sqlite3_int64 mmapSizeMax;          /* Configured FCNTL_MMAP_SIZE value */
  void *pMapRegion;                   /* Memory mapped region */
#endif
#ifdef __QNXNTO__
  int sectorSize;                     /* Device sector size */
  int deviceCharacteristics;          /* Precomputed device characteristics */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                      /* The flags specified at open() */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
  unsigned fsFlags;                   /* cached details from statfs() */
#endif
#if OS_VXWORKS
  struct vxworksFileId *pId;          /* Unique file ID */
#endif
#ifdef SQLITE_DEBUG
................................................................................
#else
# define UNIXFILE_DIRSYNC    0x00
#endif
#define UNIXFILE_PSOW        0x10     /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */
#define UNIXFILE_DELETE      0x20     /* Delete on close */
#define UNIXFILE_URI         0x40     /* Filename might have query parameters */
#define UNIXFILE_NOLOCK      0x80     /* Do no file locking */
#define UNIXFILE_WARNED    0x0100     /* verifyDbFile() warnings have been issued */


/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

/*
................................................................................
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;


  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );





  unixEnterMutex(); /* Because pFile->pInode is shared across threads */

  /* Check if a thread in this process holds such a lock */
  if( pFile->pInode->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }

................................................................................
      rc = 0;
    }
  }else{
    rc = osFcntl(pFile->h, F_SETLK, pLock);
  }
  return rc;
}



/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
................................................................................
  */
  if( pFile->eFileLock>=eFileLock ){
    OSTRACE(("LOCK    %d %s ok (already held) (unix)\n", pFile->h,
            azFileLock(eFileLock)));
    return SQLITE_OK;
  }






















  /* Make sure the locking sequence is correct.
  **  (1) We never move from unlocked to anything higher than shared lock.
  **  (2) SQLite never explicitly requests a pendig lock.
  **  (3) A shared lock is always held when a reserve lock is requested.
  */
  assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
  assert( eFileLock!=PENDING_LOCK );
................................................................................
      getpid()));

  assert( eFileLock<=SHARED_LOCK );
  if( pFile->eFileLock<=eFileLock ){
    return SQLITE_OK;
  }
  unixEnterMutex();

  pInode = pFile->pInode;
  assert( pInode->nShared!=0 );
  if( pFile->eFileLock>SHARED_LOCK ){
    assert( pInode->eFileLock==pFile->eFileLock );

#ifdef SQLITE_DEBUG
    /* When reducing a lock such that other processes can start
................................................................................
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile *)id;
  verifyDbFile(pFile);
  unixUnlock(id, NO_LOCK);
  unixEnterMutex();

  /* unixFile.pInode is always valid here. Otherwise, a different close
  ** routine (e.g. nolockClose()) would be called instead.
  */


  assert( pFile->pInode->nLock>0 || pFile->pInode->bProcessLock==0 );


  if( ALWAYS(pFile->pInode) && pFile->pInode->nLock ){
    /* If there are outstanding locks, do not actually close the file just
    ** yet because that would clear those locks.  Instead, add the file
    ** descriptor to pInode->pUnused list.  It will be automatically closed 
    ** when the last lock is cleared.
    */
    setPendingFd(pFile);
  }
  releaseInodeInfo(pFile);

  rc = closeUnixFile(id);
  unixLeaveMutex();
  return rc;
}

/************** End of the posix advisory lock implementation *****************
******************************************************************************/
................................................................................
#if 0
  assert( pFile->pUnused==0
       || offset>=PENDING_BYTE+512
       || offset+amt<=PENDING_BYTE 
  );
#endif


















#if SQLITE_MAX_MMAP_SIZE>0
  /* Deal with as much of this read request as possible by transfering
  ** data from the memory mapping using memcpy().  */
  if( offset<pFile->mmapSize ){
    if( offset+amt <= pFile->mmapSize ){
      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], amt);
      return SQLITE_OK;
................................................................................
  }
}

/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(sqlite3_file *id, i64 *pSize){

  int rc;
  struct stat buf;
  assert( id );







  rc = osFstat(((unixFile*)id)->h, &buf);

  SimulateIOError( rc=1 );
  if( rc!=0 ){
    ((unixFile*)id)->lastErrno = errno;
    return SQLITE_IOERR_FSTAT;
  }
  *pSize = buf.st_size;

................................................................................
  /* When opening a zero-size database, the findInodeInfo() procedure
  ** writes a single byte into that file in order to work around a bug
  ** in the OS-X msdos filesystem.  In order to avoid problems with upper
  ** layers, we need to report this file size as zero even though it is
  ** really 1.   Ticket #3260.
  */
  if( *pSize==1 ) *pSize = 0;


  return SQLITE_OK;
}

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
/*
** Handler for proxy-locking file-control verbs.  Defined below in the
................................................................................
  /* No locking occurs in temporary files */
  assert( zFilename!=0 || (ctrlFlags & UNIXFILE_NOLOCK)!=0 );

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->pVfs = pVfs;
  pNew->zPath = zFilename;
  pNew->ctrlFlags = (u8)ctrlFlags;
#if SQLITE_MAX_MMAP_SIZE>0
  pNew->mmapSizeMax = sqlite3GlobalConfig.szMmap;
#endif
  if( sqlite3_uri_boolean(((ctrlFlags & UNIXFILE_URI) ? zFilename : 0),
                           "psow", SQLITE_POWERSAFE_OVERWRITE) ){
    pNew->ctrlFlags |= UNIXFILE_PSOW;
  }
................................................................................
open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
  }
  return rc;
}

































/*
** Delete the file at zPath. If the dirSync argument is true, fsync()
** the directory after deleting the file.
*/
static int unixDelete(
  sqlite3_vfs *NotUsed,     /* VFS containing this as the xDelete method */
................................................................................
  #define UNIXVFS(VFSNAME, FINDER) {                        \
    3,                    /* iVersion */                    \
    sizeof(unixFile),     /* szOsFile */                    \
    MAX_PATHNAME,         /* mxPathname */                  \
    0,                    /* pNext */                       \
    VFSNAME,              /* zName */                       \
    (void*)&FINDER,       /* pAppData */                    \
    unixOpen,             /* xOpen */                       \
    unixDelete,           /* xDelete */                     \
    unixAccess,           /* xAccess */                     \
    unixFullPathname,     /* xFullPathname */               \
    unixDlOpen,           /* xDlOpen */                     \
    unixDlError,          /* xDlError */                    \
    unixDlSym,            /* xDlSym */                      \
    unixDlClose,          /* xDlClose */                    \

  sqlite3_int64 mmapSizeMax;          /* Configured FCNTL_MMAP_SIZE value */
  void *pMapRegion;                   /* Memory mapped region */
#endif
#ifdef __QNXNTO__
  int sectorSize;                     /* Device sector size */
  int deviceCharacteristics;          /* Precomputed device characteristics */
#endif

  int openFlags;                      /* The flags specified at open() */

#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
  unsigned fsFlags;                   /* cached details from statfs() */
#endif
#if OS_VXWORKS
  struct vxworksFileId *pId;          /* Unique file ID */
#endif
#ifdef SQLITE_DEBUG
................................................................................
#else
# define UNIXFILE_DIRSYNC    0x00
#endif
#define UNIXFILE_PSOW        0x10     /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */
#define UNIXFILE_DELETE      0x20     /* Delete on close */
#define UNIXFILE_URI         0x40     /* Filename might have query parameters */
#define UNIXFILE_NOLOCK      0x80     /* Do no file locking */
#define UNIXFILE_WARNED    0x0100     /* verifyDbFile() has issued warnings */
#define UNIXFILE_DEFERRED  0x0200     /* File has not yet been opened */

/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

/*
................................................................................
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );


  if( pFile->ctrlFlags==UNIXFILE_DEFERRED ){
    *pResOut = 0;
    return SQLITE_OK;
  }

  unixEnterMutex(); /* Because pFile->pInode is shared across threads */

  /* Check if a thread in this process holds such a lock */
  if( pFile->pInode->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }

................................................................................
      rc = 0;
    }
  }else{
    rc = osFcntl(pFile->h, F_SETLK, pLock);
  }
  return rc;
}

static int unixOpen(sqlite3_vfs*, const char*, sqlite3_file*, int, int *);

/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
................................................................................
  */
  if( pFile->eFileLock>=eFileLock ){
    OSTRACE(("LOCK    %d %s ok (already held) (unix)\n", pFile->h,
            azFileLock(eFileLock)));
    return SQLITE_OK;
  }

  if( pFile->ctrlFlags==UNIXFILE_DEFERRED ){
    int eOrigLock = pFile->eFileLock;
    if( eFileLock==SHARED_LOCK ){
      int statrc;
      struct stat sBuf;
      memset(&sBuf, 0, sizeof(sBuf));
      statrc = osStat(pFile->zPath, &sBuf);
      if( statrc && errno==ENOENT ){
        pFile->eFileLock = SHARED_LOCK;
        return SQLITE_OK;
      }
    }

    rc = unixOpen(pFile->pVfs, pFile->zPath, id, pFile->openFlags, 0);
    if( rc==SQLITE_OK && eOrigLock ){
      rc = unixLock(id, eOrigLock);
    }
    if( rc!=SQLITE_OK ) return rc;
  }
  assert( (pFile->ctrlFlags & UNIXFILE_DEFERRED)==0 );

  /* Make sure the locking sequence is correct.
  **  (1) We never move from unlocked to anything higher than shared lock.
  **  (2) SQLite never explicitly requests a pendig lock.
  **  (3) A shared lock is always held when a reserve lock is requested.
  */
  assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
  assert( eFileLock!=PENDING_LOCK );
................................................................................
      getpid()));

  assert( eFileLock<=SHARED_LOCK );
  if( pFile->eFileLock<=eFileLock ){
    return SQLITE_OK;
  }
  unixEnterMutex();
  if( pFile->ctrlFlags==UNIXFILE_DEFERRED ) goto end_unlock;
  pInode = pFile->pInode;
  assert( pInode->nShared!=0 );
  if( pFile->eFileLock>SHARED_LOCK ){
    assert( pInode->eFileLock==pFile->eFileLock );

#ifdef SQLITE_DEBUG
    /* When reducing a lock such that other processes can start
................................................................................
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile *)id;
  verifyDbFile(pFile);
  unixUnlock(id, NO_LOCK);
  unixEnterMutex();

  /* unixFile.pInode is always valid here. Otherwise, a different close
  ** routine (e.g. nolockClose()) would be called instead.  */

  assert( pFile->pInode==0 
       || pFile->pInode->nLock>0 
       || pFile->pInode->bProcessLock==0 
  );
  if( pFile->pInode ){
    if( pFile->pInode->nLock ){
      /* If there are outstanding locks, do not actually close the file just
      ** yet because that would clear those locks.  Instead, add the file
      ** descriptor to pInode->pUnused list.  It will be automatically closed 
      ** when the last lock is cleared.
      */
      setPendingFd(pFile);
    }
    releaseInodeInfo(pFile);
  }
  rc = closeUnixFile(id);
  unixLeaveMutex();
  return rc;
}

/************** End of the posix advisory lock implementation *****************
******************************************************************************/
................................................................................
#if 0
  assert( pFile->pUnused==0
       || offset>=PENDING_BYTE+512
       || offset+amt<=PENDING_BYTE 
  );
#endif

  if( pFile->ctrlFlags==UNIXFILE_DEFERRED ){
    int rc;
    struct stat sBuf;
    memset(&sBuf, 0, sizeof(sBuf));
    rc = osStat(pFile->zPath, &sBuf);
    if( rc!=0 ){
      memset(pBuf, 0, amt);
      rc = (errno==ENOENT ? SQLITE_IOERR_SHORT_READ : SQLITE_IOERR_FSTAT);
    }else{
      rc = unixOpen(pFile->pVfs, pFile->zPath, id, pFile->openFlags, 0);
    }
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }
  assert( (pFile->ctrlFlags & UNIXFILE_DEFERRED)==0 );

#if SQLITE_MAX_MMAP_SIZE>0
  /* Deal with as much of this read request as possible by transfering
  ** data from the memory mapping using memcpy().  */
  if( offset<pFile->mmapSize ){
    if( offset+amt <= pFile->mmapSize ){
      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], amt);
      return SQLITE_OK;
................................................................................
  }
}

/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(sqlite3_file *id, i64 *pSize){
  unixFile *pFile = (unixFile*)id;
  int rc;
  struct stat buf;
  assert( id );
  if( pFile->ctrlFlags==UNIXFILE_DEFERRED ){
    rc = osStat(pFile->zPath, &buf);
    if( rc && errno==ENOENT ){
      rc = 0;
      buf.st_size = 0;
    }
  }else{
    rc = osFstat(pFile->h, &buf);
  }
  SimulateIOError( rc=1 );
  if( rc!=0 ){
    ((unixFile*)id)->lastErrno = errno;
    return SQLITE_IOERR_FSTAT;
  }
  *pSize = buf.st_size;

................................................................................
  /* When opening a zero-size database, the findInodeInfo() procedure
  ** writes a single byte into that file in order to work around a bug
  ** in the OS-X msdos filesystem.  In order to avoid problems with upper
  ** layers, we need to report this file size as zero even though it is
  ** really 1.   Ticket #3260.
  */
  if( *pSize==1 ) *pSize = 0;


  return SQLITE_OK;
}

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
/*
** Handler for proxy-locking file-control verbs.  Defined below in the
................................................................................
  /* No locking occurs in temporary files */
  assert( zFilename!=0 || (ctrlFlags & UNIXFILE_NOLOCK)!=0 );

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->pVfs = pVfs;
  pNew->zPath = zFilename;
  pNew->ctrlFlags = (unsigned short)ctrlFlags;
#if SQLITE_MAX_MMAP_SIZE>0
  pNew->mmapSizeMax = sqlite3GlobalConfig.szMmap;
#endif
  if( sqlite3_uri_boolean(((ctrlFlags & UNIXFILE_URI) ? zFilename : 0),
                           "psow", SQLITE_POWERSAFE_OVERWRITE) ){
    pNew->ctrlFlags |= UNIXFILE_PSOW;
  }
................................................................................
open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
  }
  return rc;
}

static int unixOpenDeferred(
  sqlite3_vfs *pVfs,           /* The VFS for which this is the xOpen method */
  const char *zPath,           /* Pathname of file to be opened */
  sqlite3_file *pFile,         /* The file descriptor to be filled in */
  int flags,                   /* Input flags to control the opening */
  int *pOutFlags               /* Output flags returned to SQLite core */
){
  const int mask1 = SQLITE_OPEN_MAIN_DB | SQLITE_OPEN_READWRITE
                  | SQLITE_OPEN_CREATE;
  const int mask2 = SQLITE_OPEN_READONLY  | SQLITE_OPEN_DELETEONCLOSE
                  | SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_AUTOPROXY;
  int rc = SQLITE_OK;          /* Return code */

  /* If all the flags in mask1 are set, and all the flags in mask2 are
  ** clear, then this will be a deferred open.  */
  if( zPath && (flags & (mask1 | mask2))==mask1 ){
    unixFile *p = (unixFile*)pFile;
    memset(p, 0, sizeof(unixFile));

    p->pMethod = (**(finder_type*)pVfs->pAppData)(0, 0);
    p->pVfs = pVfs;
    p->h = -1;
    p->ctrlFlags = UNIXFILE_DEFERRED;
    p->openFlags = flags;
    p->zPath = zPath;
    if( pOutFlags ) *pOutFlags = flags;
  }else{
    rc = unixOpen(pVfs, zPath, pFile, flags, pOutFlags);
  }
  return rc;
}

/*
** Delete the file at zPath. If the dirSync argument is true, fsync()
** the directory after deleting the file.
*/
static int unixDelete(
  sqlite3_vfs *NotUsed,     /* VFS containing this as the xDelete method */
................................................................................
  #define UNIXVFS(VFSNAME, FINDER) {                        \
    3,                    /* iVersion */                    \
    sizeof(unixFile),     /* szOsFile */                    \
    MAX_PATHNAME,         /* mxPathname */                  \
    0,                    /* pNext */                       \
    VFSNAME,              /* zName */                       \
    (void*)&FINDER,       /* pAppData */                    \
    unixOpenDeferred,     /* xOpen */                       \
    unixDelete,           /* xDelete */                     \
    unixAccess,           /* xAccess */                     \
    unixFullPathname,     /* xFullPathname */               \
    unixDlOpen,           /* xDlOpen */                     \
    unixDlError,          /* xDlError */                    \
    unixDlSym,            /* xDlSym */                      \
    unixDlClose,          /* xDlClose */                    \

  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", sqlite3ErrName(rc), 0);
    sqlite3_free(zFile);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;


  rc = sqlite3OsWrite(fd, "Hello, World!", 14, offset);

  sqlite3OsCloseFree(fd);
  sqlite3_free(zFile);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", sqlite3ErrName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;

  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", sqlite3ErrName(rc), 0);
    sqlite3_free(zFile);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;
  sqlite3OsLock(fd, SHARED_LOCK);
  sqlite3OsLock(fd, EXCLUSIVE_LOCK);
  rc = sqlite3OsWrite(fd, "Hello, World!", 14, offset);
  sqlite3OsUnlock(fd, NO_LOCK);
  sqlite3OsCloseFree(fd);
  sqlite3_free(zFile);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", sqlite3ErrName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;

lappend ::testsuitelist xxx

test_suite "veryquick" -prefix "" -description {
  "Very" quick test suite. Runs in less than 5 minutes on a workstation. 
  This test suite is the same as the "quick" tests, except that some files
  that test malloc and IO errors are omitted.
} -files [
  test_set $allquicktests -exclude *malloc* *ioerr* *fault*

]

test_suite "mmap" -prefix "mm-" -description {
  Similar to veryquick. Except with memory mapping disabled.
} -presql {
  pragma mmap_size = 268435456;
} -files [

lappend ::testsuitelist xxx

test_suite "veryquick" -prefix "" -description {
  "Very" quick test suite. Runs in less than 5 minutes on a workstation. 
  This test suite is the same as the "quick" tests, except that some files
  that test malloc and IO errors are omitted.
} -files [
  test_set $allquicktests -exclude *malloc* *ioerr* *fault* \
    *multiplex* *quota* walbak.test
]

test_suite "mmap" -prefix "mm-" -description {
  Similar to veryquick. Except with memory mapping disabled.
} -presql {
  pragma mmap_size = 268435456;
} -files [