared Pager Cache {H10330} <S30900>
** KEYWORDS: {shared cache} {shared cache mode}
**
** This routine enables or disables the sharing of the database cache
** and schema data structures between [database connection | connections]
** to the same database. Sharing is enabled if the argument is true
** and disabled if the argument is false.
**
** Cache sharing is enabled and disabled for an entire process. {END}
** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
** sharing was enabled or disabled for each thread separately.
**
** The cache sharing mode set by this interface effects all subsequent
** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
** Existing database connections continue use the sharing mode
** that was in effect at the time they were opened.
**
** Virtual tables cannot be used with a shared cache.  When shared
** cache is enabled, the [sqlite3_create_module()] API used to register
** virtual tables will always return an error.
**
** This routine returns [SQLITE_OK] if shared cache was enabled or disabled
** successfully.  An [error code] is returned otherwise.
**
** Shared cache is disabled by default. But this might change in
** future releases of SQLite.  Applications that care about shared
** cache setting should set it explicitly.
**
** INVARIANTS:
**
** {H10331} A successful invocation of [sqlite3_enable_shared_cache(B)]
**          will enable or disable shared cache mode for any subsequently
**          created [database connection] in the same process.
**
** {H10336} When shared cache is enabled, the [sqlite3_create_module()]
**          interface will always return an error.
**
** {H10337} The [sqlite3_enable_shared_cache(B)] interface returns
**          [SQLITE_OK] if shared cache was enabled or disabled successfully.
**
** {H10339} Shared cache is disabled by default.
*/
int sqlite3_enable_shared_cache(int);

/*
** CAPI3REF: Attempt To Free Heap Memory {H17340} <S30220>
**
** The sqlite3_release_memory() interface attempts to free N bytes
** of heap memory by deallocating non-essential memory allocations
** held by the database library. {END}  Memory used to cache database
** pages to improve performance is an example of non-essential memory.
** sqlite3_release_memory() returns the number of bytes actually freed,
** which might be more or less than the amount requested.
**
** INVARIANTS:
**
** {H17341} The [sqlite3_release_memory(N)] interface attempts to
**          free N bytes of heap memory by deallocating non-essential
**          memory allocations held by the database library.
**
** {H16342} The [sqlite3_release_memory(N)] returns the number
**          of bytes actually freed, which might be more or less
**          than the amount requested.
*/
int sqlite3_release_memory(int);

/*
** CAPI3REF: Impose A Limit On Heap Size {H17350} <S30220>
**
** The sqlite3_soft_heap_limit() interface places a "soft" limit
** on the amount of heap memory that may be allocated by SQLite.
** If an internal allocation is requested that would exceed the
** soft heap limit, [sqlite3_release_memory()] is invoked one or
** more times to free up some space before the allocation is performed.
**
** The limit is called "soft", because if [sqlite3_release_memory()]
** cannot free sufficient memory to prevent the limit from being exceeded,
** the memory is allocated anyway and the current operation proceeds.
**
** A negative or zero value for N means that there is no soft heap limit and
** [sqlite3_release_memory()] will only be called when memory is exhausted.
** The default value for the soft heap limit is zero.
**
** SQLite makes a best effort to honor the soft heap limit.
** But if the soft heap limit cannot be honored, execution will
** continue without error or notification.  This is why the limit is
** called a "soft" limit.  It is advisory only.
**
** Prior to SQLite version 3.5.0, this routine only constrained the memory
** allocated by a single thread - the same thread in which this routine
** runs.  Beginning with SQLite version 3.5.0, the soft heap limit is
** applied to all threads. The value specified for the soft heap limit
** is an upper bound on the total memory allocation for all threads. In
** version 3.5.0 there is no mechanism for limiting the heap usage for
** individual threads.
**
** INVARIANTS:
**
** {H16351} The [sqlite3_soft_heap_limit(N)] interface places a soft limit
**          of N bytes on the amount of heap memory that may be allocated
**          using [sqlite3_malloc()] or [sqlite3_realloc()] at any point
**          in time.
**
** {H16352} If a call to [sqlite3_malloc()] or [sqlite3_realloc()] would
**          cause the total amount of allocated memory to exceed the
**          soft heap limit, then [sqlite3_release_memory()] is invoked
**          in an attempt to reduce the memory usage prior to proceeding
**          with the memory allocation attempt.
**
** {H16353} Calls to [sqlite3_malloc()] or [sqlite3_realloc()] that trigger
**          attempts to reduce memory usage through the soft heap limit
**          mechanism continue even if the attempt to reduce memory
**          usage is unsuccessful.
**
** {H16354} A negative or zero value for N in a call to
**          [sqlite3_soft_heap_limit(N)] means that there is no soft
**          heap limit and [sqlite3_release_memory()] will only be
**          called when memory is completely exhausted.
**
** {H16355} The default value for the soft heap limit is zero.
**
** {H16358} Each call to [sqlite3_soft_heap_limit(N)] overrides the
**          values set by all prior calls.
*/
void sqlite3_soft_heap_limit(int);

/*
** CAPI3REF: Extract Metadata About A Column Of A Table {H12850} <S60300>
**
** This routine returns metadata about a specific column of a specific
** database table accessible using the [database connection] handle
** passed as the first function argument.
**
** The column is identified by the second, third and fourth parameters to
** this function. The second parameter is either the name of the database
** (i.e. "main", "temp" or an attached database) containing the specified
** table or NULL. If it is NULL, then all attached databases are searched
** for the table using the same algorithm used by the database engine to
** resolve unqualified table references.
**
** The third and fourth parameters to this function are the table and column
** name of the desired column, respectively. Neither of these parameters
** may be NULL.
**
** Metadata is returned by writing to the memory locations passed as the 5th
** and subsequent parameters to this function. Any of these arguments may be
** NULL, in which case the corresponding element of metadata is omitted.
**
** <blockquote>
** <table border="1">
** <tr><th> Parameter <th> Output<br>Type <th>  Description
**
** <tr><td> 5th <td> const char* <td> Data type
** <tr><td> 6th <td> const char* <td> Name of default collation sequence
** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
** </table>
** </blockquote>
**
** The memory pointed to by the character pointers returned for the
** declaration type and collation sequence is valid only until the next
** call to any SQLite API function.
**
** If the specified table is actually a view, an [error code] is returned.
**
** If the specified column is "rowid", "oid" or "_rowid_" and an
** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
** parameters are set for the explicitly declared column. If there is no
** explicitly declared [INTEGER PRIMARY KEY] column, then the output
** parameters are set as follows:
**
** <pre>
**     data type: "INTEGER"
**     collation sequence: "BINARY"
**     not null: 0
**     primary key: 1
**     auto increment: 0
** </pre>
**
** This function may load one or more schemas from database files. If an
** error occurs during this process, or if the requested table or column
** cannot be found, an [error code] is returned and an error message left
** in the [database connection] (to be retrieved using sqlite3_errmsg()).
**
** This API is only available if the library was compiled with the
** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
*/
int sqlite3_table_column_metadata(
  sqlite3 *db,                /* Connection handle */
  const char *zDbName,        /* Database name or NULL */
  const char *zTableName,     /* Table name */
  const char *zColumnName,    /* Column name */
  char const **pzDataType,    /* OUTPUT: Declared data type */
  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
);

/*
** CAPI3REF: Load An Extension {H12600} <S20500>
**
** This interface loads an SQLite extension library from the named file.
**
** {H12601} The sqlite3_load_extension() interface attempts to load an
**          SQLite extension library contained in the file zFile.
**
** {H12602} The entry point is zProc.
**
** {H12603} zProc may be 0, in which case the name of the entry point
**          defaults to "sqlite3_extension_init".
**
** {H12604} The sqlite3_load_extension() interface shall return
**          [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
**
** {H12605} If an error occurs and pzErrMsg is not 0, then the
**          [sqlite3_load_extension()] interface shall attempt to
**          fill *pzErrMsg with error message text stored in memory
**          obtained from [sqlite3_malloc()]. {END}  The calling function
**          should free this memory by calling [sqlite3_free()].
**
** {H12606} Extension loading must be enabled using
**          [sqlite3_enable_load_extension()] prior to calling this API,
**          otherwise an error will be returned.
*/
int sqlite3_load_extension(
  sqlite3 *db,          /* Load the extension into this database connection */
  const char *zFile,    /* Name of the shared library containing extension */
  const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  char **pzErrMsg       /* Put error message here if not 0 */
);

/*
** CAPI3REF: Enable Or Disable Extension Loading {H12620} <S20500>
**
** So as not to open security holes in older applications that are
** unprepared to deal with extension loading, and as a means of disabling
** extension loading while evaluating user-entered SQL, the following API
** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
**
** Extension loading is off by default. See ticket #1863.
**
** {H12621} Call the sqlite3_enable_load_extension() routine with onoff==1
**          to turn extension loading on and call it with onoff==0 to turn
**          it back off again.
**
** {H12622} Extension loading is off by default.
*/
int sqlite3_enable_load_extension(sqlite3 *db, int onoff);

/*
** CAPI3REF: Automatically Load An Extensions {H12640} <S20500>
**
** This API can be invoked at program startup in order to register
** one or more statically linked extensions that will be available
** to all new [database connections]. {END}
**
** This routine stores a pointer to the extension in an array that is
** obtained from [sqlite3_malloc()].  If you run a memory leak checker
** on your program and it reports a leak because of this array, invoke
** [sqlite3_reset_auto_extension()] prior to shutdown to free the memory.
**
** {H12641} This function registers an extension entry point that is
**          automatically invoked whenever a new [database connection]
**          is opened using [sqlite3_open()], [sqlite3_open16()],
**          or [sqlite3_open_v2()].
**
** {H12642} Duplicate extensions are detected so calling this routine
**          multiple times with the same extension is harmless.
**
** {H12643} This routine stores a pointer to the extension in an array
**          that is obtained from [sqlite3_malloc()].
**
** {H12644} Automatic extensions apply across all threads.
*/
int sqlite3_auto_extension(void (*xEntryPoint)(void));

/*
** CAPI3REF: Reset Automatic Extension Loading {H12660} <S20500>
**
** This function disables all previously registered automatic
** extensions. {END}  It undoes the effect of all prior
** [sqlite3_auto_extension()] calls.
**
** {H12661} This function disables all previously registered
**          automatic extensions.
**
** {H12662} This function disables automatic extensions in all threads.
*/
void sqlite3_reset_auto_extension(void);

/*
****** EXPERIMENTAL - subject to change without notice **************
**
** The interface to the virtual-table mechanism is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
*/

/*
** Structures used by the virtual table interface
*/
typedef struct sqlite3_vtab sqlite3_vtab;
typedef struct sqlite3_index_info sqlite3_index_info;
typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
typedef struct sqlite3_module sqlite3_module;

/*
** CAPI3REF: Virtual Table Object {H18000} <S20400>
** KEYWORDS: sqlite3_module
** EXPERIMENTAL
**
** A module is a class of virtual tables.  Each module is defined
** by an instance of the following structure.  This structure consists
** mostly of methods for the module.
**
** This interface is experimental and is subject to change or
** removal in future releases of SQLite.
*/
struct sqlite3_module {
  int iVersion;
  int (*xCreate)(sqlite3*, void *pAux,
               int argc, const char *const*argv,
               sqlite3_vtab **ppVTab, char**);
  int (*xConnect)(sqlite3*, void *pAux,
               int argc, const char *const*argv,
               sqlite3_vtab **ppVTab, char**);
  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  int (*xDisconnect)(sqlite3_vtab *pVTab);
  int (*xDestroy)(sqlite3_vtab *pVTab);
  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  int (*xClose)(sqlite3_vtab_cursor*);
  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
                int argc, sqlite3_value **argv);
  int (*xNext)(sqlite3_vtab_cursor*);
  int (*xEof)(sqlite3_vtab_cursor*);
  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
  int (*xBegin)(sqlite3_vtab *pVTab);
  int (*xSync)(sqlite3_vtab *pVTab);
  int (*xCommit)(sqlite3_vtab *pVTab);
  int (*xRollback)(sqlite3_vtab *pVTab);
  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
                       void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
                       void **ppArg);
  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
};

/*
** CAPI3REF: Virtual Table Indexing Information {H18100} <S20400>
** KEYWORDS: sqlite3_index_info
** EXPERIMENTAL
**
** The sqlite3_index_info structure and its substructures is used to
** pass information into and receive the reply from the xBestIndex
** method of an sqlite3_module.  The fields under **Inputs** are the
** inputs to xBestIndex and are read-only.  xBestIndex inserts its
** results into the **Outputs** fields.
**
** The aConstraint[] array records WHERE clause constraints of the form:
**
** <pre>column OP expr</pre>
**
** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.  The particular operator is
** stored in aConstraint[].op.  The index of the column is stored in
** aConstraint[].iColumn.  aConstraint[].usable is TRUE if the
** expr on the right-hand side can be evaluated (and thus the constraint
** is usable) and false if it cannot.
**
** The optimizer automatically inverts terms of the form "expr OP column"
** and makes other simplifications to the WHERE clause in an attempt to
** get as many WHERE clause terms into the form shown above as possible.
** The aConstraint[] array only reports WHERE clause terms in the correct
** form that refer to the particular virtual table being queried.
**
** Information about the ORDER BY clause is stored in aOrderBy[].
** Each term of aOrderBy records a column of the ORDER BY clause.
**
** The xBestIndex method must fill aConstraintUsage[] with information
** about what parameters to pass to xFilter.  If argvIndex>0 then
** the right-hand side of the corresponding aConstraint[] is evaluated
** and becomes the argvIndex-th entry in argv.  If aConstraintUsage[].omit
** is true, then the constraint is assumed to be fully handled by the
** virtual table and is not checked again by SQLite.
**
** The idxNum and idxPtr values are recorded and passed into xFilter.
** sqlite3_free() is used to free idxPtr if needToFreeIdxPtr is true.
**
** The orderByConsumed means that output from xFilter will occur in
** the correct order to satisfy the ORDER BY clause so that no separate
** sorting step is required.
**
** The estimatedCost value is an estimate of the cost of doing the
** particular lookup.  A full scan of a table with N entries should have
** a cost of N.  A binary search of a table of N entries should have a
** cost of approximately log(N).
**
** This interface is experimental and is subject to change or
** removal in future releases of SQLite.
*/
struct sqlite3_index_info {
  /* Inputs */
  int nConstraint;           /* Number of entries in aConstraint */
  struct sqlite3_index_constraint {
     int iColumn;              /* Column on left-hand side of constraint */
     unsigned char op;         /* Constraint operator */
     unsigned char usable;     /* True if this constraint is usable */
     int iTermOffset;          /* Used internally - xBestIndex should ignore */
  } *aConstraint;            /* Table of WHERE clause constraints */
  int nOrderBy;              /* Number of terms in the ORDER BY clause */
  struct sqlite3_index_orderby {
     int iColumn;              /* Column number */
     unsigned char desc;       /* True for DESC.  False for ASC. */
  } *aOrderBy;               /* The ORDER BY clause */
  /* Outputs */
  struct sqlite3_index_constraint_usage {
    int argvIndex;           /* if >0, constraint is part of argv to xFilter */
    unsigned char omit;      /* Do not code a test for this constraint */
  } *aConstraintUsage;
  int idxNum;                /* Number used to identify the index */
  char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
  int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
  int orderByConsumed;       /* True if output is already ordered */
  double estimatedCost;      /* Estimated cost of using this index */
};
#define SQLITE_INDEX_CONSTRAINT_EQ    2
#define SQLITE_INDEX_CONSTRAINT_GT    4
#define SQLITE_INDEX_CONSTRAINT_LE    8
#define SQLITE_INDEX_CONSTRAINT_LT    16
#define SQLITE_INDEX_CONSTRAINT_GE    32
#define SQLITE_INDEX_CONSTRAINT_MATCH 64

/*
** CAPI3REF: Register A Virtual Table Implementation {H18200} <S20400>
** EXPERIMENTAL
**
** This routine is used to register a new module name with a
** [database connection].  Module names must be registered before
** creating new virtual tables on the module, or before using
** preexisting virtual tables of the module.
**
** This interface is experimental and is subject to change or
** removal in future releases of SQLite.
*/
SQLITE_EXPERIMENTAL int sqlite3_create_module(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *,    /* Methods for the module */
  void *                     /* Client data for xCreate/xConnect */
);

/*
** CAPI3REF: Register A Virtual Table Implementation {H18210} <S20400>
** EXPERIMENTAL
**
** This routine is identical to the [sqlite3_create_module()] method above,
** except that it allows a destructor function to be specified. It is
** even more experimental than the rest of the virtual tables API.
*/
SQLITE_EXPERIMENTAL int sqlite3_create_module_v2(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *,    /* Methods for the module */
  void *,                    /* Client data for xCreate/xConnect */
  void(*xDestroy)(void*)     /* Module destructor function */
);

/*
** CAPI3REF: Virtual Table Instance Object {H18010} <S20400>
** KEYWORDS: sqlite3_vtab
** EXPERIMENTAL
**
** Every module implementation uses a subclass of the following structure
** to describe a particular instance of the module.  Each subclass will
** be tailored to the specific needs of the module implementation.
** The purpose of this superclass is to define certain fields that are
** common to all module implementations.
**
** Virtual tables methods can set an error message by assigning a
** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
** take care that any prior string is freed by a call to [sqlite3_free()]
** prior to assigning a new string to zErrMsg.  After the error message
** is delivered up to the client application, the string will be automatically
** freed by sqlite3_free() and the zErrMsg field will be zeroed.  Note
** that sqlite3_mprintf() and sqlite3_free() are used on the zErrMsg field
** since virtual tables are commonly implemented in loadable extensions which
** do not have access to sqlite3MPrintf() or sqlite3Free().
**
** This interface is experimental and is subject to change or
** removal in future releases of SQLite.
*/
struct sqlite3_vtab {
  const sqlite3_module *pModule;  /* The module for this virtual table */
  int nRef;                       /* Used internally */
  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Virtual Table Cursor Object  {H18020} <S20400>
** KEYWORDS: sqlite3_vtab_cursor
** EXPERIMENTAL
**
** Every module implementation uses a subclass of the following structure
** to describe cursors that point into the virtual table and are used
** to loop through the virtual table.  Cursors are created using the
** xOpen method of the module.  Each module implementation will define
** the content of a cursor structure to suit its own needs.
**
** This superclass exists in order to define fields of the cursor that
** are common to all implementations.
**
** This interface is experimental and is subject to change or
** removal in future releases of SQLite.
*/
struct sqlite3_vtab_cursor {
  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Declare The Schema Of A Virtual Table {H18280} <S20400>
** EXPERIMENTAL
**
** The xCreate and xConnect methods of a module use the following API
** to declare the format (the names and datatypes of the columns) of
** the virtual tables they implement.
**
** This interface is experimental and is subject to change or
** removal in future releases of SQLite.
*/
SQLITE_EXPERIMENTAL int sqlite3_declare_vtab(sqlite3*, const char *zCreateTable);

/*
** CAPI3REF: Overload A Function For A Virtual Table {H18300} <S20400>
** EXPERIMENTAL
**
** Virtual tables can provide alternative implementations of functions
** using the xFindFunction method.  But global versions of those functions
** must exist in order to be overloaded.
**
** This API makes sure a global version of a function with a particular
** name and number of parameters exists.  If no such function exists
** before this API is called, a new function is created.  The implementation
** of the new function always causes an exception to be thrown.  So
** the new function is not good for anything by itself.  Its only
** purpose is to be a placeholder function that can be overloaded
** by virtual tables.
**
** This API should be considered part of the virtual table interface,
** which is experimental and subject to change.
*/
SQLITE_EXPERIMENTAL int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);

/*
** The interface to the virtual-table mechanism defined above (back up
** to a comment remarkably similar to this one) is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
**
****** EXPERIMENTAL - subject to change without notice **************
*/

/*
** CAPI3REF: A Handle To An Open BLOB {H17800} <S30230>
** KEYWORDS: {BLOB handle} {BLOB handles}
**
** An instance of this object represents an open BLOB on which
** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
** Objects of this type are created by [sqlite3_blob_open()]
** and destroyed by [sqlite3_blob_close()].
** The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
** can be used to read or write small subsections of the BLOB.
** The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
*/
typedef struct sqlite3_blob sqlite3_blob;

/*
** CAPI3REF: Open A BLOB For Incremental I/O {H17810} <S30230>
**
** This interfaces opens a [BLOB handle | handle] to the BLOB located
** in row iRow, column zColumn, table zTable in database zDb;
** in other words, the same BLOB that would be selected by:
**
** <pre>
**     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
** </pre> {END}
**
** If the flags parameter is non-zero, the the BLOB is opened for read
** and write access. If it is zero, the BLOB is opened for read access.
**
** Note that the database name is not the filename that contains
** the database but rather the symbolic name of the database that
** is assigned when the database is connected using [ATTACH].
** For the main database file, the database name is "main".
** For TEMP tables, the database name is "temp".
**
** On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
** to *ppBlob. Otherwise an [error code] is returned and any value written
** to *ppBlob should not be used by the caller.
** This function sets the [database connection] error code and message
** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()].
**
** If the row that a BLOB handle points to is modified by an
** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
** then the BLOB handle is marked as "expired".
** This is true if any column of the row is changed, even a column
** other than the one the BLOB handle is open on.
** Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
** a expired BLOB handle fail with an return code of [SQLITE_ABORT].
** Changes written into a BLOB prior to the BLOB expiring are not
** rollback by the expiration of the BLOB.  Such changes will eventually
** commit if the transaction continues to completion.
**
** INVARIANTS:
**
** {H17813} A successful invocation of the [sqlite3_blob_open(D,B,T,C,R,F,P)]
**          interface shall open an [sqlite3_blob] object P on the BLOB
**          in column C of the table T in the database B on
**          the [database connection] D.
**
** {H17814} A successful invocation of [sqlite3_blob_open(D,...)] shall start
**          a new transaction on the [database connection] D if that
**          connection is not already in a transaction.
**
** {H17816} The [sqlite3_blob_open(D,B,T,C,R,F,P)] interface shall open
**          the BLOB for read and write access if and only if the F
**          parameter is non-zero.
**
** {H17819} The [sqlite3_blob_open()] interface shall return [SQLITE_OK] on
**          success and an appropriate [error code] on failure.
**
** {H17821} If an error occurs during evaluation of [sqlite3_blob_open(D,...)]
**          then subsequent calls to [sqlite3_errcode(D)],
**          [sqlite3_extended_errcode()], 
**          [sqlite3_errmsg(D)], and [sqlite3_errmsg16(D)] shall return
**          information appropriate for that error.
**
** {H17824} If any column in the row that a [sqlite3_blob] has open is
**          changed by a separate [UPDATE] or [DELETE] statement or by
**          an [ON CONFLICT] side effect, then the [sqlite3_blob] shall
**          be marked as invalid.
*/
int sqlite3_blob_open(
  sqlite3*,
  const char *zDb,
  const char *zTable,
  const char *zColumn,
  sqlite3_int64 iRow,
  int flags,
  sqlite3_blob **ppBlob
);

/*
** CAPI3REF: Close A BLOB Handle {H17830} <S30230>
**
** Closes an open [BLOB handle].
**
** Closing a BLOB shall cause the current transaction to commit
** if there are no other BLOBs, no pending prepared statements, and the
** database connection is in [autocommit mode].
** If any writes were made to the BLOB, they might be held in cache
** until the close operation if they will fit. {END}
**
** Closing the BLOB often forces the changes
** out to disk and so if any I/O errors occur, they will likely occur
** at the time when the BLOB is closed.  {H17833} Any errors that occur during
** closing are reported as a non-zero return value.
**
** The BLOB is closed unconditionally.  Even if this routine returns
** an error code, the BLOB is still closed.
**
** INVARIANTS:
**
** {H17833} The [sqlite3_blob_close(P)] interface closes an [sqlite3_blob]
**          object P previously opened using [sqlite3_blob_open()].
**
** {H17836} Closing an [sqlite3_blob] object using
**          [sqlite3_blob_close()] shall cause the current transaction to
**          commit if there are no other open [sqlite3_blob] objects
**          or [prepared statements] on the same [database connection] and
**          the database connection is in [autocommit mode].
**
** {H17839} The [sqlite3_blob_close(P)] interfaces shall close the
**          [sqlite3_blob] object P unconditionally, even if
**          [sqlite3_blob_close(P)] returns something other than [SQLITE_OK].
*/
int sqlite3_blob_close(sqlite3_blob *);

/*
** CAPI3REF: Return The Size Of An Open BLOB {H17840} <S30230>
**
** Returns the size in bytes of the BLOB accessible via the open
** []BLOB handle] in its only argument.
**
** INVARIANTS:
**
** {H17843} The [sqlite3_blob_bytes(P)] interface returns the size
**          in bytes of the BLOB that the [sqlite3_blob] object P
**          refers to.
*/
int sqlite3_blob_bytes(sqlite3_blob *);

/*
** CAPI3REF: Read Data From A BLOB Incrementally {H17850} <S30230>
**
** This function is used to read data from an open [BLOB handle] into a
** caller-supplied buffer. N bytes of data are copied into buffer Z
** from the open BLOB, starting at offset iOffset.
**
** If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is read.  If N or iOffset is
** less than zero, [SQLITE_ERROR] is returned and no data is read.
**
** An attempt to read from an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].
**
** On success, SQLITE_OK is returned.
** Otherwise, an [error code] or an [extended error code] is returned.
**
** INVARIANTS:
**
** {H17853} A successful invocation of [sqlite3_blob_read(P,Z,N,X)] 
**          shall reads N bytes of data out of the BLOB referenced by
**          [BLOB handle] P beginning at offset X and store those bytes
**          into buffer Z.
**
** {H17856} In [sqlite3_blob_read(P,Z,N,X)] if the size of the BLOB
**          is less than N+X bytes, then the function shall leave the
**          Z buffer unchanged and return [SQLITE_ERROR].
**
** {H17859} In [sqlite3_blob_read(P,Z,N,X)] if X or N is less than zero
**          then the function shall leave the Z buffer unchanged
**          and return [SQLITE_ERROR].
**
** {H17862} The [sqlite3_blob_read(P,Z,N,X)] interface shall return [SQLITE_OK]
**          if N bytes are successfully read into buffer Z.
**
** {H17863} If the [BLOB handle] P is expired and X and N are within bounds
**          then [sqlite3_blob_read(P,Z,N,X)] shall leave the Z buffer
**          unchanged and return [SQLITE_ABORT].
**
** {H17865} If the requested read could not be completed,
**          the [sqlite3_blob_read(P,Z,N,X)] interface shall return an
**          appropriate [error code] or [extended error code].
**
** {H17868} If an error occurs during evaluation of [sqlite3_blob_read(P,...)]
**          then subsequent calls to [sqlite3_errcode(D)],
**          [sqlite3_extended_errcode()],
**          [sqlite3_errmsg(D)], and [sqlite3_errmsg16(D)] shall return
**          information appropriate for that error, where D is the
**          [database connection] that was used to open the [BLOB handle] P.
*/
int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);

/*
** CAPI3REF: Write Data Into A BLOB Incrementally {H17870} <S30230>
**
** This function is used to write data into an open [BLOB handle] from a
** caller-supplied buffer. N bytes of data are copied from the buffer Z
** into the open BLOB, starting at offset iOffset.
**
** If the [BLOB handle] passed as the first argument was not opened for
** writing (the flags parameter to [sqlite3_blob_open()] was zero),
** this function returns [SQLITE_READONLY].
**
** This function may only modify the contents of the BLOB; it is
** not possible to increase the size of a BLOB using this API.
** If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is written.  If N is
** less than zero [SQLITE_ERROR] is returned and no data is written.
**
** An attempt to write to an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].  Writes to the BLOB that occurred
** before the [BLOB handle] expired are not rolled back by the
** expiration of the handle, though of course those changes might
** have been overwritten by the statement that expired the BLOB handle
** or by other independent statements.
**
** On success, SQLITE_OK is returned.
** Otherwise, an  [error code] or an [extended error code] is returned.
**
** INVARIANTS:
**
** {H17873} A successful invocation of [sqlite3_blob_write(P,Z,N,X)]
**          shall write N bytes of data from buffer Z into the BLOB 
**          referenced by [BLOB handle] P beginning at offset X into
**          the BLOB.
**
** {H17874} In the absence of other overridding changes, the changes
**          written to a BLOB by [sqlite3_blob_write()] shall
**          remain in effect after the associated [BLOB handle] expires.
**
** {H17875} If the [BLOB handle] P was opened for reading only then
**          an invocation of [sqlite3_blob_write(P,Z,N,X)] shall leave
**          the referenced BLOB unchanged and return [SQLITE_READONLY].
**
** {H17876} If the size of the BLOB referenced by [BLOB handle] P is
**          less than N+X bytes then [sqlite3_blob_write(P,Z,N,X)] shall
**          leave the BLOB unchanged and return [SQLITE_ERROR].
**
** {H17877} If the [BLOB handle] P is expired and X and N are within bounds
**          then [sqlite3_blob_read(P,Z,N,X)] shall leave the BLOB
**          unchanged and return [SQLITE_ABORT].
**
** {H17879} If X or N are less than zero then [sqlite3_blob_write(P,Z,N,X)]
**          shall leave the BLOB referenced by [BLOB handle] P unchanged
**          and return [SQLITE_ERROR].
**
** {H17882} The [sqlite3_blob_write(P,Z,N,X)] interface shall return
**          [SQLITE_OK] if N bytes where successfully written into the BLOB.
**
** {H17885} If the requested write could not be completed,
**          the [sqlite3_blob_write(P,Z,N,X)] interface shall return an
**          appropriate [error code] or [extended error code].
**
** {H17888} If an error occurs during evaluation of [sqlite3_blob_write(D,...)]
**          then subsequent calls to [sqlite3_errcode(D)],
**          [sqlite3_extended_errcode()],
**          [sqlite3_errmsg(D)], and [sqlite3_errmsg16(D)] shall return
**          information appropriate for that error.
*/
int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);

/*
** CAPI3REF: Virtual File System Objects {H11200} <S20100>
**
** A virtual filesystem (VFS) is an [sqlite3_vfs] object
** that SQLite uses to interact
** with the underlying operating system.  Most SQLite builds come with a
** single default VFS that is appropriate for the host computer.
** New VFSes can be registered and existing VFSes can be unregistered.
** The following interfaces are provided.
**
** The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
** Names are case sensitive.
** Names are zero-terminated UTF-8 strings.
** If there is no match, a NULL pointer is returned.
** If zVfsName is NULL then the default VFS is returned.
**
** New VFSes are registered with sqlite3_vfs_register().
** Each new VFS becomes the default VFS if the makeDflt flag is set.
** The same VFS can be registered multiple times without injury.
** To make an existing VFS into the default VFS, register it again
** with the makeDflt flag set.  If two different VFSes with the
** same name are registered, the behavior is undefined.  If a
** VFS is registered with a name that is NULL or an empty string,
** then the behavior is undefined.
**
** Unregister a VFS with the sqlite3_vfs_unregister() interface.
** If the default VFS is unregistered, another VFS is chosen as
** the default.  The choice for the new VFS is arbitrary.
**
** INVARIANTS:
**
** {H11203} The [sqlite3_vfs_find(N)] interface returns a pointer to the
**          registered [sqlite3_vfs] object whose name exactly matches
**          the zero-terminated UTF-8 string N, or it returns NULL if
**          there is no match.
**
** {H11206} If the N parameter to [sqlite3_vfs_find(N)] is NULL then
**          the function returns a pointer to the default [sqlite3_vfs]
**          object if there is one, or NULL if there is no default
**          [sqlite3_vfs] object.
**
** {H11209} The [sqlite3_vfs_register(P,F)] interface registers the
**          well-formed [sqlite3_vfs] object P using the name given
**          by the zName field of the object.
**
** {H11212} Using the [sqlite3_vfs_register(P,F)] interface to register
**          the same [sqlite3_vfs] object multiple times is a harmless no-op.
**
** {H11215} The [sqlite3_vfs_register(P,F)] interface makes the [sqlite3_vfs]
**          object P the default [sqlite3_vfs] object if F is non-zero.
**
** {H11218} The [sqlite3_vfs_unregister(P)] interface unregisters the
**          [sqlite3_vfs] object P so that it is no longer returned by
**          subsequent calls to [sqlite3_vfs_find()].
*/
sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
int sqlite3_vfs_unregister(sqlite3_vfs*);

/*
** CAPI3REF: Mutexes {H17000} <S20000>
**
** The SQLite core uses these routines for thread
** synchronization. Though they are intended for internal
** use by SQLite, code that links against SQLite is
** permitted to use any of these routines.
**
** The SQLite source code contains multiple implementations
** of these mutex routines.  An appropriate implementation
** is selected automatically at compile-time.  The following
** implementations are available in the SQLite core:
**
** <ul>
** <li>   SQLITE_MUTEX_OS2
** <li>   SQLITE_MUTEX_PTHREAD
** <li>   SQLITE_MUTEX_W32
** <li>   SQLITE_MUTEX_NOOP
** </ul>
**
** The SQLITE_MUTEX_NOOP implementation is a set of routines
** that does no real locking and is appropriate for use in
** a single-threaded application.  The SQLITE_MUTEX_OS2,
** SQLITE_MUTEX_PTHREAD, and SQLITE_MUTEX_W32 implementations
** are appropriate for use on OS/2, Unix, and Windows.
**
** If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
** implementation is included with the library. In this case the
** application must supply a custom mutex implementation using the
** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
** before calling sqlite3_initialize() or any other public sqlite3_
** function that calls sqlite3_initialize().
**
** {H17011} The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it. {H17012} If it returns NULL
** that means that a mutex could not be allocated. {H17013} SQLite
** will unwind its stack and return an error. {H17014} The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST
** <li>  SQLITE_MUTEX_RECURSIVE
** <li>  SQLITE_MUTEX_STATIC_MASTER
** <li>  SQLITE_MUTEX_STATIC_MEM
** <li>  SQLITE_MUTEX_STATIC_MEM2
** <li>  SQLITE_MUTEX_STATIC_PRNG
** <li>  SQLITE_MUTEX_STATIC_LRU
** <li>  SQLITE_MUTEX_STATIC_LRU2
** </ul>
**
** {H17015} The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used. {END}
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to.  {H17016} But SQLite will only request a recursive mutex in
** cases where it really needs one.  {END} If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** {H17017} The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex. {END}  Four static mutexes are
** used by the current version of SQLite.  Future versions of SQLite
** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** {H17018} Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call.  {H17034} But for the static
** mutex types, the same mutex is returned on every call that has
** the same type number.
**
** {H17019} The sqlite3_mutex_free() routine deallocates a previously
** allocated dynamic mutex. {H17020} SQLite is careful to deallocate every
** dynamic mutex that it allocates. {A17021} The dynamic mutexes must not be in
** use when they are deallocated. {A17022} Attempting to deallocate a static
** mutex results in undefined behavior. {H17023} SQLite never deallocates
** a static mutex. {END}
**
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex. {H17024} If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY. {H17025}  The sqlite3_mutex_try() interface returns [SQLITE_OK]
** upon successful entry.  {H17026} Mutexes created using
** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
** {H17027} In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  {A17028} If the same thread tries to enter any other
** kind of mutex more than once, the behavior is undefined.
** {H17029} SQLite will never exhibit
** such behavior in its own use of mutexes.
**
** Some systems (for example, Windows 95) do not support the operation
** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
** will always return SQLITE_BUSY.  {H17030} The SQLite core only ever uses
** sqlite3_mutex_try() as an optimization so this is acceptable behavior.
**
** {H17031} The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  {A17032} The behavior
** is undefined if the mutex is not currently entered by the
** calling thread or is not currently allocated.  {H17033} SQLite will
** never do either. {END}
**
** If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
** sqlite3_mutex_leave() is a NULL pointer, then all three routines
** behave as no-ops.
**
** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
*/
sqlite3_mutex *sqlite3_mutex_alloc(int);
void sqlite3_mutex_free(sqlite3_mutex*);
void sqlite3_mutex_enter(sqlite3_mutex*);
int sqlite3_mutex_try(sqlite3_mutex*);
void sqlite3_mutex_leave(sqlite3_mutex*);

/*
** CAPI3REF: Mutex Methods Object {H17120} <S20130>
** EXPERIMENTAL
**
** An instance of this structure defines the low-level routines
** used to allocate and use mutexes.
**
** Usually, the default mutex implementations provided by SQLite are
** sufficient, however the user has the option of substituting a custom
** implementation for specialized deployments or systems for which SQLite
** does not provide a suitable implementation. In this case, the user
** creates and populates an instance of this structure to pass
** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
** Additionally, an instance of this structure can be used as an
** output variable when querying the system for the current mutex
** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
**
** The xMutexInit method defined by this structure is invoked as
** part of system initialization by the sqlite3_initialize() function.
** {H17001} The xMutexInit routine shall be called by SQLite once for each
** effective call to [sqlite3_initialize()].
**
** The xMutexEnd method defined by this structure is invoked as
** part of system shutdown by the sqlite3_shutdown() function. The
** implementation of this method is expected to release all outstanding
** resources obtained by the mutex methods implementation, especially
** those obtained by the xMutexInit method. {H17003} The xMutexEnd()
** interface shall be invoked once for each call to [sqlite3_shutdown()].
**
** The remaining seven methods defined by this structure (xMutexAlloc,
** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
** xMutexNotheld) implement the following interfaces (respectively):
**
** <ul>
**   <li>  [sqlite3_mutex_alloc()] </li>
**   <li>  [sqlite3_mutex_free()] </li>
**   <li>  [sqlite3_mutex_enter()] </li>
**   <li>  [sqlite3_mutex_try()] </li>
**   <li>  [sqlite3_mutex_leave()] </li>
**   <li>  [sqlite3_mutex_held()] </li>
**   <li>  [sqlite3_mutex_notheld()] </li>
** </ul>
**
** The only difference is that the public sqlite3_XXX functions enumerated
** above silently ignore any invocations that pass a NULL pointer instead
** of a valid mutex handle. The implementations of the methods defined
** by this structure are not required to handle this case, the results
** of passing a NULL pointer instead of a valid mutex handle are undefined
** (i.e. it is acceptable to provide an implementation that segfaults if
** it is passed a NULL pointer).
*/
typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
struct sqlite3_mutex_methods {
  int (*xMutexInit)(void);
  int (*xMutexEnd)(void);
  sqlite3_mutex *(*xMutexAlloc)(int);
  void (*xMutexFree)(sqlite3_mutex *);
  void (*xMutexEnter)(sqlite3_mutex *);
  int (*xMutexTry)(sqlite3_mutex *);
  void (*xMutexLeave)(sqlite3_mutex *);
  int (*xMutexHeld)(sqlite3_mutex *);
  int (*xMutexNotheld)(sqlite3_mutex *);
};

/*
** CAPI3REF: Mutex Verification Routines {H17080} <S20130> <S30800>
**
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
** are intended for use inside assert() statements. {H17081} The SQLite core
** never uses these routines except inside an assert() and applications
** are advised to follow the lead of the core.  {H17082} The core only
** provides implementations for these routines when it is compiled
** with the SQLITE_DEBUG flag.  {A17087} External mutex implementations
** are only required to provide these routines if SQLITE_DEBUG is
** defined and if NDEBUG is not defined.
**
** {H17083} These routines should return true if the mutex in their argument
** is held or not held, respectively, by the calling thread.
**
** {X17084} The implementation is not required to provided versions of these
** routines that actually work. If the implementation does not provide working
** versions of these routines, it should at least provide stubs that always
** return true so that one does not get spurious assertion failures.
**
** {H17085} If the argument to sqlite3_mutex_held() is a NULL pointer then
** the routine should return 1.  {END} This seems counter-intuitive since
** clearly the mutex cannot be held if it does not exist.  But the
** the reason the mutex does not exist is because the build is not
** using mutexes.  And we do not want the assert() containing the
** call to sqlite3_mutex_held() to fail, so a non-zero return is
** the appropriate thing to do.  {H17086} The sqlite3_mutex_notheld()
** interface should also return 1 when given a NULL pointer.
*/
int sqlite3_mutex_held(sqlite3_mutex*);
int sqlite3_mutex_notheld(sqlite3_mutex*);

/*
** CAPI3REF: Mutex Types {H17001} <H17000>
**
** The [sqlite3_mutex_alloc()] interface takes a single argument
** which is one of these integer constants.
**
** The set of static mutexes may change from one SQLite release to the
** next.  Applications that override the built-in mutex logic must be
** prepared to accommodate additional static mutexes.
*/
#define SQLITE_MUTEX_FAST             0
#define SQLITE_MUTEX_RECURSIVE        1
#define SQLITE_MUTEX_STATIC_MASTER    2
#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
#define SQLITE_MUTEX_STATIC_MEM2      4  /* sqlite3_release_memory() */
#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
#define SQLITE_MUTEX_STATIC_LRU2      7  /* lru page list */

/*
** CAPI3REF: Retrieve the mutex for a database connection {H17002} <H17000>
**
** This interface returns a pointer the [sqlite3_mutex] object that 
** serializes access to the [database connection] given in the argument
** when the [threading mode] is Serialized.
** If the [threading mode] is Single-thread or Multi-thread then this
** routine returns a NULL pointer.
*/
sqlite3_mutex *sqlite3_db_mutex(sqlite3*);

/*
** CAPI3REF: Low-Level Control Of Database Files {H11300} <S30800>
**
** {H11301} The [sqlite3_file_control()] interface makes a direct call to the
** xFileControl method for the [sqlite3_io_methods] object associated
** with a particular database identified by the second argument. {H11302} The
** name of the database is the name assigned to the database by the
** <a href="lang_attach.html">ATTACH</a> SQL command that opened the
** database. {H11303} To control the main database file, use the name "main"
** or a NULL pointer. {H11304} The third and fourth parameters to this routine
** are passed directly through to the second and third parameters of
** the xFileControl method.  {H11305} The return value of the xFileControl
** method becomes the return value of this routine.
**
** {H11306} If the second parameter (zDbName) does not match the name of any
** open database file, then SQLITE_ERROR is returned. {H11307} This error
** code is not remembered and will not be recalled by [sqlite3_errcode()]
** or [sqlite3_errmsg()]. {A11308} The underlying xFileControl method might
** also return SQLITE_ERROR.  {A11309} There is no way to distinguish between
** an incorrect zDbName and an SQLITE_ERROR return from the underlying
** xFileControl method. {END}
**
** See also: [SQLITE_FCNTL_LOCKSTATE]
*/
int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);

/*
** CAPI3REF: Testing Interface {H11400} <S30800>
**
** The sqlite3_test_control() interface is used to read out internal
** state of SQLite and to inject faults into SQLite for testing
** purposes.  The first parameter is an operation code that determines
** the number, meaning, and operation of all subsequent parameters.
**
** This interface is not for use by applications.  It exists solely
** for verifying the correct operation of the SQLite library.  Depending
** on how the SQLite library is compiled, this interface might not exist.
**
** The details of the operation codes, their meanings, the parameters
** they take, and what they do are all subject to change without notice.
** Unlike most of the SQLite API, this function is not guaranteed to
** operate consistently from one release to the next.
*/
int sqlite3_test_control(int op, ...);

/*
** CAPI3REF: Testing Interface Operation Codes {H11410} <H11400>
**
** These constants are the valid operation code parameters used
** as the first argument to [sqlite3_test_control()].
**
** These parameters and their meanings are subject to change
** without notice.  These values are for testing purposes only.
** Applications should not use any of these parameters or the
** [sqlite3_test_control()] interface.
*/
#define SQLITE_TESTCTRL_PRNG_SAVE                5
#define SQLITE_TESTCTRL_PRNG_RESTORE             6
#define SQLITE_TESTCTRL_PRNG_RESET               7
#define SQLITE_TESTCTRL_BITVEC_TEST              8
#define SQLITE_TESTCTRL_FAULT_INSTALL            9
#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
#define SQLITE_TESTCTRL_PENDING_BYTE            11

/*
** CAPI3REF: SQLite Runtime Status {H17200} <S60200>
** EXPERIMENTAL
**
** This interface is used to retrieve runtime status information
** about the preformance of SQLite, and optionally to reset various
** highwater marks.  The first argument is an integer code for
** the specific parameter to measure.  Recognized integer codes
** are of the form [SQLITE_STATUS_MEMORY_USED | SQLITE_STATUS_...].
** The current value of the parameter is returned into *pCurrent.
** The highest recorded value is returned in *pHighwater.  If the
** resetFlag is true, then the highest record value is reset after
** *pHighwater is written. Some parameters do not record the highest
** value.  For those parameters
** nothing is written into *pHighwater and the resetFlag is ignored.
** Other parameters record only the highwater mark and not the current
** value.  For these latter parameters nothing is written into *pCurrent.
**
** This routine returns SQLITE_OK on success and a non-zero
** [error code] on failure.
**
** This routine is threadsafe but is not atomic.  This routine can
** called while other threads are running the same or different SQLite
** interfaces.  However the values returned in *pCurrent and
** *pHighwater reflect the status of SQLite at different points in time
** and it is possible that another thread might change the parameter
** in between the times when *pCurrent and *pHighwater are written.
**
** See also: [sqlite3_db_status()]
*/
SQLITE_EXPERIMENTAL int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);


/*
** CAPI3REF: Status Parameters {H17250} <H17200>
** EXPERIMENTAL
**
** These integer constants designate various run-time status parameters
** that can be returned by [sqlite3_status()].
**
** <dl>
** <dt>SQLITE_STATUS_MEMORY_USED</dt>
** <dd>This parameter is the current amount of memory checked out
** using [sqlite3_malloc()], either directly or indirectly.  The
** figure includes calls made to [sqlite3_malloc()] by the application
** and internal memory usage by the SQLite library.  Scratch memory
** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
** this parameter.  The amount returned is the sum of the allocation
** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>
**
** <dt>SQLITE_STATUS_MALLOC_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
** internal equivalents).  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.  
** The value written into the *pCurrent parameter is undefined.</dd>
**
** <dt>SQLITE_STATUS_PAGECACHE_USED</dt>
** <dd>This parameter returns the number of pages used out of the
** [pagecache memory allocator] that was configured using 
** [SQLITE_CONFIG_PAGECACHE].  The
** value returned is in pages, not in bytes.</dd>
**
** <dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
** <dd>This parameter returns the number of bytes of page cache
** allocation which could not be statisfied by the [SQLITE_CONFIG_PAGECACHE]
** buffer and where forced to overflow to [sqlite3_malloc()].  The
** returned value includes allocations that overflowed because they
** where too large (they were larger than the "sz" parameter to
** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
** no space was left in the page cache.</dd>
**
** <dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [pagecache memory allocator].  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.  
** The value written into the *pCurrent parameter is undefined.</dd>
**
** <dt>SQLITE_STATUS_SCRATCH_USED</dt>
** <dd>This parameter returns the number of allocations used out of the
** [scratch memory allocator] configured using
** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
** in bytes.  Since a single thread may only have one scratch allocation
** outstanding at time, this parameter also reports the number of threads
** using scratch memory at the same time.</dd>
**
** <dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
** <dd>This parameter returns the number of bytes of scratch memory
** allocation which could not be statisfied by the [SQLITE_CONFIG_SCRATCH]
** buffer and where forced to overflow to [sqlite3_malloc()].  The values
** returned include overflows because the requested allocation was too
** larger (that is, because the requested allocation was larger than the
** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
** slots were available.
** </dd>
**
** <dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [scratch memory allocator].  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.  
** The value written into the *pCurrent parameter is undefined.</dd>
**
** <dt>SQLITE_STATUS_PARSER_STACK</dt>
** <dd>This parameter records the deepest parser stack.  It is only
** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>
** </dl>
**
** New status parameters may be added from time to time.
*/
#define SQLITE_STATUS_MEMORY_USED          0
#define SQLITE_STATUS_PAGECACHE_USED       1
#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
#define SQLITE_STATUS_SCRATCH_USED         3
#define SQLITE_STATUS_SCRATCH_OVERFLOW     4
#define SQLITE_STATUS_MALLOC_SIZE          5
#define SQLITE_STATUS_PARSER_STACK         6
#define SQLITE_STATUS_PAGECACHE_SIZE       7
#define SQLITE_STATUS_SCRATCH_SIZE         8

/*
** CAPI3REF: Database Connection Status {H17500} <S60200>
** EXPERIMENTAL
**
** This interface is used to retrieve runtime status information 
** about a single [database connection].  The first argument is the
** database connection object to be interrogated.  The second argument
** is the parameter to interrogate.  Currently, the only allowed value
** for the second parameter is [SQLITE_DBSTATUS_LOOKASIDE_USED].
** Additional options will likely appear in future releases of SQLite.
**
** The current value of the requested parameter is written into *pCur
** and the highest instantaneous value is written into *pHiwtr.  If
** the resetFlg is true, then the highest instantaneous value is
** reset back down to the current value.
**
** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
*/
SQLITE_EXPERIMENTAL int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);

/*
** CAPI3REF: Status Parameters for database connections {H17520} <H17500>
** EXPERIMENTAL
**
** Status verbs for [sqlite3_db_status()].
**
** <dl>
** <dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
** <dd>This parameter returns the number of lookaside memory slots currently
** checked out.</dd>
** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED     0


/*
** CAPI3REF: Prepared Statement Status {H17550} <S60200>
** EXPERIMENTAL
**
** Each prepared statement maintains various
** [SQLITE_STMTSTATUS_SORT | counters] that measure the number
** of times it has performed specific operations.  These counters can
** be used to monitor the performance characteristics of the prepared
** statements.  For example, if the number of table steps greatly exceeds
** the number of table searches or result rows, that would tend to indicate
** that the prepared statement is using a full table scan rather than
** an index.  
**
** This interface is used to retrieve and reset counter values from
** a [prepared statement].  The first argument is the prepared statement
** object to be interrogated.  The second argument
** is an integer code for a specific [SQLITE_STMTSTATUS_SORT | counter]
** to be interrogated. 
** The current value of the requested counter is returned.
** If the resetFlg is true, then the counter is reset to zero after this
** interface call returns.
**
** See also: [sqlite3_status()] and [sqlite3_db_status()].
*/
SQLITE_EXPERIMENTAL int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);

/*
** CAPI3REF: Status Parameters for prepared statements {H17570} <H17550>
** EXPERIMENTAL
**
** These preprocessor macros define integer codes that name counter
** values associated with the [sqlite3_stmt_status()] interface.
** The meanings of the various counters are as follows:
**
** <dl>
** <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
** <dd>This is the number of times that SQLite has stepped forward in
** a table as part of a full table scan.  Large numbers for this counter
** may indicate opportunities for performance improvement through 
** careful use of indices.</dd>
**
** <dt>SQLITE_STMTSTATUS_SORT</dt>
** <dd>This is the number of sort operations that have occurred.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance through careful use of indices.</dd>
**
** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2

/*
** CAPI3REF: Custom Page Cache Object
** EXPERIMENTAL
**
** The sqlite3_pcache type is opaque.  It is implemented by
** the pluggable module.  The SQLite core has no knowledge of
** its size or internal structure and never deals with the
** sqlite3_pcache object except by holding and passing pointers
** to the object.
**
** See [sqlite3_pcache_methods] for additional information.
*/
typedef struct sqlite3_pcache sqlite3_pcache;

/*
** CAPI3REF: Application Defined Page Cache.
** EXPERIMENTAL
**
** The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can
** register an alternative page cache implementation by passing in an 
** instance of the sqlite3_pcache_methods structure. The majority of the 
** heap memory used by sqlite is used by the page cache to cache data read 
** from, or ready to be written to, the database file. By implementing a 
** custom page cache using this API, an application can control more 
** precisely the amount of memory consumed by sqlite, the way in which 
** said memory is allocated and released, and the policies used to 
** determine exactly which parts of a database file are cached and for 
** how long.
**
** The contents of the structure are copied to an internal buffer by sqlite
** within the call to [sqlite3_config].
**
** The xInit() method is called once for each call to [sqlite3_initialize()]
** (usually only once during the lifetime of the process). It is passed
** a copy of the sqlite3_pcache_methods.pArg value. It can be used to set
** up global structures and mutexes required by the custom page cache 
** implementation. The xShutdown() method is called from within 
** [sqlite3_shutdown()], if the application invokes this API. It can be used
** to clean up any outstanding resources before process shutdown, if required.
**
** The xCreate() method is used to construct a new cache instance. The
** first parameter, szPage, is the size in bytes of the pages that must
** be allocated by the cache. szPage will not be a power of two. The
** second argument, bPurgeable, is true if the cache being created will
** be used to cache database pages read from a file stored on disk, or
** false if it is used for an in-memory database. The cache implementation
** does not have to do anything special based on the value of bPurgeable,
** it is purely advisory. 
**
** The xCachesize() method may be called at any time by SQLite to set the
** suggested maximum cache-size (number of pages stored by) the cache
** instance passed as the first argument. This is the value configured using
** the SQLite "[PRAGMA cache_size]" command. As with the bPurgeable parameter,
** the implementation is not required to do anything special with this
** value, it is advisory only.
**
** The xPagecount() method should return the number of pages currently
** stored in the cache supplied as an argument.
** 
** The xFetch() method is used to fetch a page and return a pointer to it. 
** A 'page', in this context, is a buffer of szPage bytes aligned at an
** 8-byte boundary. The page to be fetched is determined by the key. The
** mimimum key value is 1. After it has been retrieved using xFetch, the page 
** is considered to be pinned.
**
** If the requested page is already in the page cache, then a pointer to
** the cached buffer should be returned with its contents intact. If the
** page is not already in the cache, then the expected behaviour of the
** cache is determined by the value of the createFlag parameter passed
** to xFetch, according to the following table:
**
** <table border=1 width=85% align=center>
**   <tr><th>createFlag<th>Expected Behaviour
**   <tr><td>0<td>NULL should be returned. No new cache entry is created.
**   <tr><td>1<td>If createFlag is set to 1, this indicates that 
**                SQLite is holding pinned pages that can be unpinned
**                by writing their contents to the database file (a
**                relatively expensive operation). In this situation the
**                cache implementation has two choices: it can return NULL,
**                in which case SQLite will attempt to unpin one or more 
**                pages before re-requesting the same page, or it can
**                allocate a new page and return a pointer to it. If a new
**                page is allocated, then the first sizeof(void*) bytes of
**                it (at least) must be zeroed before it is returned.
**   <tr><td>2<td>If createFlag is set to 2, then SQLite is not holding any
**                pinned pages associated with the specific cache passed
**                as the first argument to xFetch() that can be unpinned. The
**                cache implementation should attempt to allocate a new
**                cache entry and return a pointer to it. Again, the first
**                sizeof(void*) bytes of the page should be zeroed before 
**                it is returned. If the xFetch() method returns NULL when 
**                createFlag==2, SQLite assumes that a memory allocation 
**                failed and returns SQLITE_NOMEM to the user.
** </table>
**
** xUnpin() is called by SQLite with a pointer to a currently pinned page
** as its second argument. If the third parameter, discard, is non-zero,
** then the page should be evicted from the cache. In this case SQLite 
** assumes that the next time the page is retrieved from the cache using
** the xFetch() method, it will be zeroed. If the discard parameter is
** zero, then the page is considered to be unpinned. The cache implementation
** may choose to reclaim (free or recycle) unpinned pages at any time.
** SQLite assumes that next time the page is retrieved from the cache
** it will either be zeroed, or contain the same data that it did when it
** was unpinned.
**
** The cache is not required to perform any reference counting. A single 
** call to xUnpin() unpins the page regardless of the number of prior calls 
** to xFetch().
**
** The xRekey() method is used to change the key value associated with the
** page passed as the second argument from oldKey to newKey. If the cache
** previously contains an entry associated with newKey, it should be
** discarded. Any prior cache entry associated with newKey is guaranteed not
** to be pinned.
**
** When SQLite calls the xTruncate() method, the cache must discard all
** existing cache entries with page numbers (keys) greater than or equal
** to the value of the iLimit parameter passed to xTruncate(). If any
** of these pages are pinned, they are implicitly unpinned, meaning that
** they can be safely discarded.
**
** The xDestroy() method is used to delete a cache allocated by xCreate().
** All resources associated with the specified cache should be freed. After
** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
** handle invalid, and will not use it with any other sqlite3_pcache_methods
** functions.
*/
typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
struct sqlite3_pcache_methods {
  void *pArg;
  int (*xInit)(void*);
  void (*xShutdown)(void*);
  sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
  int (*xPagecount)(sqlite3_pcache*);
  void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
  void (*xUnpin)(sqlite3_pcache*, void*, int discard);
  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
  void (*xDestroy)(sqlite3_pcache*);
};

/*
** CAPI3REF: Online Backup Object
** EXPERIMENTAL
**
** The sqlite3_backup object records state information about an ongoing
** online backup operation.  The sqlite3_backup object is created by
** a call to [sqlite3_backup_init()] and is destroyed by a call to
** [sqlite3_backup_finish()].
**
** See Also: [Using the SQLite Online Backup API]
*/
typedef struct sqlite3_backup sqlite3_backup;

/*
** CAPI3REF: Online Backup API.
** EXPERIMENTAL
**
** This API is used to overwrite the contents of one database with that
** of another. It is useful either for creating backups of databases or
** for copying in-memory databases to or from persistent files. 
**
** See Also: [Using the SQLite Online Backup API]
**
** Exclusive access is required to the destination database for the 
** duration of the operation. However the source database is only
** read-locked while it is actually being read, it is not locked
** continuously for the entire operation. Thus, the backup may be
** performed on a live database without preventing other users from
** writing to the database for an extended period of time.
** 
** To perform a backup operation: 
**   <ol>
**     <li><b>sqlite3_backup_init()</b> is called once to initialize the
**         backup, 
**     <li><b>sqlite3_backup_step()</b> is called one or more times to transfer 
**         the data between the two databases, and finally
**     <li><b>sqlite3_backup_finish()</b> is called to release all resources 
**         associated with the backup operation. 
**   </ol>
** There should be exactly one call to sqlite3_backup_finish() for each
** successful call to sqlite3_backup_init().
**
** <b>sqlite3_backup_init()</b>
**
** The first two arguments passed to [sqlite3_backup_init()] are the database
** handle associated with the destination database and the database name 
** used to attach the destination database to the handle. The database name
** is "main" for the main database, "temp" for the temporary database, or
** the name specified as part of the [ATTACH] statement if the destination is
** an attached database. The third and fourth arguments passed to 
** sqlite3_backup_init() identify the [database connection]
** and database name used
** to access the source database. The values passed for the source and 
** destination [database connection] parameters must not be the same.
**
** If an error occurs within sqlite3_backup_init(), then NULL is returned
** and an error code and error message written into the [database connection] 
** passed as the first argument. They may be retrieved using the
** [sqlite3_errcode()], [sqlite3_errmsg()], and [sqlite3_errmsg16()] functions.
** Otherwise, if successful, a pointer to an [sqlite3_backup] object is
** returned. This pointer may be used with the sqlite3_backup_step() and
** sqlite3_backup_finish() functions to perform the specified backup 
** operation.
**
** <b>sqlite3_backup_step()</b>
**
** Function [sqlite3_backup_step()] is used to copy up to nPage pages between 
** the source and destination databases, where nPage is the value of the 
** second parameter passed to sqlite3_backup_step(). If nPage is a negative
** value, all remaining source pages are copied. If the required pages are 
** succesfully copied, but there are still more pages to copy before the 
** backup is complete, it returns [SQLITE_OK]. If no error occured and there 
** are no more pages to copy, then [SQLITE_DONE] is returned. If an error 
** occurs, then an SQLite error code is returned. As well as [SQLITE_OK] and
** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
**
** As well as the case where the destination database file was opened for
** read-only access, sqlite3_backup_step() may return [SQLITE_READONLY] if
** the destination is an in-memory database with a different page size
** from the source database.
**
** If sqlite3_backup_step() cannot obtain a required file-system lock, then
** the [sqlite3_busy_handler | busy-handler function]
** is invoked (if one is specified). If the 
** busy-handler returns non-zero before the lock is available, then 
** [SQLITE_BUSY] is returned to the caller. In this case the call to
** sqlite3_backup_step() can be retried later. If the source
** [database connection]
** is being used to write to the source database when sqlite3_backup_step()
** is called, then [SQLITE_LOCKED] is returned immediately. Again, in this
** case the call to sqlite3_backup_step() can be retried later on. If
** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
** [SQLITE_READONLY] is returned, then 
** there is no point in retrying the call to sqlite3_backup_step(). These 
** errors are considered fatal. At this point the application must accept 
** that the backup operation has failed and pass the backup operation handle 
** to the sqlite3_backup_finish() to release associated resources.
**
** Following the first call to sqlite3_backup_step(), an exclusive lock is
** obtained on the destination file. It is not released until either 
** sqlite3_backup_finish() is called or the backup operation is complete 
** and sqlite3_backup_step() returns [SQLITE_DONE]. Additionally, each time 
** a call to sqlite3_backup_step() is made a [shared lock] is obtained on
** the source database file. This lock is released before the
** sqlite3_backup_step() call returns. Because the source database is not
** locked between calls to sqlite3_backup_step(), it may be modified mid-way
** through the backup procedure. If the source database is modified by an
** external process or via a database connection other than the one being
** used by the backup operation, then the backup will be transparently
** restarted by the next call to sqlite3_backup_step(). If the source 
** database is modified by the using the same database connection as is used
** by the backup operation, then the backup database is transparently 
** updated at the same time.
**
** <b>sqlite3_backup_finish()</b>
**
** Once sqlite3_backup_step() has returned [SQLITE_DONE], or when the 
** application wishes to abandon the backup operation, the [sqlite3_backup]
** object should be passed to sqlite3_backup_finish(). This releases all
** resources associated with the backup operation. If sqlite3_backup_step()
** has not yet returned [SQLITE_DONE], then any active write-transaction on the
** destination database is rolled back. The [sqlite3_backup] object is invalid
** and may not be used following a call to sqlite3_backup_finish().
**
** The value returned by sqlite3_backup_finish is [SQLITE_OK] if no error
** occurred, regardless or whether or not sqlite3_backup_step() was called
** a sufficient number of times to complete the backup operation. Or, if
** an out-of-memory condition or IO error occured during a call to
** sqlite3_backup_step() then [SQLITE_NOMEM] or an
** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] error code
** is returned. In this case the error code and an error message are
** written to the destination [database connection].
**
** A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step() is
** not a permanent error and does not affect the return value of
** sqlite3_backup_finish().
**
** <b>sqlite3_backup_remaining(), sqlite3_backup_pagecount()</b>
**
** Each call to sqlite3_backup_step() sets two values stored internally
** by an [sqlite3_backup] object. The number of pages still to be backed
** up, which may be queried by sqlite3_backup_remaining(), and the total
** number of pages in the source database file, which may be queried by
** sqlite3_backup_pagecount().
**
** The values returned by these functions are only updated by
** sqlite3_backup_step(). If the source database is modified during a backup
** operation, then the values are not updated to account for any extra
** pages that need to be updated or the size of the source database file
** changing.
**
** <b>Concurrent Usage of Database Handles</b>
**
** The source [database connection] may be used by the application for other
** purposes while a backup operation is underway or being initialized.
** If SQLite is compiled and configured to support threadsafe database
** connections, then the source database connection may be used concurrently
** from within other threads.
**
** However, the application must guarantee that the destination database
** connection handle is not passed to any other API (by any thread) after 
** sqlite3_backup_init() is called and before the corresponding call to
** sqlite3_backup_finish(). Unfortunately SQLite does not currently check
** for this, if the application does use the destination [database connection]
** for some other purpose during a backup operation, things may appear to
** work correctly but in fact be subtly malfunctioning.  Use of the
** destination database connection while a backup is in progress might
** also cause a mutex deadlock.
**
** Furthermore, if running in [shared cache mode], the application must
** guarantee that the shared cache used by the destination database
** is not accessed while the backup is running. In practice this means
** that the application must guarantee that the file-system file being 
** backed up to is not accessed by any connection within the process,
** not just the specific connection that was passed to sqlite3_backup_init().
**
** The [sqlite3_backup] object itself is partially threadsafe. Multiple 
** threads may safely make multiple concurrent calls to sqlite3_backup_step().
** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
** APIs are not strictly speaking threadsafe. If they are invoked at the
** same time as another thread is invoking sqlite3_backup_step() it is
** possible that they return invalid values.
*/
sqlite3_backup *sqlite3_backup_init(
  sqlite3 *pDest,                        /* Destination database handle */
  const char *zDestName,                 /* Destination database name */
  sqlite3 *pSource,                      /* Source database handle */
  const char *zSourceName                /* Source database name */
);
int sqlite3_backup_step(sqlite3_backup *p, int nPage);
int sqlite3_backup_finish(sqlite3_backup *p);
int sqlite3_backup_remaining(sqlite3_backup *p);
int sqlite3_backup_pagecount(sqlite3_backup *p);

/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
#endif

#ifdef __cplusplus
}  /* End of the 'extern "C"' block */
#endif
#endif