SQLite

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.435 2008/04/25 12:25:42 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include <assert.h>
#include <string.h>

/*

** A hot journal is one that needs to be played back.
**
** If the current size of the database file is 0 but a journal file
** exists, that is probably an old journal left over from a prior
** database with the same name.  Just delete the journal.
**
** Return negative if unable to determine the status of the journal.
**
** This routine does not open the journal file to examine its
** content.  Hence, the journal might contain the name of a master
** journal file that has been deleted, and hence not be hot.  Or
** the header of the journal might be zeroed out.  This routine
** does not discover these cases of a non-hot journal - if the
** journal file exists and is not empty this routine assumes it
** is hot.  The pager_playback() routine will discover that the
** journal file is not really hot and will no-op.
*/
static int hasHotJournal(Pager *pPager){
  sqlite3_vfs *pVfs = pPager->pVfs;
  int rc;
  if( !pPager->useJournal ) return 0;
  if( !pPager->fd->pMethods ) return 0;
  rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS);

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.735 2008/04/25 12:25:42 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
** The following global variable is incremented every time a cursor

  UPDATE_MAX_BLOBSIZE(pOut);
  break;
}

/* Opcode: Statement P1 * * * *
**
** Begin an individual statement transaction which is part of a larger
** transaction.  This is needed so that the statement
** can be rolled back after an error without having to roll back the
** entire transaction.  The statement transaction will automatically
** commit when the VDBE halts.
**
** If the database connection is currently in autocommit mode (that 
** is to say, if it is in between BEGIN and COMMIT)
** and if there are no other active statements on the same database
** connection, then this operation is a no-op.  No statement transaction
** is needed since any error can use the normal ROLLBACK process to
** undo changes.
**
** If a statement transaction is started, then a statement journal file
** will be allocated and initialized.
**
** The statement is begun on the database file with index P1.  The main
** database file has an index of 0 and the file used for temporary tables
** has an index of 1.
*/
case OP_Statement: {
  if( db->autoCommit==0 || db->activeVdbeCnt>1 ){