Gitiles
Code Review Sign In
gerrit.openfyde.cn / chromium.googlesource.com / chromium / deps / sqlite / fee2d25a70c09737e02b7198498f8e7df5ab56f7 / . / src / os_unix.c
blob: 6200ac1aef8b136a518300409fd4f6c5a4466c74 [file] [log] [blame]
/*
** 2004 May 22
**
** 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 file contains code that is specific to Unix systems.
*/
#include "sqliteInt.h"
#include "os.h"
#if OS_UNIX /* This file is used on unix only */
/* #define SQLITE_ENABLE_LOCKING_STYLE 0 */
/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it. If the OS lacks
** large file support, these should be no-ops.
**
** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
** on the compiler command line. This is necessary if you are compiling
** on a recent machine (ex: RedHat 7.2) but you want your code to work
** on an older machine (ex: RedHat 6.0). If you compile on RedHat 7.2
** without this option, LFS is enable. But LFS does not exist in the kernel
** in RedHat 6.0, so the code won't work. Hence, for maximum binary
** portability you should omit LFS.
*/
#ifndef SQLITE_DISABLE_LFS
# define _LARGE_FILE 1
# ifndef _FILE_OFFSET_BITS
# define _FILE_OFFSET_BITS 64
# endif
# define _LARGEFILE_SOURCE 1
#endif
/*
** standard include files.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <sys/time.h>
#include <errno.h>
#ifdef SQLITE_ENABLE_LOCKING_STYLE
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/mount.h>
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
/*
** If we are to be thread-safe, include the pthreads header and define
** the SQLITE_UNIX_THREADS macro.
*/
#ifndef THREADSAFE
# define THREADSAFE 1
#endif
#if THREADSAFE
# include <pthread.h>
# define SQLITE_UNIX_THREADS 1
#endif
/*
** Default permissions when creating a new file
*/
#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
#endif
/*
** Maximum supported path-length.
*/
#define MAX_PATHNAME 512
/*
** The unixFile structure is subclass of OsFile specific for the unix
** protability layer.
*/
typedef struct unixFile unixFile;
struct unixFile {
sqlite3_io_methods const *pMethod; /* Always the first entry */
struct openCnt *pOpen; /* Info about all open fd's on this inode */
struct lockInfo *pLock; /* Info about locks on this inode */
#ifdef SQLITE_ENABLE_LOCKING_STYLE
void *lockingContext; /* Locking style specific state */
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
int h; /* The file descriptor */
unsigned char locktype; /* The type of lock held on this fd */
unsigned char isOpen; /* True if needs to be closed */
int dirfd; /* File descriptor for the directory */
i64 offset; /* Seek offset */
#ifdef SQLITE_UNIX_THREADS
pthread_t tid; /* The thread that "owns" this OsFile */
#endif
};
/*
** Provide the ability to override some OS-layer functions during
** testing. This is used to simulate OS crashes to verify that
** commits are atomic even in the event of an OS crash.
*/
#ifdef SQLITE_CRASH_TEST
extern int sqlite3CrashTestEnable;
int sqlite3CrashFileWrap(sqlite3_file *, const char *, sqlite3_file **);
static int CRASH_TEST_OVERRIDE(const char *zFile, sqlite3_file **pId, int rc){
if( rc==SQLITE_OK && sqlite3CrashTestEnable ){
rc = sqlite3CrashFileWrap(*pId, zFile, pId);
}
return rc;
}
#else
# define CRASH_TEST_OVERRIDE(A,B,C) C
#endif
/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"
/*
** Do not include any of the File I/O interface procedures if the
** SQLITE_OMIT_DISKIO macro is defined (indicating that the database
** will be in-memory only)
*/
#ifndef SQLITE_OMIT_DISKIO
/*
** Define various macros that are missing from some systems.
*/
#ifndef O_LARGEFILE
# define O_LARGEFILE 0
#endif
#ifdef SQLITE_DISABLE_LFS
# undef O_LARGEFILE
# define O_LARGEFILE 0
#endif
#ifndef O_NOFOLLOW
# define O_NOFOLLOW 0
#endif
#ifndef O_BINARY
# define O_BINARY 0
#endif
/*
** The DJGPP compiler environment looks mostly like Unix, but it
** lacks the fcntl() system call. So redefine fcntl() to be something
** that always succeeds. This means that locking does not occur under
** DJGPP. But it's DOS - what did you expect?
*/
#ifdef __DJGPP__
# define fcntl(A,B,C) 0
#endif
/*
** The threadid macro resolves to the thread-id or to 0. Used for
** testing and debugging only.
*/
#ifdef SQLITE_UNIX_THREADS
#define threadid pthread_self()
#else
#define threadid 0
#endif
/*
** Set or check the OsFile.tid field. This field is set when an OsFile
** is first opened. All subsequent uses of the OsFile verify that the
** same thread is operating on the OsFile. Some operating systems do
** not allow locks to be overridden by other threads and that restriction
** means that sqlite3* database handles cannot be moved from one thread
** to another. This logic makes sure a user does not try to do that
** by mistake.
**
** Version 3.3.1 (2006-01-15): OsFiles can be moved from one thread to
** another as long as we are running on a system that supports threads
** overriding each others locks (which now the most common behavior)
** or if no locks are held. But the OsFile.pLock field needs to be
** recomputed because its key includes the thread-id. See the
** transferOwnership() function below for additional information
*/
#if defined(SQLITE_UNIX_THREADS)
# define SET_THREADID(X) (X)->tid = pthread_self()
# define CHECK_THREADID(X) (threadsOverrideEachOthersLocks==0 && \
!pthread_equal((X)->tid, pthread_self()))
#else
# define SET_THREADID(X)
# define CHECK_THREADID(X) 0
#endif
/*
** Here is the dirt on POSIX advisory locks: ANSI STD 1003.1 (1996)
** section 6.5.2.2 lines 483 through 490 specify that when a process
** sets or clears a lock, that operation overrides any prior locks set
** by the same process. It does not explicitly say so, but this implies
** that it overrides locks set by the same process using a different
** file descriptor. Consider this test case:
**
** int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
** int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
**
** Suppose ./file1 and ./file2 are really the same file (because
** one is a hard or symbolic link to the other) then if you set
** an exclusive lock on fd1, then try to get an exclusive lock
** on fd2, it works. I would have expected the second lock to
** fail since there was already a lock on the file due to fd1.
** But not so. Since both locks came from the same process, the
** second overrides the first, even though they were on different
** file descriptors opened on different file names.
**
** Bummer. If you ask me, this is broken. Badly broken. It means
** that we cannot use POSIX locks to synchronize file access among
** competing threads of the same process. POSIX locks will work fine
** to synchronize access for threads in separate processes, but not
** threads within the same process.
**
** To work around the problem, SQLite has to manage file locks internally
** on its own. Whenever a new database is opened, we have to find the
** specific inode of the database file (the inode is determined by the
** st_dev and st_ino fields of the stat structure that fstat() fills in)
** and check for locks already existing on that inode. When locks are
** created or removed, we have to look at our own internal record of the
** locks to see if another thread has previously set a lock on that same
** inode.
**
** The OsFile structure for POSIX is no longer just an integer file
** descriptor. It is now a structure that holds the integer file
** descriptor and a pointer to a structure that describes the internal
** locks on the corresponding inode. There is one locking structure
** per inode, so if the same inode is opened twice, both OsFile structures
** point to the same locking structure. The locking structure keeps
** a reference count (so we will know when to delete it) and a "cnt"
** field that tells us its internal lock status. cnt==0 means the
** file is unlocked. cnt==-1 means the file has an exclusive lock.
** cnt>0 means there are cnt shared locks on the file.
**
** Any attempt to lock or unlock a file first checks the locking
** structure. The fcntl() system call is only invoked to set a
** POSIX lock if the internal lock structure transitions between
** a locked and an unlocked state.
**
** 2004-Jan-11:
** More recent discoveries about POSIX advisory locks. (The more
** I discover, the more I realize the a POSIX advisory locks are
** an abomination.)
**
** If you close a file descriptor that points to a file that has locks,
** all locks on that file that are owned by the current process are
** released. To work around this problem, each OsFile structure contains
** a pointer to an openCnt structure. There is one openCnt structure
** per open inode, which means that multiple OsFiles can point to a single
** openCnt. When an attempt is made to close an OsFile, if there are
** other OsFiles open on the same inode that are holding locks, the call
** to close() the file descriptor is deferred until all of the locks clear.
** The openCnt structure keeps a list of file descriptors that need to
** be closed and that list is walked (and cleared) when the last lock
** clears.
**
** First, under Linux threads, because each thread has a separate
** process ID, lock operations in one thread do not override locks
** to the same file in other threads. Linux threads behave like
** separate processes in this respect. But, if you close a file
** descriptor in linux threads, all locks are cleared, even locks
** on other threads and even though the other threads have different
** process IDs. Linux threads is inconsistent in this respect.
** (I'm beginning to think that linux threads is an abomination too.)
** The consequence of this all is that the hash table for the lockInfo
** structure has to include the process id as part of its key because
** locks in different threads are treated as distinct. But the
** openCnt structure should not include the process id in its
** key because close() clears lock on all threads, not just the current
** thread. Were it not for this goofiness in linux threads, we could
** combine the lockInfo and openCnt structures into a single structure.
**
** 2004-Jun-28:
** On some versions of linux, threads can override each others locks.
** On others not. Sometimes you can change the behavior on the same
** system by setting the LD_ASSUME_KERNEL environment variable. The
** POSIX standard is silent as to which behavior is correct, as far
** as I can tell, so other versions of unix might show the same
** inconsistency. There is no little doubt in my mind that posix
** advisory locks and linux threads are profoundly broken.
**
** To work around the inconsistencies, we have to test at runtime
** whether or not threads can override each others locks. This test
** is run once, the first time any lock is attempted. A static
** variable is set to record the results of this test for future
** use.
*/
/*
** An instance of the following structure serves as the key used
** to locate a particular lockInfo structure given its inode.
**
** If threads cannot override each others locks, then we set the
** lockKey.tid field to the thread ID. If threads can override
** each others locks then tid is always set to zero. tid is omitted
** if we compile without threading support.
*/
struct lockKey {
dev_t dev; /* Device number */
ino_t ino; /* Inode number */
#ifdef SQLITE_UNIX_THREADS
pthread_t tid; /* Thread ID or zero if threads can override each other */
#endif
};
/*
** An instance of the following structure is allocated for each open
** inode on each thread with a different process ID. (Threads have
** different process IDs on linux, but not on most other unixes.)
**
** A single inode can have multiple file descriptors, so each OsFile
** structure contains a pointer to an instance of this object and this
** object keeps a count of the number of OsFiles pointing to it.
*/
struct lockInfo {
struct lockKey key; /* The lookup key */
int cnt; /* Number of SHARED locks held */
int locktype; /* One of SHARED_LOCK, RESERVED_LOCK etc. */
int nRef; /* Number of pointers to this structure */
};
/*
** An instance of the following structure serves as the key used
** to locate a particular openCnt structure given its inode. This
** is the same as the lockKey except that the thread ID is omitted.
*/
struct openKey {
dev_t dev; /* Device number */
ino_t ino; /* Inode number */
};
/*
** An instance of the following structure is allocated for each open
** inode. This structure keeps track of the number of locks on that
** inode. If a close is attempted against an inode that is holding
** locks, the close is deferred until all locks clear by adding the
** file descriptor to be closed to the pending list.
*/
struct openCnt {
struct openKey key; /* The lookup key */
int nRef; /* Number of pointers to this structure */
int nLock; /* Number of outstanding locks */
int nPending; /* Number of pending close() operations */
int *aPending; /* Malloced space holding fd's awaiting a close() */
};
/*
** These hash tables map inodes and file descriptors (really, lockKey and
** openKey structures) into lockInfo and openCnt structures. Access to
** these hash tables must be protected by a mutex.
*/
static Hash lockHash = {SQLITE_HASH_BINARY, 0, 0, 0, 0, 0};
static Hash openHash = {SQLITE_HASH_BINARY, 0, 0, 0, 0, 0};
#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
** The locking styles are associated with the different file locking
** capabilities supported by different file systems.
**
** POSIX locking style fully supports shared and exclusive byte-range locks
** ADP locking only supports exclusive byte-range locks
** FLOCK only supports a single file-global exclusive lock
** DOTLOCK isn't a true locking style, it refers to the use of a special
** file named the same as the database file with a '.lock' extension, this
** can be used on file systems that do not offer any reliable file locking
** NO locking means that no locking will be attempted, this is only used for
** read-only file systems currently
** UNSUPPORTED means that no locking will be attempted, this is only used for
** file systems that are known to be unsupported
*/
typedef enum {
posixLockingStyle = 0, /* standard posix-advisory locks */
afpLockingStyle, /* use afp locks */
flockLockingStyle, /* use flock() */
dotlockLockingStyle, /* use <file>.lock files */
noLockingStyle, /* useful for read-only file system */
unsupportedLockingStyle /* indicates unsupported file system */
} sqlite3LockingStyle;
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
static void enterMutex(){
sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}
static void leaveMutex(){
sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}
#ifdef SQLITE_UNIX_THREADS
/*
** This variable records whether or not threads can override each others
** locks.
**
** 0: No. Threads cannot override each others locks.
** 1: Yes. Threads can override each others locks.
** -1: We don't know yet.
**
** On some systems, we know at compile-time if threads can override each
** others locks. On those systems, the SQLITE_THREAD_OVERRIDE_LOCK macro
** will be set appropriately. On other systems, we have to check at
** runtime. On these latter systems, SQLTIE_THREAD_OVERRIDE_LOCK is
** undefined.
**
** This variable normally has file scope only. But during testing, we make
** it a global so that the test code can change its value in order to verify
** that the right stuff happens in either case.
*/
#ifndef SQLITE_THREAD_OVERRIDE_LOCK
# define SQLITE_THREAD_OVERRIDE_LOCK -1
#endif
#ifdef SQLITE_TEST
int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK;
#else
static int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK;
#endif
/*
** This structure holds information passed into individual test
** threads by the testThreadLockingBehavior() routine.
*/
struct threadTestData {
int fd; /* File to be locked */
struct flock lock; /* The locking operation */
int result; /* Result of the locking operation */
};
#ifdef SQLITE_LOCK_TRACE
/*
** Print out information about all locking operations.
**
** This routine is used for troubleshooting locks on multithreaded
** platforms. Enable by compiling with the -DSQLITE_LOCK_TRACE
** command-line option on the compiler. This code is normally
** turned off.
*/
static int lockTrace(int fd, int op, struct flock *p){
char *zOpName, *zType;
int s;
int savedErrno;
if( op==F_GETLK ){
zOpName = "GETLK";
}else if( op==F_SETLK ){
zOpName = "SETLK";
}else{
s = fcntl(fd, op, p);
sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s);
return s;
}
if( p->l_type==F_RDLCK ){
zType = "RDLCK";
}else if( p->l_type==F_WRLCK ){
zType = "WRLCK";
}else if( p->l_type==F_UNLCK ){
zType = "UNLCK";
}else{
assert( 0 );
}
assert( p->l_whence==SEEK_SET );
s = fcntl(fd, op, p);
savedErrno = errno;
sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n",
threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len,
(int)p->l_pid, s);
if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){
struct flock l2;
l2 = *p;
fcntl(fd, F_GETLK, &l2);
if( l2.l_type==F_RDLCK ){
zType = "RDLCK";
}else if( l2.l_type==F_WRLCK ){
zType = "WRLCK";
}else if( l2.l_type==F_UNLCK ){
zType = "UNLCK";
}else{
assert( 0 );
}
sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n",
zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid);
}
errno = savedErrno;
return s;
}
#define fcntl lockTrace
#endif /* SQLITE_LOCK_TRACE */
/*
** The testThreadLockingBehavior() routine launches two separate
** threads on this routine. This routine attempts to lock a file
** descriptor then returns. The success or failure of that attempt
** allows the testThreadLockingBehavior() procedure to determine
** whether or not threads can override each others locks.
*/
static void *threadLockingTest(void *pArg){
struct threadTestData *pData = (struct threadTestData*)pArg;
pData->result = fcntl(pData->fd, F_SETLK, &pData->lock);
return pArg;
}
/*
** This procedure attempts to determine whether or not threads
** can override each others locks then sets the
** threadsOverrideEachOthersLocks variable appropriately.
*/
static void testThreadLockingBehavior(int fd_orig){
int fd;
struct threadTestData d[2];
pthread_t t[2];
fd = dup(fd_orig);
if( fd<0 ) return;
memset(d, 0, sizeof(d));
d[0].fd = fd;
d[0].lock.l_type = F_RDLCK;
d[0].lock.l_len = 1;
d[0].lock.l_start = 0;
d[0].lock.l_whence = SEEK_SET;
d[1] = d[0];
d[1].lock.l_type = F_WRLCK;
pthread_create(&t[0], 0, threadLockingTest, &d[0]);
pthread_create(&t[1], 0, threadLockingTest, &d[1]);
pthread_join(t[0], 0);
pthread_join(t[1], 0);
close(fd);
threadsOverrideEachOthersLocks = d[0].result==0 && d[1].result==0;
}
#endif /* SQLITE_UNIX_THREADS */
/*
** Release a lockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct lockInfo *pLock){
if (pLock == NULL)
return;
pLock->nRef--;
if( pLock->nRef==0 ){
sqlite3HashInsert(&lockHash, &pLock->key, sizeof(pLock->key), 0);
sqlite3_free(pLock);
}
}
/*
** Release a openCnt structure previously allocated by findLockInfo().
*/
static void releaseOpenCnt(struct openCnt *pOpen){
if (pOpen == NULL)
return;
pOpen->nRef--;
if( pOpen->nRef==0 ){
sqlite3HashInsert(&openHash, &pOpen->key, sizeof(pOpen->key), 0);
free(pOpen->aPending);
sqlite3_free(pOpen);
}
}
#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
** Tests a byte-range locking query to see if byte range locks are
** supported, if not we fall back to dotlockLockingStyle.
*/
static sqlite3LockingStyle sqlite3TestLockingStyle(const char *filePath,
int fd) {
/* test byte-range lock using fcntl */
struct flock lockInfo;
lockInfo.l_len = 1;
lockInfo.l_start = 0;
lockInfo.l_whence = SEEK_SET;
lockInfo.l_type = F_RDLCK;
if (fcntl(fd, F_GETLK, &lockInfo) != -1) {
return posixLockingStyle;
}
/* testing for flock can give false positives. So if if the above test
** fails, then we fall back to using dot-lock style locking.
*/
return dotlockLockingStyle;
}
/*
** Examines the f_fstypename entry in the statfs structure as returned by
** stat() for the file system hosting the database file, assigns the
** appropriate locking style based on it's value. These values and
** assignments are based on Darwin/OSX behavior and have not been tested on
** other systems.
*/
static sqlite3LockingStyle sqlite3DetectLockingStyle(const char *filePath,
int fd) {
#ifdef SQLITE_FIXED_LOCKING_STYLE
return (sqlite3LockingStyle)SQLITE_FIXED_LOCKING_STYLE;
#else
struct statfs fsInfo;
if (statfs(filePath, &fsInfo) == -1)
return sqlite3TestLockingStyle(filePath, fd);
if (fsInfo.f_flags & MNT_RDONLY)
return noLockingStyle;
if( (!strcmp(fsInfo.f_fstypename, "hfs")) ||
(!strcmp(fsInfo.f_fstypename, "ufs")) )
return posixLockingStyle;
if(!strcmp(fsInfo.f_fstypename, "afpfs"))
return afpLockingStyle;
if(!strcmp(fsInfo.f_fstypename, "nfs"))
return sqlite3TestLockingStyle(filePath, fd);
if(!strcmp(fsInfo.f_fstypename, "smbfs"))
return flockLockingStyle;
if(!strcmp(fsInfo.f_fstypename, "msdos"))
return dotlockLockingStyle;
if(!strcmp(fsInfo.f_fstypename, "webdav"))
return unsupportedLockingStyle;
return sqlite3TestLockingStyle(filePath, fd);
#endif /* SQLITE_FIXED_LOCKING_STYLE */
}
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
/*
** Given a file descriptor, locate lockInfo and openCnt structures that
** describes that file descriptor. Create new ones if necessary. The
** return values might be uninitialized if an error occurs.
**
** Return the number of errors.
*/
static int findLockInfo(
int fd, /* The file descriptor used in the key */
struct lockInfo **ppLock, /* Return the lockInfo structure here */
struct openCnt **ppOpen /* Return the openCnt structure here */
){
int rc;
struct lockKey key1;
struct openKey key2;
struct stat statbuf;
struct lockInfo *pLock;
struct openCnt *pOpen;
rc = fstat(fd, &statbuf);
if( rc!=0 ) return 1;
memset(&key1, 0, sizeof(key1));
key1.dev = statbuf.st_dev;
key1.ino = statbuf.st_ino;
#ifdef SQLITE_UNIX_THREADS
if( threadsOverrideEachOthersLocks<0 ){
testThreadLockingBehavior(fd);
}
key1.tid = threadsOverrideEachOthersLocks ? 0 : pthread_self();
#endif
memset(&key2, 0, sizeof(key2));
key2.dev = statbuf.st_dev;
key2.ino = statbuf.st_ino;
pLock = (struct lockInfo*)sqlite3HashFind(&lockHash, &key1, sizeof(key1));
if( pLock==0 ){
struct lockInfo *pOld;
pLock = sqlite3_malloc( sizeof(*pLock) );
if( pLock==0 ){
rc = 1;
goto exit_findlockinfo;
}
pLock->key = key1;
pLock->nRef = 1;
pLock->cnt = 0;
pLock->locktype = 0;
pOld = sqlite3HashInsert(&lockHash, &pLock->key, sizeof(key1), pLock);
if( pOld!=0 ){
assert( pOld==pLock );
sqlite3_free(pLock);
rc = 1;
goto exit_findlockinfo;
}
}else{
pLock->nRef++;
}
*ppLock = pLock;
if( ppOpen!=0 ){
pOpen = (struct openCnt*)sqlite3HashFind(&openHash, &key2, sizeof(key2));
if( pOpen==0 ){
struct openCnt *pOld;
pOpen = sqlite3_malloc( sizeof(*pOpen) );
if( pOpen==0 ){
releaseLockInfo(pLock);
rc = 1;
goto exit_findlockinfo;
}
pOpen->key = key2;
pOpen->nRef = 1;
pOpen->nLock = 0;
pOpen->nPending = 0;
pOpen->aPending = 0;
pOld = sqlite3HashInsert(&openHash, &pOpen->key, sizeof(key2), pOpen);
if( pOld!=0 ){
assert( pOld==pOpen );
sqlite3_free(pOpen);
releaseLockInfo(pLock);
rc = 1;
goto exit_findlockinfo;
}
}else{
pOpen->nRef++;
}
*ppOpen = pOpen;
}
exit_findlockinfo:
return rc;
}
#ifdef SQLITE_DEBUG
/*
** Helper function for printing out trace information from debugging
** binaries. This returns the string represetation of the supplied
** integer lock-type.
*/
static const char *locktypeName(int locktype){
switch( locktype ){
case NO_LOCK: return "NONE";
case SHARED_LOCK: return "SHARED";
case RESERVED_LOCK: return "RESERVED";
case PENDING_LOCK: return "PENDING";
case EXCLUSIVE_LOCK: return "EXCLUSIVE";
}
return "ERROR";
}
#endif
/*
** If we are currently in a different thread than the thread that the
** unixFile argument belongs to, then transfer ownership of the unixFile
** over to the current thread.
**
** A unixFile is only owned by a thread on systems where one thread is
** unable to override locks created by a different thread. RedHat9 is
** an example of such a system.
**
** Ownership transfer is only allowed if the unixFile is currently unlocked.
** If the unixFile is locked and an ownership is wrong, then return
** SQLITE_MISUSE. SQLITE_OK is returned if everything works.
*/
#ifdef SQLITE_UNIX_THREADS
static int transferOwnership(unixFile *pFile){
int rc;
pthread_t hSelf;
if( threadsOverrideEachOthersLocks ){
/* Ownership transfers not needed on this system */
return SQLITE_OK;
}
hSelf = pthread_self();
if( pthread_equal(pFile->tid, hSelf) ){
/* We are still in the same thread */
OSTRACE1("No-transfer, same thread\n");
return SQLITE_OK;
}
if( pFile->locktype!=NO_LOCK ){
/* We cannot change ownership while we are holding a lock! */
return SQLITE_MISUSE;
}
OSTRACE4("Transfer ownership of %d from %d to %d\n",
pFile->h, pFile->tid, hSelf);
pFile->tid = hSelf;
if (pFile->pLock != NULL) {
releaseLockInfo(pFile->pLock);
rc = findLockInfo(pFile->h, &pFile->pLock, 0);
OSTRACE5("LOCK %d is now %s(%s,%d)\n", pFile->h,
locktypeName(pFile->locktype),
locktypeName(pFile->pLock->locktype), pFile->pLock->cnt);
return rc;
} else {
return SQLITE_OK;
}
}
#else
/* On single-threaded builds, ownership transfer is a no-op */
# define transferOwnership(X) SQLITE_OK
#endif
/*
** Delete the named file
*/
int sqlite3UnixDelete(const char *zFilename){
SimulateIOError(return SQLITE_IOERR_DELETE);
unlink(zFilename);
return SQLITE_OK;
}
/*
** Return TRUE if the named file exists.
*/
int sqlite3UnixFileExists(const char *zFilename){
return access(zFilename, 0)==0;
}
/*
** Attempt to open a file for both reading and writing. If that
** fails, try opening it read-only. If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
** and *pReadonly is set to 0 if the file was opened for reading and
** writing or 1 if the file was opened read-only. The function returns
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/
#if 0
int sqlite3UnixOpenReadWrite(
const char *zFilename,
sqlite3_file **pId,
int *pReadonly
){
int h;
assert( 0==*pId );
h = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY,
SQLITE_DEFAULT_FILE_PERMISSIONS);
if( h<0 ){
#ifdef EISDIR
if( errno==EISDIR ){
return SQLITE_CANTOPEN;
}
#endif
h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
if( h<0 ){
return SQLITE_CANTOPEN;
}
*pReadonly = 1;
}else{
*pReadonly = 0;
}
return CRASH_TEST_OVERRIDE(
zFilename, pId, allocateUnixFile(h, pId, zFilename, 0)
);
}
/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing. To avoid
** a potential security problem, we do not allow the file to have
** previously existed. Nor do we allow the file to be a symbolic
** link.
**
** If delFlag is true, then make arrangements to automatically delete
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3UnixOpenExclusive(
const char *zFilename,
sqlite3_file **pId,
int delFlag
){
int h;
assert( 0==*pId );
h = open(zFilename,
O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY,
delFlag ? 0600 : SQLITE_DEFAULT_FILE_PERMISSIONS);
if( h<0 ){
return SQLITE_CANTOPEN;
}
return CRASH_TEST_OVERRIDE(
zFilename, pId, allocateUnixFile(h, pId, zFilename, delFlag)
);
}
/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3UnixOpenReadOnly(const char *zFilename, sqlite3_file **pId){
int h;
assert( 0==*pId );
h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
if( h<0 ){
return SQLITE_CANTOPEN;
}
return CRASH_TEST_OVERRIDE(
zFilename, pId, allocateUnixFile(h, pId, zFilename, 0)
);
}
#endif
/*
** Attempt to open a file descriptor for the directory that contains a
** file. This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
**
** This routine is only meaningful for Unix. It is a no-op under
** windows since windows does not support hard links.
**
** If FULL_FSYNC is enabled, this function is not longer useful,
** a FULL_FSYNC sync applies to all pending disk operations.
**
** On success, a handle for a previously open file at *id is
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
#if 0
static int unixOpenDirectory(
OsFile *id,
const char *zDirname
){
int h;
unixFile *pFile = (unixFile*)id;
assert( pFile!=0 );
SET_THREADID(pFile);
assert( pFile->dirfd<0 );
pFile->dirfd = h = open(zDirname, O_RDONLY|O_BINARY, 0);
if( h<0 ){
return SQLITE_CANTOPEN;
}
#ifdef FD_CLOEXEC
fcntl(h, F_SETFD, fcntl(h, F_GETFD, 0) | FD_CLOEXEC);
#endif
OSTRACE3("OPENDIR %-3d %s\n", h, zDirname);
return SQLITE_OK;
}
#endif
/*
** Check that a given pathname is a directory and is writable
**
*/
int sqlite3UnixIsDirWritable(char *zBuf){
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
struct stat buf;
if( zBuf==0 ) return 0;
if( zBuf[0]==0 ) return 0;
if( stat(zBuf, &buf) ) return 0;
if( !S_ISDIR(buf.st_mode) ) return 0;
if( access(zBuf, 07) ) return 0;
#endif /* SQLITE_OMIT_PAGER_PRAGMAS */
return 1;
}
/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read. Update the offset.
*/
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
int got;
i64 newOffset;
TIMER_START;
#if defined(USE_PREAD)
got = pread(id->h, pBuf, cnt, offset);
SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
got = pread64(id->h, pBuf, cnt, offset);
SimulateIOError( got = -1 );
#else
newOffset = lseek(id->h, offset, SEEK_SET);
SimulateIOError( newOffset-- );
if( newOffset!=offset ){
return -1;
}
got = read(id->h, pBuf, cnt);
#endif
TIMER_END;
OSTRACE5("READ %-3d %5d %7lld %d\n", id->h, got, id->offset, TIMER_ELAPSED);
return got;
}
/*
** Read data from a file into a buffer. Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int unixRead(
sqlite3_file *id,
void *pBuf,
int amt,
sqlite3_int64 offset
){
int got;
assert( id );
got = seekAndRead((unixFile*)id, offset, pBuf, amt);
if( got==amt ){
return SQLITE_OK;
}else if( got<0 ){
return SQLITE_IOERR_READ;
}else{
memset(&((char*)pBuf)[got], 0, amt-got);
return SQLITE_IOERR_SHORT_READ;
}
}
/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read. Update the offset.
*/
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
int got;
i64 newOffset;
TIMER_START;
#if defined(USE_PREAD)
got = pwrite(id->h, pBuf, cnt, offset);
#elif defined(USE_PREAD64)
got = pwrite64(id->h, pBuf, cnt, offset);
#else
newOffset = lseek(id->h, offset, SEEK_SET);
if( newOffset!=offset ){
return -1;
}
got = write(id->h, pBuf, cnt);
#endif
TIMER_END;
OSTRACE5("WRITE %-3d %5d %7lld %d\n", id->h, got, offset, TIMER_ELAPSED);
return got;
}
/*
** Write data from a buffer into a file. Return SQLITE_OK on success
** or some other error code on failure.
*/
static int unixWrite(
sqlite3_file *id,
const void *pBuf,
int amt,
sqlite3_int64 offset
){
int wrote = 0;
assert( id );
assert( amt>0 );
while( amt>0 && (wrote = seekAndWrite((unixFile*)id, offset, pBuf, amt))>0 ){
amt -= wrote;
offset += wrote;
pBuf = &((char*)pBuf)[wrote];
}
SimulateIOError(( wrote=(-1), amt=1 ));
SimulateDiskfullError(( wrote=0, amt=1 ));
if( amt>0 ){
if( wrote<0 ){
return SQLITE_IOERR_WRITE;
}else{
return SQLITE_FULL;
}
}
return SQLITE_OK;
}
#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs. This is used to test
** that syncs and fullsyncs are occuring at the right times.
*/
int sqlite3_sync_count = 0;
int sqlite3_fullsync_count = 0;
#endif
/*
** Use the fdatasync() API only if the HAVE_FDATASYNC macro is defined.
** Otherwise use fsync() in its place.
*/
#ifndef HAVE_FDATASYNC
# define fdatasync fsync
#endif
/*
** Define HAVE_FULLFSYNC to 0 or 1 depending on whether or not
** the F_FULLFSYNC macro is defined. F_FULLFSYNC is currently
** only available on Mac OS X. But that could change.
*/
#ifdef F_FULLFSYNC
# define HAVE_FULLFSYNC 1
#else
# define HAVE_FULLFSYNC 0
#endif
/*
** The fsync() system call does not work as advertised on many
** unix systems. The following procedure is an attempt to make
** it work better.
**
** The SQLITE_NO_SYNC macro disables all fsync()s. This is useful
** for testing when we want to run through the test suite quickly.
** You are strongly advised *not* to deploy with SQLITE_NO_SYNC
** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash
** or power failure will likely corrupt the database file.
*/
static int full_fsync(int fd, int fullSync, int dataOnly){
int rc;
/* Record the number of times that we do a normal fsync() and
** FULLSYNC. This is used during testing to verify that this procedure
** gets called with the correct arguments.
*/
#ifdef SQLITE_TEST
if( fullSync ) sqlite3_fullsync_count++;
sqlite3_sync_count++;
#endif
/* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
** no-op
*/
#ifdef SQLITE_NO_SYNC
rc = SQLITE_OK;
#else
#if HAVE_FULLFSYNC
if( fullSync ){
rc = fcntl(fd, F_FULLFSYNC, 0);
}else{
rc = 1;
}
/* If the FULLFSYNC failed, fall back to attempting an fsync().
* It shouldn't be possible for fullfsync to fail on the local
* file system (on OSX), so failure indicates that FULLFSYNC
* isn't supported for this file system. So, attempt an fsync
* and (for now) ignore the overhead of a superfluous fcntl call.
* It'd be better to detect fullfsync support once and avoid
* the fcntl call every time sync is called.
*/
if( rc ) rc = fsync(fd);
#else
if( dataOnly ){
rc = fdatasync(fd);
}else{
rc = fsync(fd);
}
#endif /* HAVE_FULLFSYNC */
#endif /* defined(SQLITE_NO_SYNC) */
return rc;
}
/*
** Make sure all writes to a particular file are committed to disk.
**
** If dataOnly==0 then both the file itself and its metadata (file
** size, access time, etc) are synced. If dataOnly!=0 then only the
** file data is synced.
**
** Under Unix, also make sure that the directory entry for the file
** has been created by fsync-ing the directory that contains the file.
** If we do not do this and we encounter a power failure, the directory
** entry for the journal might not exist after we reboot. The next
** SQLite to access the file will not know that the journal exists (because
** the directory entry for the journal was never created) and the transaction
** will not roll back - possibly leading to database corruption.
*/
static int unixSync(sqlite3_file *id, int flags){
int rc;
unixFile *pFile = (unixFile*)id;
int isDataOnly = (flags & SQLITE_SYNC_DATAONLY);
int isFullsync = (flags & SQLITE_SYNC_FULL);
assert( pFile );
OSTRACE2("SYNC %-3d\n", pFile->h);
rc = full_fsync(pFile->h, isFullsync, isDataOnly);
SimulateIOError( rc=1 );
if( rc ){
return SQLITE_IOERR_FSYNC;
}
if( pFile->dirfd>=0 ){
OSTRACE4("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
HAVE_FULLFSYNC, isFullsync);
#ifndef SQLITE_DISABLE_DIRSYNC
/* The directory sync is only attempted if full_fsync is
** turned off or unavailable. If a full_fsync occurred above,
** then the directory sync is superfluous.
*/
if( (!HAVE_FULLFSYNC || !isFullsync) && full_fsync(pFile->dirfd,0,0) ){
/*
** We have received multiple reports of fsync() returning
** errors when applied to directories on certain file systems.
** A failed directory sync is not a big deal. So it seems
** better to ignore the error. Ticket #1657
*/
/* return SQLITE_IOERR; */
}
#endif
close(pFile->dirfd); /* Only need to sync once, so close the directory */
pFile->dirfd = -1; /* when we are done. */
}
return SQLITE_OK;
}
/*
** Sync the directory zDirname. This is a no-op on operating systems other
** than UNIX.
**
** This is used to make sure the master journal file has truely been deleted
** before making changes to individual journals on a multi-database commit.
** The F_FULLFSYNC option is not needed here.
*/
int sqlite3UnixSyncDirectory(const char *zDirname){
#ifdef SQLITE_DISABLE_DIRSYNC
return SQLITE_OK;
#else
int fd;
int r;
fd = open(zDirname, O_RDONLY|O_BINARY, 0);
OSTRACE3("DIRSYNC %-3d (%s)\n", fd, zDirname);
if( fd<0 ){
return SQLITE_CANTOPEN;
}
r = fsync(fd);
close(fd);
SimulateIOError( r=1 );
if( r ){
return SQLITE_IOERR_DIR_FSYNC;
}else{
return SQLITE_OK;
}
#endif
}
/*
** Truncate an open file to a specified size
*/
static int unixTruncate(sqlite3_file *id, i64 nByte){
int rc;
assert( id );
rc = ftruncate(((unixFile*)id)->h, (off_t)nByte);
SimulateIOError( rc=1 );
if( rc ){
return SQLITE_IOERR_TRUNCATE;
}else{
return SQLITE_OK;
}
}
/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(sqlite3_file *id, i64 *pSize){
int rc;
struct stat buf;
assert( id );
rc = fstat(((unixFile*)id)->h, &buf);
SimulateIOError( rc=1 );
if( rc!=0 ){
return SQLITE_IOERR_FSTAT;
}
*pSize = buf.st_size;
return SQLITE_OK;
}
/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero. If the file is unlocked or holds only SHARED locks, then
** return zero.
*/
static int unixCheckReservedLock(sqlite3_file *id){
int r = 0;
unixFile *pFile = (unixFile*)id;
assert( pFile );
enterMutex(); /* Because pFile->pLock is shared across threads */
/* Check if a thread in this process holds such a lock */
if( pFile->pLock->locktype>SHARED_LOCK ){
r = 1;
}
/* Otherwise see if some other process holds it.
*/
if( !r ){
struct flock lock;
lock.l_whence = SEEK_SET;
lock.l_start = RESERVED_BYTE;
lock.l_len = 1;
lock.l_type = F_WRLCK;
fcntl(pFile->h, F_GETLK, &lock);
if( lock.l_type!=F_UNLCK ){
r = 1;
}
}
leaveMutex();
OSTRACE3("TEST WR-LOCK %d %d\n", pFile->h, r);
return r;
}
/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
** (1) SHARED_LOCK
** (2) RESERVED_LOCK
** (3) PENDING_LOCK
** (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between. The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal. The following chart shows the allowed
** transitions and the inserted intermediate states:
**
** UNLOCKED -> SHARED
** SHARED -> RESERVED
** SHARED -> (PENDING) -> EXCLUSIVE
** RESERVED -> (PENDING) -> EXCLUSIVE
** PENDING -> EXCLUSIVE
**
** This routine will only increase a lock. Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int unixLock(sqlite3_file *id, int locktype){
/* The following describes the implementation of the various locks and
** lock transitions in terms of the POSIX advisory shared and exclusive
** lock primitives (called read-locks and write-locks below, to avoid
** confusion with SQLite lock names). The algorithms are complicated
** slightly in order to be compatible with windows systems simultaneously
** accessing the same database file, in case that is ever required.
**
** Symbols defined in os.h indentify the 'pending byte' and the 'reserved
** byte', each single bytes at well known offsets, and the 'shared byte
** range', a range of 510 bytes at a well known offset.
**
** To obtain a SHARED lock, a read-lock is obtained on the 'pending
** byte'. If this is successful, a random byte from the 'shared byte
** range' is read-locked and the lock on the 'pending byte' released.
**
** A process may only obtain a RESERVED lock after it has a SHARED lock.
** A RESERVED lock is implemented by grabbing a write-lock on the
** 'reserved byte'.
**
** A process may only obtain a PENDING lock after it has obtained a
** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
** on the 'pending byte'. This ensures that no new SHARED locks can be
** obtained, but existing SHARED locks are allowed to persist. A process
** does not have to obtain a RESERVED lock on the way to a PENDING lock.
** This property is used by the algorithm for rolling back a journal file
** after a crash.
**
** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
** implemented by obtaining a write-lock on the entire 'shared byte
** range'. Since all other locks require a read-lock on one of the bytes
** within this range, this ensures that no other locks are held on the
** database.
**
** The reason a single byte cannot be used instead of the 'shared byte
** range' is that some versions of windows do not support read-locks. By
** locking a random byte from a range, concurrent SHARED locks may exist
** even if the locking primitive used is always a write-lock.
*/
int rc = SQLITE_OK;
unixFile *pFile = (unixFile*)id;
struct lockInfo *pLock = pFile->pLock;
struct flock lock;
int s;
assert( pFile );
OSTRACE7("LOCK %d %s was %s(%s,%d) pid=%d\n", pFile->h,
locktypeName(locktype), locktypeName(pFile->locktype),
locktypeName(pLock->locktype), pLock->cnt , getpid());
/* If there is already a lock of this type or more restrictive on the
** OsFile, do nothing. Don't use the end_lock: exit path, as
** enterMutex() hasn't been called yet.
*/
if( pFile->locktype>=locktype ){
OSTRACE3("LOCK %d %s ok (already held)\n", pFile->h,
locktypeName(locktype));
return SQLITE_OK;
}
/* Make sure the locking sequence is correct
*/
assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
assert( locktype!=PENDING_LOCK );
assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );
/* This mutex is needed because pFile->pLock is shared across threads
*/
enterMutex();
/* Make sure the current thread owns the pFile.
*/
rc = transferOwnership(pFile);
if( rc!=SQLITE_OK ){
leaveMutex();
return rc;
}
pLock = pFile->pLock;
/* If some thread using this PID has a lock via a different OsFile*
** handle that precludes the requested lock, return BUSY.
*/
if( (pFile->locktype!=pLock->locktype &&
(pLock->locktype>=PENDING_LOCK || locktype>SHARED_LOCK))
){
rc = SQLITE_BUSY;
goto end_lock;
}
/* If a SHARED lock is requested, and some thread using this PID already
** has a SHARED or RESERVED lock, then increment reference counts and
** return SQLITE_OK.
*/
if( locktype==SHARED_LOCK &&
(pLock->locktype==SHARED_LOCK || pLock->locktype==RESERVED_LOCK) ){
assert( locktype==SHARED_LOCK );
assert( pFile->locktype==0 );
assert( pLock->cnt>0 );
pFile->locktype = SHARED_LOCK;
pLock->cnt++;
pFile->pOpen->nLock++;
goto end_lock;
}
lock.l_len = 1L;
lock.l_whence = SEEK_SET;
/* A PENDING lock is needed before acquiring a SHARED lock and before
** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will
** be released.
*/
if( locktype==SHARED_LOCK
|| (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
){
lock.l_type = (locktype==SHARED_LOCK?F_RDLCK:F_WRLCK);
lock.l_start = PENDING_BYTE;
s = fcntl(pFile->h, F_SETLK, &lock);
if( s==(-1) ){
rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
goto end_lock;
}
}
/* If control gets to this point, then actually go ahead and make
** operating system calls for the specified lock.
*/
if( locktype==SHARED_LOCK ){
assert( pLock->cnt==0 );
assert( pLock->locktype==0 );
/* Now get the read-lock */
lock.l_start = SHARED_FIRST;
lock.l_len = SHARED_SIZE;
s = fcntl(pFile->h, F_SETLK, &lock);
/* Drop the temporary PENDING lock */
lock.l_start = PENDING_BYTE;
lock.l_len = 1L;
lock.l_type = F_UNLCK;
if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){
rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
goto end_lock;
}
if( s==(-1) ){
rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
}else{
pFile->locktype = SHARED_LOCK;
pFile->pOpen->nLock++;
pLock->cnt = 1;
}
}else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){
/* We are trying for an exclusive lock but another thread in this
** same process is still holding a shared lock. */
rc = SQLITE_BUSY;
}else{
/* The request was for a RESERVED or EXCLUSIVE lock. It is
** assumed that there is a SHARED or greater lock on the file
** already.
*/
assert( 0!=pFile->locktype );
lock.l_type = F_WRLCK;
switch( locktype ){
case RESERVED_LOCK:
lock.l_start = RESERVED_BYTE;
break;
case EXCLUSIVE_LOCK:
lock.l_start = SHARED_FIRST;
lock.l_len = SHARED_SIZE;
break;
default:
assert(0);
}
s = fcntl(pFile->h, F_SETLK, &lock);
if( s==(-1) ){
rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
}
}
if( rc==SQLITE_OK ){
pFile->locktype = locktype;
pLock->locktype = locktype;
}else if( locktype==EXCLUSIVE_LOCK ){
pFile->locktype = PENDING_LOCK;
pLock->locktype = PENDING_LOCK;
}
end_lock:
leaveMutex();
OSTRACE4("LOCK %d %s %s\n", pFile->h, locktypeName(locktype),
rc==SQLITE_OK ? "ok" : "failed");
return rc;
}
/*
** Lower the locking level on file descriptor pFile to locktype. locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int locktype){
struct lockInfo *pLock;
struct flock lock;
int rc = SQLITE_OK;
unixFile *pFile = (unixFile*)id;
assert( pFile );
OSTRACE7("UNLOCK %d %d was %d(%d,%d) pid=%d\n", pFile->h, locktype,
pFile->locktype, pFile->pLock->locktype, pFile->pLock->cnt, getpid());
assert( locktype<=SHARED_LOCK );
if( pFile->locktype<=locktype ){
return SQLITE_OK;
}
if( CHECK_THREADID(pFile) ){
return SQLITE_MISUSE;
}
enterMutex();
pLock = pFile->pLock;
assert( pLock->cnt!=0 );
if( pFile->locktype>SHARED_LOCK ){
assert( pLock->locktype==pFile->locktype );
if( locktype==SHARED_LOCK ){
lock.l_type = F_RDLCK;
lock.l_whence = SEEK_SET;
lock.l_start = SHARED_FIRST;
lock.l_len = SHARED_SIZE;
if( fcntl(pFile->h, F_SETLK, &lock)==(-1) ){
/* This should never happen */
rc = SQLITE_IOERR_RDLOCK;
}
}
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = PENDING_BYTE;
lock.l_len = 2L; assert( PENDING_BYTE+1==RESERVED_BYTE );
if( fcntl(pFile->h, F_SETLK, &lock)!=(-1) ){
pLock->locktype = SHARED_LOCK;
}else{
rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
}
}
if( locktype==NO_LOCK ){
struct openCnt *pOpen;
/* Decrement the shared lock counter. Release the lock using an
** OS call only when all threads in this same process have released
** the lock.
*/
pLock->cnt--;
if( pLock->cnt==0 ){
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = lock.l_len = 0L;
if( fcntl(pFile->h, F_SETLK, &lock)!=(-1) ){
pLock->locktype = NO_LOCK;
}else{
rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
}
}
/* Decrement the count of locks against this same file. When the
** count reaches zero, close any other file descriptors whose close
** was deferred because of outstanding locks.
*/
pOpen = pFile->pOpen;
pOpen->nLock--;
assert( pOpen->nLock>=0 );
if( pOpen->nLock==0 && pOpen->nPending>0 ){
int i;
for(i=0; i<pOpen->nPending; i++){
close(pOpen->aPending[i]);
}
free(pOpen->aPending);
pOpen->nPending = 0;
pOpen->aPending = 0;
}
}
leaveMutex();
pFile->locktype = locktype;
return rc;
}
/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
unixFile *pFile = (unixFile *)id;
if( !pFile ) return SQLITE_OK;
unixUnlock(id, NO_LOCK);
if( pFile->dirfd>=0 ) close(pFile->dirfd);
pFile->dirfd = -1;
enterMutex();
if( pFile->pOpen->nLock ){
/* If there are outstanding locks, do not actually close the file just
** yet because that would clear those locks. Instead, add the file
** descriptor to pOpen->aPending. It will be automatically closed when
** the last lock is cleared.
*/
int *aNew;
struct openCnt *pOpen = pFile->pOpen;
aNew = realloc( pOpen->aPending, (pOpen->nPending+1)*sizeof(int) );
if( aNew==0 ){
/* If a malloc fails, just leak the file descriptor */
}else{
pOpen->aPending = aNew;
pOpen->aPending[pOpen->nPending] = pFile->h;
pOpen->nPending++;
}
}else{
/* There are no outstanding locks so we can close the file immediately */
close(pFile->h);
}
releaseLockInfo(pFile->pLock);
releaseOpenCnt(pFile->pOpen);
leaveMutex();
pFile->isOpen = 0;
OSTRACE2("CLOSE %-3d\n", pFile->h);
OpenCounter(-1);
memset(pFile, 0, sizeof(unixFile));
return SQLITE_OK;
}
#ifdef SQLITE_ENABLE_LOCKING_STYLE
#pragma mark AFP Support
/*
** The afpLockingContext structure contains all afp lock specific state
*/
typedef struct afpLockingContext afpLockingContext;
struct afpLockingContext {
unsigned long long sharedLockByte;
char *filePath;
};
struct ByteRangeLockPB2
{
unsigned long long offset; /* offset to first byte to lock */
unsigned long long length; /* nbr of bytes to lock */
unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */
unsigned char unLockFlag; /* 1 = unlock, 0 = lock */
unsigned char startEndFlag; /* 1=rel to end of fork, 0=rel to start */
int fd; /* file desc to assoc this lock with */
};
#define afpfsByteRangeLock2FSCTL _IOWR('z', 23, struct ByteRangeLockPB2)
/* return 0 on success, 1 on failure. To match the behavior of the
normal posix file locking (used in unixLock for example), we should
provide 'richer' return codes - specifically to differentiate between
'file busy' and 'file system error' results */
static int _AFPFSSetLock(const char *path, int fd, unsigned long long offset,
unsigned long long length, int setLockFlag)
{
struct ByteRangeLockPB2 pb;
int err;
pb.unLockFlag = setLockFlag ? 0 : 1;
pb.startEndFlag = 0;
pb.offset = offset;
pb.length = length;
pb.fd = fd;
OSTRACE5("AFPLOCK setting lock %s for %d in range %llx:%llx\n",
(setLockFlag?"ON":"OFF"), fd, offset, length);
err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
if ( err==-1 ) {
OSTRACE4("AFPLOCK failed to fsctl() '%s' %d %s\n", path, errno,
strerror(errno));
return 1; /* error */
} else {
return 0;
}
}
/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero. If the file is unlocked or holds only SHARED locks, then
** return zero.
*/
static int afpUnixCheckReservedLock(OsFile *id){
int r = 0;
unixFile *pFile = (unixFile*)id;
assert( pFile );
afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
/* Check if a thread in this process holds such a lock */
if( pFile->locktype>SHARED_LOCK ){
r = 1;
}
/* Otherwise see if some other process holds it.
*/
if ( !r ) {
/* lock the byte */
int failed = _AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1,1);
if (failed) {
/* if we failed to get the lock then someone else must have it */
r = 1;
} else {
/* if we succeeded in taking the reserved lock, unlock it to restore
** the original state */
_AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1, 0);
}
}
OSTRACE3("TEST WR-LOCK %d %d\n", pFile->h, r);
return r;
}
/* AFP-style locking following the behavior of unixLock, see the unixLock
** function comments for details of lock management. */
static int afpUnixLock(OsFile *id, int locktype)
{
int rc = SQLITE_OK;
unixFile *pFile = (unixFile*)id;
afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
int gotPendingLock = 0;
assert( pFile );
OSTRACE5("LOCK %d %s was %s pid=%d\n", pFile->h,
locktypeName(locktype), locktypeName(pFile->locktype), getpid());
/* If there is already a lock of this type or more restrictive on the
** OsFile, do nothing. Don't use the afp_end_lock: exit path, as
** enterMutex() hasn't been called yet.
*/
if( pFile->locktype>=locktype ){
OSTRACE3("LOCK %d %s ok (already held)\n", pFile->h,
locktypeName(locktype));
return SQLITE_OK;
}
/* Make sure the locking sequence is correct
*/
assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
assert( locktype!=PENDING_LOCK );
assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );
/* This mutex is needed because pFile->pLock is shared across threads
*/
enterMutex();
/* Make sure the current thread owns the pFile.
*/
rc = transferOwnership(pFile);
if( rc!=SQLITE_OK ){
leaveMutex();
return rc;
}
/* A PENDING lock is needed before acquiring a SHARED lock and before
** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will
** be released.
*/
if( locktype==SHARED_LOCK
|| (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
){
int failed = _AFPFSSetLock(context->filePath, pFile->h,
PENDING_BYTE, 1, 1);
if (failed) {
rc = SQLITE_BUSY;
goto afp_end_lock;
}
}
/* If control gets to this point, then actually go ahead and make
** operating system calls for the specified lock.
*/
if( locktype==SHARED_LOCK ){
int lk, failed;
int tries = 0;
/* Now get the read-lock */
/* note that the quality of the randomness doesn't matter that much */
lk = random();
context->sharedLockByte = (lk & 0x7fffffff)%(SHARED_SIZE - 1);
failed = _AFPFSSetLock(context->filePath, pFile->h,
SHARED_FIRST+context->sharedLockByte, 1, 1);
/* Drop the temporary PENDING lock */
if (_AFPFSSetLock(context->filePath, pFile->h, PENDING_BYTE, 1, 0)) {
rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
goto afp_end_lock;
}
if( failed ){
rc = SQLITE_BUSY;
} else {
pFile->locktype = SHARED_LOCK;
}
}else{
/* The request was for a RESERVED or EXCLUSIVE lock. It is
** assumed that there is a SHARED or greater lock on the file
** already.
*/
int failed = 0;
assert( 0!=pFile->locktype );
if (locktype >= RESERVED_LOCK && pFile->locktype < RESERVED_LOCK) {
/* Acquire a RESERVED lock */
failed = _AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1,1);
}
if (!failed && locktype == EXCLUSIVE_LOCK) {
/* Acquire an EXCLUSIVE lock */
/* Remove the shared lock before trying the range. we'll need to
** reestablish the shared lock if we can't get the afpUnixUnlock
*/
if (!_AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST +
context->sharedLockByte, 1, 0)) {
/* now attemmpt to get the exclusive lock range */
failed = _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST,
SHARED_SIZE, 1);
if (failed && _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST +
context->sharedLockByte, 1, 1)) {
rc = SQLITE_IOERR_RDLOCK; /* this should never happen */
}
} else {
/* */
rc = SQLITE_IOERR_UNLOCK; /* this should never happen */
}
}
if( failed && rc == SQLITE_OK){
rc = SQLITE_BUSY;
}
}
if( rc==SQLITE_OK ){
pFile->locktype = locktype;
}else if( locktype==EXCLUSIVE_LOCK ){
pFile->locktype = PENDING_LOCK;
}
afp_end_lock:
leaveMutex();
OSTRACE4("LOCK %d %s %s\n", pFile->h, locktypeName(locktype),
rc==SQLITE_OK ? "ok" : "failed");
return rc;
}
/*
** Lower the locking level on file descriptor pFile to locktype. locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int afpUnixUnlock(OsFile *id, int locktype) {
struct flock lock;
int rc = SQLITE_OK;
unixFile *pFile = (unixFile*)id;
afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
assert( pFile );
OSTRACE5("UNLOCK %d %d was %d pid=%d\n", pFile->h, locktype,
pFile->locktype, getpid());
assert( locktype<=SHARED_LOCK );
if( pFile->locktype<=locktype ){
return SQLITE_OK;
}
if( CHECK_THREADID(pFile) ){
return SQLITE_MISUSE;
}
enterMutex();
if( pFile->locktype>SHARED_LOCK ){
if( locktype==SHARED_LOCK ){
int failed = 0;
/* unlock the exclusive range - then re-establish the shared lock */
if (pFile->locktype==EXCLUSIVE_LOCK) {
failed = _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST,
SHARED_SIZE, 0);
if (!failed) {
/* successfully removed the exclusive lock */
if (_AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST+
context->sharedLockByte, 1, 1)) {
/* failed to re-establish our shared lock */
rc = SQLITE_IOERR_RDLOCK; /* This should never happen */
}
} else {
/* This should never happen - failed to unlock the exclusive range */
rc = SQLITE_IOERR_UNLOCK;
}
}
}
if (rc == SQLITE_OK && pFile->locktype>=PENDING_LOCK) {
if (_AFPFSSetLock(context->filePath, pFile->h, PENDING_BYTE, 1, 0)){
/* failed to release the pending lock */
rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
}
}
if (rc == SQLITE_OK && pFile->locktype>=RESERVED_LOCK) {
if (_AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1, 0)) {
/* failed to release the reserved lock */
rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
}
}
}
if( locktype==NO_LOCK ){
int failed = _AFPFSSetLock(context->filePath, pFile->h,
SHARED_FIRST + context->sharedLockByte, 1, 0);
if (failed) {
rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
}
}
if (rc == SQLITE_OK)
pFile->locktype = locktype;
leaveMutex();
return rc;
}
/*
** Close a file & cleanup AFP specific locking context
*/
static int afpUnixClose(OsFile **pId) {
unixFile *id = (unixFile*)*pId;
if( !id ) return SQLITE_OK;
afpUnixUnlock(*pId, NO_LOCK);
/* free the AFP locking structure */
if (id->lockingContext != NULL) {
if (((afpLockingContext *)id->lockingContext)->filePath != NULL)
sqlite3_free(((afpLockingContext*)id->lockingContext)->filePath);
sqlite3_free(id->lockingContext);
}
if( id->dirfd>=0 ) close(id->dirfd);
id->dirfd = -1;
close(id->h);
id->isOpen = 0;
OSTRACE2("CLOSE %-3d\n", id->h);
OpenCounter(-1);
sqlite3_free(id);
*pId = 0;
return SQLITE_OK;
}
#pragma mark flock() style locking
/*
** The flockLockingContext is not used
*/
typedef void flockLockingContext;
static int flockUnixCheckReservedLock(OsFile *id) {
unixFile *pFile = (unixFile*)id;
if (pFile->locktype == RESERVED_LOCK) {
return 1; /* already have a reserved lock */
} else {
/* attempt to get the lock */
int rc = flock(pFile->h, LOCK_EX | LOCK_NB);
if (!rc) {
/* got the lock, unlock it */
flock(pFile->h, LOCK_UN);
return 0; /* no one has it reserved */
}
return 1; /* someone else might have it reserved */
}
}
static int flockUnixLock(OsFile *id, int locktype) {
unixFile *pFile = (unixFile*)id;
/* if we already have a lock, it is exclusive.
** Just adjust level and punt on outta here. */
if (pFile->locktype > NO_LOCK) {
pFile->locktype = locktype;
return SQLITE_OK;
}
/* grab an exclusive lock */
int rc = flock(pFile->h, LOCK_EX | LOCK_NB);
if (rc) {
/* didn't get, must be busy */
return SQLITE_BUSY;
} else {
/* got it, set the type and return ok */
pFile->locktype = locktype;
return SQLITE_OK;
}
}
static int flockUnixUnlock(OsFile *id, int locktype) {
unixFile *pFile = (unixFile*)id;
assert( locktype<=SHARED_LOCK );
/* no-op if possible */
if( pFile->locktype==locktype ){
return SQLITE_OK;
}
/* shared can just be set because we always have an exclusive */
if (locktype==SHARED_LOCK) {
pFile->locktype = locktype;
return SQLITE_OK;
}
/* no, really, unlock. */
int rc = flock(pFile->h, LOCK_UN);
if (rc)
return SQLITE_IOERR_UNLOCK;
else {
pFile->locktype = NO_LOCK;
return SQLITE_OK;
}
}
/*
** Close a file.
*/
static int flockUnixClose(OsFile **pId) {
unixFile *id = (unixFile*)*pId;
if( !id ) return SQLITE_OK;
flockUnixUnlock(*pId, NO_LOCK);
if( id->dirfd>=0 ) close(id->dirfd);
id->dirfd = -1;
enterMutex();
close(id->h);
leaveMutex();
id->isOpen = 0;
OSTRACE2("CLOSE %-3d\n", id->h);
OpenCounter(-1);
sqlite3_free(id);
*pId = 0;
return SQLITE_OK;
}
#pragma mark Old-School .lock file based locking
/*
** The dotlockLockingContext structure contains all dotlock (.lock) lock
** specific state
*/
typedef struct dotlockLockingContext dotlockLockingContext;
struct dotlockLockingContext {
char *lockPath;
};
static int dotlockUnixCheckReservedLock(OsFile *id) {
unixFile *pFile = (unixFile*)id;
dotlockLockingContext *context =
(dotlockLockingContext *) pFile->lockingContext;
if (pFile->locktype == RESERVED_LOCK) {
return 1; /* already have a reserved lock */
} else {
struct stat statBuf;
if (lstat(context->lockPath,&statBuf) == 0)
/* file exists, someone else has the lock */
return 1;
else
/* file does not exist, we could have it if we want it */
return 0;
}
}
static int dotlockUnixLock(OsFile *id, int locktype) {
unixFile *pFile = (unixFile*)id;
dotlockLockingContext *context =
(dotlockLockingContext *) pFile->lockingContext;
/* if we already have a lock, it is exclusive.
** Just adjust level and punt on outta here. */
if (pFile->locktype > NO_LOCK) {
pFile->locktype = locktype;
/* Always update the timestamp on the old file */
utimes(context->lockPath,NULL);
return SQLITE_OK;
}
/* check to see if lock file already exists */
struct stat statBuf;
if (lstat(context->lockPath,&statBuf) == 0){
return SQLITE_BUSY; /* it does, busy */
}
/* grab an exclusive lock */
int fd = open(context->lockPath,O_RDONLY|O_CREAT|O_EXCL,0600);
if (fd < 0) {
/* failed to open/create the file, someone else may have stolen the lock */
return SQLITE_BUSY;
}
close(fd);
/* got it, set the type and return ok */
pFile->locktype = locktype;
return SQLITE_OK;
}
static int dotlockUnixUnlock(OsFile *id, int locktype) {
unixFile *pFile = (unixFile*)id;
dotlockLockingContext *context =
(dotlockLockingContext *) pFile->lockingContext;
assert( locktype<=SHARED_LOCK );
/* no-op if possible */
if( pFile->locktype==locktype ){
return SQLITE_OK;
}
/* shared can just be set because we always have an exclusive */
if (locktype==SHARED_LOCK) {
pFile->locktype = locktype;
return SQLITE_OK;
}
/* no, really, unlock. */
unlink(context->lockPath);
pFile->locktype = NO_LOCK;
return SQLITE_OK;
}
/*
** Close a file.
*/
static int dotlockUnixClose(OsFile **pId) {
unixFile *id = (unixFile*)*pId;
if( !id ) return SQLITE_OK;
dotlockUnixUnlock(*pId, NO_LOCK);
/* free the dotlock locking structure */
if (id->lockingContext != NULL) {
if (((dotlockLockingContext *)id->lockingContext)->lockPath != NULL)
sqlite3_free( ( (dotlockLockingContext *)
id->lockingContext)->lockPath);
sqlite3_free(id->lockingContext);
}
if( id->dirfd>=0 ) close(id->dirfd);
id->dirfd = -1;
enterMutex();
close(id->h);
leaveMutex();
id->isOpen = 0;
OSTRACE2("CLOSE %-3d\n", id->h);
OpenCounter(-1);
sqlite3_free(id);
*pId = 0;
return SQLITE_OK;
}
#pragma mark No locking
/*
** The nolockLockingContext is void
*/
typedef void nolockLockingContext;
static int nolockUnixCheckReservedLock(OsFile *id) {
return 0;
}
static int nolockUnixLock(OsFile *id, int locktype) {
return SQLITE_OK;
}
static int nolockUnixUnlock(OsFile *id, int locktype) {
return SQLITE_OK;
}
/*
** Close a file.
*/
static int nolockUnixClose(OsFile **pId) {
unixFile *id = (unixFile*)*pId;
if( !id ) return SQLITE_OK;
if( id->dirfd>=0 ) close(id->dirfd);
id->dirfd = -1;
enterMutex();
close(id->h);
leaveMutex();
id->isOpen = 0;
OSTRACE2("CLOSE %-3d\n", id->h);
OpenCounter(-1);
sqlite3_free(id);
*pId = 0;
return SQLITE_OK;
}
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
#if 0
/*
** Change the value of the fullsync flag in the given file descriptor.
*/
static void unixSetFullSync(OsFile *id, int v){
((unixFile*)id)->fullSync = v;
}
/*
** Return the underlying file handle for an OsFile
*/
static int unixFileHandle(OsFile *id){
return ((unixFile*)id)->h;
}
#endif
/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
**
** SQLite code assumes this function cannot fail. It also assumes that
** if two files are created in the same file-system directory (i.e.
** a database and it's journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(sqlite3_file *id){
return SQLITE_DEFAULT_SECTOR_SIZE;
}
/*
** Return the device characteristics for the file. This is always 0.
*/
static int unixDeviceCharacteristics(sqlite3_file *id){
return 0;
}
static int unixBreakLock(sqlite3_file *id){
assert(!"TODO: unixBreakLock()");
return 0;
}
/*
** Return an integer that indices the type of lock currently held
** by this handle. (Used for testing and analysis only.)
*/
static int unixLockState(sqlite3_file *id){
return ((unixFile*)id)->locktype;
}
/*
** This vector defines all the methods that can operate on an OsFile
** for unix.
*/
static const sqlite3_io_methods sqlite3UnixIoMethod = {
1, /* iVersion */
unixClose,
unixRead,
unixWrite,
unixTruncate,
unixSync,
unixFileSize,
unixLock,
unixUnlock,
unixCheckReservedLock,
unixBreakLock,
unixLockState,
unixSectorSize,
unixDeviceCharacteristics
};
#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
** This vector defines all the methods that can operate on an OsFile
** for unix with AFP style file locking.
*/
static const IoMethod sqlite3AFPLockingUnixIoMethod = {
afpUnixClose,
unixOpenDirectory,
unixRead,
unixWrite,
unixSeek,
unixTruncate,
unixSync,
unixSetFullSync,
unixFileHandle,
unixFileSize,
afpUnixLock,
afpUnixUnlock,
unixLockState,
afpUnixCheckReservedLock,
unixSectorSize,
};
/*
** This vector defines all the methods that can operate on an OsFile
** for unix with flock() style file locking.
*/
static const IoMethod sqlite3FlockLockingUnixIoMethod = {
flockUnixClose,
unixOpenDirectory,
unixRead,
unixWrite,
unixSeek,
unixTruncate,
unixSync,
unixSetFullSync,
unixFileHandle,
unixFileSize,
flockUnixLock,
flockUnixUnlock,
unixLockState,
flockUnixCheckReservedLock,
unixSectorSize,
};
/*
** This vector defines all the methods that can operate on an OsFile
** for unix with dotlock style file locking.
*/
static const IoMethod sqlite3DotlockLockingUnixIoMethod = {
dotlockUnixClose,
unixOpenDirectory,
unixRead,
unixWrite,
unixSeek,
unixTruncate,
unixSync,
unixSetFullSync,
unixFileHandle,
unixFileSize,
dotlockUnixLock,
dotlockUnixUnlock,
unixLockState,
dotlockUnixCheckReservedLock,
unixSectorSize,
};
/*
** This vector defines all the methods that can operate on an OsFile
** for unix with dotlock style file locking.
*/
static const IoMethod sqlite3NolockLockingUnixIoMethod = {
nolockUnixClose,
unixOpenDirectory,
unixRead,
unixWrite,
unixSeek,
unixTruncate,
unixSync,
unixSetFullSync,
unixFileHandle,
unixFileSize,
nolockUnixLock,
nolockUnixUnlock,
unixLockState,
nolockUnixCheckReservedLock,
unixSectorSize,
};
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
/*
** Allocate memory for a new unixFile and initialize that unixFile.
** Write a pointer to the new unixFile into *pId.
** If we run out of memory, close the file and return an error.
*/
#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
** When locking extensions are enabled, the filepath and locking style
** are needed to determine the unixFile pMethod to use for locking operations.
** The locking-style specific lockingContext data structure is created
** and assigned here also.
*/
static int allocateUnixFile(
int h, /* Open file descriptor of file being opened */
OsFile **pId, /* Write completed initialization here */
const char *zFilename, /* Name of the file being opened */
int delFlag /* Delete-on-or-before-close flag */
){
sqlite3LockingStyle lockingStyle;
unixFile *pNew;
unixFile f;
int rc;
memset(&f, 0, sizeof(f));
lockingStyle = sqlite3DetectLockingStyle(zFilename, h);
if ( lockingStyle == posixLockingStyle ) {
enterMutex();
rc = findLockInfo(h, &f.pLock, &f.pOpen);
leaveMutex();
if( rc ){
close(h);
unlink(zFilename);
return SQLITE_NOMEM;
}
} else {
/* pLock and pOpen are only used for posix advisory locking */
f.pLock = NULL;
f.pOpen = NULL;
}
if( delFlag ){
unlink(zFilename);
}
f.dirfd = -1;
f.h = h;
SET_THREADID(&f);
pNew = sqlite3_malloc( sizeof(unixFile) );
if( pNew==0 ){
close(h);
enterMutex();
releaseLockInfo(f.pLock);
releaseOpenCnt(f.pOpen);
leaveMutex();
*pId = 0;
return SQLITE_NOMEM;
}else{
*pNew = f;
switch(lockingStyle) {
case afpLockingStyle: {
/* afp locking uses the file path so it needs to be included in
** the afpLockingContext */
int nFilename;
pNew->pMethod = &sqlite3AFPLockingUnixIoMethod;
pNew->lockingContext =
sqlite3_malloc(sizeof(afpLockingContext));
nFilename = strlen(zFilename)+1;
((afpLockingContext *)pNew->lockingContext)->filePath =
sqlite3_malloc(nFilename);
memcpy(((afpLockingContext *)pNew->lockingContext)->filePath,
zFilename, nFilename);
srandomdev();
break;
}
case flockLockingStyle:
/* flock locking doesn't need additional lockingContext information */
pNew->pMethod = &sqlite3FlockLockingUnixIoMethod;
break;
case dotlockLockingStyle: {
/* dotlock locking uses the file path so it needs to be included in
** the dotlockLockingContext */
int nFilename;
pNew->pMethod = &sqlite3DotlockLockingUnixIoMethod;
pNew->lockingContext = sqlite3_malloc(
sizeof(dotlockLockingContext));
nFilename = strlen(zFilename) + 6;
((dotlockLockingContext *)pNew->lockingContext)->lockPath =
sqlite3_malloc( nFilename );
sqlite3_snprintf(nFilename,
((dotlockLockingContext *)pNew->lockingContext)->lockPath,
"%s.lock", zFilename);
break;
}
case posixLockingStyle:
/* posix locking doesn't need additional lockingContext information */
pNew->pMethod = &sqlite3UnixIoMethod;
break;
case noLockingStyle:
case unsupportedLockingStyle:
default:
pNew->pMethod = &sqlite3NolockLockingUnixIoMethod;
}
*pId = (OsFile*)pNew;
OpenCounter(+1);
return SQLITE_OK;
}
}
#else /* SQLITE_ENABLE_LOCKING_STYLE */
static int fillInUnixFile(
int h, /* Open file descriptor on file being opened */
int dirfd,
sqlite3_file *pId, /* Write to the unixFile structure here */
const char *zFilename /* Name of the file being opened */
){
unixFile *pNew = (unixFile *)pId;
int rc;
#ifdef FD_CLOEXEC
fcntl(h, F_SETFD, fcntl(h, F_GETFD, 0) | FD_CLOEXEC);
#endif
enterMutex();
rc = findLockInfo(h, &pNew->pLock, &pNew->pOpen);
leaveMutex();
if( rc ){
close(h);
return SQLITE_NOMEM;
}
OSTRACE3("OPEN %-3d %s\n", h, zFilename);
pNew->dirfd = -1;
pNew->h = h;
pNew->dirfd = dirfd;
SET_THREADID(pNew);
pNew->pMethod = &sqlite3UnixIoMethod;
OpenCounter(+1);
return SQLITE_OK;
}
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
#endif /* SQLITE_OMIT_DISKIO */
/***************************************************************************
** Everything above deals with file I/O. Everything that follows deals
** with other miscellanous aspects of the operating system interface
****************************************************************************/
static int openDirectory(const char *zFilename, int *pFd){
char *zDirname;
int ii;
int fd;
zDirname = (char *)sqlite3_malloc(MAX_PATHNAME);
if( !zDirname ){
return SQLITE_NOMEM;
}
strncpy(zDirname, zFilename, MAX_PATHNAME);
zDirname[MAX_PATHNAME-1] = '\0';
for(ii=strlen(zDirname); ii>=0 && zDirname[ii]!='/'; ii--);
if( ii>0 ){
zDirname[ii] = '\0';
fd = open(zDirname, O_RDONLY|O_BINARY, 0);
if( fd>0 ){
#ifdef FD_CLOEXEC
fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif
OSTRACE3("OPENDIR %-3d %s\n", fd, zDirname);
}
}
sqlite3_free(zDirname);
*pFd = fd;
return (fd>0?SQLITE_OK:SQLITE_CANTOPEN);
}
/*
** Previously, the SQLite OS layer used three functions in place of this
** one:
**
** sqlite3OsOpenReadWrite();
** sqlite3OsOpenReadOnly();
** sqlite3OsOpenExclusive();
**
** These calls correspond to the following combinations of flags:
**
** ReadWrite() -> (READWRITE | CREATE)
** ReadOnly() -> (READONLY)
** OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE)
**
** The old OpenExclusive() accepted a boolean argument - "delFlag". If
** true, the file was configured to be automatically deleted when the
** file handle closed. To achieve the same effect using this new
** interface, add the DELETEONCLOSE flag to those specified above for
** OpenExclusive().
*/
static int unixOpen(
void *pNotUsed,
const char *zPath,
sqlite3_file *pFile,
int flags,
int *pOutFlags
){
int fd = 0; /* File descriptor returned by open() */
int dirfd = -1; /* Directory file descriptor */
int oflags = 0; /* Flags to pass to open() */
int eType = flags&0xFFFFFF00; /* Type of file to open */
int isExclusive = (flags & SQLITE_OPEN_EXCLUSIVE);
int isDelete = (flags & SQLITE_OPEN_DELETEONCLOSE);
int isCreate = (flags & SQLITE_OPEN_CREATE);
int isReadonly = (flags & SQLITE_OPEN_READONLY);
int isReadWrite = (flags & SQLITE_OPEN_READWRITE);
/* If creating a master or main-file journal, this function will open
** a file-descriptor on the directory too. The first time unixSync()
** is called the directory file descriptor will be fsync()ed and close()d.
*/
int isOpenDirectory = (isCreate &&
(eType==SQLITE_OPEN_MASTER_JOURNAL || eType==SQLITE_OPEN_MAIN_JOURNAL)
);
/* Check the following statements are true:
**
** (a) Exactly one of the READWRITE and READONLY flags must be set, and
** (b) if CREATE is set, then READWRITE must also be set, and
** (c) if EXCLUSIVE is set, then CREATE must also be set.
*/
assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
assert(isCreate==0 || isReadWrite);
assert(isExclusive==0 || isCreate);
/* Assert that the upper layer has set one of the "file-type" flags. */
assert( eType==SQLITE_OPEN_MAIN_DB || eType==SQLITE_OPEN_TEMP_DB
|| eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL
|| eType==SQLITE_OPEN_SUBJOURNAL || eType==SQLITE_OPEN_MASTER_JOURNAL
);
if( isReadonly ) oflags |= O_RDONLY;
if( isReadWrite ) oflags |= O_RDWR;
if( isCreate ) oflags |= O_CREAT;
if( isExclusive ) oflags |= (O_EXCL|O_NOFOLLOW);
oflags |= (O_LARGEFILE|O_BINARY);
memset(pFile, 0, sizeof(unixFile));
fd = open(zPath, oflags, isDelete?0600:SQLITE_DEFAULT_FILE_PERMISSIONS);
if( fd<0 && isReadWrite && !isExclusive ){
/* Failed to open the file for read/write access. Try read-only. */
flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
flags |= SQLITE_OPEN_READONLY;
return unixOpen(pNotUsed, zPath, pFile, flags, pOutFlags);
}
if( fd<0 ){
return SQLITE_CANTOPEN;
}
if( isDelete ){
unlink(zPath);
}
if( pOutFlags ){
*pOutFlags = flags;
}
assert(fd!=0);
if( isOpenDirectory ){
int rc = openDirectory(zPath, &dirfd);
if( rc!=SQLITE_OK ){
close(fd);
return rc;
}
}
return fillInUnixFile(fd, dirfd, pFile, zPath);
}
/*
** Delete the file at zPath. If the dirSync argument is true, fsync()
** the directory after deleting the file.
*/
static int unixDelete(void *pNotUsed, const char *zPath, int dirSync){
int rc = SQLITE_OK;
SimulateIOError(return SQLITE_IOERR_DELETE);
unlink(zPath);
if( dirSync ){
int fd;
rc = openDirectory(zPath, &fd);
if( rc==SQLITE_OK ){
if( fsync(fd) ){
rc = SQLITE_IOERR_DIR_FSYNC;
}
close(fd);
}
}
return rc;
}
/*
** Test the existance of or access permissions of file zPath. The
** test performed depends on the value of flags:
**
** SQLITE_ACCESS_EXISTS: Return 1 if the file exists
** SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
** SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
**
** Otherwise return 0.
*/
static int unixAccess(void *pNotUsed, const char *zPath, int flags){
int amode;
switch( flags ){
case SQLITE_ACCESS_EXISTS:
amode = F_OK;
break;
case SQLITE_ACCESS_READWRITE:
amode = W_OK|R_OK;
break;
case SQLITE_ACCESS_READONLY:
amode = R_OK;
break;
default:
assert(!"Invalid flags argument");
}
return (access(zPath, amode)==0);
}
/*
** Create a temporary file name in zBuf. zBuf must be big enough to
** hold at least MAX_PATHNAME characters.
*/
static int unixGetTempName(void *pNotUsed, char *zBuf){
static const char *azDirs[] = {
0,
"/var/tmp",
"/usr/tmp",
"/tmp",
".",
};
static const unsigned char zChars[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789";
int i, j;
struct stat buf;
const char *zDir = ".";
azDirs[0] = sqlite3_temp_directory;
for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
if( azDirs[i]==0 ) continue;
if( stat(azDirs[i], &buf) ) continue;
if( !S_ISDIR(buf.st_mode) ) continue;
if( access(azDirs[i], 07) ) continue;
zDir = azDirs[i];
break;
}
do{
sqlite3_snprintf(MAX_PATHNAME-17, zBuf, "%s/"TEMP_FILE_PREFIX, zDir);
j = strlen(zBuf);
sqlite3Randomness(15, &zBuf[j]);
for(i=0; i<15; i++, j++){
zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
}
zBuf[j] = 0;
}while( access(zBuf,0)==0 );
return SQLITE_OK;
}
/*
** Turn a relative pathname into a full pathname. The relative path
** is stored as a nul-terminated string in the buffer pointed to by
** zPath.
**
** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes
** (in this case, MAX_PATHNAME bytes). The full-path is written to
** this buffer before returning.
*/
static int unixFullPathname(void *pNotUsed, const char *zPath, char *zOut){
zOut[MAX_PATHNAME-1] = '\0';
if( zPath[0]=='/' ){
strncpy(zOut, zPath, MAX_PATHNAME-1);
}else{
int nCwd;
if( getcwd(zOut, MAX_PATHNAME-1)==0 ){
return SQLITE_ERROR;
}
nCwd = strlen(zOut);
zOut[nCwd] = '/';
strncpy(&zOut[nCwd+1], zPath, MAX_PATHNAME-1-nCwd-1);
}
return SQLITE_OK;
#if 0
/*
** Remove "/./" path elements and convert "/A/./" path elements
** to just "/".
*/
if( zFull ){
int i, j;
for(i=j=0; zFull[i]; i++){
if( zFull[i]=='/' ){
if( zFull[i+1]=='/' ) continue;
if( zFull[i+1]=='.' && zFull[i+2]=='/' ){
i += 1;
continue;
}
if( zFull[i+1]=='.' && zFull[i+2]=='.' && zFull[i+3]=='/' ){
while( j>0 && zFull[j-1]!='/' ){ j--; }
i += 3;
continue;
}
}
zFull[j++] = zFull[i];
}
zFull[j] = 0;
}
#endif
}
#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
#include <dlfcn.h>
static void *unixDlOpen(void *pNotUsed, const char *zFilename){
return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
}
static void unixDlError(void *pNotUsed, int nBuf, char *zBufOut){
char *zErr;
enterMutex();
zErr = dlerror();
if( zErr ){
strncpy(zBufOut, zErr, nBuf-1);
zBufOut[nBuf-1] = '\0';
}else if(nBuf>0) {
zBufOut[0] = '\0';
}
leaveMutex();
}
void *unixDlSym(void *pHandle, const char *zSymbol){
return dlsym(pHandle, zSymbol);
}
void unixDlClose(void *pHandle){
dlclose(pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
#define unixDlOpen 0
#define unixDlError 0
#define unixDlSym 0
#define unixDlClose 0
#endif
/*
** Write nBuf bytes of random data to the supplied buffer zBuf.
*/
static int unixRandomness(void *pNotUsed, int nBuf, char *zBuf){
assert(nBuf>=(sizeof(time_t)+sizeof(int)));
/* We have to initialize zBuf to prevent valgrind from reporting
** errors. The reports issued by valgrind are incorrect - we would
** prefer that the randomness be increased by making use of the
** uninitialized space in zBuf - but valgrind errors tend to worry
** some users. Rather than argue, it seems easier just to initialize
** the whole array and silence valgrind, even if that means less randomness
** in the random seed.
**
** When testing, initializing zBuf[] to zero is all we do. That means
** that we always use the same random number sequence. This makes the
** tests repeatable.
*/
memset(zBuf, 0, nBuf);
#if !defined(SQLITE_TEST)
{
int pid, fd;
fd = open("/dev/urandom", O_RDONLY);
if( fd<0 ){
time_t t;
time(&t);
memcpy(zBuf, &t, sizeof(t));
pid = getpid();
memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
}else{
read(fd, zBuf, nBuf);
close(fd);
}
}
#endif
return SQLITE_OK;
}
/*
** Sleep for a little while. Return the amount of time slept.
** The argument is the number of microseconds we want to sleep.
*/
static int unixSleep(void *pNotUsed, int microseconds){
#if defined(HAVE_USLEEP) && HAVE_USLEEP
usleep(microseconds);
return microseconds;
#else
int seconds = (microseconds+999999)/1000000;
sleep(seconds);
return seconds;
#endif
}
/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime(). This is used for testing.
*/
#ifdef SQLITE_TEST
int sqlite3_current_time = 0;
#endif
/*
** Find the current time (in Universal Coordinated Time). Write the
** current time and date as a Julian Day number into *prNow and
** return 0. Return 1 if the time and date cannot be found.
*/
static int unixCurrentTime(void *pNotUsed, double *prNow){
#ifdef NO_GETTOD
time_t t;
time(&t);
*prNow = t/86400.0 + 2440587.5;
#else
struct timeval sNow;
gettimeofday(&sNow, 0);
*prNow = 2440587.5 + sNow.tv_sec/86400.0 + sNow.tv_usec/86400000000.0;
#endif
#ifdef SQLITE_TEST
if( sqlite3_current_time ){
*prNow = sqlite3_current_time/86400.0 + 2440587.5;
}
#endif
return 0;
}
sqlite3_vfs sqlite3DefaultVfs = {
1, /* iVersion */
sizeof(unixFile), /* szOsFile */
MAX_PATHNAME, /* mxPathname */
0, /* nRef */
0, /* vfsMutex */
0, /* pNext */
0, /* pPrev */
"unix", /* zName */
0, /* pAppData */
unixOpen, /* xOpen */
unixDelete, /* xDelete */
unixAccess, /* xAccess */
unixGetTempName, /* xGetTempName */
unixFullPathname, /* xFullPathname */
unixDlOpen, /* xDlOpen */
unixDlError, /* xDlError */
unixDlSym, /* xDlSym */
unixDlClose, /* xDlClose */
unixRandomness, /* xRandomness */
unixSleep, /* xSleep */
unixCurrentTime /* xCurrentTime */
};
#endif /* OS_UNIX */