src/tclsqlite.c

/*
** Copyright (c) 1999, 2000 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public
** License as published by the Free Software Foundation; either
** version 2 of the License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
** General Public License for more details.
** 
** You should have received a copy of the GNU General Public
** License along with this library; if not, write to the
** Free Software Foundation, Inc., 59 Temple Place - Suite 330,
** Boston, MA  02111-1307, USA.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** A TCL Interface to SQLite
**
** $Id: tclsqlite.c,v 1.7 2000/08/04 14:56:25 drh Exp $
*/
#include "sqlite.h"
#include <tcl.h>
#include <stdlib.h>
#include <string.h>

/*
** There is one instance of this structure for each SQLite database
** that has been opened by the SQLite TCL interface.
*/
typedef struct SqliteDb SqliteDb;
struct SqliteDb {
  sqlite *db;           /* The "real" database structure */
  Tcl_Interp *interp;   /* The interpreter used for this database */
  char *zBusy;          /* The name of the busy callback routine */
};

/*
** An instance of this structure passes information thru the sqlite
** logic from the original TCL command into the callback routine.
*/
typedef struct CallbackData CallbackData;
struct CallbackData {
  Tcl_Interp *interp;       /* The TCL interpreter */
  char *zArray;             /* The array into which data is written */
  char *zCode;              /* The code to execute for each row */
  int once;                 /* Set only for the first invocation of callback */
};

/*
** Called for each row of the result.
*/
static int DbEvalCallback(
  void *clientData,      /* An instance of CallbackData */
  int nCol,              /* Number of columns in the result */
  char ** azCol,         /* Data for each column */
  char ** azN            /* Name for each column */
){
  CallbackData *cbData = (CallbackData*)clientData;
  int i, rc;
  if( cbData->zArray[0] ){
    if( cbData->once ){
      for(i=0; i<nCol; i++){
        Tcl_SetVar2(cbData->interp, cbData->zArray, "*", azN[i],
           TCL_LIST_ELEMENT|TCL_APPEND_VALUE);
      }
    }
    for(i=0; i<nCol; i++){
      char *z = azCol[i];
      if( z==0 ) z = "";
      Tcl_SetVar2(cbData->interp, cbData->zArray, azN[i], z, 0);
    }
  }else{
    for(i=0; i<nCol; i++){
      char *z = azCol[i];
      if( z==0 ) z = "";
      Tcl_SetVar(cbData->interp, azN[i], z, 0);
    }
  }
  cbData->once = 0;
  rc = Tcl_Eval(cbData->interp, cbData->zCode);
  return rc;
}

/*
** Called when the command is deleted.
*/
static void DbDeleteCmd(void *db){
  SqliteDb *pDb = (SqliteDb*)db;
  sqlite_close(pDb->db);
  if( pDb->zBusy ){
    Tcl_Free(pDb->zBusy);
  }
  Tcl_Free((char*)pDb);
}

/*
** This routine is called when a database file is locked while trying
** to execute SQL.
*/
static int DbBusyHandler(void *cd, const char *zTable, int nTries){
  SqliteDb *pDb = (SqliteDb*)cd;
  int rc;
  char zVal[30];
  char *zCmd;
  char *zResult;
  Tcl_DString cmd;

  Tcl_DStringInit(&cmd);
  Tcl_DStringAppend(&cmd, pDb->zBusy, -1);
  Tcl_DStringAppendElement(&cmd, zTable);
  sprintf(zVal, " %d", nTries);
  Tcl_DStringAppend(&cmd, zVal, -1);
  zCmd = Tcl_DStringValue(&cmd);
  rc = Tcl_Eval(pDb->interp, zCmd);
  Tcl_DStringFree(&cmd);
  if( rc!=TCL_OK || atoi(Tcl_GetStringResult(pDb->interp)) ){
    return 0;
  }
  return 1;
}

/*
** The "sqlite" command below creates a new Tcl command for each
** connection it opens to an SQLite database.  This routine is invoked
** whenever one of those connection-specific commands is executed
** in Tcl.  For example, if you run Tcl code like this:
**
**       sqlite db1  "my_database"
**       db1 close
**
** The first command opens a connection to the "my_database" database
** and calls that connection "db1".  The second command causes this
** subroutine to be invoked.
*/
static int DbCmd(void *cd, Tcl_Interp *interp, int argc, char **argv){
  char *z;
  int n, c;
  SqliteDb *pDb = (SqliteDb*)cd;
  if( argc<2 ){
    Tcl_AppendResult(interp,"wrong # args: should be \"", argv[0],
        " SUBCOMMAND ...\"", 0);
    return TCL_ERROR;
  }
  z = argv[1];
  n = strlen(z);
  c = z[0];

  /*    $db busy ?CALLBACK?
  **
  ** Invoke the given callback if an SQL statement attempts to open
  ** a locked database file.
  */
  if( c=='b' && strncmp(z,"busy",n)==0 ){
    if( argc>3 ){
      Tcl_AppendResult(interp,"wrong # args: should be \"",
         argv[0], " busy ?CALLBACK?", 0);
      return TCL_ERROR;
    }else if( argc==2 ){
      if( pDb->zBusy ){
        Tcl_AppendResult(interp, pDb->zBusy, 0);
      }
    }else{
      if( pDb->zBusy ){
        Tcl_Free(pDb->zBusy);
        pDb->zBusy = 0;
      }
      if( argv[2][0] ){
        pDb->zBusy = Tcl_Alloc( strlen(argv[2]) + 1 );
        if( pDb->zBusy ){
          strcpy(pDb->zBusy, argv[2]);
        }
      }
      if( pDb->zBusy ){
        pDb->interp = interp;
        sqlite_busy_handler(pDb->db, DbBusyHandler, pDb);
      }
    }
  }else

  /*    $db close
  **
  ** Shutdown the database
  */
  if( c=='c' && n>=2 && strncmp(z,"close",n)==0 ){
    Tcl_DeleteCommand(interp, argv[0]);
  }else

  /*    $db complete SQL
  **
  ** Return TRUE if SQL is a complete SQL statement.  Return FALSE if
  ** additional lines of input are needed.  This is similar to the
  ** built-in "info complete" command of Tcl.
  */
  if( c=='c' && n>=2 && strncmp(z,"complete",n)==0 ){
    char *zRes;
    if( argc!=3 ){
      Tcl_AppendResult(interp,"wrong # args: should be \"", argv[0],
          " complete SQL\"", 0);
      return TCL_ERROR;
    }
    zRes = sqlite_complete(argv[2]) ? "1" : "0";
    Tcl_SetResult(interp, zRes, TCL_VOLATILE);
  }else
   
  /*
  **    $db eval $sql ?array {  ...code... }?
  **
  ** The SQL statement in $sql is evaluated.  For each row, the values are
  ** placed in elements of the array named "array" and ...code... is executed.
  ** If "array" and "code" are omitted, then no callback is every invoked.
  ** If "array" is an empty string, then the values are placed in variables
  ** that have the same name as the fields extracted by the query.
  */
  if( c=='e' && strncmp(z,"eval",n)==0 ){
    CallbackData cbData;
    char *zErrMsg;
    int rc;

    if( argc!=5 && argc!=3 ){
      Tcl_AppendResult(interp,"wrong # args: should be \"", argv[0],
         " eval SQL ?ARRAY-NAME CODE?", 0);
      return TCL_ERROR;
    }
    pDb->interp = interp;
    if( argc==5 ){
      cbData.interp = interp;
      cbData.once = 1;
      cbData.zArray = argv[3];
      cbData.zCode = argv[4];
      zErrMsg = 0;
      rc = sqlite_exec(pDb->db, argv[2], DbEvalCallback, &cbData, &zErrMsg);
    }else{
      rc = sqlite_exec(pDb->db, argv[2], 0, 0, &zErrMsg);
    }
    if( zErrMsg ){
      Tcl_SetResult(interp, zErrMsg, TCL_VOLATILE);
      free(zErrMsg);
    }
    return rc;
  }else

  /*
  **     $db timeout MILLESECONDS
  **
  ** Delay for the number of milliseconds specified when a file is locked.
  */
  if( c=='t' && strncmp(z,"timeout",n)==0 ){
    int ms;
    if( argc!=3 ){
      Tcl_AppendResult(interp,"wrong # args: should be \"", argv[0],
          " timeout MILLISECONDS", 0);
      return TCL_ERROR;
    }
    if( Tcl_GetInt(interp, argv[2], &ms) ) return TCL_ERROR;
    sqlite_busy_timeout(pDb->db, ms);
  }else

  /* The default
  */
  {
    Tcl_AppendResult(interp,"unknown subcommand \"", z, 
        "\" - should be one of: close complete eval", 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}

/*
**   sqlite DBNAME FILENAME ?MODE?
**
** This is the main Tcl command.  When the "sqlite" Tcl command is
** invoked, this routine runs to process that command.
**
** The first argument, DBNAME, is an arbitrary name for a new
** database connection.  This command creates a new command named
** DBNAME that is used to control that connection.  The database
** connection is deleted when the DBNAME command is deleted.
**
** The second argument is the name of the directory that contains
** the sqlite database that is to be accessed.
*/
static int DbMain(void *cd, Tcl_Interp *interp, int argc, char **argv){
  int mode;
  SqliteDb *p;
  char *zErrMsg;
  if( argc!=3 && argc!=4 ){
    Tcl_AppendResult(interp,"wrong # args: should be \"", argv[0],
       " HANDLE FILENAME ?MODE?\"", 0);
    return TCL_ERROR;
  }
  if( argc==3 ){
    mode = 0666;
  }else if( Tcl_GetInt(interp, argv[3], &mode)!=TCL_OK ){
    return TCL_ERROR;
  }
  zErrMsg = 0;
  p = (SqliteDb*)Tcl_Alloc( sizeof(*p) );
  if( p==0 ){
    Tcl_SetResult(interp, "malloc failed", TCL_STATIC);
    return TCL_ERROR;
  }
  memset(p, 0, sizeof(*p));
  p->db = sqlite_open(argv[2], mode, &zErrMsg);
  if( p->db==0 ){
    Tcl_SetResult(interp, zErrMsg, TCL_VOLATILE);
    Tcl_Free((char*)p);
    free(zErrMsg);
    return TCL_ERROR;
  }
  Tcl_CreateCommand(interp, argv[1], DbCmd, (char*)p, DbDeleteCmd);
  return TCL_OK;
}

/*
** Initialize this module.
**
** This Tcl module contains only a single new Tcl command named "sqlite".
** (Hence there is no namespace.  There is no point in using a namespace
** if the extension only supplies one new name!)  The "sqlite" command is
** used to open a new SQLite database.  See the DbMain() routine above
** for additional information.
*/
int Sqlite_Init(Tcl_Interp *interp){
  Tcl_CreateCommand(interp, "sqlite", DbMain, 0, 0);
  return TCL_OK;
}
int Sqlite_SafeInit(Tcl_Interp *interp){
  return TCL_OK;
}

/*
** If compiled using mktclapp, this routine runs to initialize
** everything.
*/
int Et_AppInit(Tcl_Interp *interp){
  return Sqlite_Init(interp);
}

/*
** If the macro TCLSH is defined and is one, then put in code for the
** "main" routine that will initialize Tcl.
*/
#if defined(TCLSH) && TCLSH==1
static char zMainloop[] =
  "set line {}\n"
  "while {![eof stdin]} {\n"
    "if {$line!=\"\"} {\n"
      "puts -nonewline \"> \"\n"
    "} else {\n"
      "puts -nonewline \"% \"\n"
    "}\n"
    "flush stdout\n"
    "append line [gets stdin]\n"
    "if {[info complete $line]} {\n"
      "if {[catch {uplevel #0 $line} result]} {\n"
        "puts stderr \"Error: $result\"\n"
      "} elseif {$result!=\"\"} {\n"
        "puts $result\n"
      "}\n"
      "set line {}\n"
    "} else {\n"
      "append line \\n\n"
    "}\n"
  "}\n"
;

#define TCLSH_MAIN main   /* Needed to fake out mktclapp */
int TCLSH_MAIN(int argc, char **argv){
  Tcl_Interp *interp;
  interp = Tcl_CreateInterp();
  Sqlite_Init(interp);
  if( argc>=2 ){
    int i;
    Tcl_SetVar(interp,"argv0",argv[1],TCL_GLOBAL_ONLY);
    Tcl_SetVar(interp,"argv", "", TCL_GLOBAL_ONLY);
    for(i=2; i<argc; i++){
      Tcl_SetVar(interp, "argv", argv[i],
          TCL_GLOBAL_ONLY | TCL_LIST_ELEMENT | TCL_APPEND_VALUE);
    }
    if( Tcl_EvalFile(interp, argv[1])!=TCL_OK ){
      char *zInfo = Tcl_GetVar(interp, "errorInfo", TCL_GLOBAL_ONLY);
      if( zInfo==0 ) zInfo = interp->result;
      fprintf(stderr,"%s: %s\n", *argv, zInfo);
      return 1;
    }
  }else{
    Tcl_GlobalEval(interp, zMainloop);
  }
  return 0;
}
#endif /* TCLSH */