if( zWide ){
    exists = GetFileAttributesW(zWide) != 0xffffffff;
    sqliteFree(zWide);
  }else{
#if OS_WINCE
    return SQLITE_NOMEM;
#else
    exists = GetFileAttributesA(zFilename) != 0xffffffff;
#endif
  }
  return exists;
}

/* Forward declaration */
static int allocateWinFile(winFile *pInit, OsFile **pId);

/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
** and *pReadonly is set to 0 if the file was opened for reading and
** writing or 1 if the file was opened read-only.  The function returns
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/
int sqlite3WinOpenReadWrite(
  const char *zFilename,
  OsFile **pId,
  int *pReadonly
){
  winFile f;
  HANDLE h;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId==0 );
  if( zWide ){
    h = CreateFileW(zWide,
       GENERIC_READ | GENERIC_WRITE,
       FILE_SHARE_READ | FILE_SHARE_WRITE,
       NULL,
       OPEN_ALWAYS,
       FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
       NULL
    );
    if( h==INVALID_HANDLE_VALUE ){
      h = CreateFileW(zWide,
         GENERIC_READ,
         FILE_SHARE_READ | FILE_SHARE_WRITE,
         NULL,
         OPEN_ALWAYS,
         FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
         NULL
      );
      if( h==INVALID_HANDLE_VALUE ){
        sqliteFree(zWide);
        return SQLITE_CANTOPEN;
      }
      *pReadonly = 1;
    }else{
      *pReadonly = 0;
    }
#if OS_WINCE
    if (!winceCreateLock(zFilename, &f)){
      CloseHandle(h);
      sqliteFree(zWide);
      return SQLITE_CANTOPEN;
    }
#endif
    sqliteFree(zWide);
  }else{
#if OS_WINCE
    return SQLITE_NOMEM;
#else
    h = CreateFileA(zFilename,
       GENERIC_READ | GENERIC_WRITE,
       FILE_SHARE_READ | FILE_SHARE_WRITE,
       NULL,
       OPEN_ALWAYS,
       FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
       NULL
    );
    if( h==INVALID_HANDLE_VALUE ){
      h = CreateFileA(zFilename,
         GENERIC_READ,
         FILE_SHARE_READ | FILE_SHARE_WRITE,
         NULL,
         OPEN_ALWAYS,
         FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
         NULL
      );
      if( h==INVALID_HANDLE_VALUE ){
        return SQLITE_CANTOPEN;
      }
      *pReadonly = 1;
    }else{
      *pReadonly = 0;
    }
#endif /* OS_WINCE */
  }
  f.h = h;
#if OS_WINCE
  f.zDeleteOnClose = 0;
#endif
  TRACE3("OPEN R/W %d \"%s\"\n", h, zFilename);
  return allocateWinFile(&f, pId);
}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
** previously existed.  Nor do we allow the file to be a symbolic
** link.
**
** If delFlag is true, then make arrangements to automatically delete
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
**
** Sometimes if we have just deleted a prior journal file, windows
** will fail to open a new one because there is a "pending delete".
** To work around this bug, we pause for 100 milliseconds and attempt
** a second open after the first one fails.  The whole operation only
** fails if both open attempts are unsuccessful.
*/
int sqlite3WinOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  winFile f;
  HANDLE h;
  int fileflags;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId == 0 );
  fileflags = FILE_FLAG_RANDOM_ACCESS;
#if !OS_WINCE
  if( delFlag ){
    fileflags |= FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE;
  }
#endif
  if( zWide ){
    int cnt = 0;
    do{
      h = CreateFileW(zWide,
         GENERIC_READ | GENERIC_WRITE,
         0,
         NULL,
         CREATE_ALWAYS,
         fileflags,
         NULL
      );
    }while( h==INVALID_HANDLE_VALUE && cnt++ < 2 && (Sleep(100), 1) );
    sqliteFree(zWide);
  }else{
#if OS_WINCE
    return SQLITE_NOMEM;
#else
    int cnt = 0;
    do{
      h = CreateFileA(zFilename,
        GENERIC_READ | GENERIC_WRITE,
        0,
        NULL,
        CREATE_ALWAYS,
        fileflags,
        NULL
      );
    }while( h==INVALID_HANDLE_VALUE && cnt++ < 2 && (Sleep(100), 1) );
#endif /* OS_WINCE */
  }
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  f.h = h;
#if OS_WINCE
  f.zDeleteOnClose = delFlag ? utf8ToUnicode(zFilename) : 0;
  f.hMutex = NULL;
#endif
  TRACE3("OPEN EX %d \"%s\"\n", h, zFilename);
  return allocateWinFile(&f, pId);
}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3WinOpenReadOnly(const char *zFilename, OsFile **pId){
  winFile f;
  HANDLE h;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId==0 );
  if( zWide ){
    h = CreateFileW(zWide,
       GENERIC_READ,
       0,
       NULL,
       OPEN_EXISTING,
       FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
       NULL
    );
    sqliteFree(zWide);
  }else{
#if OS_WINCE
    return SQLITE_NOMEM;
#else
    h = CreateFileA(zFilename,
       GENERIC_READ,
       0,
       NULL,
       OPEN_EXISTING,
       FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
       NULL
    );
#endif
  }
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  f.h = h;
#if OS_WINCE
  f.zDeleteOnClose = 0;
  f.hMutex = NULL;
#endif
  TRACE3("OPEN RO %d \"%s\"\n", h, zFilename);
  return allocateWinFile(&f, pId);
}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
**
** This routine is only meaningful for Unix.  It is a no-op under
** windows since windows does not support hard links.
**
** On success, a handle for a previously open file is at *id is
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
static int winOpenDirectory(
  OsFile *id,
  const char *zDirname
){
  return SQLITE_OK;
}

/*
** 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.
*/
char *sqlite3_temp_directory = 0;

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at least SQLITE_TEMPNAME_SIZE characters.
*/
int sqlite3WinTempFileName(char *zBuf){
  static char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  char zTempPath[SQLITE_TEMPNAME_SIZE];
  if( sqlite3_temp_directory ){
    strncpy(zTempPath, sqlite3_temp_directory, SQLITE_TEMPNAME_SIZE-30);
    zTempPath[SQLITE_TEMPNAME_SIZE-30] = 0;
  }else if( isNT() ){
    char *zMulti;
    WCHAR zWidePath[SQLITE_TEMPNAME_SIZE];
    GetTempPathW(SQLITE_TEMPNAME_SIZE-30, zWidePath);
    zMulti = unicodeToUtf8(zWidePath);
    if( zMulti ){
      strncpy(zTempPath, zMulti, SQLITE_TEMPNAME_SIZE-30);
      zTempPath[SQLITE_TEMPNAME_SIZE-30] = 0;
      sqliteFree(zMulti);
    }
  }else{
    GetTempPathA(SQLITE_TEMPNAME_SIZE-30, zTempPath);
  }
  for(i=strlen(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
  zTempPath[i] = 0;
  for(;;){
    sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zTempPath);
    j = strlen(zBuf);
    sqlite3Randomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
    if( !sqlite3OsFileExists(zBuf) ) break;
  }
  TRACE2("TEMP FILENAME: %s\n", zBuf);
  return SQLITE_OK; 
}

/*
** Close a file.
**
** It is reported that an attempt to close a handle might sometimes
** fail.  This is a very unreasonable result, but windows is notorious
** for being unreasonable so I do not doubt that it might happen.  If
** the close fails, we pause for 100 milliseconds and try again.  As
** many as MX_CLOSE_ATTEMPT attempts to close the handle are made before
** giving up and returning an error.
*/
#define MX_CLOSE_ATTEMPT 3
static int winClose(OsFile **pId){
  winFile *pFile;
  int rc = 1;
  if( pId && (pFile = (winFile*)*pId)!=0 ){
    int rc, cnt = 0;
    TRACE2("CLOSE %d\n", pFile->h);
    do{
      rc = CloseHandle(pFile->h);
    }while( rc==0 && cnt++ < MX_CLOSE_ATTEMPT && (Sleep(100), 1) );
#if OS_WINCE
    winceDestroyLock(pFile);
    if( pFile->zDeleteOnClose ){
      DeleteFileW(pFile->zDeleteOnClose);
      sqliteFree(pFile->zDeleteOnClose);
    }
#endif
    OpenCounter(-1);
    sqliteFree(pFile);
    *pId = 0;
  }
  return rc ? SQLITE_OK : SQLITE_IOERR;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int winRead(OsFile *id, void *pBuf, int amt){
  DWORD got;
  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR);
  TRACE3("READ %d lock=%d\n", ((winFile*)id)->h, ((winFile*)id)->locktype);
  if( !ReadFile(((winFile*)id)->h, pBuf, amt, &got, 0) ){
    got = 0;
  }
  if( got==(DWORD)amt ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
}

/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/
static int winWrite(OsFile *id, const void *pBuf, int amt){
  int rc = 0;
  DWORD wrote;
  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR);
  SimulateDiskfullError(return SQLITE_FULL);
  TRACE3("WRITE %d lock=%d\n", ((winFile*)id)->h, ((winFile*)id)->locktype);
  assert( amt>0 );
  while( amt>0 && (rc = WriteFile(((winFile*)id)->h, pBuf, amt, &wrote, 0))!=0
         && wrote>0 ){
    amt -= wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  if( !rc || amt>(int)wrote ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
}

/*
** Some microsoft compilers lack this definition.
*/
#ifndef INVALID_SET_FILE_POINTER
# define INVALID_SET_FILE_POINTER ((DWORD)-1)
#endif

/*
** Move the read/write pointer in a file.
*/
static int winSeek(OsFile *id, i64 offset){
  LONG upperBits = offset>>32;
  LONG lowerBits = offset & 0xffffffff;
  DWORD rc;
  assert( id!=0 );
#ifdef SQLITE_TEST
  if( offset ) SimulateDiskfullError(return SQLITE_FULL);
#endif
  SEEK(offset/1024 + 1);
  rc = SetFilePointer(((winFile*)id)->h, lowerBits, &upperBits, FILE_BEGIN);
  TRACE3("SEEK %d %lld\n", ((winFile*)id)->h, offset);
  if( rc==INVALID_SET_FILE_POINTER && GetLastError()!=NO_ERROR ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
}

/*
** Make sure all writes to a particular file are committed to disk.
*/
static int winSync(OsFile *id, int dataOnly){
  assert( id!=0 );
  TRACE3("SYNC %d lock=%d\n", ((winFile*)id)->h, ((winFile*)id)->locktype);
  if( FlushFileBuffers(((winFile*)id)->h) ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
}

/*
** Sync the directory zDirname. This is a no-op on operating systems other
** than UNIX.
*/
int sqlite3WinSyncDirectory(const char *zDirname){
  SimulateIOError(return SQLITE_IOERR);
  return SQLITE_OK;
}

/*
** Truncate an open file to a specified size
*/
static int winTruncate(OsFile *id, i64 nByte){
  LONG upperBits = nByte>>32;
  assert( id!=0 );
  TRACE3("TRUNCATE %d %lld\n", ((winFile*)id)->h, nByte);
  SimulateIOError(return SQLITE_IOERR);
  SetFilePointer(((winFile*)id)->h, nByte, &upperBits, FILE_BEGIN);
  SetEndOfFile(((winFile*)id)->h);
  return SQLITE_OK;
}

/*
** Determine the current size of a file in bytes
*/
static int winFileSize(OsFile *id, i64 *pSize){
  DWORD upperBits, lowerBits;
  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR);
  lowerBits = GetFileSize(((winFile*)id)->h, &upperBits);
  *pSize = (((i64)upperBits)<<32) + lowerBits;
  return SQLITE_OK;
}

/*
** LOCKFILE_FAIL_IMMEDIATELY is undefined on some Windows systems.
*/
#ifndef LOCKFILE_FAIL_IMMEDIATELY
# define LOCKFILE_FAIL_IMMEDIATELY 1
#endif

/*
** Acquire a reader lock.
** Different API routines are called depending on whether or not this
** is Win95 or WinNT.
*/
static int getReadLock(winFile *id){
  int res;
  if( isNT() ){
    OVERLAPPED ovlp;
    ovlp.Offset = SHARED_FIRST;
    ovlp.OffsetHigh = 0;
    ovlp.hEvent = 0;
    res = LockFileEx(id->h, LOCKFILE_FAIL_IMMEDIATELY, 0, SHARED_SIZE,0,&ovlp);
  }else{
    int lk;
    sqlite3Randomness(sizeof(lk), &lk);
    id->sharedLockByte = (lk & 0x7fffffff)%(SHARED_SIZE - 1);
    res = LockFile(id->h, SHARED_FIRST+id->sharedLockByte, 0, 1, 0);
  }
  return res;
}

/*
** Undo a readlock
*/
static int unlockReadLock(winFile *pFile){
  int res;
  if( isNT() ){
    res = UnlockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
  }else{
    res = UnlockFile(pFile->h, SHARED_FIRST + pFile->sharedLockByte, 0, 1, 0);
  }
  return res;
}

#ifndef SQLITE_OMIT_PAGER_PRAGMAS
/*
** Check that a given pathname is a directory and is writable 
**
*/
int sqlite3WinIsDirWritable(char *zDirname){
  int fileAttr;
  WCHAR *zWide;
  if( zDirname==0 ) return 0;
  if( !isNT() && strlen(zDirname)>MAX_PATH ) return 0;
  zWide = utf8ToUnicode(zDirname);
  if( zWide ){
    fileAttr = GetFileAttributesW(zWide);
    sqliteFree(zWide);
  }else{
#if OS_WINCE
    return 0;
#else
    fileAttr = GetFileAttributesA(zDirname);
#endif
  }