len = 0;
    if( p1<0 ){
      for(z2=z; *z2; len++){
        SQLITE_SKIP_UTF8(z2);
      }
    }
  }








  if( argc==3 ){
    p2 = sqlite3_value_int(argv[2]);
    if( p2<0 ){
      p2 = -p2;
      negP2 = 1;
    }
  }else{

    len = 0;
    if( p1<0 ){
      for(z2=z; *z2; len++){
        SQLITE_SKIP_UTF8(z2);
      }
    }
  }
#ifdef SQLITE_SUBSTR_COMPATIBILITY
  /* If SUBSTR_COMPATIBILITY is defined then substr(X,0,N) work the same as
  ** as substr(X,1,N) - it returns the first N characters of X.  This
  ** is essentially a back-out of the bug-fix in check-in [5fc125d362df4b8]
  ** from 2009-02-02 for compatibility of applications that exploited the
  ** old buggy behavior. */
  if( p1==0 ) p1 = 1; /* <rdar://problem/6778339> */
#endif
  if( argc==3 ){
    p2 = sqlite3_value_int(argv[2]);
    if( p2<0 ){
      p2 = -p2;
      negP2 = 1;
    }
  }else{

  db->szMmap = sqlite3GlobalConfig.szMmap;
  db->nextPagesize = 0;
  db->nMaxSorterMmap = 0x7FFFFFFF;
  db->flags |= SQLITE_ShortColNames | SQLITE_EnableTrigger | SQLITE_CacheSpill
#if !defined(SQLITE_DEFAULT_AUTOMATIC_INDEX) || SQLITE_DEFAULT_AUTOMATIC_INDEX
                 | SQLITE_AutoIndex
#endif



#if SQLITE_DEFAULT_FILE_FORMAT<4
                 | SQLITE_LegacyFileFmt
#endif
#ifdef SQLITE_ENABLE_LOAD_EXTENSION
                 | SQLITE_LoadExtension
#endif
#if SQLITE_DEFAULT_RECURSIVE_TRIGGERS
................................................................................
      rc = sqlite3OsFileControl(fd, op, pArg);
    }else{
      rc = SQLITE_NOTFOUND;
    }
    sqlite3BtreeLeave(pBtree);
  }
  sqlite3_mutex_leave(db->mutex);
  return rc;   
}

/*
** Interface to the testing logic.
*/
int sqlite3_test_control(int op, ...){
  int rc = 0;

  db->szMmap = sqlite3GlobalConfig.szMmap;
  db->nextPagesize = 0;
  db->nMaxSorterMmap = 0x7FFFFFFF;
  db->flags |= SQLITE_ShortColNames | SQLITE_EnableTrigger | SQLITE_CacheSpill
#if !defined(SQLITE_DEFAULT_AUTOMATIC_INDEX) || SQLITE_DEFAULT_AUTOMATIC_INDEX
                 | SQLITE_AutoIndex
#endif
#if SQLITE_DEFAULT_CKPTFULLFSYNC
                 | SQLITE_CkptFullFSync
#endif
#if SQLITE_DEFAULT_FILE_FORMAT<4
                 | SQLITE_LegacyFileFmt
#endif
#ifdef SQLITE_ENABLE_LOAD_EXTENSION
                 | SQLITE_LoadExtension
#endif
#if SQLITE_DEFAULT_RECURSIVE_TRIGGERS
................................................................................
      rc = sqlite3OsFileControl(fd, op, pArg);
    }else{
      rc = SQLITE_NOTFOUND;
    }
    sqlite3BtreeLeave(pBtree);
  }
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

/*
** Interface to the testing logic.
*/
int sqlite3_test_control(int op, ...){
  int rc = 0;

** opcode causes the xFileControl method to swap the file handle with the one
** pointed to by the pArg argument.  This capability is used during testing
** and only needs to be supported when SQLITE_TEST is defined.
**
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_GET_LOCKPROXYFILE             2
#define SQLITE_SET_LOCKPROXYFILE             3
#define SQLITE_LAST_ERRNO                    4
#define SQLITE_FCNTL_SIZE_HINT               5
#define SQLITE_FCNTL_CHUNK_SIZE              6
#define SQLITE_FCNTL_FILE_POINTER            7
#define SQLITE_FCNTL_SYNC_OMITTED            8
#define SQLITE_FCNTL_WIN32_AV_RETRY          9
#define SQLITE_FCNTL_PERSIST_WAL            10
#define SQLITE_FCNTL_OVERWRITE              11
................................................................................
#define SQLITE_FCNTL_TEMPFILENAME           16
#define SQLITE_FCNTL_MMAP_SIZE              18
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23







/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
................................................................................
**
** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
** successfully.  An [error code] is returned otherwise.)^
**
** ^Shared cache is disabled by default. But this might change in
** future releases of SQLite.  Applications that care about shared
** cache setting should set it explicitly.





**
** This interface is threadsafe on processors where writing a
** 32-bit integer is atomic.
**
** See Also:  [SQLite Shared-Cache Mode]
*/
int sqlite3_enable_shared_cache(int);

** opcode causes the xFileControl method to swap the file handle with the one
** pointed to by the pArg argument.  This capability is used during testing
** and only needs to be supported when SQLITE_TEST is defined.
**
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
#define SQLITE_FCNTL_SIZE_HINT               5
#define SQLITE_FCNTL_CHUNK_SIZE              6
#define SQLITE_FCNTL_FILE_POINTER            7
#define SQLITE_FCNTL_SYNC_OMITTED            8
#define SQLITE_FCNTL_WIN32_AV_RETRY          9
#define SQLITE_FCNTL_PERSIST_WAL            10
#define SQLITE_FCNTL_OVERWRITE              11
................................................................................
#define SQLITE_FCNTL_TEMPFILENAME           16
#define SQLITE_FCNTL_MMAP_SIZE              18
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO


/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
................................................................................
**
** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
** successfully.  An [error code] is returned otherwise.)^
**
** ^Shared cache is disabled by default. But this might change in
** future releases of SQLite.  Applications that care about shared
** cache setting should set it explicitly.
**
** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0
** and will always return SQLITE_MISUSE. On those systems, 
** shared cache mode should be enabled per-database connection via 
** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].
**
** This interface is threadsafe on processors where writing a
** 32-bit integer is atomic.
**
** See Also:  [SQLite Shared-Cache Mode]
*/
int sqlite3_enable_shared_cache(int);

**
*************************************************************************
** This file contains test logic for the sqlite3_backup() interface.
**
*/

#include "tcl.h"
#include <sqlite3.h>
#include <assert.h>

/* These functions are implemented in main.c. */
extern const char *sqlite3ErrName(int);

/* These functions are implemented in test1.c. */
extern int getDbPointer(Tcl_Interp *, const char *, sqlite3 **);

**
*************************************************************************
** This file contains test logic for the sqlite3_backup() interface.
**
*/

#include "tcl.h"
#include "sqlite3.h"
#include <assert.h>

/* These functions are implemented in main.c. */
extern const char *sqlite3ErrName(int);

/* These functions are implemented in test1.c. */
extern int getDbPointer(Tcl_Interp *, const char *, sqlite3 **);

**
**   Much more efficient if the underlying OS is not caching write 
**   operations.
*/

#if !defined(SQLITE_TEST) || SQLITE_OS_UNIX

#include <sqlite3.h>

#include <assert.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/param.h>

**
**   Much more efficient if the underlying OS is not caching write 
**   operations.
*/

#if !defined(SQLITE_TEST) || SQLITE_OS_UNIX

#include "sqlite3.h"

#include <assert.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/param.h>

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces. This code
** is not included in the SQLite library. 
*/

#include <sqlite3.h>
#include <tcl.h>

/* Solely for the UNUSED_PARAMETER() macro. */
#include "sqliteInt.h"

#ifdef SQLITE_ENABLE_RTREE
/* 

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces. This code
** is not included in the SQLite library. 
*/

#include "sqlite3.h"
#include <tcl.h>

/* Solely for the UNUSED_PARAMETER() macro. */
#include "sqliteInt.h"

#ifdef SQLITE_ENABLE_RTREE
/* 

** mode database files. The interface to the example code in this file 
** consists of the following two functions:
**
**   sqlite3demo_superlock()
**   sqlite3demo_superunlock()
*/

#include <sqlite3.h>
#include <string.h>               /* memset(), strlen() */
#include <assert.h>               /* assert() */

/*
** A structure to collect a busy-handler callback and argument and a count
** of the number of times it has been invoked.
*/

** mode database files. The interface to the example code in this file 
** consists of the following two functions:
**
**   sqlite3demo_superlock()
**   sqlite3demo_superunlock()
*/

#include "sqlite3.h"
#include <string.h>               /* memset(), strlen() */
#include <assert.h>               /* assert() */

/*
** A structure to collect a busy-handler callback and argument and a count
** of the number of times it has been invoked.
*/

    DELETE FROM t1;
  }

  do_test 4.2 {
    execsql { 
      PRAGMA journal_mode = WAL;
      PRAGMA incremental_vacuum(1);
      PRAGMA wal_checkpoint;
    }



    file size test.db-wal
  } [expr {32+2*(512+24)}]

  do_test 4.3 {
    db close
    sqlite3 db test.db
    set maxsz 0

    DELETE FROM t1;
  }

  do_test 4.2 {
    execsql { 
      PRAGMA journal_mode = WAL;
      PRAGMA incremental_vacuum(1);

    }
  } {wal}
  do_test 4.2.1 {
    execsql { PRAGMA wal_checkpoint }
    file size test.db-wal
  } [expr {32+2*(512+24)}]

  do_test 4.3 {
    db close
    sqlite3 db test.db
    set maxsz 0