text: /*
  ** 2001 September 15
  **
  ** The author disclaims copyright to this source code.  In place of
  ** a legal notice, here is a blessing:
  **
  **    May you do good and not evil.
  **    May you find forgiveness for yourself and forgive others.
  **    May you share freely, never taking more than you give.
  **
  *************************************************************************
  ** Main file for the SQLite library.  The routines in this file
  ** implement the programmer interface to the library.  Routines in
  ** other files are for internal use by SQLite and should not be
  ** accessed by users of the library.
  */
  #include "sqliteInt.h"
  
  #ifdef SQLITE_ENABLE_FTS3
  # include "fts3.h"
  #endif
  #ifdef SQLITE_ENABLE_RTREE
  # include "rtree.h"
  #endif
  #if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
  # include "sqliteicu.h"
  #endif
  
  /*
  ** This is an extension initializer that is a no-op and always
  ** succeeds, except that it fails if the fault-simulation is set
  ** to 500.
  */
  static int sqlite3TestExtInit(sqlite3 *db){
    (void)db;
    return sqlite3FaultSim(500);
  }
  
  
  /*
  ** Forward declarations of external module initializer functions
  ** for modules that need them.
  */
  #ifdef SQLITE_ENABLE_FTS1
  int sqlite3Fts1Init(sqlite3*);
  #endif
  #ifdef SQLITE_ENABLE_FTS2
  int sqlite3Fts2Init(sqlite3*);
  #endif
  #ifdef SQLITE_ENABLE_FTS5
  int sqlite3Fts5Init(sqlite3*);
  #endif
  #ifdef SQLITE_ENABLE_JSON1
  int sqlite3Json1Init(sqlite3*);
  #endif
  #ifdef SQLITE_ENABLE_STMTVTAB
  int sqlite3StmtVtabInit(sqlite3*);
  #endif
  
  /*
  ** An array of pointers to extension initializer functions for
  ** built-in extensions.
  */
  static int (*const sqlite3BuiltinExtensions[])(sqlite3*) = {
  #ifdef SQLITE_ENABLE_FTS1
    sqlite3Fts1Init,
  #endif
  #ifdef SQLITE_ENABLE_FTS2
    sqlite3Fts2Init,
  #endif
  #ifdef SQLITE_ENABLE_FTS3
    sqlite3Fts3Init,
  #endif
  #ifdef SQLITE_ENABLE_FTS5
    sqlite3Fts5Init,
  #endif
  #if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
    sqlite3IcuInit,
  #endif
  #ifdef SQLITE_ENABLE_RTREE
    sqlite3RtreeInit,
  #endif
  #ifdef SQLITE_ENABLE_DBPAGE_VTAB
    sqlite3DbpageRegister,
  #endif
  #ifdef SQLITE_ENABLE_DBSTAT_VTAB
    sqlite3DbstatRegister,
  #endif
    sqlite3TestExtInit,
  #ifdef SQLITE_ENABLE_JSON1
    sqlite3Json1Init,
  #endif
  #ifdef SQLITE_ENABLE_STMTVTAB
    sqlite3StmtVtabInit,
  #endif
  #ifdef SQLITE_ENABLE_BYTECODE_VTAB
    sqlite3VdbeBytecodeVtabInit,
  #endif
  };
  
  #ifndef SQLITE_AMALGAMATION
  /* IMPLEMENTATION-OF: R-46656-45156 The sqlite3_version[] string constant
  ** contains the text of SQLITE_VERSION macro.
  */
  const char sqlite3_version[] = SQLITE_VERSION;
  #endif
  
  /* IMPLEMENTATION-OF: R-53536-42575 The sqlite3_libversion() function returns
  ** a pointer to the to the sqlite3_version[] string constant. 
  */
  const char *sqlite3_libversion(void){ return sqlite3_version; }
  
  /* IMPLEMENTATION-OF: R-25063-23286 The sqlite3_sourceid() function returns a
  ** pointer to a string constant whose value is the same as the
  ** SQLITE_SOURCE_ID C preprocessor macro. Except if SQLite is built using
  ** an edited copy of the amalgamation, then the last four characters of
  ** the hash might be different from SQLITE_SOURCE_ID.
  */
  const char *sqlite3_sourceid(void){ return SQLITE_SOURCE_ID; }
  
  /* IMPLEMENTATION-OF: R-35210-63508 The sqlite3_libversion_number() function
  ** returns an integer equal to SQLITE_VERSION_NUMBER.
  */
  int sqlite3_libversion_number(void){ return SQLITE_VERSION_NUMBER; }
  
  /* IMPLEMENTATION-OF: R-20790-14025 The sqlite3_threadsafe() function returns
  ** zero if and only if SQLite was compiled with mutexing code omitted due to
  ** the SQLITE_THREADSAFE compile-time option being set to 0.
  */
  int sqlite3_threadsafe(void){ return SQLITE_THREADSAFE; }
  
  /*
  ** When compiling the test fixture or with debugging enabled (on Win32),
  ** this variable being set to non-zero will cause OSTRACE macros to emit
  ** extra diagnostic information.
  */
  #ifdef SQLITE_HAVE_OS_TRACE
  # ifndef SQLITE_DEBUG_OS_TRACE
  #   define SQLITE_DEBUG_OS_TRACE 0
  # endif
    int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
  #endif
  
  #if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
  /*
  ** If the following function pointer is not NULL and if
  ** SQLITE_ENABLE_IOTRACE is enabled, then messages describing
  ** I/O active are written using this function.  These messages
  ** are intended for debugging activity only.
  */
  SQLITE_API void (SQLITE_CDECL *sqlite3IoTrace)(const char*, ...) = 0;
  #endif
  
  /*
  ** If the following global variable points to a string which is the
  ** name of a directory, then that directory will be used to store
  ** temporary files.
  **
  ** See also the "PRAGMA temp_store_directory" SQL command.
  */
  char *sqlite3_temp_directory = 0;
  
  /*
  ** If the following global variable points to a string which is the
  ** name of a directory, then that directory will be used to store
  ** all database files specified with a relative pathname.
  **
  ** See also the "PRAGMA data_store_directory" SQL command.
  */
  char *sqlite3_data_directory = 0;
  
  /*
  ** Initialize SQLite.  
  **
  ** This routine must be called to initialize the memory allocation,
  ** VFS, and mutex subsystems prior to doing any serious work with
  ** SQLite.  But as long as you do not compile with SQLITE_OMIT_AUTOINIT
  ** this routine will be called automatically by key routines such as
  ** sqlite3_open().  
  **
  ** This routine is a no-op except on its very first call for the process,
  ** or for the first call after a call to sqlite3_shutdown.
  **
  ** The first thread to call this routine runs the initialization to
  ** completion.  If subsequent threads call this routine before the first
  ** thread has finished the initialization process, then the subsequent
  ** threads must block until the first thread finishes with the initialization.
  **
  ** The first thread might call this routine recursively.  Recursive
  ** calls to this routine should not block, of course.  Otherwise the
  ** initialization process would never complete.
  **
  ** Let X be the first thread to enter this routine.  Let Y be some other
  ** thread.  Then while the initial invocation of this routine by X is
  ** incomplete, it is required that:
  **
  **    *  Calls to this routine from Y must block until the outer-most
  **       call by X completes.
  **
  **    *  Recursive calls to this routine from thread X return immediately
  **       without blocking.
  */
  int sqlite3_initialize(void){
    MUTEX_LOGIC( sqlite3_mutex *pMainMtx; )      /* The main static mutex */
    int rc;                                      /* Result code */
  #ifdef SQLITE_EXTRA_INIT
    int bRunExtraInit = 0;                       /* Extra initialization needed */
  #endif
  
  #ifdef SQLITE_OMIT_WSD
    rc = sqlite3_wsd_init(4096, 24);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  #endif
  
    /* If the following assert() fails on some obscure processor/compiler
    ** combination, the work-around is to set the correct pointer
    ** size at compile-time using -DSQLITE_PTRSIZE=n compile-time option */
    assert( SQLITE_PTRSIZE==sizeof(char*) );
  
    /* If SQLite is already completely initialized, then this call
    ** to sqlite3_initialize() should be a no-op.  But the initialization
    ** must be complete.  So isInit must not be set until the very end
    ** of this routine.
    */
    if( sqlite3GlobalConfig.isInit ){
      sqlite3MemoryBarrier();
      return SQLITE_OK;
    }
  
    /* Make sure the mutex subsystem is initialized.  If unable to 
    ** initialize the mutex subsystem, return early with the error.
    ** If the system is so sick that we are unable to allocate a mutex,
    ** there is not much SQLite is going to be able to do.
    **
    ** The mutex subsystem must take care of serializing its own
    ** initialization.
    */
    rc = sqlite3MutexInit();
    if( rc ) return rc;
  
    /* Initialize the malloc() system and the recursive pInitMutex mutex.
    ** This operation is protected by the STATIC_MAIN mutex.  Note that
    ** MutexAlloc() is called for a static mutex prior to initializing the
    ** malloc subsystem - this implies that the allocation of a static
    ** mutex must not require support from the malloc subsystem.
    */
    MUTEX_LOGIC( pMainMtx = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN); )
    sqlite3_mutex_enter(pMainMtx);
    sqlite3GlobalConfig.isMutexInit = 1;
    if( !sqlite3GlobalConfig.isMallocInit ){
      rc = sqlite3MallocInit();
    }
    if( rc==SQLITE_OK ){
      sqlite3GlobalConfig.isMallocInit = 1;
      if( !sqlite3GlobalConfig.pInitMutex ){
        sqlite3GlobalConfig.pInitMutex =
             sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
        if( sqlite3GlobalConfig.bCoreMutex && !sqlite3GlobalConfig.pInitMutex ){
          rc = SQLITE_NOMEM_BKPT;
        }
      }
    }
    if( rc==SQLITE_OK ){
      sqlite3GlobalConfig.nRefInitMutex++;
    }
    sqlite3_mutex_leave(pMainMtx);
  
    /* If rc is not SQLITE_OK at this point, then either the malloc
    ** subsystem could not be initialized or the system failed to allocate
    ** the pInitMutex mutex. Return an error in either case.  */
    if( rc!=SQLITE_OK ){
      return rc;
    }
  
    /* Do the rest of the initialization under the recursive mutex so
    ** that we will be able to handle recursive calls into
    ** sqlite3_initialize().  The recursive calls normally come through
    ** sqlite3_os_init() when it invokes sqlite3_vfs_register(), but other
    ** recursive calls might also be possible.
    **
    ** IMPLEMENTATION-OF: R-00140-37445 SQLite automatically serializes calls
    ** to the xInit method, so the xInit method need not be threadsafe.
    **
    ** The following mutex is what serializes access to the appdef pcache xInit
    ** methods.  The sqlite3_pcache_methods.xInit() all is embedded in the
    ** call to sqlite3PcacheInitialize().
    */
    sqlite3_mutex_enter(sqlite3GlobalConfig.pInitMutex);
    if( sqlite3GlobalConfig.isInit==0 && sqlite3GlobalConfig.inProgress==0 ){
      sqlite3GlobalConfig.inProgress = 1;
  #ifdef SQLITE_ENABLE_SQLLOG
      {
        extern void sqlite3_init_sqllog(void);
        sqlite3_init_sqllog();
      }
  #endif
      memset(&sqlite3BuiltinFunctions, 0, sizeof(sqlite3BuiltinFunctions));
      sqlite3RegisterBuiltinFunctions();
      if( sqlite3GlobalConfig.isPCacheInit==0 ){
        rc = sqlite3PcacheInitialize();
      }
      if( rc==SQLITE_OK ){
        sqlite3GlobalConfig.isPCacheInit = 1;
        rc = sqlite3OsInit();
      }
  #ifdef SQLITE_ENABLE_DESERIALIZE
      if( rc==SQLITE_OK ){
        rc = sqlite3MemdbInit();
      }
  #endif
      if( rc==SQLITE_OK ){
        sqlite3PCacheBufferSetup( sqlite3GlobalConfig.pPage, 
            sqlite3GlobalConfig.szPage, sqlite3GlobalConfig.nPage);
        sqlite3MemoryBarrier();
        sqlite3GlobalConfig.isInit = 1;
  #ifdef SQLITE_EXTRA_INIT
        bRunExtraInit = 1;
  #endif
      }
      sqlite3GlobalConfig.inProgress = 0;
    }
    sqlite3_mutex_leave(sqlite3GlobalConfig.pInitMutex);
  
    /* Go back under the static mutex and clean up the recursive
    ** mutex to prevent a resource leak.
    */
    sqlite3_mutex_enter(pMainMtx);
    sqlite3GlobalConfig.nRefInitMutex--;
    if( sqlite3GlobalConfig.nRefInitMutex<=0 ){
      assert( sqlite3GlobalConfig.nRefInitMutex==0 );
      sqlite3_mutex_free(sqlite3GlobalConfig.pInitMutex);
      sqlite3GlobalConfig.pInitMutex = 0;
    }
    sqlite3_mutex_leave(pMainMtx);
  
    /* The following is just a sanity check to make sure SQLite has
    ** been compiled correctly.  It is important to run this code, but
    ** we don't want to run it too often and soak up CPU cycles for no
    ** reason.  So we run it once during initialization.
    */
  #ifndef NDEBUG
  #ifndef SQLITE_OMIT_FLOATING_POINT
    /* This section of code's only "output" is via assert() statements. */
    if( rc==SQLITE_OK ){
      u64 x = (((u64)1)<<63)-1;
      double y;
      assert(sizeof(x)==8);
      assert(sizeof(x)==sizeof(y));
      memcpy(&y, &x, 8);
      assert( sqlite3IsNaN(y) );
    }
  #endif
  #endif
  
    /* Do extra initialization steps requested by the SQLITE_EXTRA_INIT
    ** compile-time option.
    */
  #ifdef SQLITE_EXTRA_INIT
    if( bRunExtraInit ){
      int SQLITE_EXTRA_INIT(const char*);
      rc = SQLITE_EXTRA_INIT(0);
    }
  #endif
  
    return rc;
  }
  
  /*
  ** Undo the effects of sqlite3_initialize().  Must not be called while
  ** there are outstanding database connections or memory allocations or
  ** while any part of SQLite is otherwise in use in any thread.  This
  ** routine is not threadsafe.  But it is safe to invoke this routine
  ** on when SQLite is already shut down.  If SQLite is already shut down
  ** when this routine is invoked, then this routine is a harmless no-op.
  */
  int sqlite3_shutdown(void){
  #ifdef SQLITE_OMIT_WSD
    int rc = sqlite3_wsd_init(4096, 24);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  #endif
  
    if( sqlite3GlobalConfig.isInit ){
  #ifdef SQLITE_EXTRA_SHUTDOWN
      void SQLITE_EXTRA_SHUTDOWN(void);
      SQLITE_EXTRA_SHUTDOWN();
  #endif
      sqlite3_os_end();
      sqlite3_reset_auto_extension();
      sqlite3GlobalConfig.isInit = 0;
    }
    if( sqlite3GlobalConfig.isPCacheInit ){
      sqlite3PcacheShutdown();
      sqlite3GlobalConfig.isPCacheInit = 0;
    }
    if( sqlite3GlobalConfig.isMallocInit ){
      sqlite3MallocEnd();
      sqlite3GlobalConfig.isMallocInit = 0;
  
  #ifndef SQLITE_OMIT_SHUTDOWN_DIRECTORIES
      /* The heap subsystem has now been shutdown and these values are supposed
      ** to be NULL or point to memory that was obtained from sqlite3_malloc(),
      ** which would rely on that heap subsystem; therefore, make sure these
      ** values cannot refer to heap memory that was just invalidated when the
      ** heap subsystem was shutdown.  This is only done if the current call to
      ** this function resulted in the heap subsystem actually being shutdown.
      */
      sqlite3_data_directory = 0;
      sqlite3_temp_directory = 0;
  #endif
    }
    if( sqlite3GlobalConfig.isMutexInit ){
      sqlite3MutexEnd();
      sqlite3GlobalConfig.isMutexInit = 0;
    }
  
    return SQLITE_OK;
  }
  
  /*
  ** This API allows applications to modify the global configuration of
  ** the SQLite library at run-time.
  **
  ** This routine should only be called when there are no outstanding
  ** database connections or memory allocations.  This routine is not
  ** threadsafe.  Failure to heed these warnings can lead to unpredictable
  ** behavior.
  */
  int sqlite3_config(int op, ...){
    va_list ap;
    int rc = SQLITE_OK;
  
    /* sqlite3_config() shall return SQLITE_MISUSE if it is invoked while
    ** the SQLite library is in use. */
    if( sqlite3GlobalConfig.isInit ) return SQLITE_MISUSE_BKPT;
  
    va_start(ap, op);
    switch( op ){
  
      /* Mutex configuration options are only available in a threadsafe
      ** compile.
      */
  #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0  /* IMP: R-54466-46756 */
      case SQLITE_CONFIG_SINGLETHREAD: {
        /* EVIDENCE-OF: R-02748-19096 This option sets the threading mode to
        ** Single-thread. */
        sqlite3GlobalConfig.bCoreMutex = 0;  /* Disable mutex on core */
        sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
        break;
      }
  #endif
  #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-20520-54086 */
      case SQLITE_CONFIG_MULTITHREAD: {
        /* EVIDENCE-OF: R-14374-42468 This option sets the threading mode to
        ** Multi-thread. */
        sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
        sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
        break;
      }
  #endif
  #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-59593-21810 */
      case SQLITE_CONFIG_SERIALIZED: {
        /* EVIDENCE-OF: R-41220-51800 This option sets the threading mode to
        ** Serialized. */
        sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
        sqlite3GlobalConfig.bFullMutex = 1;  /* Enable mutex on connections */
        break;
      }
  #endif
  #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-63666-48755 */
      case SQLITE_CONFIG_MUTEX: {
        /* Specify an alternative mutex implementation */
        sqlite3GlobalConfig.mutex = *va_arg(ap, sqlite3_mutex_methods*);
        break;
      }
  #endif
  #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-14450-37597 */
      case SQLITE_CONFIG_GETMUTEX: {
        /* Retrieve the current mutex implementation */
        *va_arg(ap, sqlite3_mutex_methods*) = sqlite3GlobalConfig.mutex;
        break;
      }
  #endif
  
      case SQLITE_CONFIG_MALLOC: {
        /* EVIDENCE-OF: R-55594-21030 The SQLITE_CONFIG_MALLOC option takes a
        ** single argument which is a pointer to an instance of the
        ** sqlite3_mem_methods structure. The argument specifies alternative
        ** low-level memory allocation routines to be used in place of the memory
        ** allocation routines built into SQLite. */
        sqlite3GlobalConfig.m = *va_arg(ap, sqlite3_mem_methods*);
        break;
      }
      case SQLITE_CONFIG_GETMALLOC: {
        /* EVIDENCE-OF: R-51213-46414 The SQLITE_CONFIG_GETMALLOC option takes a
        ** single argument which is a pointer to an instance of the
        ** sqlite3_mem_methods structure. The sqlite3_mem_methods structure is
        ** filled with the currently defined memory allocation routines. */
        if( sqlite3GlobalConfig.m.xMalloc==0 ) sqlite3MemSetDefault();
        *va_arg(ap, sqlite3_mem_methods*) = sqlite3GlobalConfig.m;
        break;
      }
      case SQLITE_CONFIG_MEMSTATUS: {
        /* EVIDENCE-OF: R-61275-35157 The SQLITE_CONFIG_MEMSTATUS option takes
        ** single argument of type int, interpreted as a boolean, which enables
        ** or disables the collection of memory allocation statistics. */
        sqlite3GlobalConfig.bMemstat = va_arg(ap, int);
        break;
      }
      case SQLITE_CONFIG_SMALL_MALLOC: {
        sqlite3GlobalConfig.bSmallMalloc = va_arg(ap, int);
        break;
      }
      case SQLITE_CONFIG_PAGECACHE: {
        /* EVIDENCE-OF: R-18761-36601 There are three arguments to
        ** SQLITE_CONFIG_PAGECACHE: A pointer to 8-byte aligned memory (pMem),
        ** the size of each page cache line (sz), and the number of cache lines
        ** (N). */
        sqlite3GlobalConfig.pPage = va_arg(ap, void*);
        sqlite3GlobalConfig.szPage = va_arg(ap, int);
        sqlite3GlobalConfig.nPage = va_arg(ap, int);
        break;
      }
      case SQLITE_CONFIG_PCACHE_HDRSZ: {
        /* EVIDENCE-OF: R-39100-27317 The SQLITE_CONFIG_PCACHE_HDRSZ option takes
        ** a single parameter which is a pointer to an integer and writes into
        ** that integer the number of extra bytes per page required for each page
        ** in SQLITE_CONFIG_PAGECACHE. */
        *va_arg(ap, int*) = 
            sqlite3HeaderSizeBtree() +
            sqlite3HeaderSizePcache() +
            sqlite3HeaderSizePcache1();
        break;
      }
  
      case SQLITE_CONFIG_PCACHE: {
        /* no-op */
        break;
      }
      case SQLITE_CONFIG_GETPCACHE: {
        /* now an error */
        rc = SQLITE_ERROR;
        break;
      }
  
      case SQLITE_CONFIG_PCACHE2: {
        /* EVIDENCE-OF: R-63325-48378 The SQLITE_CONFIG_PCACHE2 option takes a
        ** single argument which is a pointer to an sqlite3_pcache_methods2
        ** object. This object specifies the interface to a custom page cache
        ** implementation. */
        sqlite3GlobalConfig.pcache2 = *va_arg(ap, sqlite3_pcache_methods2*);
        break;
      }
      case SQLITE_CONFIG_GETPCACHE2: {
        /* EVIDENCE-OF: R-22035-46182 The SQLITE_CONFIG_GETPCACHE2 option takes a
        ** single argument which is a pointer to an sqlite3_pcache_methods2
        ** object. SQLite copies of the current page cache implementation into
        ** that object. */
        if( sqlite3GlobalConfig.pcache2.xInit==0 ){
          sqlite3PCacheSetDefault();
        }
        *va_arg(ap, sqlite3_pcache_methods2*) = sqlite3GlobalConfig.pcache2;
        break;
      }
  
  /* EVIDENCE-OF: R-06626-12911 The SQLITE_CONFIG_HEAP option is only
  ** available if SQLite is compiled with either SQLITE_ENABLE_MEMSYS3 or
  ** SQLITE_ENABLE_MEMSYS5 and returns SQLITE_ERROR if invoked otherwise. */
  #if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
      case SQLITE_CONFIG_HEAP: {
        /* EVIDENCE-OF: R-19854-42126 There are three arguments to
        ** SQLITE_CONFIG_HEAP: An 8-byte aligned pointer to the memory, the
        ** number of bytes in the memory buffer, and the minimum allocation size.
        */
        sqlite3GlobalConfig.pHeap = va_arg(ap, void*);
        sqlite3GlobalConfig.nHeap = va_arg(ap, int);
        sqlite3GlobalConfig.mnReq = va_arg(ap, int);
  
        if( sqlite3GlobalConfig.mnReq<1 ){
          sqlite3GlobalConfig.mnReq = 1;
        }else if( sqlite3GlobalConfig.mnReq>(1<<12) ){
          /* cap min request size at 2^12 */
          sqlite3GlobalConfig.mnReq = (1<<12);
        }
  
        if( sqlite3GlobalConfig.pHeap==0 ){
          /* EVIDENCE-OF: R-49920-60189 If the first pointer (the memory pointer)
          ** is NULL, then SQLite reverts to using its default memory allocator
          ** (the system malloc() implementation), undoing any prior invocation of
          ** SQLITE_CONFIG_MALLOC.
          **
          ** Setting sqlite3GlobalConfig.m to all zeros will cause malloc to
          ** revert to its default implementation when sqlite3_initialize() is run
          */
          memset(&sqlite3GlobalConfig.m, 0, sizeof(sqlite3GlobalConfig.m));
        }else{
          /* EVIDENCE-OF: R-61006-08918 If the memory pointer is not NULL then the
          ** alternative memory allocator is engaged to handle all of SQLites
          ** memory allocation needs. */
  #ifdef SQLITE_ENABLE_MEMSYS3
          sqlite3GlobalConfig.m = *sqlite3MemGetMemsys3();
  #endif
  #ifdef SQLITE_ENABLE_MEMSYS5
          sqlite3GlobalConfig.m = *sqlite3MemGetMemsys5();
  #endif
        }
        break;
      }
  #endif
  
      case SQLITE_CONFIG_LOOKASIDE: {
        sqlite3GlobalConfig.szLookaside = va_arg(ap, int);
        sqlite3GlobalConfig.nLookaside = va_arg(ap, int);
        break;
      }
      
      /* Record a pointer to the logger function and its first argument.
      ** The default is NULL.  Logging is disabled if the function pointer is
      ** NULL.
      */
      case SQLITE_CONFIG_LOG: {
        /* MSVC is picky about pulling func ptrs from va lists.
        ** http://support.microsoft.com/kb/47961
        ** sqlite3GlobalConfig.xLog = va_arg(ap, void(*)(void*,int,const char*));
        */
        typedef void(*LOGFUNC_t)(void*,int,const char*);
        sqlite3GlobalConfig.xLog = va_arg(ap, LOGFUNC_t);
        sqlite3GlobalConfig.pLogArg = va_arg(ap, void*);
        break;
      }
  
      /* EVIDENCE-OF: R-55548-33817 The compile-time setting for URI filenames
      ** can be changed at start-time using the
      ** sqlite3_config(SQLITE_CONFIG_URI,1) or
      ** sqlite3_config(SQLITE_CONFIG_URI,0) configuration calls.
      */
      case SQLITE_CONFIG_URI: {
        /* EVIDENCE-OF: R-25451-61125 The SQLITE_CONFIG_URI option takes a single
        ** argument of type int. If non-zero, then URI handling is globally
        ** enabled. If the parameter is zero, then URI handling is globally
        ** disabled. */
        sqlite3GlobalConfig.bOpenUri = va_arg(ap, int);
        break;
      }
  
      case SQLITE_CONFIG_COVERING_INDEX_SCAN: {
        /* EVIDENCE-OF: R-36592-02772 The SQLITE_CONFIG_COVERING_INDEX_SCAN
        ** option takes a single integer argument which is interpreted as a
        ** boolean in order to enable or disable the use of covering indices for
        ** full table scans in the query optimizer. */
        sqlite3GlobalConfig.bUseCis = va_arg(ap, int);
        break;
      }
  
  #ifdef SQLITE_ENABLE_SQLLOG
      case SQLITE_CONFIG_SQLLOG: {
        typedef void(*SQLLOGFUNC_t)(void*, sqlite3*, const char*, int);
        sqlite3GlobalConfig.xSqllog = va_arg(ap, SQLLOGFUNC_t);
        sqlite3GlobalConfig.pSqllogArg = va_arg(ap, void *);
        break;
      }
  #endif
  
      case SQLITE_CONFIG_MMAP_SIZE: {
        /* EVIDENCE-OF: R-58063-38258 SQLITE_CONFIG_MMAP_SIZE takes two 64-bit
        ** integer (sqlite3_int64) values that are the default mmap size limit
        ** (the default setting for PRAGMA mmap_size) and the maximum allowed
        ** mmap size limit. */
        sqlite3_int64 szMmap = va_arg(ap, sqlite3_int64);
        sqlite3_int64 mxMmap = va_arg(ap, sqlite3_int64);
        /* EVIDENCE-OF: R-53367-43190 If either argument to this option is
        ** negative, then that argument is changed to its compile-time default.
        **
        ** EVIDENCE-OF: R-34993-45031 The maximum allowed mmap size will be
        ** silently truncated if necessary so that it does not exceed the
        ** compile-time maximum mmap size set by the SQLITE_MAX_MMAP_SIZE
        ** compile-time option.
        */
        if( mxMmap<0 || mxMmap>SQLITE_MAX_MMAP_SIZE ){
          mxMmap = SQLITE_MAX_MMAP_SIZE;
        }
        if( szMmap<0 ) szMmap = SQLITE_DEFAULT_MMAP_SIZE;
        if( szMmap>mxMmap) szMmap = mxMmap;
        sqlite3GlobalConfig.mxMmap = mxMmap;
        sqlite3GlobalConfig.szMmap = szMmap;
        break;
      }
  
  #if SQLITE_OS_WIN && defined(SQLITE_WIN32_MALLOC) /* IMP: R-04780-55815 */
      case SQLITE_CONFIG_WIN32_HEAPSIZE: {
        /* EVIDENCE-OF: R-34926-03360 SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit
        ** unsigned integer value that specifies the maximum size of the created
        ** heap. */
        sqlite3GlobalConfig.nHeap = va_arg(ap, int);
        break;
      }
  #endif
  
      case SQLITE_CONFIG_PMASZ: {
        sqlite3GlobalConfig.szPma = va_arg(ap, unsigned int);
        break;
      }
  
      case SQLITE_CONFIG_STMTJRNL_SPILL: {
        sqlite3GlobalConfig.nStmtSpill = va_arg(ap, int);
        break;
      }
  
  #ifdef SQLITE_ENABLE_SORTER_REFERENCES
      case SQLITE_CONFIG_SORTERREF_SIZE: {
        int iVal = va_arg(ap, int);
        if( iVal<0 ){
          iVal = SQLITE_DEFAULT_SORTERREF_SIZE;
        }
        sqlite3GlobalConfig.szSorterRef = (u32)iVal;
        break;
      }
  #endif /* SQLITE_ENABLE_SORTER_REFERENCES */
  
  #ifdef SQLITE_ENABLE_DESERIALIZE
      case SQLITE_CONFIG_MEMDB_MAXSIZE: {
        sqlite3GlobalConfig.mxMemdbSize = va_arg(ap, sqlite3_int64);
        break;
      }
  #endif /* SQLITE_ENABLE_DESERIALIZE */
  
      default: {
        rc = SQLITE_ERROR;
        break;
      }
    }
    va_end(ap);
    return rc;
  }
  
  /*
  ** Set up the lookaside buffers for a database connection.
  ** Return SQLITE_OK on success.  
  ** If lookaside is already active, return SQLITE_BUSY.
  **
  ** The sz parameter is the number of bytes in each lookaside slot.
  ** The cnt parameter is the number of slots.  If pStart is NULL the
  ** space for the lookaside memory is obtained from sqlite3_malloc().
  ** If pStart is not NULL then it is sz*cnt bytes of memory to use for
  ** the lookaside memory.
  */
  static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
  #ifndef SQLITE_OMIT_LOOKASIDE
    void *pStart;
    sqlite3_int64 szAlloc = sz*(sqlite3_int64)cnt;
    int nBig;   /* Number of full-size slots */
    int nSm;    /* Number smaller LOOKASIDE_SMALL-byte slots */
    
    if( sqlite3LookasideUsed(db,0)>0 ){
      return SQLITE_BUSY;
    }
    /* Free any existing lookaside buffer for this handle before
    ** allocating a new one so we don't have to have space for 
    ** both at the same time.
    */
    if( db->lookaside.bMalloced ){
      sqlite3_free(db->lookaside.pStart);
    }
    /* The size of a lookaside slot after ROUNDDOWN8 needs to be larger
    ** than a pointer to be useful.
    */
    sz = ROUNDDOWN8(sz);  /* IMP: R-33038-09382 */
    if( sz<=(int)sizeof(LookasideSlot*) ) sz = 0;
    if( cnt<0 ) cnt = 0;
    if( sz==0 || cnt==0 ){
      sz = 0;
      pStart = 0;
    }else if( pBuf==0 ){
      sqlite3BeginBenignMalloc();
      pStart = sqlite3Malloc( szAlloc );  /* IMP: R-61949-35727 */
      sqlite3EndBenignMalloc();
      if( pStart ) szAlloc = sqlite3MallocSize(pStart);
    }else{
      pStart = pBuf;
    }
  #ifndef SQLITE_OMIT_TWOSIZE_LOOKASIDE
    if( sz>=LOOKASIDE_SMALL*3 ){
      nBig = szAlloc/(3*LOOKASIDE_SMALL+sz);
      nSm = (szAlloc - sz*nBig)/LOOKASIDE_SMALL;
    }else if( sz>=LOOKASIDE_SMALL*2 ){
      nBig = szAlloc/(LOOKASIDE_SMALL+sz);
      nSm = (szAlloc - sz*nBig)/LOOKASIDE_SMALL;
    }else
  #endif /* SQLITE_OMIT_TWOSIZE_LOOKASIDE */
    if( sz>0 ){
      nBig = szAlloc/sz;
      nSm = 0;
    }else{
      nBig = nSm = 0;
    }
    db->lookaside.pStart = pStart;
    db->lookaside.pInit = 0;
    db->lookaside.pFree = 0;
    db->lookaside.sz = (u16)sz;
    db->lookaside.szTrue = (u16)sz;
    if( pStart ){
      int i;
      LookasideSlot *p;
      assert( sz > (int)sizeof(LookasideSlot*) );
      p = (LookasideSlot*)pStart;
      for(i=0; i<nBig; i++){
        p->pNext = db->lookaside.pInit;
        db->lookaside.pInit = p;
        p = (LookasideSlot*)&((u8*)p)[sz];
      }
  #ifndef SQLITE_OMIT_TWOSIZE_LOOKASIDE
      db->lookaside.pSmallInit = 0;
      db->lookaside.pSmallFree = 0;
      db->lookaside.pMiddle = p;
      for(i=0; i<nSm; i++){
        p->pNext = db->lookaside.pSmallInit;
        db->lookaside.pSmallInit = p;
        p = (LookasideSlot*)&((u8*)p)[LOOKASIDE_SMALL];
      }
  #endif /* SQLITE_OMIT_TWOSIZE_LOOKASIDE */
      assert( ((uptr)p)<=szAlloc + (uptr)pStart );
      db->lookaside.pEnd = p;
      db->lookaside.bDisable = 0;
      db->lookaside.bMalloced = pBuf==0 ?1:0;
      db->lookaside.nSlot = nBig+nSm;
    }else{
      db->lookaside.pStart = db;
  #ifndef SQLITE_OMIT_TWOSIZE_LOOKASIDE
      db->lookaside.pSmallInit = 0;
      db->lookaside.pSmallFree = 0;
      db->lookaside.pMiddle = db;
  #endif /* SQLITE_OMIT_TWOSIZE_LOOKASIDE */
      db->lookaside.pEnd = db;
      db->lookaside.bDisable = 1;
      db->lookaside.sz = 0;
      db->lookaside.bMalloced = 0;
      db->lookaside.nSlot = 0;
    }
    assert( sqlite3LookasideUsed(db,0)==0 );
  #endif /* SQLITE_OMIT_LOOKASIDE */
    return SQLITE_OK;
  }
  
  /*
  ** Return the mutex associated with a database connection.
  */
  sqlite3_mutex *sqlite3_db_mutex(sqlite3 *db){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    return db->mutex;
  }
  
  /*
  ** Free up as much memory as we can from the given database
  ** connection.
  */
  int sqlite3_db_release_memory(sqlite3 *db){
    int i;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    sqlite3BtreeEnterAll(db);
    for(i=0; i<db->nDb; i++){
      Btree *pBt = db->aDb[i].pBt;
      if( pBt ){
        Pager *pPager = sqlite3BtreePager(pBt);
        sqlite3PagerShrink(pPager);
      }
    }
    sqlite3BtreeLeaveAll(db);
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_OK;
  }
  
  /*
  ** Flush any dirty pages in the pager-cache for any attached database
  ** to disk.
  */
  int sqlite3_db_cacheflush(sqlite3 *db){
    int i;
    int rc = SQLITE_OK;
    int bSeenBusy = 0;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    sqlite3BtreeEnterAll(db);
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
      Btree *pBt = db->aDb[i].pBt;
      if( pBt && sqlite3BtreeTxnState(pBt)==SQLITE_TXN_WRITE ){
        Pager *pPager = sqlite3BtreePager(pBt);
        rc = sqlite3PagerFlush(pPager);
        if( rc==SQLITE_BUSY ){
          bSeenBusy = 1;
          rc = SQLITE_OK;
        }
      }
    }
    sqlite3BtreeLeaveAll(db);
    sqlite3_mutex_leave(db->mutex);
    return ((rc==SQLITE_OK && bSeenBusy) ? SQLITE_BUSY : rc);
  }
  
  /*
  ** Configuration settings for an individual database connection
  */
  int sqlite3_db_config(sqlite3 *db, int op, ...){
    va_list ap;
    int rc;
    va_start(ap, op);
    switch( op ){
      case SQLITE_DBCONFIG_MAINDBNAME: {
        /* IMP: R-06824-28531 */
        /* IMP: R-36257-52125 */
        db->aDb[0].zDbSName = va_arg(ap,char*);
        rc = SQLITE_OK;
        break;
      }
      case SQLITE_DBCONFIG_LOOKASIDE: {
        void *pBuf = va_arg(ap, void*); /* IMP: R-26835-10964 */
        int sz = va_arg(ap, int);       /* IMP: R-47871-25994 */
        int cnt = va_arg(ap, int);      /* IMP: R-04460-53386 */
        rc = setupLookaside(db, pBuf, sz, cnt);
        break;
      }
      default: {
        static const struct {
          int op;      /* The opcode */
          u32 mask;    /* Mask of the bit in sqlite3.flags to set/clear */
        } aFlagOp[] = {
          { SQLITE_DBCONFIG_ENABLE_FKEY,           SQLITE_ForeignKeys    },
          { SQLITE_DBCONFIG_ENABLE_TRIGGER,        SQLITE_EnableTrigger  },
          { SQLITE_DBCONFIG_ENABLE_VIEW,           SQLITE_EnableView     },
          { SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER, SQLITE_Fts3Tokenizer  },
          { SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, SQLITE_LoadExtension  },
          { SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE,      SQLITE_NoCkptOnClose  },
          { SQLITE_DBCONFIG_ENABLE_QPSG,           SQLITE_EnableQPSG     },
          { SQLITE_DBCONFIG_TRIGGER_EQP,           SQLITE_TriggerEQP     },
          { SQLITE_DBCONFIG_RESET_DATABASE,        SQLITE_ResetDatabase  },
          { SQLITE_DBCONFIG_DEFENSIVE,             SQLITE_Defensive      },
          { SQLITE_DBCONFIG_WRITABLE_SCHEMA,       SQLITE_WriteSchema|
                                                   SQLITE_NoSchemaError  },
          { SQLITE_DBCONFIG_LEGACY_ALTER_TABLE,    SQLITE_LegacyAlter    },
          { SQLITE_DBCONFIG_DQS_DDL,               SQLITE_DqsDDL         },
          { SQLITE_DBCONFIG_DQS_DML,               SQLITE_DqsDML         },
          { SQLITE_DBCONFIG_LEGACY_FILE_FORMAT,    SQLITE_LegacyFileFmt  },
          { SQLITE_DBCONFIG_TRUSTED_SCHEMA,        SQLITE_TrustedSchema  },
        };
        unsigned int i;
        rc = SQLITE_ERROR; /* IMP: R-42790-23372 */
        for(i=0; i<ArraySize(aFlagOp); i++){
          if( aFlagOp[i].op==op ){
            int onoff = va_arg(ap, int);
            int *pRes = va_arg(ap, int*);
            u64 oldFlags = db->flags;
            if( onoff>0 ){
              db->flags |= aFlagOp[i].mask;
            }else if( onoff==0 ){
              db->flags &= ~(u64)aFlagOp[i].mask;
            }
            if( oldFlags!=db->flags ){
              sqlite3ExpirePreparedStatements(db, 0);
            }
            if( pRes ){
              *pRes = (db->flags & aFlagOp[i].mask)!=0;
            }
            rc = SQLITE_OK;
            break;
          }
        }
        break;
      }
    }
    va_end(ap);
    return rc;
  }
  
  /*
  ** This is the default collating function named "BINARY" which is always
  ** available.
  */
  static int binCollFunc(
    void *NotUsed,
    int nKey1, const void *pKey1,
    int nKey2, const void *pKey2
  ){
    int rc, n;
    UNUSED_PARAMETER(NotUsed);
    n = nKey1<nKey2 ? nKey1 : nKey2;
    /* EVIDENCE-OF: R-65033-28449 The built-in BINARY collation compares
    ** strings byte by byte using the memcmp() function from the standard C
    ** library. */
    assert( pKey1 && pKey2 );
    rc = memcmp(pKey1, pKey2, n);
    if( rc==0 ){
      rc = nKey1 - nKey2;
    }
    return rc;
  }
  
  /*
  ** This is the collating function named "RTRIM" which is always
  ** available.  Ignore trailing spaces.
  */
  static int rtrimCollFunc(
    void *pUser,
    int nKey1, const void *pKey1,
    int nKey2, const void *pKey2
  ){
    const u8 *pK1 = (const u8*)pKey1;
    const u8 *pK2 = (const u8*)pKey2;
    while( nKey1 && pK1[nKey1-1]==' ' ) nKey1--;
    while( nKey2 && pK2[nKey2-1]==' ' ) nKey2--;
    return binCollFunc(pUser, nKey1, pKey1, nKey2, pKey2);
  }
  
  /*
  ** Return true if CollSeq is the default built-in BINARY.
  */
  int sqlite3IsBinary(const CollSeq *p){
    assert( p==0 || p->xCmp!=binCollFunc || strcmp(p->zName,"BINARY")==0 );
    return p==0 || p->xCmp==binCollFunc;
  }
  
  /*
  ** Another built-in collating sequence: NOCASE. 
  **
  ** This collating sequence is intended to be used for "case independent
  ** comparison". SQLite's knowledge of upper and lower case equivalents
  ** extends only to the 26 characters used in the English language.
  **
  ** At the moment there is only a UTF-8 implementation.
  */
  static int nocaseCollatingFunc(
    void *NotUsed,
    int nKey1, const void *pKey1,
    int nKey2, const void *pKey2
  ){
    int r = sqlite3StrNICmp(
        (const char *)pKey1, (const char *)pKey2, (nKey1<nKey2)?nKey1:nKey2);
    UNUSED_PARAMETER(NotUsed);
    if( 0==r ){
      r = nKey1-nKey2;
    }
    return r;
  }
  
  /*
  ** Return the ROWID of the most recent insert
  */
  sqlite_int64 sqlite3_last_insert_rowid(sqlite3 *db){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    return db->lastRowid;
  }
  
  /*
  ** Set the value returned by the sqlite3_last_insert_rowid() API function.
  */
  void sqlite3_set_last_insert_rowid(sqlite3 *db, sqlite3_int64 iRowid){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    db->lastRowid = iRowid;
    sqlite3_mutex_leave(db->mutex);
  }
  
  /*
  ** Return the number of changes in the most recent call to sqlite3_exec().
  */
  int sqlite3_changes(sqlite3 *db){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    return db->nChange;
  }
  
  /*
  ** Return the number of changes since the database handle was opened.
  */
  int sqlite3_total_changes(sqlite3 *db){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    return db->nTotalChange;
  }
  
  /*
  ** Close all open savepoints. This function only manipulates fields of the
  ** database handle object, it does not close any savepoints that may be open
  ** at the b-tree/pager level.
  */
  void sqlite3CloseSavepoints(sqlite3 *db){
    while( db->pSavepoint ){
      Savepoint *pTmp = db->pSavepoint;
      db->pSavepoint = pTmp->pNext;
      sqlite3DbFree(db, pTmp);
    }
    db->nSavepoint = 0;
    db->nStatement = 0;
    db->isTransactionSavepoint = 0;
  }
  
  /*
  ** Invoke the destructor function associated with FuncDef p, if any. Except,
  ** if this is not the last copy of the function, do not invoke it. Multiple
  ** copies of a single function are created when create_function() is called
  ** with SQLITE_ANY as the encoding.
  */
  static void functionDestroy(sqlite3 *db, FuncDef *p){
    FuncDestructor *pDestructor = p->u.pDestructor;
    if( pDestructor ){
      pDestructor->nRef--;
      if( pDestructor->nRef==0 ){
        pDestructor->xDestroy(pDestructor->pUserData);
        sqlite3DbFree(db, pDestructor);
      }
    }
  }
  
  /*
  ** Disconnect all sqlite3_vtab objects that belong to database connection
  ** db. This is called when db is being closed.
  */
  static void disconnectAllVtab(sqlite3 *db){
  #ifndef SQLITE_OMIT_VIRTUALTABLE
    int i;
    HashElem *p;
    sqlite3BtreeEnterAll(db);
    for(i=0; i<db->nDb; i++){
      Schema *pSchema = db->aDb[i].pSchema;
      if( pSchema ){
        for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
          Table *pTab = (Table *)sqliteHashData(p);
          if( IsVirtual(pTab) ) sqlite3VtabDisconnect(db, pTab);
        }
      }
    }
    for(p=sqliteHashFirst(&db->aModule); p; p=sqliteHashNext(p)){
      Module *pMod = (Module *)sqliteHashData(p);
      if( pMod->pEpoTab ){
        sqlite3VtabDisconnect(db, pMod->pEpoTab);
      }
    }
    sqlite3VtabUnlockList(db);
    sqlite3BtreeLeaveAll(db);
  #else
    UNUSED_PARAMETER(db);
  #endif
  }
  
  /*
  ** Return TRUE if database connection db has unfinalized prepared
  ** statements or unfinished sqlite3_backup objects.  
  */
  static int connectionIsBusy(sqlite3 *db){
    int j;
    assert( sqlite3_mutex_held(db->mutex) );
    if( db->pVdbe ) return 1;
    for(j=0; j<db->nDb; j++){
      Btree *pBt = db->aDb[j].pBt;
      if( pBt && sqlite3BtreeIsInBackup(pBt) ) return 1;
    }
    return 0;
  }
  
  /*
  ** Close an existing SQLite database
  */
  static int sqlite3Close(sqlite3 *db, int forceZombie){
    if( !db ){
      /* EVIDENCE-OF: R-63257-11740 Calling sqlite3_close() or
      ** sqlite3_close_v2() with a NULL pointer argument is a harmless no-op. */
      return SQLITE_OK;
    }
    if( !sqlite3SafetyCheckSickOrOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
    sqlite3_mutex_enter(db->mutex);
    if( db->mTrace & SQLITE_TRACE_CLOSE ){
      db->trace.xV2(SQLITE_TRACE_CLOSE, db->pTraceArg, db, 0);
    }
  
    /* Force xDisconnect calls on all virtual tables */
    disconnectAllVtab(db);
  
    /* If a transaction is open, the disconnectAllVtab() call above
    ** will not have called the xDisconnect() method on any virtual
    ** tables in the db->aVTrans[] array. The following sqlite3VtabRollback()
    ** call will do so. We need to do this before the check for active
    ** SQL statements below, as the v-table implementation may be storing
    ** some prepared statements internally.
    */
    sqlite3VtabRollback(db);
  
    /* Legacy behavior (sqlite3_close() behavior) is to return
    ** SQLITE_BUSY if the connection can not be closed immediately.
    */
    if( !forceZombie && connectionIsBusy(db) ){
      sqlite3ErrorWithMsg(db, SQLITE_BUSY, "unable to close due to unfinalized "
         "statements or unfinished backups");
      sqlite3_mutex_leave(db->mutex);
      return SQLITE_BUSY;
    }
  
  #ifdef SQLITE_ENABLE_SQLLOG
    if( sqlite3GlobalConfig.xSqllog ){
      /* Closing the handle. Fourth parameter is passed the value 2. */
      sqlite3GlobalConfig.xSqllog(sqlite3GlobalConfig.pSqllogArg, db, 0, 2);
    }
  #endif
  
    /* Convert the connection into a zombie and then close it.
    */
    db->magic = SQLITE_MAGIC_ZOMBIE;
    sqlite3LeaveMutexAndCloseZombie(db);
    return SQLITE_OK;
  }
  
  /*
  ** Return the transaction state for a single databse, or the maximum
  ** transaction state over all attached databases if zSchema is null.
  */
  int sqlite3_txn_state(sqlite3 *db, const char *zSchema){
    int iDb, nDb;
    int iTxn = -1;
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return -1;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    if( zSchema ){
      nDb = iDb = sqlite3FindDbName(db, zSchema);
      if( iDb<0 ) nDb--;
    }else{
      iDb = 0;
      nDb = db->nDb-1;
    }
    for(; iDb<=nDb; iDb++){
      Btree *pBt = db->aDb[iDb].pBt;
      int x = pBt!=0 ? sqlite3BtreeTxnState(pBt) : SQLITE_TXN_NONE;
      if( x>iTxn ) iTxn = x;
    }
    sqlite3_mutex_leave(db->mutex);
    return iTxn;
  }
  
  /*
  ** Two variations on the public interface for closing a database
  ** connection. The sqlite3_close() version returns SQLITE_BUSY and
  ** leaves the connection open if there are unfinalized prepared
  ** statements or unfinished sqlite3_backups.  The sqlite3_close_v2()
  ** version forces the connection to become a zombie if there are
  ** unclosed resources, and arranges for deallocation when the last
  ** prepare statement or sqlite3_backup closes.
  */
  int sqlite3_close(sqlite3 *db){ return sqlite3Close(db,0); }
  int sqlite3_close_v2(sqlite3 *db){ return sqlite3Close(db,1); }
  
  
  /*
  ** Close the mutex on database connection db.
  **
  ** Furthermore, if database connection db is a zombie (meaning that there
  ** has been a prior call to sqlite3_close(db) or sqlite3_close_v2(db)) and
  ** every sqlite3_stmt has now been finalized and every sqlite3_backup has
  ** finished, then free all resources.
  */
  void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
    HashElem *i;                    /* Hash table iterator */
    int j;
  
    /* If there are outstanding sqlite3_stmt or sqlite3_backup objects
    ** or if the connection has not yet been closed by sqlite3_close_v2(),
    ** then just leave the mutex and return.
    */
    if( db->magic!=SQLITE_MAGIC_ZOMBIE || connectionIsBusy(db) ){
      sqlite3_mutex_leave(db->mutex);
      return;
    }
  
    /* If we reach this point, it means that the database connection has
    ** closed all sqlite3_stmt and sqlite3_backup objects and has been
    ** passed to sqlite3_close (meaning that it is a zombie).  Therefore,
    ** go ahead and free all resources.
    */
  
    /* If a transaction is open, roll it back. This also ensures that if
    ** any database schemas have been modified by an uncommitted transaction
    ** they are reset. And that the required b-tree mutex is held to make
    ** the pager rollback and schema reset an atomic operation. */
    sqlite3RollbackAll(db, SQLITE_OK);
  
    /* Free any outstanding Savepoint structures. */
    sqlite3CloseSavepoints(db);
  
    /* Close all database connections */
    for(j=0; j<db->nDb; j++){
      struct Db *pDb = &db->aDb[j];
      if( pDb->pBt ){
        sqlite3BtreeClose(pDb->pBt);
        pDb->pBt = 0;
        if( j!=1 ){
          pDb->pSchema = 0;
        }
      }
    }
    /* Clear the TEMP schema separately and last */
    if( db->aDb[1].pSchema ){
      sqlite3SchemaClear(db->aDb[1].pSchema);
    }
    sqlite3VtabUnlockList(db);
  
    /* Free up the array of auxiliary databases */
    sqlite3CollapseDatabaseArray(db);
    assert( db->nDb<=2 );
    assert( db->aDb==db->aDbStatic );
  
    /* Tell the code in notify.c that the connection no longer holds any
    ** locks and does not require any further unlock-notify callbacks.
    */
    sqlite3ConnectionClosed(db);
  
    for(i=sqliteHashFirst(&db->aFunc); i; i=sqliteHashNext(i)){
      FuncDef *pNext, *p;
      p = sqliteHashData(i);
      do{
        functionDestroy(db, p);
        pNext = p->pNext;
        sqlite3DbFree(db, p);
        p = pNext;
      }while( p );
    }
    sqlite3HashClear(&db->aFunc);
    for(i=sqliteHashFirst(&db->aCollSeq); i; i=sqliteHashNext(i)){
      CollSeq *pColl = (CollSeq *)sqliteHashData(i);
      /* Invoke any destructors registered for collation sequence user data. */
      for(j=0; j<3; j++){
        if( pColl[j].xDel ){
          pColl[j].xDel(pColl[j].pUser);
        }
      }
      sqlite3DbFree(db, pColl);
    }
    sqlite3HashClear(&db->aCollSeq);
  #ifndef SQLITE_OMIT_VIRTUALTABLE
    for(i=sqliteHashFirst(&db->aModule); i; i=sqliteHashNext(i)){
      Module *pMod = (Module *)sqliteHashData(i);
      sqlite3VtabEponymousTableClear(db, pMod);
      sqlite3VtabModuleUnref(db, pMod);
    }
    sqlite3HashClear(&db->aModule);
  #endif
  
    sqlite3Error(db, SQLITE_OK); /* Deallocates any cached error strings. */
    sqlite3ValueFree(db->pErr);
    sqlite3CloseExtensions(db);
  #if SQLITE_USER_AUTHENTICATION
    sqlite3_free(db->auth.zAuthUser);
    sqlite3_free(db->auth.zAuthPW);
  #endif
  
    db->magic = SQLITE_MAGIC_ERROR;
  
    /* The temp-database schema is allocated differently from the other schema
    ** objects (using sqliteMalloc() directly, instead of sqlite3BtreeSchema()).
    ** So it needs to be freed here. Todo: Why not roll the temp schema into
    ** the same sqliteMalloc() as the one that allocates the database 
    ** structure?
    */
    sqlite3DbFree(db, db->aDb[1].pSchema);
    sqlite3_mutex_leave(db->mutex);
    db->magic = SQLITE_MAGIC_CLOSED;
    sqlite3_mutex_free(db->mutex);
    assert( sqlite3LookasideUsed(db,0)==0 );
    if( db->lookaside.bMalloced ){
      sqlite3_free(db->lookaside.pStart);
    }
    sqlite3_free(db);
  }
  
  /*
  ** Rollback all database files.  If tripCode is not SQLITE_OK, then
  ** any write cursors are invalidated ("tripped" - as in "tripping a circuit
  ** breaker") and made to return tripCode if there are any further
  ** attempts to use that cursor.  Read cursors remain open and valid
  ** but are "saved" in case the table pages are moved around.
  */
  void sqlite3RollbackAll(sqlite3 *db, int tripCode){
    int i;
    int inTrans = 0;
    int schemaChange;
    assert( sqlite3_mutex_held(db->mutex) );
    sqlite3BeginBenignMalloc();
  
    /* Obtain all b-tree mutexes before making any calls to BtreeRollback(). 
    ** This is important in case the transaction being rolled back has
    ** modified the database schema. If the b-tree mutexes are not taken
    ** here, then another shared-cache connection might sneak in between
    ** the database rollback and schema reset, which can cause false
    ** corruption reports in some cases.  */
    sqlite3BtreeEnterAll(db);
    schemaChange = (db->mDbFlags & DBFLAG_SchemaChange)!=0 && db->init.busy==0;
  
    for(i=0; i<db->nDb; i++){
      Btree *p = db->aDb[i].pBt;
      if( p ){
        if( sqlite3BtreeTxnState(p)==SQLITE_TXN_WRITE ){
          inTrans = 1;
        }
        sqlite3BtreeRollback(p, tripCode, !schemaChange);
      }
    }
    sqlite3VtabRollback(db);
    sqlite3EndBenignMalloc();
  
    if( schemaChange ){
      sqlite3ExpirePreparedStatements(db, 0);
      sqlite3ResetAllSchemasOfConnection(db);
    }
    sqlite3BtreeLeaveAll(db);
  
    /* Any deferred constraint violations have now been resolved. */
    db->nDeferredCons = 0;
    db->nDeferredImmCons = 0;
    db->flags &= ~(u64)SQLITE_DeferFKs;
  
    /* If one has been configured, invoke the rollback-hook callback */
    if( db->xRollbackCallback && (inTrans || !db->autoCommit) ){
      db->xRollbackCallback(db->pRollbackArg);
    }
  }
  
  /*
  ** Return a static string containing the name corresponding to the error code
  ** specified in the argument.
  */
  #if defined(SQLITE_NEED_ERR_NAME)
  const char *sqlite3ErrName(int rc){
    const char *zName = 0;
    int i, origRc = rc;
    for(i=0; i<2 && zName==0; i++, rc &= 0xff){
      switch( rc ){
        case SQLITE_OK:                 zName = "SQLITE_OK";                break;
        case SQLITE_ERROR:              zName = "SQLITE_ERROR";             break;
        case SQLITE_ERROR_SNAPSHOT:     zName = "SQLITE_ERROR_SNAPSHOT";    break;
        case SQLITE_INTERNAL:           zName = "SQLITE_INTERNAL";          break;
        case SQLITE_PERM:               zName = "SQLITE_PERM";              break;
        case SQLITE_ABORT:              zName = "SQLITE_ABORT";             break;
        case SQLITE_ABORT_ROLLBACK:     zName = "SQLITE_ABORT_ROLLBACK";    break;
        case SQLITE_BUSY:               zName = "SQLITE_BUSY";              break;
        case SQLITE_BUSY_RECOVERY:      zName = "SQLITE_BUSY_RECOVERY";     break;
        case SQLITE_BUSY_SNAPSHOT:      zName = "SQLITE_BUSY_SNAPSHOT";     break;
        case SQLITE_LOCKED:             zName = "SQLITE_LOCKED";            break;
        case SQLITE_LOCKED_SHAREDCACHE: zName = "SQLITE_LOCKED_SHAREDCACHE";break;
        case SQLITE_NOMEM:              zName = "SQLITE_NOMEM";             break;
        case SQLITE_READONLY:           zName = "SQLITE_READONLY";          break;
        case SQLITE_READONLY_RECOVERY:  zName = "SQLITE_READONLY_RECOVERY"; break;
        case SQLITE_READONLY_CANTINIT:  zName = "SQLITE_READONLY_CANTINIT"; break;
        case SQLITE_READONLY_ROLLBACK:  zName = "SQLITE_READONLY_ROLLBACK"; break;
        case SQLITE_READONLY_DBMOVED:   zName = "SQLITE_READONLY_DBMOVED";  break;
        case SQLITE_READONLY_DIRECTORY: zName = "SQLITE_READONLY_DIRECTORY";break;
        case SQLITE_INTERRUPT:          zName = "SQLITE_INTERRUPT";         break;
        case SQLITE_IOERR:              zName = "SQLITE_IOERR";             break;
        case SQLITE_IOERR_READ:         zName = "SQLITE_IOERR_READ";        break;
        case SQLITE_IOERR_SHORT_READ:   zName = "SQLITE_IOERR_SHORT_READ";  break;
        case SQLITE_IOERR_WRITE:        zName = "SQLITE_IOERR_WRITE";       break;
        case SQLITE_IOERR_FSYNC:        zName = "SQLITE_IOERR_FSYNC";       break;
        case SQLITE_IOERR_DIR_FSYNC:    zName = "SQLITE_IOERR_DIR_FSYNC";   break;
        case SQLITE_IOERR_TRUNCATE:     zName = "SQLITE_IOERR_TRUNCATE";    break;
        case SQLITE_IOERR_FSTAT:        zName = "SQLITE_IOERR_FSTAT";       break;
        case SQLITE_IOERR_UNLOCK:       zName = "SQLITE_IOERR_UNLOCK";      break;
        case SQLITE_IOERR_RDLOCK:       zName = "SQLITE_IOERR_RDLOCK";      break;
        case SQLITE_IOERR_DELETE:       zName = "SQLITE_IOERR_DELETE";      break;
        case SQLITE_IOERR_NOMEM:        zName = "SQLITE_IOERR_NOMEM";       break;
        case SQLITE_IOERR_ACCESS:       zName = "SQLITE_IOERR_ACCESS";      break;
        case SQLITE_IOERR_CHECKRESERVEDLOCK:
                                  zName = "SQLITE_IOERR_CHECKRESERVEDLOCK"; break;
        case SQLITE_IOERR_LOCK:         zName = "SQLITE_IOERR_LOCK";        break;
        case SQLITE_IOERR_CLOSE:        zName = "SQLITE_IOERR_CLOSE";       break;
        case SQLITE_IOERR_DIR_CLOSE:    zName = "SQLITE_IOERR_DIR_CLOSE";   break;
        case SQLITE_IOERR_SHMOPEN:      zName = "SQLITE_IOERR_SHMOPEN";     break;
        case SQLITE_IOERR_SHMSIZE:      zName = "SQLITE_IOERR_SHMSIZE";     break;
        case SQLITE_IOERR_SHMLOCK:      zName = "SQLITE_IOERR_SHMLOCK";     break;
        case SQLITE_IOERR_SHMMAP:       zName = "SQLITE_IOERR_SHMMAP";      break;
        case SQLITE_IOERR_SEEK:         zName = "SQLITE_IOERR_SEEK";        break;
        case SQLITE_IOERR_DELETE_NOENT: zName = "SQLITE_IOERR_DELETE_NOENT";break;
        case SQLITE_IOERR_MMAP:         zName = "SQLITE_IOERR_MMAP";        break;
        case SQLITE_IOERR_GETTEMPPATH:  zName = "SQLITE_IOERR_GETTEMPPATH"; break;
        case SQLITE_IOERR_CONVPATH:     zName = "SQLITE_IOERR_CONVPATH";    break;
        case SQLITE_CORRUPT:            zName = "SQLITE_CORRUPT";           break;
        case SQLITE_CORRUPT_VTAB:       zName = "SQLITE_CORRUPT_VTAB";      break;
        case SQLITE_NOTFOUND:           zName = "SQLITE_NOTFOUND";          break;
        case SQLITE_FULL:               zName = "SQLITE_FULL";              break;
        case SQLITE_CANTOPEN:           zName = "SQLITE_CANTOPEN";          break;
        case SQLITE_CANTOPEN_NOTEMPDIR: zName = "SQLITE_CANTOPEN_NOTEMPDIR";break;
        case SQLITE_CANTOPEN_ISDIR:     zName = "SQLITE_CANTOPEN_ISDIR";    break;
        case SQLITE_CANTOPEN_FULLPATH:  zName = "SQLITE_CANTOPEN_FULLPATH"; break;
        case SQLITE_CANTOPEN_CONVPATH:  zName = "SQLITE_CANTOPEN_CONVPATH"; break;
        case SQLITE_CANTOPEN_SYMLINK:   zName = "SQLITE_CANTOPEN_SYMLINK";  break;
        case SQLITE_PROTOCOL:           zName = "SQLITE_PROTOCOL";          break;
        case SQLITE_EMPTY:              zName = "SQLITE_EMPTY";             break;
        case SQLITE_SCHEMA:             zName = "SQLITE_SCHEMA";            break;
        case SQLITE_TOOBIG:             zName = "SQLITE_TOOBIG";            break;
        case SQLITE_CONSTRAINT:         zName = "SQLITE_CONSTRAINT";        break;
        case SQLITE_CONSTRAINT_UNIQUE:  zName = "SQLITE_CONSTRAINT_UNIQUE"; break;
        case SQLITE_CONSTRAINT_TRIGGER: zName = "SQLITE_CONSTRAINT_TRIGGER";break;
        case SQLITE_CONSTRAINT_FOREIGNKEY:
                                  zName = "SQLITE_CONSTRAINT_FOREIGNKEY";   break;
        case SQLITE_CONSTRAINT_CHECK:   zName = "SQLITE_CONSTRAINT_CHECK";  break;
        case SQLITE_CONSTRAINT_PRIMARYKEY:
                                  zName = "SQLITE_CONSTRAINT_PRIMARYKEY";   break;
        case SQLITE_CONSTRAINT_NOTNULL: zName = "SQLITE_CONSTRAINT_NOTNULL";break;
        case SQLITE_CONSTRAINT_COMMITHOOK:
                                  zName = "SQLITE_CONSTRAINT_COMMITHOOK";   break;
        case SQLITE_CONSTRAINT_VTAB:    zName = "SQLITE_CONSTRAINT_VTAB";   break;
        case SQLITE_CONSTRAINT_FUNCTION:
                                  zName = "SQLITE_CONSTRAINT_FUNCTION";     break;
        case SQLITE_CONSTRAINT_ROWID:   zName = "SQLITE_CONSTRAINT_ROWID";  break;
        case SQLITE_MISMATCH:           zName = "SQLITE_MISMATCH";          break;
        case SQLITE_MISUSE:             zName = "SQLITE_MISUSE";            break;
        case SQLITE_NOLFS:              zName = "SQLITE_NOLFS";             break;
        case SQLITE_AUTH:               zName = "SQLITE_AUTH";              break;
        case SQLITE_FORMAT:             zName = "SQLITE_FORMAT";            break;
        case SQLITE_RANGE:              zName = "SQLITE_RANGE";             break;
        case SQLITE_NOTADB:             zName = "SQLITE_NOTADB";            break;
        case SQLITE_ROW:                zName = "SQLITE_ROW";               break;
        case SQLITE_NOTICE:             zName = "SQLITE_NOTICE";            break;
        case SQLITE_NOTICE_RECOVER_WAL: zName = "SQLITE_NOTICE_RECOVER_WAL";break;
        case SQLITE_NOTICE_RECOVER_ROLLBACK:
                                  zName = "SQLITE_NOTICE_RECOVER_ROLLBACK"; break;
        case SQLITE_WARNING:            zName = "SQLITE_WARNING";           break;
        case SQLITE_WARNING_AUTOINDEX:  zName = "SQLITE_WARNING_AUTOINDEX"; break;
        case SQLITE_DONE:               zName = "SQLITE_DONE";              break;
      }
    }
    if( zName==0 ){
      static char zBuf[50];
      sqlite3_snprintf(sizeof(zBuf), zBuf, "SQLITE_UNKNOWN(%d)", origRc);
      zName = zBuf;
    }
    return zName;
  }
  #endif
  
  /*
  ** Return a static string that describes the kind of error specified in the
  ** argument.
  */
  const char *sqlite3ErrStr(int rc){
    static const char* const aMsg[] = {
      /* SQLITE_OK          */ "not an error",
      /* SQLITE_ERROR       */ "SQL logic error",
      /* SQLITE_INTERNAL    */ 0,
      /* SQLITE_PERM        */ "access permission denied",
      /* SQLITE_ABORT       */ "query aborted",
      /* SQLITE_BUSY        */ "database is locked",
      /* SQLITE_LOCKED      */ "database table is locked",
      /* SQLITE_NOMEM       */ "out of memory",
      /* SQLITE_READONLY    */ "attempt to write a readonly database",
      /* SQLITE_INTERRUPT   */ "interrupted",
      /* SQLITE_IOERR       */ "disk I/O error",
      /* SQLITE_CORRUPT     */ "database disk image is malformed",
      /* SQLITE_NOTFOUND    */ "unknown operation",
      /* SQLITE_FULL        */ "database or disk is full",
      /* SQLITE_CANTOPEN    */ "unable to open database file",
      /* SQLITE_PROTOCOL    */ "locking protocol",
      /* SQLITE_EMPTY       */ 0,
      /* SQLITE_SCHEMA      */ "database schema has changed",
      /* SQLITE_TOOBIG      */ "string or blob too big",
      /* SQLITE_CONSTRAINT  */ "constraint failed",
      /* SQLITE_MISMATCH    */ "datatype mismatch",
      /* SQLITE_MISUSE      */ "bad parameter or other API misuse",
  #ifdef SQLITE_DISABLE_LFS
      /* SQLITE_NOLFS       */ "large file support is disabled",
  #else
      /* SQLITE_NOLFS       */ 0,
  #endif
      /* SQLITE_AUTH        */ "authorization denied",
      /* SQLITE_FORMAT      */ 0,
      /* SQLITE_RANGE       */ "column index out of range",
      /* SQLITE_NOTADB      */ "file is not a database",
      /* SQLITE_NOTICE      */ "notification message",
      /* SQLITE_WARNING     */ "warning message",
    };
    const char *zErr = "unknown error";
    switch( rc ){
      case SQLITE_ABORT_ROLLBACK: {
        zErr = "abort due to ROLLBACK";
        break;
      }
      case SQLITE_ROW: {
        zErr = "another row available";
        break;
      }
      case SQLITE_DONE: {
        zErr = "no more rows available";
        break;
      }
      default: {
        rc &= 0xff;
        if( ALWAYS(rc>=0) && rc<ArraySize(aMsg) && aMsg[rc]!=0 ){
          zErr = aMsg[rc];
        }
        break;
      }
    }
    return zErr;
  }
  
  /*
  ** This routine implements a busy callback that sleeps and tries
  ** again until a timeout value is reached.  The timeout value is
  ** an integer number of milliseconds passed in as the first
  ** argument.
  **
  ** Return non-zero to retry the lock.  Return zero to stop trying
  ** and cause SQLite to return SQLITE_BUSY.
  */
  static int sqliteDefaultBusyCallback(
    void *ptr,               /* Database connection */
    int count                /* Number of times table has been busy */
  ){
  #if SQLITE_OS_WIN || HAVE_USLEEP
    /* This case is for systems that have support for sleeping for fractions of
    ** a second.  Examples:  All windows systems, unix systems with usleep() */
    static const u8 delays[] =
       { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
    static const u8 totals[] =
       { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
  # define NDELAY ArraySize(delays)
    sqlite3 *db = (sqlite3 *)ptr;
    int tmout = db->busyTimeout;
    int delay, prior;
  
    assert( count>=0 );
    if( count < NDELAY ){
      delay = delays[count];
      prior = totals[count];
    }else{
      delay = delays[NDELAY-1];
      prior = totals[NDELAY-1] + delay*(count-(NDELAY-1));
    }
    if( prior + delay > tmout ){
      delay = tmout - prior;
      if( delay<=0 ) return 0;
    }
    sqlite3OsSleep(db->pVfs, delay*1000);
    return 1;
  #else
    /* This case for unix systems that lack usleep() support.  Sleeping
    ** must be done in increments of whole seconds */
    sqlite3 *db = (sqlite3 *)ptr;
    int tmout = ((sqlite3 *)ptr)->busyTimeout;
    if( (count+1)*1000 > tmout ){
      return 0;
    }
    sqlite3OsSleep(db->pVfs, 1000000);
    return 1;
  #endif
  }
  
  /*
  ** Invoke the given busy handler.
  **
  ** This routine is called when an operation failed to acquire a
  ** lock on VFS file pFile.
  **
  ** If this routine returns non-zero, the lock is retried.  If it
  ** returns 0, the operation aborts with an SQLITE_BUSY error.
  */
  int sqlite3InvokeBusyHandler(BusyHandler *p){
    int rc;
    if( p->xBusyHandler==0 || p->nBusy<0 ) return 0;
    rc = p->xBusyHandler(p->pBusyArg, p->nBusy);
    if( rc==0 ){
      p->nBusy = -1;
    }else{
      p->nBusy++;
    }
    return rc; 
  }
  
  /*
  ** This routine sets the busy callback for an Sqlite database to the
  ** given callback function with the given argument.
  */
  int sqlite3_busy_handler(
    sqlite3 *db,
    int (*xBusy)(void*,int),
    void *pArg
  ){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    db->busyHandler.xBusyHandler = xBusy;
    db->busyHandler.pBusyArg = pArg;
    db->busyHandler.nBusy = 0;
    db->busyTimeout = 0;
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_OK;
  }
  
  #ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  /*
  ** This routine sets the progress callback for an Sqlite database to the
  ** given callback function with the given argument. The progress callback will
  ** be invoked every nOps opcodes.
  */
  void sqlite3_progress_handler(
    sqlite3 *db, 
    int nOps,
    int (*xProgress)(void*), 
    void *pArg
  ){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    if( nOps>0 ){
      db->xProgress = xProgress;
      db->nProgressOps = (unsigned)nOps;
      db->pProgressArg = pArg;
    }else{
      db->xProgress = 0;
      db->nProgressOps = 0;
      db->pProgressArg = 0;
    }
    sqlite3_mutex_leave(db->mutex);
  }
  #endif
  
  
  /*
  ** This routine installs a default busy handler that waits for the
  ** specified number of milliseconds before returning 0.
  */
  int sqlite3_busy_timeout(sqlite3 *db, int ms){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    if( ms>0 ){
      sqlite3_busy_handler(db, (int(*)(void*,int))sqliteDefaultBusyCallback,
                               (void*)db);
      db->busyTimeout = ms;
    }else{
      sqlite3_busy_handler(db, 0, 0);
    }
    return SQLITE_OK;
  }
  
  /*
  ** Cause any pending operation to stop at its earliest opportunity.
  */
  void sqlite3_interrupt(sqlite3 *db){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) && (db==0 || db->magic!=SQLITE_MAGIC_ZOMBIE) ){
      (void)SQLITE_MISUSE_BKPT;
      return;
    }
  #endif
    AtomicStore(&db->u1.isInterrupted, 1);
  }
  
  
  /*
  ** This function is exactly the same as sqlite3_create_function(), except
  ** that it is designed to be called by internal code. The difference is
  ** that if a malloc() fails in sqlite3_create_function(), an error code
  ** is returned and the mallocFailed flag cleared. 
  */
  int sqlite3CreateFunc(
    sqlite3 *db,
    const char *zFunctionName,
    int nArg,
    int enc,
    void *pUserData,
    void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
    void (*xStep)(sqlite3_context*,int,sqlite3_value **),
    void (*xFinal)(sqlite3_context*),
    void (*xValue)(sqlite3_context*),
    void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
    FuncDestructor *pDestructor
  ){
    FuncDef *p;
    int nName;
    int extraFlags;
  
    assert( sqlite3_mutex_held(db->mutex) );
    assert( xValue==0 || xSFunc==0 );
    if( zFunctionName==0                /* Must have a valid name */
     || (xSFunc!=0 && xFinal!=0)        /* Not both xSFunc and xFinal */
     || ((xFinal==0)!=(xStep==0))       /* Both or neither of xFinal and xStep */
     || ((xValue==0)!=(xInverse==0))    /* Both or neither of xValue, xInverse */
     || (nArg<-1 || nArg>SQLITE_MAX_FUNCTION_ARG)
     || (255<(nName = sqlite3Strlen30( zFunctionName)))
    ){
      return SQLITE_MISUSE_BKPT;
    }
  
    assert( SQLITE_FUNC_CONSTANT==SQLITE_DETERMINISTIC );
    assert( SQLITE_FUNC_DIRECT==SQLITE_DIRECTONLY );
    extraFlags = enc &  (SQLITE_DETERMINISTIC|SQLITE_DIRECTONLY|
                         SQLITE_SUBTYPE|SQLITE_INNOCUOUS);
    enc &= (SQLITE_FUNC_ENCMASK|SQLITE_ANY);
  
    /* The SQLITE_INNOCUOUS flag is the same bit as SQLITE_FUNC_UNSAFE.  But
    ** the meaning is inverted.  So flip the bit. */
    assert( SQLITE_FUNC_UNSAFE==SQLITE_INNOCUOUS );
    extraFlags ^= SQLITE_FUNC_UNSAFE;
  
    
  #ifndef SQLITE_OMIT_UTF16
    /* If SQLITE_UTF16 is specified as the encoding type, transform this
    ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
    ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
    **
    ** If SQLITE_ANY is specified, add three versions of the function
    ** to the hash table.
    */
    if( enc==SQLITE_UTF16 ){
      enc = SQLITE_UTF16NATIVE;
    }else if( enc==SQLITE_ANY ){
      int rc;
      rc = sqlite3CreateFunc(db, zFunctionName, nArg,
           (SQLITE_UTF8|extraFlags)^SQLITE_FUNC_UNSAFE,
           pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
      if( rc==SQLITE_OK ){
        rc = sqlite3CreateFunc(db, zFunctionName, nArg,
             (SQLITE_UTF16LE|extraFlags)^SQLITE_FUNC_UNSAFE,
             pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
      }
      if( rc!=SQLITE_OK ){
        return rc;
      }
      enc = SQLITE_UTF16BE;
    }
  #else
    enc = SQLITE_UTF8;
  #endif
    
    /* Check if an existing function is being overridden or deleted. If so,
    ** and there are active VMs, then return SQLITE_BUSY. If a function
    ** is being overridden/deleted but there are no active VMs, allow the
    ** operation to continue but invalidate all precompiled statements.
    */
    p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 0);
    if( p && (p->funcFlags & SQLITE_FUNC_ENCMASK)==(u32)enc && p->nArg==nArg ){
      if( db->nVdbeActive ){
        sqlite3ErrorWithMsg(db, SQLITE_BUSY, 
          "unable to delete/modify user-function due to active statements");
        assert( !db->mallocFailed );
        return SQLITE_BUSY;
      }else{
        sqlite3ExpirePreparedStatements(db, 0);
      }
    }
  
    p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 1);
    assert(p || db->mallocFailed);
    if( !p ){
      return SQLITE_NOMEM_BKPT;
    }
  
    /* If an older version of the function with a configured destructor is
    ** being replaced invoke the destructor function here. */
    functionDestroy(db, p);
  
    if( pDestructor ){
      pDestructor->nRef++;
    }
    p->u.pDestructor = pDestructor;
    p->funcFlags = (p->funcFlags & SQLITE_FUNC_ENCMASK) | extraFlags;
    testcase( p->funcFlags & SQLITE_DETERMINISTIC );
    testcase( p->funcFlags & SQLITE_DIRECTONLY );
    p->xSFunc = xSFunc ? xSFunc : xStep;
    p->xFinalize = xFinal;
    p->xValue = xValue;
    p->xInverse = xInverse;
    p->pUserData = pUserData;
    p->nArg = (u16)nArg;
    return SQLITE_OK;
  }
  
  /*
  ** Worker function used by utf-8 APIs that create new functions:
  **
  **    sqlite3_create_function()
  **    sqlite3_create_function_v2()
  **    sqlite3_create_window_function()
  */
  static int createFunctionApi(
    sqlite3 *db,
    const char *zFunc,
    int nArg,
    int enc,
    void *p,
    void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
    void (*xStep)(sqlite3_context*,int,sqlite3_value**),
    void (*xFinal)(sqlite3_context*),
    void (*xValue)(sqlite3_context*),
    void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
    void(*xDestroy)(void*)
  ){
    int rc = SQLITE_ERROR;
    FuncDestructor *pArg = 0;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    if( xDestroy ){
      pArg = (FuncDestructor *)sqlite3Malloc(sizeof(FuncDestructor));
      if( !pArg ){
        sqlite3OomFault(db);
        xDestroy(p);
        goto out;
      }
      pArg->nRef = 0;
      pArg->xDestroy = xDestroy;
      pArg->pUserData = p;
    }
    rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p, 
        xSFunc, xStep, xFinal, xValue, xInverse, pArg
    );
    if( pArg && pArg->nRef==0 ){
      assert( rc!=SQLITE_OK );
      xDestroy(p);
      sqlite3_free(pArg);
    }
  
   out:
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
    return rc;
  }
  
  /*
  ** Create new user functions.
  */
  int sqlite3_create_function(
    sqlite3 *db,
    const char *zFunc,
    int nArg,
    int enc,
    void *p,
    void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
    void (*xStep)(sqlite3_context*,int,sqlite3_value **),
    void (*xFinal)(sqlite3_context*)
  ){
    return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
                                      xFinal, 0, 0, 0);
  }
  int sqlite3_create_function_v2(
    sqlite3 *db,
    const char *zFunc,
    int nArg,
    int enc,
    void *p,
    void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
    void (*xStep)(sqlite3_context*,int,sqlite3_value **),
    void (*xFinal)(sqlite3_context*),
    void (*xDestroy)(void *)
  ){
    return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
                                      xFinal, 0, 0, xDestroy);
  }
  int sqlite3_create_window_function(
    sqlite3 *db,
    const char *zFunc,
    int nArg,
    int enc,
    void *p,
    void (*xStep)(sqlite3_context*,int,sqlite3_value **),
    void (*xFinal)(sqlite3_context*),
    void (*xValue)(sqlite3_context*),
    void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
    void (*xDestroy)(void *)
  ){
    return createFunctionApi(db, zFunc, nArg, enc, p, 0, xStep,
                                      xFinal, xValue, xInverse, xDestroy);
  }
  
  #ifndef SQLITE_OMIT_UTF16
  int sqlite3_create_function16(
    sqlite3 *db,
    const void *zFunctionName,
    int nArg,
    int eTextRep,
    void *p,
    void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
    void (*xStep)(sqlite3_context*,int,sqlite3_value**),
    void (*xFinal)(sqlite3_context*)
  ){
    int rc;
    char *zFunc8;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) || zFunctionName==0 ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    assert( !db->mallocFailed );
    zFunc8 = sqlite3Utf16to8(db, zFunctionName, -1, SQLITE_UTF16NATIVE);
    rc = sqlite3CreateFunc(db, zFunc8, nArg, eTextRep, p, xSFunc,xStep,xFinal,0,0,0);
    sqlite3DbFree(db, zFunc8);
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
    return rc;
  }
  #endif
  
  
  /*
  ** The following is the implementation of an SQL function that always
  ** fails with an error message stating that the function is used in the
  ** wrong context.  The sqlite3_overload_function() API might construct
  ** SQL function that use this routine so that the functions will exist
  ** for name resolution but are actually overloaded by the xFindFunction
  ** method of virtual tables.
  */
  static void sqlite3InvalidFunction(
    sqlite3_context *context,  /* The function calling context */
    int NotUsed,               /* Number of arguments to the function */
    sqlite3_value **NotUsed2   /* Value of each argument */
  ){
    const char *zName = (const char*)sqlite3_user_data(context);
    char *zErr;
    UNUSED_PARAMETER2(NotUsed, NotUsed2);
    zErr = sqlite3_mprintf(
        "unable to use function %s in the requested context", zName);
    sqlite3_result_error(context, zErr, -1);
    sqlite3_free(zErr);
  }
  
  /*
  ** Declare that a function has been overloaded by a virtual table.
  **
  ** If the function already exists as a regular global function, then
  ** this routine is a no-op.  If the function does not exist, then create
  ** a new one that always throws a run-time error.  
  **
  ** When virtual tables intend to provide an overloaded function, they
  ** should call this routine to make sure the global function exists.
  ** A global function must exist in order for name resolution to work
  ** properly.
  */
  int sqlite3_overload_function(
    sqlite3 *db,
    const char *zName,
    int nArg
  ){
    int rc;
    char *zCopy;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) || zName==0 || nArg<-2 ){
      return SQLITE_MISUSE_BKPT;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    rc = sqlite3FindFunction(db, zName, nArg, SQLITE_UTF8, 0)!=0;
    sqlite3_mutex_leave(db->mutex);
    if( rc ) return SQLITE_OK;
    zCopy = sqlite3_mprintf(zName);
    if( zCopy==0 ) return SQLITE_NOMEM;
    return sqlite3_create_function_v2(db, zName, nArg, SQLITE_UTF8,
                             zCopy, sqlite3InvalidFunction, 0, 0, sqlite3_free);
  }
  
  #ifndef SQLITE_OMIT_TRACE
  /*
  ** Register a trace function.  The pArg from the previously registered trace
  ** is returned.  
  **
  ** A NULL trace function means that no tracing is executes.  A non-NULL
  ** trace is a pointer to a function that is invoked at the start of each
  ** SQL statement.
  */
  #ifndef SQLITE_OMIT_DEPRECATED
  void *sqlite3_trace(sqlite3 *db, void(*xTrace)(void*,const char*), void *pArg){
    void *pOld;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    pOld = db->pTraceArg;
    db->mTrace = xTrace ? SQLITE_TRACE_LEGACY : 0;
    db->trace.xLegacy = xTrace;
    db->pTraceArg = pArg;
    sqlite3_mutex_leave(db->mutex);
    return pOld;
  }
  #endif /* SQLITE_OMIT_DEPRECATED */
  
  /* Register a trace callback using the version-2 interface.
  */
  int sqlite3_trace_v2(
    sqlite3 *db,                               /* Trace this connection */
    unsigned mTrace,                           /* Mask of events to be traced */
    int(*xTrace)(unsigned,void*,void*,void*),  /* Callback to invoke */
    void *pArg                                 /* Context */
  ){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    if( mTrace==0 ) xTrace = 0;
    if( xTrace==0 ) mTrace = 0;
    db->mTrace = mTrace;
    db->trace.xV2 = xTrace;
    db->pTraceArg = pArg;
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_OK;
  }
  
  #ifndef SQLITE_OMIT_DEPRECATED
  /*
  ** Register a profile function.  The pArg from the previously registered 
  ** profile function is returned.  
  **
  ** A NULL profile function means that no profiling is executes.  A non-NULL
  ** profile is a pointer to a function that is invoked at the conclusion of
  ** each SQL statement that is run.
  */
  void *sqlite3_profile(
    sqlite3 *db,
    void (*xProfile)(void*,const char*,sqlite_uint64),
    void *pArg
  ){
    void *pOld;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    pOld = db->pProfileArg;
    db->xProfile = xProfile;
    db->pProfileArg = pArg;
    db->mTrace &= SQLITE_TRACE_NONLEGACY_MASK;
    if( db->xProfile ) db->mTrace |= SQLITE_TRACE_XPROFILE;
    sqlite3_mutex_leave(db->mutex);
    return pOld;
  }
  #endif /* SQLITE_OMIT_DEPRECATED */
  #endif /* SQLITE_OMIT_TRACE */
  
  /*
  ** Register a function to be invoked when a transaction commits.
  ** If the invoked function returns non-zero, then the commit becomes a
  ** rollback.
  */
  void *sqlite3_commit_hook(
    sqlite3 *db,              /* Attach the hook to this database */
    int (*xCallback)(void*),  /* Function to invoke on each commit */
    void *pArg                /* Argument to the function */
  ){
    void *pOld;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    pOld = db->pCommitArg;
    db->xCommitCallback = xCallback;
    db->pCommitArg = pArg;
    sqlite3_mutex_leave(db->mutex);
    return pOld;
  }
  
  /*
  ** Register a callback to be invoked each time a row is updated,
  ** inserted or deleted using this database connection.
  */
  void *sqlite3_update_hook(
    sqlite3 *db,              /* Attach the hook to this database */
    void (*xCallback)(void*,int,char const *,char const *,sqlite_int64),
    void *pArg                /* Argument to the function */
  ){
    void *pRet;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    pRet = db->pUpdateArg;
    db->xUpdateCallback = xCallback;
    db->pUpdateArg = pArg;
    sqlite3_mutex_leave(db->mutex);
    return pRet;
  }
  
  /*
  ** Register a callback to be invoked each time a transaction is rolled
  ** back by this database connection.
  */
  void *sqlite3_rollback_hook(
    sqlite3 *db,              /* Attach the hook to this database */
    void (*xCallback)(void*), /* Callback function */
    void *pArg                /* Argument to the function */
  ){
    void *pRet;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    pRet = db->pRollbackArg;
    db->xRollbackCallback = xCallback;
    db->pRollbackArg = pArg;
    sqlite3_mutex_leave(db->mutex);
    return pRet;
  }
  
  #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
  /*
  ** Register a callback to be invoked each time a row is updated,
  ** inserted or deleted using this database connection.
  */
  void *sqlite3_preupdate_hook(
    sqlite3 *db,              /* Attach the hook to this database */
    void(*xCallback)(         /* Callback function */
      void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64),
    void *pArg                /* First callback argument */
  ){
    void *pRet;
    sqlite3_mutex_enter(db->mutex);
    pRet = db->pPreUpdateArg;
    db->xPreUpdateCallback = xCallback;
    db->pPreUpdateArg = pArg;
    sqlite3_mutex_leave(db->mutex);
    return pRet;
  }
  #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
  
  #ifndef SQLITE_OMIT_WAL
  /*
  ** The sqlite3_wal_hook() callback registered by sqlite3_wal_autocheckpoint().
  ** Invoke sqlite3_wal_checkpoint if the number of frames in the log file
  ** is greater than sqlite3.pWalArg cast to an integer (the value configured by
  ** wal_autocheckpoint()).
  */ 
  int sqlite3WalDefaultHook(
    void *pClientData,     /* Argument */
    sqlite3 *db,           /* Connection */
    const char *zDb,       /* Database */
    int nFrame             /* Size of WAL */
  ){
    if( nFrame>=SQLITE_PTR_TO_INT(pClientData) ){
      sqlite3BeginBenignMalloc();
      sqlite3_wal_checkpoint(db, zDb);
      sqlite3EndBenignMalloc();
    }
    return SQLITE_OK;
  }
  #endif /* SQLITE_OMIT_WAL */
  
  /*
  ** Configure an sqlite3_wal_hook() callback to automatically checkpoint
  ** a database after committing a transaction if there are nFrame or
  ** more frames in the log file. Passing zero or a negative value as the
  ** nFrame parameter disables automatic checkpoints entirely.
  **
  ** The callback registered by this function replaces any existing callback
  ** registered using sqlite3_wal_hook(). Likewise, registering a callback
  ** using sqlite3_wal_hook() disables the automatic checkpoint mechanism
  ** configured by this function.
  */
  int sqlite3_wal_autocheckpoint(sqlite3 *db, int nFrame){
  #ifdef SQLITE_OMIT_WAL
    UNUSED_PARAMETER(db);
    UNUSED_PARAMETER(nFrame);
  #else
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    if( nFrame>0 ){
      sqlite3_wal_hook(db, sqlite3WalDefaultHook, SQLITE_INT_TO_PTR(nFrame));
    }else{
      sqlite3_wal_hook(db, 0, 0);
    }
  #endif
    return SQLITE_OK;
  }
  
  /*
  ** Register a callback to be invoked each time a transaction is written
  ** into the write-ahead-log by this database connection.
  */
  void *sqlite3_wal_hook(
    sqlite3 *db,                    /* Attach the hook to this db handle */
    int(*xCallback)(void *, sqlite3*, const char*, int),
    void *pArg                      /* First argument passed to xCallback() */
  ){
  #ifndef SQLITE_OMIT_WAL
    void *pRet;
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    pRet = db->pWalArg;
    db->xWalCallback = xCallback;
    db->pWalArg = pArg;
    sqlite3_mutex_leave(db->mutex);
    return pRet;
  #else
    return 0;
  #endif
  }
  
  /*
  ** Checkpoint database zDb.
  */
  int sqlite3_wal_checkpoint_v2(
    sqlite3 *db,                    /* Database handle */
    const char *zDb,                /* Name of attached database (or NULL) */
    int eMode,                      /* SQLITE_CHECKPOINT_* value */
    int *pnLog,                     /* OUT: Size of WAL log in frames */
    int *pnCkpt                     /* OUT: Total number of frames checkpointed */
  ){
  #ifdef SQLITE_OMIT_WAL
    return SQLITE_OK;
  #else
    int rc;                         /* Return code */
    int iDb;                        /* Schema to checkpoint */
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
  
    /* Initialize the output variables to -1 in case an error occurs. */
    if( pnLog ) *pnLog = -1;
    if( pnCkpt ) *pnCkpt = -1;
  
    assert( SQLITE_CHECKPOINT_PASSIVE==0 );
    assert( SQLITE_CHECKPOINT_FULL==1 );
    assert( SQLITE_CHECKPOINT_RESTART==2 );
    assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
    if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_TRUNCATE ){
      /* EVIDENCE-OF: R-03996-12088 The M parameter must be a valid checkpoint
      ** mode: */
      return SQLITE_MISUSE;
    }
  
    sqlite3_mutex_enter(db->mutex);
    if( zDb && zDb[0] ){
      iDb = sqlite3FindDbName(db, zDb);
    }else{
      iDb = SQLITE_MAX_DB;   /* This means process all schemas */
    }
    if( iDb<0 ){
      rc = SQLITE_ERROR;
      sqlite3ErrorWithMsg(db, SQLITE_ERROR, "unknown database: %s", zDb);
    }else{
      db->busyHandler.nBusy = 0;
      rc = sqlite3Checkpoint(db, iDb, eMode, pnLog, pnCkpt);
      sqlite3Error(db, rc);
    }
    rc = sqlite3ApiExit(db, rc);
  
    /* If there are no active statements, clear the interrupt flag at this
    ** point.  */
    if( db->nVdbeActive==0 ){
      AtomicStore(&db->u1.isInterrupted, 0);
    }
  
    sqlite3_mutex_leave(db->mutex);
    return rc;
  #endif
  }
  
  
  /*
  ** Checkpoint database zDb. If zDb is NULL, or if the buffer zDb points
  ** to contains a zero-length string, all attached databases are 
  ** checkpointed.
  */
  int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb){
    /* EVIDENCE-OF: R-41613-20553 The sqlite3_wal_checkpoint(D,X) is equivalent to
    ** sqlite3_wal_checkpoint_v2(D,X,SQLITE_CHECKPOINT_PASSIVE,0,0). */
    return sqlite3_wal_checkpoint_v2(db,zDb,SQLITE_CHECKPOINT_PASSIVE,0,0);
  }
  
  #ifndef SQLITE_OMIT_WAL
  /*
  ** Run a checkpoint on database iDb. This is a no-op if database iDb is
  ** not currently open in WAL mode.
  **
  ** If a transaction is open on the database being checkpointed, this 
  ** function returns SQLITE_LOCKED and a checkpoint is not attempted. If 
  ** an error occurs while running the checkpoint, an SQLite error code is 
  ** returned (i.e. SQLITE_IOERR). Otherwise, SQLITE_OK.
  **
  ** The mutex on database handle db should be held by the caller. The mutex
  ** associated with the specific b-tree being checkpointed is taken by
  ** this function while the checkpoint is running.
  **
  ** If iDb is passed SQLITE_MAX_DB then all attached databases are
  ** checkpointed. If an error is encountered it is returned immediately -
  ** no attempt is made to checkpoint any remaining databases.
  **
  ** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL, RESTART
  ** or TRUNCATE.
  */
  int sqlite3Checkpoint(sqlite3 *db, int iDb, int eMode, int *pnLog, int *pnCkpt){
    int rc = SQLITE_OK;             /* Return code */
    int i;                          /* Used to iterate through attached dbs */
    int bBusy = 0;                  /* True if SQLITE_BUSY has been encountered */
  
    assert( sqlite3_mutex_held(db->mutex) );
    assert( !pnLog || *pnLog==-1 );
    assert( !pnCkpt || *pnCkpt==-1 );
    testcase( iDb==SQLITE_MAX_ATTACHED ); /* See forum post a006d86f72 */
    testcase( iDb==SQLITE_MAX_DB );
  
    for(i=0; i<db->nDb && rc==SQLITE_OK; i++){
      if( i==iDb || iDb==SQLITE_MAX_DB ){
        rc = sqlite3BtreeCheckpoint(db->aDb[i].pBt, eMode, pnLog, pnCkpt);
        pnLog = 0;
        pnCkpt = 0;
        if( rc==SQLITE_BUSY ){
          bBusy = 1;
          rc = SQLITE_OK;
        }
      }
    }
  
    return (rc==SQLITE_OK && bBusy) ? SQLITE_BUSY : rc;
  }
  #endif /* SQLITE_OMIT_WAL */
  
  /*
  ** This function returns true if main-memory should be used instead of
  ** a temporary file for transient pager files and statement journals.
  ** The value returned depends on the value of db->temp_store (runtime
  ** parameter) and the compile time value of SQLITE_TEMP_STORE. The
  ** following table describes the relationship between these two values
  ** and this functions return value.
  **
  **   SQLITE_TEMP_STORE     db->temp_store     Location of temporary database
  **   -----------------     --------------     ------------------------------
  **   0                     any                file      (return 0)
  **   1                     1                  file      (return 0)
  **   1                     2                  memory    (return 1)
  **   1                     0                  file      (return 0)
  **   2                     1                  file      (return 0)
  **   2                     2                  memory    (return 1)
  **   2                     0                  memory    (return 1)
  **   3                     any                memory    (return 1)
  */
  int sqlite3TempInMemory(const sqlite3 *db){
  #if SQLITE_TEMP_STORE==1
    return ( db->temp_store==2 );
  #endif
  #if SQLITE_TEMP_STORE==2
    return ( db->temp_store!=1 );
  #endif
  #if SQLITE_TEMP_STORE==3
    UNUSED_PARAMETER(db);
    return 1;
  #endif
  #if SQLITE_TEMP_STORE<1 || SQLITE_TEMP_STORE>3
    UNUSED_PARAMETER(db);
    return 0;
  #endif
  }
  
  /*
  ** Return UTF-8 encoded English language explanation of the most recent
  ** error.
  */
  const char *sqlite3_errmsg(sqlite3 *db){
    const char *z;
    if( !db ){
      return sqlite3ErrStr(SQLITE_NOMEM_BKPT);
    }
    if( !sqlite3SafetyCheckSickOrOk(db) ){
      return sqlite3ErrStr(SQLITE_MISUSE_BKPT);
    }
    sqlite3_mutex_enter(db->mutex);
    if( db->mallocFailed ){
      z = sqlite3ErrStr(SQLITE_NOMEM_BKPT);
    }else{
      testcase( db->pErr==0 );
      z = db->errCode ? (char*)sqlite3_value_text(db->pErr) : 0;
      assert( !db->mallocFailed );
      if( z==0 ){
        z = sqlite3ErrStr(db->errCode);
      }
    }
    sqlite3_mutex_leave(db->mutex);
    return z;
  }
  
  #ifndef SQLITE_OMIT_UTF16
  /*
  ** Return UTF-16 encoded English language explanation of the most recent
  ** error.
  */
  const void *sqlite3_errmsg16(sqlite3 *db){
    static const u16 outOfMem[] = {
      'o', 'u', 't', ' ', 'o', 'f', ' ', 'm', 'e', 'm', 'o', 'r', 'y', 0
    };
    static const u16 misuse[] = {
      'b', 'a', 'd', ' ', 'p', 'a', 'r', 'a', 'm', 'e', 't', 'e', 'r', ' ',
      'o', 'r', ' ', 'o', 't', 'h', 'e', 'r', ' ', 'A', 'P', 'I', ' ',
      'm', 'i', 's', 'u', 's', 'e', 0
    };
  
    const void *z;
    if( !db ){
      return (void *)outOfMem;
    }
    if( !sqlite3SafetyCheckSickOrOk(db) ){
      return (void *)misuse;
    }
    sqlite3_mutex_enter(db->mutex);
    if( db->mallocFailed ){
      z = (void *)outOfMem;
    }else{
      z = sqlite3_value_text16(db->pErr);
      if( z==0 ){
        sqlite3ErrorWithMsg(db, db->errCode, sqlite3ErrStr(db->errCode));
        z = sqlite3_value_text16(db->pErr);
      }
      /* A malloc() may have failed within the call to sqlite3_value_text16()
      ** above. If this is the case, then the db->mallocFailed flag needs to
      ** be cleared before returning. Do this directly, instead of via
      ** sqlite3ApiExit(), to avoid setting the database handle error message.
      */
      sqlite3OomClear(db);
    }
    sqlite3_mutex_leave(db->mutex);
    return z;
  }
  #endif /* SQLITE_OMIT_UTF16 */
  
  /*
  ** Return the most recent error code generated by an SQLite routine. If NULL is
  ** passed to this function, we assume a malloc() failed during sqlite3_open().
  */
  int sqlite3_errcode(sqlite3 *db){
    if( db && !sqlite3SafetyCheckSickOrOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
    if( !db || db->mallocFailed ){
      return SQLITE_NOMEM_BKPT;
    }
    return db->errCode & db->errMask;
  }
  int sqlite3_extended_errcode(sqlite3 *db){
    if( db && !sqlite3SafetyCheckSickOrOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
    if( !db || db->mallocFailed ){
      return SQLITE_NOMEM_BKPT;
    }
    return db->errCode;
  }
  int sqlite3_system_errno(sqlite3 *db){
    return db ? db->iSysErrno : 0;
  }  
  
  /*
  ** Return a string that describes the kind of error specified in the
  ** argument.  For now, this simply calls the internal sqlite3ErrStr()
  ** function.
  */
  const char *sqlite3_errstr(int rc){
    return sqlite3ErrStr(rc);
  }
  
  /*
  ** Create a new collating function for database "db".  The name is zName
  ** and the encoding is enc.
  */
  static int createCollation(
    sqlite3* db,
    const char *zName, 
    u8 enc,
    void* pCtx,
    int(*xCompare)(void*,int,const void*,int,const void*),
    void(*xDel)(void*)
  ){
    CollSeq *pColl;
    int enc2;
    
    assert( sqlite3_mutex_held(db->mutex) );
  
    /* If SQLITE_UTF16 is specified as the encoding type, transform this
    ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
    ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
    */
    enc2 = enc;
    testcase( enc2==SQLITE_UTF16 );
    testcase( enc2==SQLITE_UTF16_ALIGNED );
    if( enc2==SQLITE_UTF16 || enc2==SQLITE_UTF16_ALIGNED ){
      enc2 = SQLITE_UTF16NATIVE;
    }
    if( enc2<SQLITE_UTF8 || enc2>SQLITE_UTF16BE ){
      return SQLITE_MISUSE_BKPT;
    }
  
    /* Check if this call is removing or replacing an existing collation 
    ** sequence. If so, and there are active VMs, return busy. If there
    ** are no active VMs, invalidate any pre-compiled statements.
    */
    pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 0);
    if( pColl && pColl->xCmp ){
      if( db->nVdbeActive ){
        sqlite3ErrorWithMsg(db, SQLITE_BUSY, 
          "unable to delete/modify collation sequence due to active statements");
        return SQLITE_BUSY;
      }
      sqlite3ExpirePreparedStatements(db, 0);
  
      /* If collation sequence pColl was created directly by a call to
      ** sqlite3_create_collation, and not generated by synthCollSeq(),
      ** then any copies made by synthCollSeq() need to be invalidated.
      ** Also, collation destructor - CollSeq.xDel() - function may need
      ** to be called.
      */ 
      if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
        CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName);
        int j;
        for(j=0; j<3; j++){
          CollSeq *p = &aColl[j];
          if( p->enc==pColl->enc ){
            if( p->xDel ){
              p->xDel(p->pUser);
            }
            p->xCmp = 0;
          }
        }
      }
    }
  
    pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 1);
    if( pColl==0 ) return SQLITE_NOMEM_BKPT;
    pColl->xCmp = xCompare;
    pColl->pUser = pCtx;
    pColl->xDel = xDel;
    pColl->enc = (u8)(enc2 | (enc & SQLITE_UTF16_ALIGNED));
    sqlite3Error(db, SQLITE_OK);
    return SQLITE_OK;
  }
  
  
  /*
  ** This array defines hard upper bounds on limit values.  The
  ** initializer must be kept in sync with the SQLITE_LIMIT_*
  ** #defines in sqlite3.h.
  */
  static const int aHardLimit[] = {
    SQLITE_MAX_LENGTH,
    SQLITE_MAX_SQL_LENGTH,
    SQLITE_MAX_COLUMN,
    SQLITE_MAX_EXPR_DEPTH,
    SQLITE_MAX_COMPOUND_SELECT,
    SQLITE_MAX_VDBE_OP,
    SQLITE_MAX_FUNCTION_ARG,
    SQLITE_MAX_ATTACHED,
    SQLITE_MAX_LIKE_PATTERN_LENGTH,
    SQLITE_MAX_VARIABLE_NUMBER,      /* IMP: R-38091-32352 */
    SQLITE_MAX_TRIGGER_DEPTH,
    SQLITE_MAX_WORKER_THREADS,
  };
  
  /*
  ** Make sure the hard limits are set to reasonable values
  */
  #if SQLITE_MAX_LENGTH<100
  # error SQLITE_MAX_LENGTH must be at least 100
  #endif
  #if SQLITE_MAX_SQL_LENGTH<100
  # error SQLITE_MAX_SQL_LENGTH must be at least 100
  #endif
  #if SQLITE_MAX_SQL_LENGTH>SQLITE_MAX_LENGTH
  # error SQLITE_MAX_SQL_LENGTH must not be greater than SQLITE_MAX_LENGTH
  #endif
  #if SQLITE_MAX_COMPOUND_SELECT<2
  # error SQLITE_MAX_COMPOUND_SELECT must be at least 2
  #endif
  #if SQLITE_MAX_VDBE_OP<40
  # error SQLITE_MAX_VDBE_OP must be at least 40
  #endif
  #if SQLITE_MAX_FUNCTION_ARG<0 || SQLITE_MAX_FUNCTION_ARG>127
  # error SQLITE_MAX_FUNCTION_ARG must be between 0 and 127
  #endif
  #if SQLITE_MAX_ATTACHED<0 || SQLITE_MAX_ATTACHED>125
  # error SQLITE_MAX_ATTACHED must be between 0 and 125
  #endif
  #if SQLITE_MAX_LIKE_PATTERN_LENGTH<1
  # error SQLITE_MAX_LIKE_PATTERN_LENGTH must be at least 1
  #endif
  #if SQLITE_MAX_COLUMN>32767
  # error SQLITE_MAX_COLUMN must not exceed 32767
  #endif
  #if SQLITE_MAX_TRIGGER_DEPTH<1
  # error SQLITE_MAX_TRIGGER_DEPTH must be at least 1
  #endif
  #if SQLITE_MAX_WORKER_THREADS<0 || SQLITE_MAX_WORKER_THREADS>50
  # error SQLITE_MAX_WORKER_THREADS must be between 0 and 50
  #endif
  
  
  /*
  ** Change the value of a limit.  Report the old value.
  ** If an invalid limit index is supplied, report -1.
  ** Make no changes but still report the old value if the
  ** new limit is negative.
  **
  ** A new lower limit does not shrink existing constructs.
  ** It merely prevents new constructs that exceed the limit
  ** from forming.
  */
  int sqlite3_limit(sqlite3 *db, int limitId, int newLimit){
    int oldLimit;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return -1;
    }
  #endif
  
    /* EVIDENCE-OF: R-30189-54097 For each limit category SQLITE_LIMIT_NAME
    ** there is a hard upper bound set at compile-time by a C preprocessor
    ** macro called SQLITE_MAX_NAME. (The "_LIMIT_" in the name is changed to
    ** "_MAX_".)
    */
    assert( aHardLimit[SQLITE_LIMIT_LENGTH]==SQLITE_MAX_LENGTH );
    assert( aHardLimit[SQLITE_LIMIT_SQL_LENGTH]==SQLITE_MAX_SQL_LENGTH );
    assert( aHardLimit[SQLITE_LIMIT_COLUMN]==SQLITE_MAX_COLUMN );
    assert( aHardLimit[SQLITE_LIMIT_EXPR_DEPTH]==SQLITE_MAX_EXPR_DEPTH );
    assert( aHardLimit[SQLITE_LIMIT_COMPOUND_SELECT]==SQLITE_MAX_COMPOUND_SELECT);
    assert( aHardLimit[SQLITE_LIMIT_VDBE_OP]==SQLITE_MAX_VDBE_OP );
    assert( aHardLimit[SQLITE_LIMIT_FUNCTION_ARG]==SQLITE_MAX_FUNCTION_ARG );
    assert( aHardLimit[SQLITE_LIMIT_ATTACHED]==SQLITE_MAX_ATTACHED );
    assert( aHardLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]==
                                                 SQLITE_MAX_LIKE_PATTERN_LENGTH );
    assert( aHardLimit[SQLITE_LIMIT_VARIABLE_NUMBER]==SQLITE_MAX_VARIABLE_NUMBER);
    assert( aHardLimit[SQLITE_LIMIT_TRIGGER_DEPTH]==SQLITE_MAX_TRIGGER_DEPTH );
    assert( aHardLimit[SQLITE_LIMIT_WORKER_THREADS]==SQLITE_MAX_WORKER_THREADS );
    assert( SQLITE_LIMIT_WORKER_THREADS==(SQLITE_N_LIMIT-1) );
  
  
    if( limitId<0 || limitId>=SQLITE_N_LIMIT ){
      return -1;
    }
    oldLimit = db->aLimit[limitId];
    if( newLimit>=0 ){                   /* IMP: R-52476-28732 */
      if( newLimit>aHardLimit[limitId] ){
        newLimit = aHardLimit[limitId];  /* IMP: R-51463-25634 */
      }
      db->aLimit[limitId] = newLimit;
    }
    return oldLimit;                     /* IMP: R-53341-35419 */
  }
  
  /*
  ** This function is used to parse both URIs and non-URI filenames passed by the
  ** user to API functions sqlite3_open() or sqlite3_open_v2(), and for database
  ** URIs specified as part of ATTACH statements.
  **
  ** The first argument to this function is the name of the VFS to use (or
  ** a NULL to signify the default VFS) if the URI does not contain a "vfs=xxx"
  ** query parameter. The second argument contains the URI (or non-URI filename)
  ** itself. When this function is called the *pFlags variable should contain
  ** the default flags to open the database handle with. The value stored in
  ** *pFlags may be updated before returning if the URI filename contains 
  ** "cache=xxx" or "mode=xxx" query parameters.
  **
  ** If successful, SQLITE_OK is returned. In this case *ppVfs is set to point to
  ** the VFS that should be used to open the database file. *pzFile is set to
  ** point to a buffer containing the name of the file to open.  The value
  ** stored in *pzFile is a database name acceptable to sqlite3_uri_parameter()
  ** and is in the same format as names created using sqlite3_create_filename().
  ** The caller must invoke sqlite3_free_filename() (not sqlite3_free()!) on
  ** the value returned in *pzFile to avoid a memory leak.
  **
  ** If an error occurs, then an SQLite error code is returned and *pzErrMsg
  ** may be set to point to a buffer containing an English language error 
  ** message. It is the responsibility of the caller to eventually release
  ** this buffer by calling sqlite3_free().
  */
  int sqlite3ParseUri(
    const char *zDefaultVfs,        /* VFS to use if no "vfs=xxx" query option */
    const char *zUri,               /* Nul-terminated URI to parse */
    unsigned int *pFlags,           /* IN/OUT: SQLITE_OPEN_XXX flags */
    sqlite3_vfs **ppVfs,            /* OUT: VFS to use */ 
    char **pzFile,                  /* OUT: Filename component of URI */
    char **pzErrMsg                 /* OUT: Error message (if rc!=SQLITE_OK) */
  ){
    int rc = SQLITE_OK;
    unsigned int flags = *pFlags;
    const char *zVfs = zDefaultVfs;
    char *zFile;
    char c;
    int nUri = sqlite3Strlen30(zUri);
  
    assert( *pzErrMsg==0 );
  
    if( ((flags & SQLITE_OPEN_URI)             /* IMP: R-48725-32206 */
              || sqlite3GlobalConfig.bOpenUri) /* IMP: R-51689-46548 */
     && nUri>=5 && memcmp(zUri, "file:", 5)==0 /* IMP: R-57884-37496 */
    ){
      char *zOpt;
      int eState;                   /* Parser state when parsing URI */
      int iIn;                      /* Input character index */
      int iOut = 0;                 /* Output character index */
      u64 nByte = nUri+8;           /* Bytes of space to allocate */
  
      /* Make sure the SQLITE_OPEN_URI flag is set to indicate to the VFS xOpen 
      ** method that there may be extra parameters following the file-name.  */
      flags |= SQLITE_OPEN_URI;
  
      for(iIn=0; iIn<nUri; iIn++) nByte += (zUri[iIn]=='&');
      zFile = sqlite3_malloc64(nByte);
      if( !zFile ) return SQLITE_NOMEM_BKPT;
  
      memset(zFile, 0, 4);  /* 4-byte of 0x00 is the start of DB name marker */
      zFile += 4;
  
      iIn = 5;
  #ifdef SQLITE_ALLOW_URI_AUTHORITY
      if( strncmp(zUri+5, "///", 3)==0 ){
        iIn = 7;
        /* The following condition causes URIs with five leading / characters
        ** like file://///host/path to be converted into UNCs like //host/path.
        ** The correct URI for that UNC has only two or four leading / characters
        ** file://host/path or file:////host/path.  But 5 leading slashes is a 
        ** common error, we are told, so we handle it as a special case. */
        if( strncmp(zUri+7, "///", 3)==0 ){ iIn++; }
      }else if( strncmp(zUri+5, "//localhost/", 12)==0 ){
        iIn = 16;
      }
  #else
      /* Discard the scheme and authority segments of the URI. */
      if( zUri[5]=='/' && zUri[6]=='/' ){
        iIn = 7;
        while( zUri[iIn] && zUri[iIn]!='/' ) iIn++;
        if( iIn!=7 && (iIn!=16 || memcmp("localhost", &zUri[7], 9)) ){
          *pzErrMsg = sqlite3_mprintf("invalid uri authority: %.*s", 
              iIn-7, &zUri[7]);
          rc = SQLITE_ERROR;
          goto parse_uri_out;
        }
      }
  #endif
  
      /* Copy the filename and any query parameters into the zFile buffer. 
      ** Decode %HH escape codes along the way. 
      **
      ** Within this loop, variable eState may be set to 0, 1 or 2, depending
      ** on the parsing context. As follows:
      **
      **   0: Parsing file-name.
      **   1: Parsing name section of a name=value query parameter.
      **   2: Parsing value section of a name=value query parameter.
      */
      eState = 0;
      while( (c = zUri[iIn])!=0 && c!='#' ){
        iIn++;
        if( c=='%' 
         && sqlite3Isxdigit(zUri[iIn]) 
         && sqlite3Isxdigit(zUri[iIn+1]) 
        ){
          int octet = (sqlite3HexToInt(zUri[iIn++]) << 4);
          octet += sqlite3HexToInt(zUri[iIn++]);
  
          assert( octet>=0 && octet<256 );
          if( octet==0 ){
  #ifndef SQLITE_ENABLE_URI_00_ERROR
            /* This branch is taken when "%00" appears within the URI. In this
            ** case we ignore all text in the remainder of the path, name or
            ** value currently being parsed. So ignore the current character
            ** and skip to the next "?", "=" or "&", as appropriate. */
            while( (c = zUri[iIn])!=0 && c!='#' 
                && (eState!=0 || c!='?')
                && (eState!=1 || (c!='=' && c!='&'))
                && (eState!=2 || c!='&')
            ){
              iIn++;
            }
            continue;
  #else
            /* If ENABLE_URI_00_ERROR is defined, "%00" in a URI is an error. */
            *pzErrMsg = sqlite3_mprintf("unexpected %%00 in uri");
            rc = SQLITE_ERROR;
            goto parse_uri_out;
  #endif
          }
          c = octet;
        }else if( eState==1 && (c=='&' || c=='=') ){
          if( zFile[iOut-1]==0 ){
            /* An empty option name. Ignore this option altogether. */
            while( zUri[iIn] && zUri[iIn]!='#' && zUri[iIn-1]!='&' ) iIn++;
            continue;
          }
          if( c=='&' ){
            zFile[iOut++] = '\0';
          }else{
            eState = 2;
          }
          c = 0;
        }else if( (eState==0 && c=='?') || (eState==2 && c=='&') ){
          c = 0;
          eState = 1;
        }
        zFile[iOut++] = c;
      }
      if( eState==1 ) zFile[iOut++] = '\0';
      memset(zFile+iOut, 0, 4); /* end-of-options + empty journal filenames */
  
      /* Check if there were any options specified that should be interpreted 
      ** here. Options that are interpreted here include "vfs" and those that
      ** correspond to flags that may be passed to the sqlite3_open_v2()
      ** method. */
      zOpt = &zFile[sqlite3Strlen30(zFile)+1];
      while( zOpt[0] ){
        int nOpt = sqlite3Strlen30(zOpt);
        char *zVal = &zOpt[nOpt+1];
        int nVal = sqlite3Strlen30(zVal);
  
        if( nOpt==3 && memcmp("vfs", zOpt, 3)==0 ){
          zVfs = zVal;
        }else{
          struct OpenMode {
            const char *z;
            int mode;
          } *aMode = 0;
          char *zModeType = 0;
          int mask = 0;
          int limit = 0;
  
          if( nOpt==5 && memcmp("cache", zOpt, 5)==0 ){
            static struct OpenMode aCacheMode[] = {
              { "shared",  SQLITE_OPEN_SHAREDCACHE },
              { "private", SQLITE_OPEN_PRIVATECACHE },
              { 0, 0 }
            };
  
            mask = SQLITE_OPEN_SHAREDCACHE|SQLITE_OPEN_PRIVATECACHE;
            aMode = aCacheMode;
            limit = mask;
            zModeType = "cache";
          }
          if( nOpt==4 && memcmp("mode", zOpt, 4)==0 ){
            static struct OpenMode aOpenMode[] = {
              { "ro",  SQLITE_OPEN_READONLY },
              { "rw",  SQLITE_OPEN_READWRITE }, 
              { "rwc", SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE },
              { "memory", SQLITE_OPEN_MEMORY },
              { 0, 0 }
            };
  
            mask = SQLITE_OPEN_READONLY | SQLITE_OPEN_READWRITE
                     | SQLITE_OPEN_CREATE | SQLITE_OPEN_MEMORY;
            aMode = aOpenMode;
            limit = mask & flags;
            zModeType = "access";
          }
  
          if( aMode ){
            int i;
            int mode = 0;
            for(i=0; aMode[i].z; i++){
              const char *z = aMode[i].z;
              if( nVal==sqlite3Strlen30(z) && 0==memcmp(zVal, z, nVal) ){
                mode = aMode[i].mode;
                break;
              }
            }
            if( mode==0 ){
              *pzErrMsg = sqlite3_mprintf("no such %s mode: %s", zModeType, zVal);
              rc = SQLITE_ERROR;
              goto parse_uri_out;
            }
            if( (mode & ~SQLITE_OPEN_MEMORY)>limit ){
              *pzErrMsg = sqlite3_mprintf("%s mode not allowed: %s",
                                          zModeType, zVal);
              rc = SQLITE_PERM;
              goto parse_uri_out;
            }
            flags = (flags & ~mask) | mode;
          }
        }
  
        zOpt = &zVal[nVal+1];
      }
  
    }else{
      zFile = sqlite3_malloc64(nUri+8);
      if( !zFile ) return SQLITE_NOMEM_BKPT;
      memset(zFile, 0, 4);
      zFile += 4;
      if( nUri ){
        memcpy(zFile, zUri, nUri);
      }
      memset(zFile+nUri, 0, 4);
      flags &= ~SQLITE_OPEN_URI;
    }
  
    *ppVfs = sqlite3_vfs_find(zVfs);
    if( *ppVfs==0 ){
      *pzErrMsg = sqlite3_mprintf("no such vfs: %s", zVfs);
      rc = SQLITE_ERROR;
    }
   parse_uri_out:
    if( rc!=SQLITE_OK ){
      sqlite3_free_filename(zFile);
      zFile = 0;
    }
    *pFlags = flags;
    *pzFile = zFile;
    return rc;
  }
  
  /*
  ** This routine does the core work of extracting URI parameters from a
  ** database filename for the sqlite3_uri_parameter() interface.
  */
  static const char *uriParameter(const char *zFilename, const char *zParam){
    zFilename += sqlite3Strlen30(zFilename) + 1;
    while( zFilename[0] ){
      int x = strcmp(zFilename, zParam);
      zFilename += sqlite3Strlen30(zFilename) + 1;
      if( x==0 ) return zFilename;
      zFilename += sqlite3Strlen30(zFilename) + 1;
    }
    return 0;
  }
  
  
  
  /*
  ** This routine does the work of opening a database on behalf of
  ** sqlite3_open() and sqlite3_open16(). The database filename "zFilename"  
  ** is UTF-8 encoded.
  */
  static int openDatabase(
    const char *zFilename, /* Database filename UTF-8 encoded */
    sqlite3 **ppDb,        /* OUT: Returned database handle */
    unsigned int flags,    /* Operational flags */
    const char *zVfs       /* Name of the VFS to use */
  ){
    sqlite3 *db;                    /* Store allocated handle here */
    int rc;                         /* Return code */
    int isThreadsafe;               /* True for threadsafe connections */
    char *zOpen = 0;                /* Filename argument to pass to BtreeOpen() */
    char *zErrMsg = 0;              /* Error message from sqlite3ParseUri() */
    int i;                          /* Loop counter */
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
  #endif
    *ppDb = 0;
  #ifndef SQLITE_OMIT_AUTOINIT
    rc = sqlite3_initialize();
    if( rc ) return rc;
  #endif
  
    if( sqlite3GlobalConfig.bCoreMutex==0 ){
      isThreadsafe = 0;
    }else if( flags & SQLITE_OPEN_NOMUTEX ){
      isThreadsafe = 0;
    }else if( flags & SQLITE_OPEN_FULLMUTEX ){
      isThreadsafe = 1;
    }else{
      isThreadsafe = sqlite3GlobalConfig.bFullMutex;
    }
  
    if( flags & SQLITE_OPEN_PRIVATECACHE ){
      flags &= ~SQLITE_OPEN_SHAREDCACHE;
    }else if( sqlite3GlobalConfig.sharedCacheEnabled ){
      flags |= SQLITE_OPEN_SHAREDCACHE;
    }
  
    /* Remove harmful bits from the flags parameter
    **
    ** The SQLITE_OPEN_NOMUTEX and SQLITE_OPEN_FULLMUTEX flags were
    ** dealt with in the previous code block.  Besides these, the only
    ** valid input flags for sqlite3_open_v2() are SQLITE_OPEN_READONLY,
    ** SQLITE_OPEN_READWRITE, SQLITE_OPEN_CREATE, SQLITE_OPEN_SHAREDCACHE,
    ** SQLITE_OPEN_PRIVATECACHE, and some reserved bits.  Silently mask
    ** off all other flags.
    */
    flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
                 SQLITE_OPEN_EXCLUSIVE |
                 SQLITE_OPEN_MAIN_DB |
                 SQLITE_OPEN_TEMP_DB | 
                 SQLITE_OPEN_TRANSIENT_DB | 
                 SQLITE_OPEN_MAIN_JOURNAL | 
                 SQLITE_OPEN_TEMP_JOURNAL | 
                 SQLITE_OPEN_SUBJOURNAL | 
                 SQLITE_OPEN_SUPER_JOURNAL |
                 SQLITE_OPEN_NOMUTEX |
                 SQLITE_OPEN_FULLMUTEX |
                 SQLITE_OPEN_WAL
               );
  
    /* Allocate the sqlite data structure */
    db = sqlite3MallocZero( sizeof(sqlite3) );
    if( db==0 ) goto opendb_out;
    if( isThreadsafe 
  #ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
     || sqlite3GlobalConfig.bCoreMutex
  #endif
    ){
      db->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
      if( db->mutex==0 ){
        sqlite3_free(db);
        db = 0;
        goto opendb_out;
      }
      if( isThreadsafe==0 ){
        sqlite3MutexWarnOnContention(db->mutex);
      }
    }
    sqlite3_mutex_enter(db->mutex);
    db->errMask = 0xff;
    db->nDb = 2;
    db->magic = SQLITE_MAGIC_BUSY;
    db->aDb = db->aDbStatic;
    db->lookaside.bDisable = 1;
    db->lookaside.sz = 0;
  
    assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
    memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
    db->aLimit[SQLITE_LIMIT_WORKER_THREADS] = SQLITE_DEFAULT_WORKER_THREADS;
    db->autoCommit = 1;
    db->nextAutovac = -1;
    db->szMmap = sqlite3GlobalConfig.szMmap;
    db->nextPagesize = 0;
    db->nMaxSorterMmap = 0x7FFFFFFF;
    db->flags |= SQLITE_ShortColNames
                   | SQLITE_EnableTrigger
                   | SQLITE_EnableView
                   | SQLITE_CacheSpill
  #if !defined(SQLITE_TRUSTED_SCHEMA) || SQLITE_TRUSTED_SCHEMA+0!=0
                   | SQLITE_TrustedSchema
  #endif
  /* The SQLITE_DQS compile-time option determines the default settings
  ** for SQLITE_DBCONFIG_DQS_DDL and SQLITE_DBCONFIG_DQS_DML.
  **
  **    SQLITE_DQS     SQLITE_DBCONFIG_DQS_DDL    SQLITE_DBCONFIG_DQS_DML
  **    ----------     -----------------------    -----------------------
  **     undefined               on                          on   
  **         3                   on                          on
  **         2                   on                         off
  **         1                  off                          on
  **         0                  off                         off
  **
  ** Legacy behavior is 3 (double-quoted string literals are allowed anywhere)
  ** and so that is the default.  But developers are encouranged to use
  ** -DSQLITE_DQS=0 (best) or -DSQLITE_DQS=1 (second choice) if possible.
  */
  #if !defined(SQLITE_DQS)
  # define SQLITE_DQS 3
  #endif
  #if (SQLITE_DQS&1)==1
                   | SQLITE_DqsDML
  #endif
  #if (SQLITE_DQS&2)==2
                   | SQLITE_DqsDDL
  #endif
  
  #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
                   | SQLITE_RecTriggers
  #endif
  #if defined(SQLITE_DEFAULT_FOREIGN_KEYS) && SQLITE_DEFAULT_FOREIGN_KEYS
                   | SQLITE_ForeignKeys
  #endif
  #if defined(SQLITE_REVERSE_UNORDERED_SELECTS)
                   | SQLITE_ReverseOrder
  #endif
  #if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
                   | SQLITE_CellSizeCk
  #endif
  #if defined(SQLITE_ENABLE_FTS3_TOKENIZER)
                   | SQLITE_Fts3Tokenizer
  #endif
  #if defined(SQLITE_ENABLE_QPSG)
                   | SQLITE_EnableQPSG
  #endif
  #if defined(SQLITE_DEFAULT_DEFENSIVE)
                   | SQLITE_Defensive
  #endif
  #if defined(SQLITE_DEFAULT_LEGACY_ALTER_TABLE)
                   | SQLITE_LegacyAlter
  #endif
        ;
    sqlite3HashInit(&db->aCollSeq);
  #ifndef SQLITE_OMIT_VIRTUALTABLE
    sqlite3HashInit(&db->aModule);
  #endif
  
    /* Add the default collation sequence BINARY. BINARY works for both UTF-8
    ** and UTF-16, so add a version for each to avoid any unnecessary
    ** conversions. The only error that can occur here is a malloc() failure.
    **
    ** EVIDENCE-OF: R-52786-44878 SQLite defines three built-in collating
    ** functions:
    */
    createCollation(db, sqlite3StrBINARY, SQLITE_UTF8, 0, binCollFunc, 0);
    createCollation(db, sqlite3StrBINARY, SQLITE_UTF16BE, 0, binCollFunc, 0);
    createCollation(db, sqlite3StrBINARY, SQLITE_UTF16LE, 0, binCollFunc, 0);
    createCollation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc, 0);
    createCollation(db, "RTRIM", SQLITE_UTF8, 0, rtrimCollFunc, 0);
    if( db->mallocFailed ){
      goto opendb_out;
    }
  
    /* Parse the filename/URI argument
    **
    ** Only allow sensible combinations of bits in the flags argument.  
    ** Throw an error if any non-sense combination is used.  If we
    ** do not block illegal combinations here, it could trigger
    ** assert() statements in deeper layers.  Sensible combinations
    ** are:
    **
    **  1:  SQLITE_OPEN_READONLY
    **  2:  SQLITE_OPEN_READWRITE
    **  6:  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE
    */
    db->openFlags = flags;
    assert( SQLITE_OPEN_READONLY  == 0x01 );
    assert( SQLITE_OPEN_READWRITE == 0x02 );
    assert( SQLITE_OPEN_CREATE    == 0x04 );
    testcase( (1<<(flags&7))==0x02 ); /* READONLY */
    testcase( (1<<(flags&7))==0x04 ); /* READWRITE */
    testcase( (1<<(flags&7))==0x40 ); /* READWRITE | CREATE */
    if( ((1<<(flags&7)) & 0x46)==0 ){
      rc = SQLITE_MISUSE_BKPT;  /* IMP: R-18321-05872 */
    }else{
      rc = sqlite3ParseUri(zVfs, zFilename, &flags, &db->pVfs, &zOpen, &zErrMsg);
    }
    if( rc!=SQLITE_OK ){
      if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
      sqlite3ErrorWithMsg(db, rc, zErrMsg ? "%s" : 0, zErrMsg);
      sqlite3_free(zErrMsg);
      goto opendb_out;
    }
  
    /* Open the backend database driver */
    rc = sqlite3BtreeOpen(db->pVfs, zOpen, db, &db->aDb[0].pBt, 0,
                          flags | SQLITE_OPEN_MAIN_DB);
    if( rc!=SQLITE_OK ){
      if( rc==SQLITE_IOERR_NOMEM ){
        rc = SQLITE_NOMEM_BKPT;
      }
      sqlite3Error(db, rc);
      goto opendb_out;
    }
    sqlite3BtreeEnter(db->aDb[0].pBt);
    db->aDb[0].pSchema = sqlite3SchemaGet(db, db->aDb[0].pBt);
    if( !db->mallocFailed ){
      sqlite3SetTextEncoding(db, SCHEMA_ENC(db));
    }
    sqlite3BtreeLeave(db->aDb[0].pBt);
    db->aDb[1].pSchema = sqlite3SchemaGet(db, 0);
  
    /* The default safety_level for the main database is FULL; for the temp
    ** database it is OFF. This matches the pager layer defaults.  
    */
    db->aDb[0].zDbSName = "main";
    db->aDb[0].safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
    db->aDb[1].zDbSName = "temp";
    db->aDb[1].safety_level = PAGER_SYNCHRONOUS_OFF;
  
    db->magic = SQLITE_MAGIC_OPEN;
    if( db->mallocFailed ){
      goto opendb_out;
    }
  
    /* Register all built-in functions, but do not attempt to read the
    ** database schema yet. This is delayed until the first time the database
    ** is accessed.
    */
    sqlite3Error(db, SQLITE_OK);
    sqlite3RegisterPerConnectionBuiltinFunctions(db);
    rc = sqlite3_errcode(db);
  
  
    /* Load compiled-in extensions */
    for(i=0; rc==SQLITE_OK && i<ArraySize(sqlite3BuiltinExtensions); i++){
      rc = sqlite3BuiltinExtensions[i](db);
    }
  
    /* Load automatic extensions - extensions that have been registered
    ** using the sqlite3_automatic_extension() API.
    */
    if( rc==SQLITE_OK ){
      sqlite3AutoLoadExtensions(db);
      rc = sqlite3_errcode(db);
      if( rc!=SQLITE_OK ){
        goto opendb_out;
      }
    }
  
  #ifdef SQLITE_ENABLE_INTERNAL_FUNCTIONS
    /* Testing use only!!! The -DSQLITE_ENABLE_INTERNAL_FUNCTIONS=1 compile-time
    ** option gives access to internal functions by default.  
    ** Testing use only!!! */
    db->mDbFlags |= DBFLAG_InternalFunc;
  #endif
  
    /* -DSQLITE_DEFAULT_LOCKING_MODE=1 makes EXCLUSIVE the default locking
    ** mode.  -DSQLITE_DEFAULT_LOCKING_MODE=0 make NORMAL the default locking
    ** mode.  Doing nothing at all also makes NORMAL the default.
    */
  #ifdef SQLITE_DEFAULT_LOCKING_MODE
    db->dfltLockMode = SQLITE_DEFAULT_LOCKING_MODE;
    sqlite3PagerLockingMode(sqlite3BtreePager(db->aDb[0].pBt),
                            SQLITE_DEFAULT_LOCKING_MODE);
  #endif
  
    if( rc ) sqlite3Error(db, rc);
  
    /* Enable the lookaside-malloc subsystem */
    setupLookaside(db, 0, sqlite3GlobalConfig.szLookaside,
                          sqlite3GlobalConfig.nLookaside);
  
    sqlite3_wal_autocheckpoint(db, SQLITE_DEFAULT_WAL_AUTOCHECKPOINT);
  
  opendb_out:
    if( db ){
      assert( db->mutex!=0 || isThreadsafe==0
             || sqlite3GlobalConfig.bFullMutex==0 );
      sqlite3_mutex_leave(db->mutex);
    }
    rc = sqlite3_errcode(db);
    assert( db!=0 || rc==SQLITE_NOMEM );
    if( rc==SQLITE_NOMEM ){
      sqlite3_close(db);
      db = 0;
    }else if( rc!=SQLITE_OK ){
      db->magic = SQLITE_MAGIC_SICK;
    }
    *ppDb = db;
  #ifdef SQLITE_ENABLE_SQLLOG
    if( sqlite3GlobalConfig.xSqllog ){
      /* Opening a db handle. Fourth parameter is passed 0. */
      void *pArg = sqlite3GlobalConfig.pSqllogArg;
      sqlite3GlobalConfig.xSqllog(pArg, db, zFilename, 0);
    }
  #endif
    sqlite3_free_filename(zOpen);
    return rc & 0xff;
  }
  
  
  /*
  ** Open a new database handle.
  */
  int sqlite3_open(
    const char *zFilename, 
    sqlite3 **ppDb 
  ){
    return openDatabase(zFilename, ppDb,
                        SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
  }
  int sqlite3_open_v2(
    const char *filename,   /* Database filename (UTF-8) */
    sqlite3 **ppDb,         /* OUT: SQLite db handle */
    int flags,              /* Flags */
    const char *zVfs        /* Name of VFS module to use */
  ){
    return openDatabase(filename, ppDb, (unsigned int)flags, zVfs);
  }
  
  #ifndef SQLITE_OMIT_UTF16
  /*
  ** Open a new database handle.
  */
  int sqlite3_open16(
    const void *zFilename, 
    sqlite3 **ppDb
  ){
    char const *zFilename8;   /* zFilename encoded in UTF-8 instead of UTF-16 */
    sqlite3_value *pVal;
    int rc;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
  #endif
    *ppDb = 0;
  #ifndef SQLITE_OMIT_AUTOINIT
    rc = sqlite3_initialize();
    if( rc ) return rc;
  #endif
    if( zFilename==0 ) zFilename = "\000\000";
    pVal = sqlite3ValueNew(0);
    sqlite3ValueSetStr(pVal, -1, zFilename, SQLITE_UTF16NATIVE, SQLITE_STATIC);
    zFilename8 = sqlite3ValueText(pVal, SQLITE_UTF8);
    if( zFilename8 ){
      rc = openDatabase(zFilename8, ppDb,
                        SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
      assert( *ppDb || rc==SQLITE_NOMEM );
      if( rc==SQLITE_OK && !DbHasProperty(*ppDb, 0, DB_SchemaLoaded) ){
        SCHEMA_ENC(*ppDb) = ENC(*ppDb) = SQLITE_UTF16NATIVE;
      }
    }else{
      rc = SQLITE_NOMEM_BKPT;
    }
    sqlite3ValueFree(pVal);
  
    return rc & 0xff;
  }
  #endif /* SQLITE_OMIT_UTF16 */
  
  /*
  ** Register a new collation sequence with the database handle db.
  */
  int sqlite3_create_collation(
    sqlite3* db, 
    const char *zName, 
    int enc, 
    void* pCtx,
    int(*xCompare)(void*,int,const void*,int,const void*)
  ){
    return sqlite3_create_collation_v2(db, zName, enc, pCtx, xCompare, 0);
  }
  
  /*
  ** Register a new collation sequence with the database handle db.
  */
  int sqlite3_create_collation_v2(
    sqlite3* db, 
    const char *zName, 
    int enc, 
    void* pCtx,
    int(*xCompare)(void*,int,const void*,int,const void*),
    void(*xDel)(void*)
  ){
    int rc;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    assert( !db->mallocFailed );
    rc = createCollation(db, zName, (u8)enc, pCtx, xCompare, xDel);
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
    return rc;
  }
  
  #ifndef SQLITE_OMIT_UTF16
  /*
  ** Register a new collation sequence with the database handle db.
  */
  int sqlite3_create_collation16(
    sqlite3* db, 
    const void *zName,
    int enc, 
    void* pCtx,
    int(*xCompare)(void*,int,const void*,int,const void*)
  ){
    int rc = SQLITE_OK;
    char *zName8;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    assert( !db->mallocFailed );
    zName8 = sqlite3Utf16to8(db, zName, -1, SQLITE_UTF16NATIVE);
    if( zName8 ){
      rc = createCollation(db, zName8, (u8)enc, pCtx, xCompare, 0);
      sqlite3DbFree(db, zName8);
    }
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
    return rc;
  }
  #endif /* SQLITE_OMIT_UTF16 */
  
  /*
  ** Register a collation sequence factory callback with the database handle
  ** db. Replace any previously installed collation sequence factory.
  */
  int sqlite3_collation_needed(
    sqlite3 *db, 
    void *pCollNeededArg, 
    void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*)
  ){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    db->xCollNeeded = xCollNeeded;
    db->xCollNeeded16 = 0;
    db->pCollNeededArg = pCollNeededArg;
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_OK;
  }
  
  #ifndef SQLITE_OMIT_UTF16
  /*
  ** Register a collation sequence factory callback with the database handle
  ** db. Replace any previously installed collation sequence factory.
  */
  int sqlite3_collation_needed16(
    sqlite3 *db, 
    void *pCollNeededArg, 
    void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*)
  ){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    db->xCollNeeded = 0;
    db->xCollNeeded16 = xCollNeeded16;
    db->pCollNeededArg = pCollNeededArg;
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_OK;
  }
  #endif /* SQLITE_OMIT_UTF16 */
  
  #ifndef SQLITE_OMIT_DEPRECATED
  /*
  ** This function is now an anachronism. It used to be used to recover from a
  ** malloc() failure, but SQLite now does this automatically.
  */
  int sqlite3_global_recover(void){
    return SQLITE_OK;
  }
  #endif
  
  /*
  ** Test to see whether or not the database connection is in autocommit
  ** mode.  Return TRUE if it is and FALSE if not.  Autocommit mode is on
  ** by default.  Autocommit is disabled by a BEGIN statement and reenabled
  ** by the next COMMIT or ROLLBACK.
  */
  int sqlite3_get_autocommit(sqlite3 *db){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    return db->autoCommit;
  }
  
  /*
  ** The following routines are substitutes for constants SQLITE_CORRUPT,
  ** SQLITE_MISUSE, SQLITE_CANTOPEN, SQLITE_NOMEM and possibly other error
  ** constants.  They serve two purposes:
  **
  **   1.  Serve as a convenient place to set a breakpoint in a debugger
  **       to detect when version error conditions occurs.
  **
  **   2.  Invoke sqlite3_log() to provide the source code location where
  **       a low-level error is first detected.
  */
  int sqlite3ReportError(int iErr, int lineno, const char *zType){
    sqlite3_log(iErr, "%s at line %d of [%.10s]",
                zType, lineno, 20+sqlite3_sourceid());
    return iErr;
  }
  int sqlite3CorruptError(int lineno){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    return sqlite3ReportError(SQLITE_CORRUPT, lineno, "database corruption");
  }
  int sqlite3MisuseError(int lineno){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    return sqlite3ReportError(SQLITE_MISUSE, lineno, "misuse");
  }
  int sqlite3CantopenError(int lineno){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    return sqlite3ReportError(SQLITE_CANTOPEN, lineno, "cannot open file");
  }
  #if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_CORRUPT_PGNO)
  int sqlite3CorruptPgnoError(int lineno, Pgno pgno){
    char zMsg[100];
    sqlite3_snprintf(sizeof(zMsg), zMsg, "database corruption page %d", pgno);
    testcase( sqlite3GlobalConfig.xLog!=0 );
    return sqlite3ReportError(SQLITE_CORRUPT, lineno, zMsg);
  }
  #endif
  #ifdef SQLITE_DEBUG
  int sqlite3NomemError(int lineno){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    return sqlite3ReportError(SQLITE_NOMEM, lineno, "OOM");
  }
  int sqlite3IoerrnomemError(int lineno){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    return sqlite3ReportError(SQLITE_IOERR_NOMEM, lineno, "I/O OOM error");
  }
  #endif
  
  #ifndef SQLITE_OMIT_DEPRECATED
  /*
  ** This is a convenience routine that makes sure that all thread-specific
  ** data for this thread has been deallocated.
  **
  ** SQLite no longer uses thread-specific data so this routine is now a
  ** no-op.  It is retained for historical compatibility.
  */
  void sqlite3_thread_cleanup(void){
  }
  #endif
  
  /*
  ** Return meta information about a specific column of a database table.
  ** See comment in sqlite3.h (sqlite.h.in) for details.
  */
  int sqlite3_table_column_metadata(
    sqlite3 *db,                /* Connection handle */
    const char *zDbName,        /* Database name or NULL */
    const char *zTableName,     /* Table name */
    const char *zColumnName,    /* Column name */
    char const **pzDataType,    /* OUTPUT: Declared data type */
    char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
    int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
    int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
    int *pAutoinc               /* OUTPUT: True if column is auto-increment */
  ){
    int rc;
    char *zErrMsg = 0;
    Table *pTab = 0;
    Column *pCol = 0;
    int iCol = 0;
    char const *zDataType = 0;
    char const *zCollSeq = 0;
    int notnull = 0;
    int primarykey = 0;
    int autoinc = 0;
  
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) || zTableName==0 ){
      return SQLITE_MISUSE_BKPT;
    }
  #endif
  
    /* Ensure the database schema has been loaded */
    sqlite3_mutex_enter(db->mutex);
    sqlite3BtreeEnterAll(db);
    rc = sqlite3Init(db, &zErrMsg);
    if( SQLITE_OK!=rc ){
      goto error_out;
    }
  
    /* Locate the table in question */
    pTab = sqlite3FindTable(db, zTableName, zDbName);
    if( !pTab || pTab->pSelect ){
      pTab = 0;
      goto error_out;
    }
  
    /* Find the column for which info is requested */
    if( zColumnName==0 ){
      /* Query for existance of table only */
    }else{
      for(iCol=0; iCol<pTab->nCol; iCol++){
        pCol = &pTab->aCol[iCol];
        if( 0==sqlite3StrICmp(pCol->zName, zColumnName) ){
          break;
        }
      }
      if( iCol==pTab->nCol ){
        if( HasRowid(pTab) && sqlite3IsRowid(zColumnName) ){
          iCol = pTab->iPKey;
          pCol = iCol>=0 ? &pTab->aCol[iCol] : 0;
        }else{
          pTab = 0;
          goto error_out;
        }
      }
    }
  
    /* The following block stores the meta information that will be returned
    ** to the caller in local variables zDataType, zCollSeq, notnull, primarykey
    ** and autoinc. At this point there are two possibilities:
    ** 
    **     1. The specified column name was rowid", "oid" or "_rowid_" 
    **        and there is no explicitly declared IPK column. 
    **
    **     2. The table is not a view and the column name identified an 
    **        explicitly declared column. Copy meta information from *pCol.
    */ 
    if( pCol ){
      zDataType = sqlite3ColumnType(pCol,0);
      zCollSeq = pCol->zColl;
      notnull = pCol->notNull!=0;
      primarykey  = (pCol->colFlags & COLFLAG_PRIMKEY)!=0;
      autoinc = pTab->iPKey==iCol && (pTab->tabFlags & TF_Autoincrement)!=0;
    }else{
      zDataType = "INTEGER";
      primarykey = 1;
    }
    if( !zCollSeq ){
      zCollSeq = sqlite3StrBINARY;
    }
  
  error_out:
    sqlite3BtreeLeaveAll(db);
  
    /* Whether the function call succeeded or failed, set the output parameters
    ** to whatever their local counterparts contain. If an error did occur,
    ** this has the effect of zeroing all output parameters.
    */
    if( pzDataType ) *pzDataType = zDataType;
    if( pzCollSeq ) *pzCollSeq = zCollSeq;
    if( pNotNull ) *pNotNull = notnull;
    if( pPrimaryKey ) *pPrimaryKey = primarykey;
    if( pAutoinc ) *pAutoinc = autoinc;
  
    if( SQLITE_OK==rc && !pTab ){
      sqlite3DbFree(db, zErrMsg);
      zErrMsg = sqlite3MPrintf(db, "no such table column: %s.%s", zTableName,
          zColumnName);
      rc = SQLITE_ERROR;
    }
    sqlite3ErrorWithMsg(db, rc, (zErrMsg?"%s":0), zErrMsg);
    sqlite3DbFree(db, zErrMsg);
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
    return rc;
  }
  
  /*
  ** Sleep for a little while.  Return the amount of time slept.
  */
  int sqlite3_sleep(int ms){
    sqlite3_vfs *pVfs;
    int rc;
    pVfs = sqlite3_vfs_find(0);
    if( pVfs==0 ) return 0;
  
    /* This function works in milliseconds, but the underlying OsSleep() 
    ** API uses microseconds. Hence the 1000's.
    */
    rc = (sqlite3OsSleep(pVfs, 1000*ms)/1000);
    return rc;
  }
  
  /*
  ** Enable or disable the extended result codes.
  */
  int sqlite3_extended_result_codes(sqlite3 *db, int onoff){
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    db->errMask = onoff ? 0xffffffff : 0xff;
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_OK;
  }
  
  /*
  ** Invoke the xFileControl method on a particular database.
  */
  int sqlite3_file_control(sqlite3 *db, const char *zDbName, int op, void *pArg){
    int rc = SQLITE_ERROR;
    Btree *pBtree;
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  #endif
    sqlite3_mutex_enter(db->mutex);
    pBtree = sqlite3DbNameToBtree(db, zDbName);
    if( pBtree ){
      Pager *pPager;
      sqlite3_file *fd;
      sqlite3BtreeEnter(pBtree);
      pPager = sqlite3BtreePager(pBtree);
      assert( pPager!=0 );
      fd = sqlite3PagerFile(pPager);
      assert( fd!=0 );
      if( op==SQLITE_FCNTL_FILE_POINTER ){
        *(sqlite3_file**)pArg = fd;
        rc = SQLITE_OK;
      }else if( op==SQLITE_FCNTL_VFS_POINTER ){
        *(sqlite3_vfs**)pArg = sqlite3PagerVfs(pPager);
        rc = SQLITE_OK;
      }else if( op==SQLITE_FCNTL_JOURNAL_POINTER ){
        *(sqlite3_file**)pArg = sqlite3PagerJrnlFile(pPager);
        rc = SQLITE_OK;
      }else if( op==SQLITE_FCNTL_DATA_VERSION ){
        *(unsigned int*)pArg = sqlite3PagerDataVersion(pPager);
        rc = SQLITE_OK;
      }else if( op==SQLITE_FCNTL_RESERVE_BYTES ){
        int iNew = *(int*)pArg;
        *(int*)pArg = sqlite3BtreeGetRequestedReserve(pBtree);
        if( iNew>=0 && iNew<=255 ){
          sqlite3BtreeSetPageSize(pBtree, 0, iNew, 0);
        }
        rc = SQLITE_OK;
      }else{
        int nSave = db->busyHandler.nBusy;
        rc = sqlite3OsFileControl(fd, op, pArg);
        db->busyHandler.nBusy = nSave;
      }
      sqlite3BtreeLeave(pBtree);
    }
    sqlite3_mutex_leave(db->mutex);
    return rc;
  }
  
  /*
  ** Interface to the testing logic.
  */
  int sqlite3_test_control(int op, ...){
    int rc = 0;
  #ifdef SQLITE_UNTESTABLE
    UNUSED_PARAMETER(op);
  #else
    va_list ap;
    va_start(ap, op);
    switch( op ){
  
      /*
      ** Save the current state of the PRNG.
      */
      case SQLITE_TESTCTRL_PRNG_SAVE: {
        sqlite3PrngSaveState();
        break;
      }
  
      /*
      ** Restore the state of the PRNG to the last state saved using
      ** PRNG_SAVE.  If PRNG_SAVE has never before been called, then
      ** this verb acts like PRNG_RESET.
      */
      case SQLITE_TESTCTRL_PRNG_RESTORE: {
        sqlite3PrngRestoreState();
        break;
      }
  
      /*  sqlite3_test_control(SQLITE_TESTCTRL_PRNG_SEED, int x, sqlite3 *db);
      **
      ** Control the seed for the pseudo-random number generator (PRNG) that
      ** is built into SQLite.  Cases:
      **
      **    x!=0 && db!=0       Seed the PRNG to the current value of the
      **                        schema cookie in the main database for db, or
      **                        x if the schema cookie is zero.  This case
      **                        is convenient to use with database fuzzers
      **                        as it allows the fuzzer some control over the
      **                        the PRNG seed.
      **
      **    x!=0 && db==0       Seed the PRNG to the value of x.
      **
      **    x==0 && db==0       Revert to default behavior of using the
      **                        xRandomness method on the primary VFS.
      **
      ** This test-control also resets the PRNG so that the new seed will
      ** be used for the next call to sqlite3_randomness().
      */
  #ifndef SQLITE_OMIT_WSD
      case SQLITE_TESTCTRL_PRNG_SEED: {
        int x = va_arg(ap, int);
        int y;
        sqlite3 *db = va_arg(ap, sqlite3*);
        assert( db==0 || db->aDb[0].pSchema!=0 );
        if( db && (y = db->aDb[0].pSchema->schema_cookie)!=0 ){ x = y; }
        sqlite3Config.iPrngSeed = x;
        sqlite3_randomness(0,0);
        break;
      }
  #endif
  
      /*
      **  sqlite3_test_control(BITVEC_TEST, size, program)
      **
      ** Run a test against a Bitvec object of size.  The program argument
      ** is an array of integers that defines the test.  Return -1 on a
      ** memory allocation error, 0 on success, or non-zero for an error.
      ** See the sqlite3BitvecBuiltinTest() for additional information.
      */
      case SQLITE_TESTCTRL_BITVEC_TEST: {
        int sz = va_arg(ap, int);
        int *aProg = va_arg(ap, int*);
        rc = sqlite3BitvecBuiltinTest(sz, aProg);
        break;
      }
  
      /*
      **  sqlite3_test_control(FAULT_INSTALL, xCallback)
      **
      ** Arrange to invoke xCallback() whenever sqlite3FaultSim() is called,
      ** if xCallback is not NULL.
      **
      ** As a test of the fault simulator mechanism itself, sqlite3FaultSim(0)
      ** is called immediately after installing the new callback and the return
      ** value from sqlite3FaultSim(0) becomes the return from
      ** sqlite3_test_control().
      */
      case SQLITE_TESTCTRL_FAULT_INSTALL: {
        /* MSVC is picky about pulling func ptrs from va lists.
        ** http://support.microsoft.com/kb/47961
        ** sqlite3GlobalConfig.xTestCallback = va_arg(ap, int(*)(int));
        */
        typedef int(*TESTCALLBACKFUNC_t)(int);
        sqlite3GlobalConfig.xTestCallback = va_arg(ap, TESTCALLBACKFUNC_t);
        rc = sqlite3FaultSim(0);
        break;
      }
  
      /*
      **  sqlite3_test_control(BENIGN_MALLOC_HOOKS, xBegin, xEnd)
      **
      ** Register hooks to call to indicate which malloc() failures 
      ** are benign.
      */
      case SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS: {
        typedef void (*void_function)(void);
        void_function xBenignBegin;
        void_function xBenignEnd;
        xBenignBegin = va_arg(ap, void_function);
        xBenignEnd = va_arg(ap, void_function);
        sqlite3BenignMallocHooks(xBenignBegin, xBenignEnd);
        break;
      }
  
      /*
      **  sqlite3_test_control(SQLITE_TESTCTRL_PENDING_BYTE, unsigned int X)
      **
      ** Set the PENDING byte to the value in the argument, if X>0.
      ** Make no changes if X==0.  Return the value of the pending byte
      ** as it existing before this routine was called.
      **
      ** IMPORTANT:  Changing the PENDING byte from 0x40000000 results in
      ** an incompatible database file format.  Changing the PENDING byte
      ** while any database connection is open results in undefined and
      ** deleterious behavior.
      */
      case SQLITE_TESTCTRL_PENDING_BYTE: {
        rc = PENDING_BYTE;
  #ifndef SQLITE_OMIT_WSD
        {
          unsigned int newVal = va_arg(ap, unsigned int);
          if( newVal ) sqlite3PendingByte = newVal;
        }
  #endif
        break;
      }
  
      /*
      **  sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, int X)
      **
      ** This action provides a run-time test to see whether or not
      ** assert() was enabled at compile-time.  If X is true and assert()
      ** is enabled, then the return value is true.  If X is true and
      ** assert() is disabled, then the return value is zero.  If X is
      ** false and assert() is enabled, then the assertion fires and the
      ** process aborts.  If X is false and assert() is disabled, then the
      ** return value is zero.
      */
      case SQLITE_TESTCTRL_ASSERT: {
        volatile int x = 0;
        assert( /*side-effects-ok*/ (x = va_arg(ap,int))!=0 );
        rc = x;
        break;
      }
  
  
      /*
      **  sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, int X)
      **
      ** This action provides a run-time test to see how the ALWAYS and
      ** NEVER macros were defined at compile-time.
      **
      ** The return value is ALWAYS(X) if X is true, or 0 if X is false.
      **
      ** The recommended test is X==2.  If the return value is 2, that means
      ** ALWAYS() and NEVER() are both no-op pass-through macros, which is the
      ** default setting.  If the return value is 1, then ALWAYS() is either
      ** hard-coded to true or else it asserts if its argument is false.
      ** The first behavior (hard-coded to true) is the case if
      ** SQLITE_TESTCTRL_ASSERT shows that assert() is disabled and the second
      ** behavior (assert if the argument to ALWAYS() is false) is the case if
      ** SQLITE_TESTCTRL_ASSERT shows that assert() is enabled.
      **
      ** The run-time test procedure might look something like this:
      **
      **    if( sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, 2)==2 ){
      **      // ALWAYS() and NEVER() are no-op pass-through macros
      **    }else if( sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, 1) ){
      **      // ALWAYS(x) asserts that x is true. NEVER(x) asserts x is false.
      **    }else{
      **      // ALWAYS(x) is a constant 1.  NEVER(x) is a constant 0.
      **    }
      */
      case SQLITE_TESTCTRL_ALWAYS: {
        int x = va_arg(ap,int);
        rc = x ? ALWAYS(x) : 0;
        break;
      }
  
      /*
      **   sqlite3_test_control(SQLITE_TESTCTRL_BYTEORDER);
      **
      ** The integer returned reveals the byte-order of the computer on which
      ** SQLite is running:
      **
      **       1     big-endian,    determined at run-time
      **      10     little-endian, determined at run-time
      **  432101     big-endian,    determined at compile-time
      **  123410     little-endian, determined at compile-time
      */ 
      case SQLITE_TESTCTRL_BYTEORDER: {
        rc = SQLITE_BYTEORDER*100 + SQLITE_LITTLEENDIAN*10 + SQLITE_BIGENDIAN;
        break;
      }
  
      /*  sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS, sqlite3 *db, int N)
      **
      ** Enable or disable various optimizations for testing purposes.  The 
      ** argument N is a bitmask of optimizations to be disabled.  For normal
      ** operation N should be 0.  The idea is that a test program (like the
      ** SQL Logic Test or SLT test module) can run the same SQL multiple times
      ** with various optimizations disabled to verify that the same answer
      ** is obtained in every case.
      */
      case SQLITE_TESTCTRL_OPTIMIZATIONS: {
        sqlite3 *db = va_arg(ap, sqlite3*);
        db->dbOptFlags = va_arg(ap, u32);
        break;
      }
  
      /*   sqlite3_test_control(SQLITE_TESTCTRL_LOCALTIME_FAULT, int onoff);
      **
      ** If parameter onoff is non-zero, subsequent calls to localtime()
      ** and its variants fail. If onoff is zero, undo this setting.
      */
      case SQLITE_TESTCTRL_LOCALTIME_FAULT: {
        sqlite3GlobalConfig.bLocaltimeFault = va_arg(ap, int);
        break;
      }
  
      /*   sqlite3_test_control(SQLITE_TESTCTRL_INTERNAL_FUNCTIONS, sqlite3*);
      **
      ** Toggle the ability to use internal functions on or off for
      ** the database connection given in the argument.
      */
      case SQLITE_TESTCTRL_INTERNAL_FUNCTIONS: {
        sqlite3 *db = va_arg(ap, sqlite3*);
        db->mDbFlags ^= DBFLAG_InternalFunc;
        break;
      }
  
      /*   sqlite3_test_control(SQLITE_TESTCTRL_NEVER_CORRUPT, int);
      **
      ** Set or clear a flag that indicates that the database file is always well-
      ** formed and never corrupt.  This flag is clear by default, indicating that
      ** database files might have arbitrary corruption.  Setting the flag during
      ** testing causes certain assert() statements in the code to be activated
      ** that demonstrat invariants on well-formed database files.
      */
      case SQLITE_TESTCTRL_NEVER_CORRUPT: {
        sqlite3GlobalConfig.neverCorrupt = va_arg(ap, int);
        break;
      }
  
      /*   sqlite3_test_control(SQLITE_TESTCTRL_EXTRA_SCHEMA_CHECKS, int);
      **
      ** Set or clear a flag that causes SQLite to verify that type, name,
      ** and tbl_name fields of the sqlite_schema table.  This is normally
      ** on, but it is sometimes useful to turn it off for testing.
      **
      ** 2020-07-22:  Disabling EXTRA_SCHEMA_CHECKS also disables the
      ** verification of rootpage numbers when parsing the schema.  This
      ** is useful to make it easier to reach strange internal error states
      ** during testing.  The EXTRA_SCHEMA_CHECKS setting is always enabled
      ** in production.
      */
      case SQLITE_TESTCTRL_EXTRA_SCHEMA_CHECKS: {
        sqlite3GlobalConfig.bExtraSchemaChecks = va_arg(ap, int);
        break;
      }
  
      /* Set the threshold at which OP_Once counters reset back to zero.
      ** By default this is 0x7ffffffe (over 2 billion), but that value is
      ** too big to test in a reasonable amount of time, so this control is
      ** provided to set a small and easily reachable reset value.
      */
      case SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD: {
        sqlite3GlobalConfig.iOnceResetThreshold = va_arg(ap, int);
        break;
      }
  
      /*   sqlite3_test_control(SQLITE_TESTCTRL_VDBE_COVERAGE, xCallback, ptr);
      **
      ** Set the VDBE coverage callback function to xCallback with context 
      ** pointer ptr.
      */
      case SQLITE_TESTCTRL_VDBE_COVERAGE: {
  #ifdef SQLITE_VDBE_COVERAGE
        typedef void (*branch_callback)(void*,unsigned int,
                                        unsigned char,unsigned char);
        sqlite3GlobalConfig.xVdbeBranch = va_arg(ap,branch_callback);
        sqlite3GlobalConfig.pVdbeBranchArg = va_arg(ap,void*);
  #endif
        break;
      }
  
      /*   sqlite3_test_control(SQLITE_TESTCTRL_SORTER_MMAP, db, nMax); */
      case SQLITE_TESTCTRL_SORTER_MMAP: {
        sqlite3 *db = va_arg(ap, sqlite3*);
        db->nMaxSorterMmap = va_arg(ap, int);
        break;
      }
  
      /*   sqlite3_test_control(SQLITE_TESTCTRL_ISINIT);
      **
      ** Return SQLITE_OK if SQLite has been initialized and SQLITE_ERROR if
      ** not.
      */
      case SQLITE_TESTCTRL_ISINIT: {
        if( sqlite3GlobalConfig.isInit==0 ) rc = SQLITE_ERROR;
        break;
      }
  
      /*  sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, db, dbName, onOff, tnum);
      **
      ** This test control is used to create imposter tables.  "db" is a pointer
      ** to the database connection.  dbName is the database name (ex: "main" or
      ** "temp") which will receive the imposter.  "onOff" turns imposter mode on
      ** or off.  "tnum" is the root page of the b-tree to which the imposter
      ** table should connect.
      **
      ** Enable imposter mode only when the schema has already been parsed.  Then
      ** run a single CREATE TABLE statement to construct the imposter table in
      ** the parsed schema.  Then turn imposter mode back off again.
      **
      ** If onOff==0 and tnum>0 then reset the schema for all databases, causing
      ** the schema to be reparsed the next time it is needed.  This has the
      ** effect of erasing all imposter tables.
      */
      case SQLITE_TESTCTRL_IMPOSTER: {
        sqlite3 *db = va_arg(ap, sqlite3*);
        sqlite3_mutex_enter(db->mutex);
        db->init.iDb = sqlite3FindDbName(db, va_arg(ap,const char*));
        db->init.busy = db->init.imposterTable = va_arg(ap,int);
        db->init.newTnum = va_arg(ap,int);
        if( db->init.busy==0 && db->init.newTnum>0 ){
          sqlite3ResetAllSchemasOfConnection(db);
        }
        sqlite3_mutex_leave(db->mutex);
        break;
      }
  
  #if defined(YYCOVERAGE)
      /*  sqlite3_test_control(SQLITE_TESTCTRL_PARSER_COVERAGE, FILE *out)
      **
      ** This test control (only available when SQLite is compiled with
      ** -DYYCOVERAGE) writes a report onto "out" that shows all
      ** state/lookahead combinations in the parser state machine
      ** which are never exercised.  If any state is missed, make the
      ** return code SQLITE_ERROR.
      */
      case SQLITE_TESTCTRL_PARSER_COVERAGE: {
        FILE *out = va_arg(ap, FILE*);
        if( sqlite3ParserCoverage(out) ) rc = SQLITE_ERROR;
        break;
      }
  #endif /* defined(YYCOVERAGE) */
  
      /*  sqlite3_test_control(SQLITE_TESTCTRL_RESULT_INTREAL, sqlite3_context*);
      **
      ** This test-control causes the most recent sqlite3_result_int64() value
      ** to be interpreted as a MEM_IntReal instead of as an MEM_Int.  Normally,
      ** MEM_IntReal values only arise during an INSERT operation of integer
      ** values into a REAL column, so they can be challenging to test.  This
      ** test-control enables us to write an intreal() SQL function that can
      ** inject an intreal() value at arbitrary places in an SQL statement,
      ** for testing purposes.
      */
      case SQLITE_TESTCTRL_RESULT_INTREAL: {
        sqlite3_context *pCtx = va_arg(ap, sqlite3_context*);
        sqlite3ResultIntReal(pCtx);
        break;
      }
  
      /*  sqlite3_test_control(SQLITE_TESTCTRL_SEEK_COUNT,
      **    sqlite3 *db,    // Database connection
      **    u64 *pnSeek     // Write seek count here
      **  );
      **
      ** This test-control queries the seek-counter on the "main" database
      ** file.  The seek-counter is written into *pnSeek and is then reset.
      ** The seek-count is only available if compiled with SQLITE_DEBUG.
      */
      case SQLITE_TESTCTRL_SEEK_COUNT: {
        sqlite3 *db = va_arg(ap, sqlite3*);
        u64 *pn = va_arg(ap, sqlite3_uint64*);
        *pn = sqlite3BtreeSeekCount(db->aDb->pBt);
        (void)db;  /* Silence harmless unused variable warning */
        break;
      }
  
      /*  sqlite3_test_control(SQLITE_TESTCTRL_TRACEFLAGS, op, ptr)
      **
      **  "ptr" is a pointer to a u32.  
      **
      **   op==0       Store the current sqlite3SelectTrace in *ptr
      **   op==1       Set sqlite3SelectTrace to the value *ptr
      **   op==3       Store the current sqlite3WhereTrace in *ptr
      **   op==3       Set sqlite3WhereTrace to the value *ptr
      */
      case SQLITE_TESTCTRL_TRACEFLAGS: {
         int opTrace = va_arg(ap, int);
         u32 *ptr = va_arg(ap, u32*);
         switch( opTrace ){
           case 0:   *ptr = sqlite3SelectTrace;      break;
           case 1:   sqlite3SelectTrace = *ptr;      break;
           case 2:   *ptr = sqlite3WhereTrace;       break;
           case 3:   sqlite3WhereTrace = *ptr;       break;
         }
         break;
      }
    }
    va_end(ap);
  #endif /* SQLITE_UNTESTABLE */
    return rc;
  }
  
  /*
  ** The Pager stores the Database filename, Journal filename, and WAL filename
  ** consecutively in memory, in that order.  The database filename is prefixed
  ** by four zero bytes.  Locate the start of the database filename by searching
  ** backwards for the first byte following four consecutive zero bytes.
  **
  ** This only works if the filename passed in was obtained from the Pager.
  */
  static const char *databaseName(const char *zName){
    while( zName[-1]!=0 || zName[-2]!=0 || zName[-3]!=0 || zName[-4]!=0 ){
      zName--;
    }
    return zName;
  }
  
  /*
  ** Append text z[] to the end of p[].  Return a pointer to the first
  ** character after then zero terminator on the new text in p[].
  */
  static char *appendText(char *p, const char *z){
    size_t n = strlen(z);
    memcpy(p, z, n+1);
    return p+n+1;
  }
  
  /*
  ** Allocate memory to hold names for a database, journal file, WAL file,
  ** and query parameters.  The pointer returned is valid for use by
  ** sqlite3_filename_database() and sqlite3_uri_parameter() and related
  ** functions.
  **
  ** Memory layout must be compatible with that generated by the pager
  ** and expected by sqlite3_uri_parameter() and databaseName().
  */
  char *sqlite3_create_filename(
    const char *zDatabase,
    const char *zJournal,
    const char *zWal,
    int nParam,
    const char **azParam
  ){
    sqlite3_int64 nByte;
    int i;
    char *pResult, *p;
    nByte = strlen(zDatabase) + strlen(zJournal) + strlen(zWal) + 10;
    for(i=0; i<nParam*2; i++){
      nByte += strlen(azParam[i])+1;
    }
    pResult = p = sqlite3_malloc64( nByte );
    if( p==0 ) return 0;
    memset(p, 0, 4);
    p += 4;
    p = appendText(p, zDatabase);
    for(i=0; i<nParam*2; i++){
      p = appendText(p, azParam[i]);
    }
    *(p++) = 0;
    p = appendText(p, zJournal);
    p = appendText(p, zWal);
    *(p++) = 0;
    *(p++) = 0;
    assert( (sqlite3_int64)(p - pResult)==nByte );
    return pResult + 4;
  }
  
  /*
  ** Free memory obtained from sqlite3_create_filename().  It is a severe
  ** error to call this routine with any parameter other than a pointer
  ** previously obtained from sqlite3_create_filename() or a NULL pointer.
  */
  void sqlite3_free_filename(char *p){
    if( p==0 ) return;
    p = (char*)databaseName(p);
    sqlite3_free(p - 4);
  }
  
  
  /*
  ** This is a utility routine, useful to VFS implementations, that checks
  ** to see if a database file was a URI that contained a specific query 
  ** parameter, and if so obtains the value of the query parameter.
  **
  ** The zFilename argument is the filename pointer passed into the xOpen()
  ** method of a VFS implementation.  The zParam argument is the name of the
  ** query parameter we seek.  This routine returns the value of the zParam
  ** parameter if it exists.  If the parameter does not exist, this routine
  ** returns a NULL pointer.
  */
  const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
    if( zFilename==0 || zParam==0 ) return 0;
    zFilename = databaseName(zFilename);
    return uriParameter(zFilename, zParam);
  }
  
  /*
  ** Return a pointer to the name of Nth query parameter of the filename.
  */
  const char *sqlite3_uri_key(const char *zFilename, int N){
    if( zFilename==0 || N<0 ) return 0;
    zFilename = databaseName(zFilename);
    zFilename += sqlite3Strlen30(zFilename) + 1;
    while( zFilename[0] && (N--)>0 ){
      zFilename += sqlite3Strlen30(zFilename) + 1;
      zFilename += sqlite3Strlen30(zFilename) + 1;
    }
    return zFilename[0] ? zFilename : 0;
  }
  
  /*
  ** Return a boolean value for a query parameter.
  */
  int sqlite3_uri_boolean(const char *zFilename, const char *zParam, int bDflt){
    const char *z = sqlite3_uri_parameter(zFilename, zParam);
    bDflt = bDflt!=0;
    return z ? sqlite3GetBoolean(z, bDflt) : bDflt;
  }
  
  /*
  ** Return a 64-bit integer value for a query parameter.
  */
  sqlite3_int64 sqlite3_uri_int64(
    const char *zFilename,    /* Filename as passed to xOpen */
    const char *zParam,       /* URI parameter sought */
    sqlite3_int64 bDflt       /* return if parameter is missing */
  ){
    const char *z = sqlite3_uri_parameter(zFilename, zParam);
    sqlite3_int64 v;
    if( z && sqlite3DecOrHexToI64(z, &v)==0 ){
      bDflt = v;
    }
    return bDflt;
  }
  
  /*
  ** Translate a filename that was handed to a VFS routine into the corresponding
  ** database, journal, or WAL file.
  **
  ** It is an error to pass this routine a filename string that was not
  ** passed into the VFS from the SQLite core.  Doing so is similar to
  ** passing free() a pointer that was not obtained from malloc() - it is
  ** an error that we cannot easily detect but that will likely cause memory
  ** corruption.
  */
  const char *sqlite3_filename_database(const char *zFilename){
    return databaseName(zFilename);
  }
  const char *sqlite3_filename_journal(const char *zFilename){
    zFilename = databaseName(zFilename);
    zFilename += sqlite3Strlen30(zFilename) + 1;
    while( zFilename[0] ){
      zFilename += sqlite3Strlen30(zFilename) + 1;
      zFilename += sqlite3Strlen30(zFilename) + 1;
    }
    return zFilename + 1;
  }
  const char *sqlite3_filename_wal(const char *zFilename){
  #ifdef SQLITE_OMIT_WAL
    return 0;
  #else
    zFilename = sqlite3_filename_journal(zFilename);
    zFilename += sqlite3Strlen30(zFilename) + 1;
    return zFilename;
  #endif
  }
  
  /*
  ** Return the Btree pointer identified by zDbName.  Return NULL if not found.
  */
  Btree *sqlite3DbNameToBtree(sqlite3 *db, const char *zDbName){
    int iDb = zDbName ? sqlite3FindDbName(db, zDbName) : 0;
    return iDb<0 ? 0 : db->aDb[iDb].pBt;
  }
  
  /*
  ** Return the filename of the database associated with a database
  ** connection.
  */
  const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName){
    Btree *pBt;
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
    pBt = sqlite3DbNameToBtree(db, zDbName);
    return pBt ? sqlite3BtreeGetFilename(pBt) : 0;
  }
  
  /*
  ** Return 1 if database is read-only or 0 if read/write.  Return -1 if
  ** no such database exists.
  */
  int sqlite3_db_readonly(sqlite3 *db, const char *zDbName){
    Btree *pBt;
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      (void)SQLITE_MISUSE_BKPT;
      return -1;
    }
  #endif
    pBt = sqlite3DbNameToBtree(db, zDbName);
    return pBt ? sqlite3BtreeIsReadonly(pBt) : -1;
  }
  
  #ifdef SQLITE_ENABLE_SNAPSHOT
  /*
  ** Obtain a snapshot handle for the snapshot of database zDb currently 
  ** being read by handle db.
  */
  int sqlite3_snapshot_get(
    sqlite3 *db, 
    const char *zDb,
    sqlite3_snapshot **ppSnapshot
  ){
    int rc = SQLITE_ERROR;
  #ifndef SQLITE_OMIT_WAL
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
  
    if( db->autoCommit==0 ){
      int iDb = sqlite3FindDbName(db, zDb);
      if( iDb==0 || iDb>1 ){
        Btree *pBt = db->aDb[iDb].pBt;
        if( SQLITE_TXN_WRITE!=sqlite3BtreeTxnState(pBt) ){
          rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
          if( rc==SQLITE_OK ){
            rc = sqlite3PagerSnapshotGet(sqlite3BtreePager(pBt), ppSnapshot);
          }
        }
      }
    }
  
    sqlite3_mutex_leave(db->mutex);
  #endif   /* SQLITE_OMIT_WAL */
    return rc;
  }
  
  /*
  ** Open a read-transaction on the snapshot idendified by pSnapshot.
  */
  int sqlite3_snapshot_open(
    sqlite3 *db, 
    const char *zDb, 
    sqlite3_snapshot *pSnapshot
  ){
    int rc = SQLITE_ERROR;
  #ifndef SQLITE_OMIT_WAL
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
  #endif
    sqlite3_mutex_enter(db->mutex);
    if( db->autoCommit==0 ){
      int iDb;
      iDb = sqlite3FindDbName(db, zDb);
      if( iDb==0 || iDb>1 ){
        Btree *pBt = db->aDb[iDb].pBt;
        if( sqlite3BtreeTxnState(pBt)!=SQLITE_TXN_WRITE ){
          Pager *pPager = sqlite3BtreePager(pBt);
          int bUnlock = 0;
          if( sqlite3BtreeTxnState(pBt)!=SQLITE_TXN_NONE ){
            if( db->nVdbeActive==0 ){
              rc = sqlite3PagerSnapshotCheck(pPager, pSnapshot);
              if( rc==SQLITE_OK ){
                bUnlock = 1;
                rc = sqlite3BtreeCommit(pBt);
              }
            }
          }else{
            rc = SQLITE_OK;
          }
          if( rc==SQLITE_OK ){
            rc = sqlite3PagerSnapshotOpen(pPager, pSnapshot);
          }
          if( rc==SQLITE_OK ){
            rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
            sqlite3PagerSnapshotOpen(pPager, 0);
          }
          if( bUnlock ){
            sqlite3PagerSnapshotUnlock(pPager);
          }
        }
      }
    }
  
    sqlite3_mutex_leave(db->mutex);
  #endif   /* SQLITE_OMIT_WAL */
    return rc;
  }
  
  /*
  ** Recover as many snapshots as possible from the wal file associated with
  ** schema zDb of database db.
  */
  int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb){
    int rc = SQLITE_ERROR;
    int iDb;
  #ifndef SQLITE_OMIT_WAL
  
  #ifdef SQLITE_ENABLE_API_ARMOR
    if( !sqlite3SafetyCheckOk(db) ){
      return SQLITE_MISUSE_BKPT;
    }
  #endif
  
    sqlite3_mutex_enter(db->mutex);
    iDb = sqlite3FindDbName(db, zDb);
    if( iDb==0 || iDb>1 ){
      Btree *pBt = db->aDb[iDb].pBt;
      if( SQLITE_TXN_NONE==sqlite3BtreeTxnState(pBt) ){
        rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
        if( rc==SQLITE_OK ){
          rc = sqlite3PagerSnapshotRecover(sqlite3BtreePager(pBt));
          sqlite3BtreeCommit(pBt);
        }
      }
    }
    sqlite3_mutex_leave(db->mutex);
  #endif   /* SQLITE_OMIT_WAL */
    return rc;
  }
  
  /*
  ** Free a snapshot handle obtained from sqlite3_snapshot_get().
  */
  void sqlite3_snapshot_free(sqlite3_snapshot *pSnapshot){
    sqlite3_free(pSnapshot);
  }
  #endif /* SQLITE_ENABLE_SNAPSHOT */
  
  #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
  /*
  ** Given the name of a compile-time option, return true if that option
  ** was used and false if not.
  **
  ** The name can optionally begin with "SQLITE_" but the "SQLITE_" prefix
  ** is not required for a match.
  */
  int sqlite3_compileoption_used(const char *zOptName){
    int i, n;
    int nOpt;
    const char **azCompileOpt;
   
  #if SQLITE_ENABLE_API_ARMOR
    if( zOptName==0 ){
      (void)SQLITE_MISUSE_BKPT;
      return 0;
    }
  #endif
  
    azCompileOpt = sqlite3CompileOptions(&nOpt);
  
    if( sqlite3StrNICmp(zOptName, "SQLITE_", 7)==0 ) zOptName += 7;
    n = sqlite3Strlen30(zOptName);
  
    /* Since nOpt is normally in single digits, a linear search is 
    ** adequate. No need for a binary search. */
    for(i=0; i<nOpt; i++){
      if( sqlite3StrNICmp(zOptName, azCompileOpt[i], n)==0
       && sqlite3IsIdChar((unsigned char)azCompileOpt[i][n])==0
      ){
        return 1;
      }
    }
    return 0;
  }
  
  /*
  ** Return the N-th compile-time option string.  If N is out of range,
  ** return a NULL pointer.
  */
  const char *sqlite3_compileoption_get(int N){
    int nOpt;
    const char **azCompileOpt;
    azCompileOpt = sqlite3CompileOptions(&nOpt);
    if( N>=0 && N<nOpt ){
      return azCompileOpt[N];
    }
    return 0;
  }
  #endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
  