SQLite

  if(!strcmp(fsInfo.f_fstypename, "msdos"))
    return dotlockLockingStyle;
  
  if(!strcmp(fsInfo.f_fstypename, "webdav"))
    return unsupportedLockingStyle;
  
  return sqlite3TestLockingStyle(filePath, fd);  
#endif /* SQLITE_FIXED_LOCKING_STYLE */
}

#endif /* SQLITE_ENABLE_LOCKING_STYLE */

/*
** Given a file descriptor, locate lockInfo and openCnt structures that
** describes that file descriptor.  Create new ones if necessary.  The

  pb.fd = fd;
  OSTRACE5("AFPLOCK setting lock %s for %d in range %llx:%llx\n", 
    (setLockFlag?"ON":"OFF"), fd, offset, length);
  err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
  if ( err==-1 ) {
    OSTRACE4("AFPLOCK failed to fsctl() '%s' %d %s\n", path, errno, 
      strerror(errno));
    return 1; /* error */
  } else {
    return 0;
  }
}

/*
 ** This routine checks if there is a RESERVED lock held on the specified

  if( pFile->locktype>SHARED_LOCK ){
    r = 1;
  }
  
  /* Otherwise see if some other process holds it.
   */
  if ( !r ) {
    /* lock the byte */
    int failed = _AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1,1);  
    if (failed) {
      /* if we failed to get the lock then someone else must have it */
      r = 1;
    } else {
      /* if we succeeded in taking the reserved lock, unlock it to restore
      ** the original state */

 */
typedef void flockLockingContext;

static int flockUnixCheckReservedLock(OsFile *id) {
  unixFile *pFile = (unixFile*)id;
  
  if (pFile->locktype == RESERVED_LOCK) {
    return 1; /* already have a reserved lock */
  } else {
    /* attempt to get the lock */
    int rc = flock(pFile->h, LOCK_EX | LOCK_NB);
    if (!rc) {
      /* got the lock, unlock it */
      flock(pFile->h, LOCK_UN);
      return 0;  /* no one has it reserved */
    }
    return 1; /* someone else might have it reserved */
  }
}

static int flockUnixLock(OsFile *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  
  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  int rc = flock(pFile->h, LOCK_EX | LOCK_NB);
  if (rc) {
    /* didn't get, must be busy */
    return SQLITE_BUSY;
  } else {
    /* got it, set the type and return ok */
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
}

static int flockUnixUnlock(OsFile *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  
  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  int rc = flock(pFile->h, LOCK_UN);
  if (rc)
    return SQLITE_IOERR_UNLOCK;
  else {
    pFile->locktype = NO_LOCK;
    return SQLITE_OK;
  }

static int dotlockUnixCheckReservedLock(OsFile *id) {
  unixFile *pFile = (unixFile*)id;
  dotlockLockingContext *context = 
    (dotlockLockingContext *) pFile->lockingContext;
  
  if (pFile->locktype == RESERVED_LOCK) {
    return 1; /* already have a reserved lock */
  } else {
    struct stat statBuf;
    if (lstat(context->lockPath,&statBuf) == 0)
      /* file exists, someone else has the lock */
      return 1;
    else
      /* file does not exist, we could have it if we want it */
      return 0;
  }
}

static int dotlockUnixLock(OsFile *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  dotlockLockingContext *context = 
    (dotlockLockingContext *) pFile->lockingContext;
  
  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    
    /* Always update the timestamp on the old file */
    utimes(context->lockPath,NULL);
    return SQLITE_OK;
  }
  
  /* check to see if lock file already exists */
  struct stat statBuf;
  if (lstat(context->lockPath,&statBuf) == 0){
    return SQLITE_BUSY; /* it does, busy */
  }
  
  /* grab an exclusive lock */
  int fd = open(context->lockPath,O_RDONLY|O_CREAT|O_EXCL,0600);
  if (fd < 0) {
    /* failed to open/create the file, someone else may have stolen the lock */
    return SQLITE_BUSY; 
  }
  close(fd);
  
  /* got it, set the type and return ok */
  pFile->locktype = locktype;
  return SQLITE_OK;
}

static int dotlockUnixUnlock(OsFile *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  dotlockLockingContext *context = 
    (dotlockLockingContext *) pFile->lockingContext;
  
  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  unlink(context->lockPath);
  pFile->locktype = NO_LOCK;
  return SQLITE_OK;
}

/*
 ** Close a file.

    sqlite3OsLeaveMutex();
    if( rc ){
      close(h);
      unlink(zFilename);
      return SQLITE_NOMEM;
    }
  } else {
    /*  pLock and pOpen are only used for posix advisory locking */
    f.pLock = NULL;
    f.pOpen = NULL;
  }
  if( delFlag ){
    unlink(zFilename);
  }
  f.dirfd = -1;