modules/hook_file/hook_file.module

<?php
// $Id$

/**
 *  @file
 *  Backport of the hook_file patch from Drupal 7 to 6.
 *  API for handling file uploads and server file management.
 */


/**
 * @defgroup file File interface
 * @{
 * Common file handling functions.
 *
 * Fields on the file object:
 * - fid - File ID
 * - uid - The {users}.uid of the user who is associated with the file.
 * - filename - Name of the file with no path components. This may differ from
 *   the basename of the filepath if the file is renamed to avoid overwriting
 *   an existing file.
 * - filepath - Path of the file relative to Drupal root.
 * - filemime - The file's MIME type.
 * - filesize - The size of the file in bytes.
 * - status - A bitmapped field indicating the status of the file the least
 *   sigifigant bit indicates temporary (1) or permanent (0). Temporary files
 *   older than DRUPAL_MAXIMUM_TEMP_FILE_AGE will be removed during a cron run.
 * - timestamp - UNIX timestamp for the date the file was added to the database.
 */

/**
 * Flag to indicate that the 'public' file download method is enabled.
 *
 * When using this method, files are available from a regular HTTP request,
 * which provides no additional access restrictions.
 */
// define('FILE_DOWNLOADS_PUBLIC', 1);

/**
 * Flag to indicate that the 'private' file download method is enabled.
 *
 * When using this method, all file requests are served by Drupal, during which
 * access-control checking can be performed.
 */
// define('FILE_DOWNLOADS_PRIVATE', 2);

/**
 * Flag used by hook_file_check_directory() -- create directory if not present.
 */
// define('FILE_CREATE_DIRECTORY', 1);

/**
 * Flag used by hook_file_check_directory() -- file permissions may be changed.
 */
// define('FILE_MODIFY_PERMISSIONS', 2);

/**
 * Flag for dealing with existing files: Appends number until name is unique.
 */
// define('FILE_EXISTS_RENAME', 0);

/**
 * Flag for dealing with existing files: Replace the existing file.
 */
// define('FILE_EXISTS_REPLACE', 1);

/**
 * Flag for dealing with existing files: Do nothing and return FALSE.
 */
// define('FILE_EXISTS_ERROR', 2);

/**
 * File status -- File has been temporarily saved to the {files} tables.
 *
 * Drupal's file garbage collection will delete the file and remove it from the
 * files table after a set period of time.
 */
// define('FILE_STATUS_TEMPORARY', 0);

/**
 * File status -- File has been permanently saved to the {files} tables.
 *
 * If you wish to add custom statuses for use by contrib modules please expand
 * as binary flags and consider the first 8 bits reserved.
 * (0,1,2,4,8,16,32,64,128).
 */
// define('FILE_STATUS_PERMANENT', 1);

/**
 * Create the download path to a file.
 *
 * @param $path A string containing the path of the file to generate URL for.
 * @return A string containing a URL that can be used to download the file.
 */
function hook_file_create_url($path) {
  // Strip hook_file_directory_path from $path. We only include relative paths in
  // URLs.
  if (strpos($path, hook_file_directory_path() . '/') === 0) {
    $path = trim(substr($path, strlen(hook_file_directory_path())), '\\/');
  }
  switch (variable_get('hook_file_downloads', FILE_DOWNLOADS_PUBLIC)) {
    case FILE_DOWNLOADS_PUBLIC:
      return $GLOBALS['base_url'] . '/' . hook_file_directory_path() . '/' . str_replace('\\', '/', $path);
    case FILE_DOWNLOADS_PRIVATE:
      return url('system/files/' . $path, array('absolute' => TRUE));
  }
}

/**
 * Make sure the destination is a complete path and resides in the file system
 * directory, if it is not prepend the file system directory.
 *
 * @param $destination
 *   A string containing the path to verify. If this value is omitted, Drupal's
 *   'files' directory will be used.
 * @return
 *   A string containing the path to file, with file system directory appended
 *   if necessary, or FALSE if the path is invalid (i.e. outside the configured
 *   'files' or temp directories).
 */
function hook_file_create_path($destination = NULL) {
  $hook_file_path = hook_file_directory_path();
  if (is_null($destination)) {
    return $hook_file_path;
  }
  // hook_file_check_location() checks whether the destination is inside the Drupal
  // files directory.
  if (hook_file_check_location($destination, $hook_file_path)) {
    return $destination;
  }
  // Check if the destination is instead inside the Drupal temporary files
  // directory.
  elseif (hook_file_check_location($destination, hook_file_directory_temp())) {
    return $destination;
  }
  // Not found, try again with prefixed directory path.
  elseif (hook_file_check_location($hook_file_path . '/' . $destination, $hook_file_path)) {
    return $hook_file_path . '/' . $destination;
  }
  // File not found.
  return FALSE;
}

/**
 * Check that the directory exists and is writable.
 *
 * Directories need to have execute permissions to be considered a directory by
 * FTP servers, etc.
 *
 * @param $directory
 *   A string containing the name of a directory path.
 * @param $mode
 *   A bitmask to indicate if the directory should be created if it does
 *   not exist (FILE_CREATE_DIRECTORY) or made writable if it is read-only
 *   (FILE_MODIFY_PERMISSIONS).
 * @param $form_item
 *   An optional string containing the name of a form item that any errors will
 *   be attached to. This is useful for settings forms that require the user to
 *   specify a writable directory. If it can't be made to work, a form error
 *   will be set preventing them from saving the settings.
 * @return
 *   FALSE when directory not found, or TRUE when directory exists.
 */
function hook_file_check_directory(&$directory, $mode = 0, $form_item = NULL) {
  $directory = rtrim($directory, '/\\');

  // Check if directory exists.
  if (!is_dir($directory)) {
    if (($mode & FILE_CREATE_DIRECTORY) && @mkdir($directory)) {
      @chmod($directory, 0775); // Necessary for non-webserver users.
    }
    else {
      if ($form_item) {
        form_set_error($form_item, t('The directory %directory does not exist.', array('%directory' => $directory)));
        watchdog('file system', 'The directory %directory does not exist.', array('%directory' => $directory), WATCHDOG_ERROR);
      }
      return FALSE;
    }
  }

  // Check to see if the directory is writable.
  if (!is_writable($directory)) {
    // If not able to modify permissions, or if able to, but chmod
    // fails, return false.
    if (!$mode || (($mode & FILE_MODIFY_PERMISSIONS) && !@chmod($directory, 0775))) {
      if ($form_item) {
        form_set_error($form_item, t('The directory %directory is not writable', array('%directory' => $directory)));
        watchdog('file system', 'The directory %directory is not writable, because it does not have the correct permissions set.', array('%directory' => $directory), WATCHDOG_ERROR);
      }
      return FALSE;
    }
  }

  if ((hook_file_directory_path() == $directory || hook_file_directory_temp() == $directory) && !is_file("$directory/.htaccess")) {
    $htaccess_lines = "SetHandler Drupal_Security_Do_Not_Remove_See_SA_2006_006\nOptions None\nOptions +FollowSymLinks";
    if (($fp = fopen("$directory/.htaccess", 'w')) && fputs($fp, $htaccess_lines)) {
      fclose($fp);
      chmod($directory . '/.htaccess', 0664);
    }
    else {
      $variables = array('%directory' => $directory, '!htaccess' => '<br />' . nl2br(check_plain($htaccess_lines)));
      form_set_error($form_item, t("Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines: <code>!htaccess</code>", $variables));
      watchdog('security', "Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines: <code>!htaccess</code>", $variables, WATCHDOG_ERROR);
    }
  }

  return TRUE;
}

/**
 * Checks path to see if it is a directory, or a directory/file.
 *
 * @param $path
 *   A string containing a file path. This will be set to the directory's path.
 * @return
 *   If the directory is not in a Drupal writable directory, FALSE is returned.
 *   Otherwise, the base name of the path is returned.
 */
function hook_file_check_path(&$path) {
  // Check if path is a directory.
  if (hook_file_check_directory($path)) {
    return '';
  }

  // Check if path is a possible dir/file.
  $filename = basename($path);
  $path = dirname($path);
  if (hook_file_check_directory($path)) {
    return $filename;
  }

  return FALSE;
}

/**
 * Check if a file is really located inside $directory.
 *
 * This should be used to make sure a file specified is really located within
 * the directory to prevent exploits. Note that the file or path being checked
 * does not actually need to exist yet.
 *
 * @code
 *   // Returns FALSE:
 *   hook_file_check_location('/www/example.com/files/../../../etc/passwd', '/www/example.com/files');
 * @endcode
 *
 * @param $source
 *   A string set to the file to check.
 * @param $directory
 *   A string where the file should be located.
 * @return
 *   FALSE if the path does not exist in the directory; otherwise, the real
 *   path of the source.
 */
function hook_file_check_location($source, $directory = '') {
  $check = realpath($source);
  if ($check) {
    $source = $check;
  }
  else {
    // This file does not yet exist.
    $source = realpath(dirname($source)) . '/' . basename($source);
  }
  $directory = realpath($directory);
  if ($directory && strpos($source, $directory) !== 0) {
    return FALSE;
  }
  return $source;
}

/**
 * Load a file object from the database.
 *
 * @param $param
 *   Either the id of a file or an array of conditions to match against in the
 *   database query.
 * @param $reset
 *   Whether to reset the internal hook_file_load cache.
 * @return
 *   A file object.
 *
 * @see hook_hook_file_load()
 */
function hook_file_load($param, $reset = NULL) {
  static $files = array();

  if ($reset) {
    $files = array();
  }

  if (is_numeric($param)) {
    if (isset($files[(string) $param])) {
      return is_object($files[$param]) ? clone $files[$param] : $files[$param];
    }
    $result = db_query('SELECT f.* FROM {files} f WHERE f.fid = :fid', array(':fid' => $param));
  }
  elseif (is_array($param)) {
    // Turn the conditions into a query.
    $cond = array();
    $arguments = array();
    foreach ($param as $key => $value) {
      $cond[] = 'f.' . db_escape_table($key) . " = '%s'";
      $arguments[] = $value;
    }
    $result = db_query('SELECT f.* FROM {files} f WHERE ' . implode(' AND ', $cond), $arguments);
  }
  else {
    return FALSE;
  }
  $file = $result->fetch(PDO::FETCH_OBJ);

  if ($file && $file->fid) {
    // Allow modules to add or change the file object.
    module_invoke_all('hook_file_load', $file);

    // Cache the fully loaded value.
    $files[(string) $file->fid] = clone $file;
  }

  return $file;
}

/**
 * Save a file object to the database.
 *
 * If the $file->fid is not set a new record will be added. Re-saving an
 * existing file will not change its status.
 *
 * @param $file
 *   A file object returned by hook_file_load().
 * @return
 *   The updated file object.
 *
 * @see hook_hook_file_insert()
 * @see hook_hook_file_update()
 */
function hook_file_save($file) {
  $file = (object)$file;
  $file->timestamp = REQUEST_TIME;
  $file->filesize = filesize($file->filepath);

  if (empty($file->fid)) {
    drupal_write_record('files', $file);
    // Inform modules about the newly added file.
    module_invoke_all('hook_file_insert', $file);
  }
  else {
    drupal_write_record('files', $file, 'fid');
    // Inform modules that the file has been updated.
    module_invoke_all('hook_file_update', $file);
  }

  return $file;
}

/**
 * Copy a file to a new location and adds a file record to the database.
 *
 * This function should be used when manipulating files that have records
 * stored in the database. This is a powerful function that in many ways
 * performs like an advanced version of copy().
 * - Checks if $source and $destination are valid and readable/writable.
 * - Checks that $source is not equal to $destination; if they are an error
 *   is reported.
 * - If file already exists in $destination either the call will error out,
 *   replace the file or rename the file based on the $replace parameter.
 * - Adds the new file to the files database. If the source file is a
 *   temporary file, the resulting file will also be a temporary file.
 *   @see hook_file_save_upload about temporary files.
 *
 * @param $source
 *   A file object.
 * @param $destination
 *   A string containing the directory $source should be copied to. If this
 *   value is omitted, Drupal's 'files' directory will be used.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *                          unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 * @return
 *   File object if the copy is successful, or FALSE in the event of an error.
 *
 * @see hook_file_unmanaged_copy()
 * @see hook_hook_file_copy()
 */
function hook_file_copy($source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  $source = (object)$source;

  if ($filepath = hook_file_unmanaged_copy($source->filepath, $destination, $replace)) {
    $file = clone $source;
    $file->fid      = NULL;
    $file->filename = basename($filepath);
    $file->filepath = $filepath;
    if ($file = hook_file_save($file)) {
      // Inform modules that the file has been copied.
      module_invoke_all('hook_file_copy', $file, $source);
      return $file;
    }
  }
  return FALSE;
}

/**
 * Copy a file to a new location without calling any hooks or making any
 * changes to the database.
 *
 * This is a powerful function that in many ways performs like an advanced
 * version of copy().
 * - Checks if $source and $destination are valid and readable/writable.
 * - Checks that $source is not equal to $destination; if they are an error
 *   is reported.
 * - If file already exists in $destination either the call will error out,
 *   replace the file or rename the file based on the $replace parameter.
 *
 * @param $source
 *   A string specifying the file location of the original file.
 * @param $destination
 *   A string containing the directory $source should be copied to. If this
 *   value is omitted, Drupal's 'files' directory will be used.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *                          unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 * @return
 *   The path to the new file, or FALSE in the event of an error.
 *
 * @see hook_file_copy()
 */
function hook_file_unmanaged_copy($source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  $source = realpath($source);
  if (!hook_file_exists($source)) {
    drupal_set_message(t('The specified file %file could not be copied, because no file by that name exists. Please check that you supplied the correct filename.', array('%file' => $source)), 'error');
    return FALSE;
  }

  $destination = hook_file_create_path($destination);
  $directory = $destination;
  $basename = hook_file_check_path($directory);

  // Make sure we at least have a valid directory.
  if ($basename === FALSE) {
    drupal_set_message(t('The specified file %file could not be copied, because the destination %directory is not properly configured.', array('%file' => $source, '%directory' => $destination)), 'error');
    return FALSE;
  }

  // If the destination file is not specified then use the filename of the
  // source file.
  $basename = $basename ? $basename : basename($source);
  $destination = hook_file_destination($directory . '/' . $basename, $replace);

  if ($destination === FALSE) {
    drupal_set_message(t('The specified file %file could not be copied because a file by that name already exists in the destination.', array('%file' => $source)), 'error');
    return FALSE;
  }
  // Make sure source and destination filenames are not the same, makes no
  // sense to copy it if they are. In fact copying the file will most likely
  // result in a 0 byte file. Which is bad. Real bad.
  if ($source == realpath($destination)) {
    drupal_set_message(t('The specified file %file was not copied because it would overwrite itself.', array('%file' => $source)), 'error');
    return FALSE;
  }
  if (!@copy($source, $destination)) {
    drupal_set_message(t('The specified file %file could not be copied.', array('%file' => $source)), 'error');
    return FALSE;
  }

  // Give everyone read access so that FTP'd users or
  // non-webserver users can see/read these files,
  // and give group write permissions so group members
  // can alter files uploaded by the webserver.
  @chmod($destination, 0664);

  return $destination;
}

/**
 * Determines the destination path for a file depending on how replacement of
 * existing files should be handled.
 *
 * @param $destination
 *   A string specifying the desired path.
 * @param $replace
 *   Replace behavior when the destination file already exists.
 *   - FILE_EXISTS_REPLACE - Replace the existing file.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *                          unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 * @return
 *   The destination file path or FALSE if the file already exists and
 *   FILE_EXISTS_ERROR was specified.
 */
function hook_file_destination($destination, $replace) {
  if (hook_file_exists($destination)) {
    switch ($replace) {
      case FILE_EXISTS_REPLACE:
        // Do nothing here, we want to overwrite the existing file.
        break;

      case FILE_EXISTS_RENAME:
        $basename = basename($destination);
        $directory = dirname($destination);
        $destination = hook_file_create_filename($basename, $directory);
        break;

      case FILE_EXISTS_ERROR:
        drupal_set_message(t('The specified file %file could not be copied, because a file by that name already exists in the destination.', array('%file' => $destination)), 'error');
        return FALSE;
    }
  }
  return $destination;
}

/**
 * Move a file to a new location and update the file's database entry.
 *
 * Moving a file is performed by copying the file to the new location and then
 * deleting the original.
 * - Checks if $source and $destination are valid and readable/writable.
 * - Performs a file move if $source is not equal to $destination.
 * - If file already exists in $destination either the call will error out,
 *   replace the file or rename the file based on the $replace parameter.
 * - Adds the new file to the files database.
 *
 * @param $source
 *   A file object.
 * @param $destination
 *   A string containing the directory $source should be copied to. If this
 *   value is omitted, Drupal's 'files' directory will be used.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *                          unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 * @return
 *   Resulting file object for success, or FALSE in the event of an error.
 *
 * @see hook_file_unmanaged_move()
 * @see hook_hook_file_move()
 */
function hook_file_move($source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  $source = (object)$source;

  if ($filepath = hook_file_unmanaged_move($source->filepath, $destination, $replace)) {
    $file = clone $source;
    $file->filename = basename($filepath);
    $file->filepath = $filepath;
    if ($file = hook_file_save($file)) {
      // Inform modules that the file has been moved.
      module_invoke_all('hook_file_move', $file, $source);
      return $file;
    }
    drupal_set_message(t('The removal of the original file %file has failed.', array('%file' => $source->filepath)), 'error');
  }
  return FALSE;
}

/**
 * Move a file to a new location without calling any hooks or making any
 * changes to the database.
 *
 * @param $source
 *   A string specifying the file location of the original file.
 * @param $destination
 *   A string containing the directory $source should be copied to. If this
 *   value is omitted, Drupal's 'files' directory will be used.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *                          unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 * @return
 *   The filepath of the moved file, or FALSE in the event of an error.
 *
 * @see hook_file_move()
 */
function hook_file_unmanaged_move($source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  $filepath = hook_file_unmanaged_copy($source, $destination, $replace);
  if ($filepath == FALSE || hook_file_unmanaged_delete($source) == FALSE) {
    return FALSE;
  }
  return $filepath;
}

/**
 * Munge the filename as needed for security purposes.
 *
 * For instance the file name "exploit.php.pps" would become "exploit.php_.pps".
 *
 * @param $filename
 *   The name of a file to modify.
 * @param $extensions
 *   A space separated list of extensions that should not be altered.
 * @param $alerts
 *   Whether alerts (watchdog, drupal_set_message()) should be displayed.
 * @return
 *   $filename The potentially modified $filename.
 */
function hook_file_munge_filename($filename, $extensions, $alerts = TRUE) {
  $original = $filename;

  // Allow potentially insecure uploads for very savvy users and admin
  if (!variable_get('allow_insecure_uploads', 0)) {
    $whitelist = array_unique(explode(' ', trim($extensions)));

    // Split the filename up by periods. The first part becomes the basename
    // the last part the final extension.
    $filename_parts = explode('.', $filename);
    $new_filename = array_shift($filename_parts); // Remove file basename.
    $final_extension = array_pop($filename_parts); // Remove final extension.

    // Loop through the middle parts of the name and add an underscore to the
    // end of each section that could be a file extension but isn't in the list
    // of allowed extensions.
    foreach ($filename_parts as $filename_part) {
      $new_filename .= '.' . $filename_part;
      if (!in_array($filename_part, $whitelist) && preg_match("/^[a-zA-Z]{2,5}\d?$/", $filename_part)) {
        $new_filename .= '_';
      }
    }
    $filename = $new_filename . '.' . $final_extension;

    if ($alerts && $original != $filename) {
      drupal_set_message(t('For security reasons, your upload has been renamed to %filename.', array('%filename' => $filename)));
    }
  }

  return $filename;
}

/**
 * Undo the effect of upload_munge_filename().
 *
 * @param $filename
 *   String with the filename to be unmunged.
 * @return
 *   An unmunged filename string.
 */
function hook_file_unmunge_filename($filename) {
  return str_replace('_.', '.', $filename);
}

/**
 * Create a full file path from a directory and filename.
 *
 * If a file with the specified name already exists, an alternative will be
 * used.
 *
 * @param $basename
 *   String filename
 * @param $directory
 *   String directory
 * @return
 *   File path consisting of $directory and a unique filename based off
 *   of $basename.
 */
function hook_file_create_filename($basename, $directory) {
  $destination = $directory . '/' . $basename;

  if (hook_file_exists($destination)) {
    // Destination file already exists, generate an alternative.
    $pos = strrpos($basename, '.');
    if ($pos !== FALSE) {
      $name = substr($basename, 0, $pos);
      $ext = substr($basename, $pos);
    }
    else {
      $name = $basename;
      $ext = '';
    }

    $counter = 0;
    do {
      $destination = $directory . '/' . $name . '_' . $counter++ . $ext;
    } while (hook_file_exists($destination));
  }

  return $destination;
}

/**
 * Delete a file and its database record.
 *
 * If the $force parameter is not TRUE hook_hook_file_references() will be called
 * to determine if the file is being used by any modules. If the file is being
 * used is the delete will be canceled.
 *
 * @param $file
 *   A file object.
 * @param $force
 *   Boolean indicating that the file should be deleted even if
 *   hook_hook_file_references() reports that the file is in use.
 * @return mixed
 *   TRUE for success, FALSE in the event of an error, or an array if the file
 *   is being used by another module. The array keys are the module's name and
 *   the values are the number of references.
 *
 * @see hook_file_unmanaged_delete()
 * @see hook_hook_file_references()
 * @see hook_hook_file_delete()
 */
function hook_file_delete($file, $force = FALSE) {
  $file = (object)$file;

  // If any module returns a value from the reference hook, the file will not
  // be deleted from Drupal, but hook_file_delete will return a populated array that
  // tests as TRUE.
  if (!$force && ($references = module_invoke_all('hook_file_references', $file))) {
    return $references;
  }

  // Let other modules clean up any references to the deleted file.
  module_invoke_all('hook_file_delete', $file);

  // Make sure the file is deleted before removing its row from the
  // database, so UIs can still find the file in the database.
  if (hook_file_unmanaged_delete($file->filepath)) {
    db_delete('files')->condition('fid', $file->fid)->execute();
    return TRUE;
  }
  return FALSE;
}

/**
 * Delete a file without calling any hooks or making any changes to the
 * database.
 *
 * This function should be used when the file to be deleted does not have an
 * entry recorded in the files table.
 *
 * @param $path
 *   A string containing a file path.
 * @return
 *   TRUE for success or path does not exist, or FALSE in the event of an
 *   error.
 *
 * @see hook_file_delete()
 */
function hook_file_unmanaged_delete($path) {
  if (is_dir($path)) {
    watchdog('file', '%path is a directory and cannot be removed using hook_file_unmanaged_delete().', array('%path' => $path), WATCHDOG_ERROR);
    return FALSE;
  }
  if (is_file($path)) {
    return unlink($path);
  }
  // Return TRUE for non-existant file, but log that nothing was actually
  // deleted, as the current state is the indended result.
  if (!hook_file_exists($path)) {
    watchdog('file', 'The file %path was not deleted, because it does not exist.', array('%path' => $path), WATCHDOG_NOTICE);
    return TRUE;
  }
  // Catch all for everything else: sockets, symbolic links, etc.
  return FALSE;
}

/**
 * Determine total disk space used by a single user or the whole filesystem.
 *
 * @param $uid
 *   Optional. A user id, specifying NULL returns the total space used by all
 *   non-temporary files.
 * @param $status
 *   Optional. File Status to return. Combine with a bitwise OR(|) to return
 *   multiple statuses. The default status is FILE_STATUS_PERMANENT.
 * @return
 *   An integer containing the number of bytes used.
 */
function hook_file_space_used($uid = NULL, $status = FILE_STATUS_PERMANENT) {
  if (!is_null($uid)) {
    return db_query('SELECT SUM(filesize) FROM {files} WHERE uid = :uid AND status = :status', array(':uid' => $uid, ':status' => $status))->fetchField();
  }
  return db_query('SELECT SUM(filesize) FROM {files} WHERE status = :status', array(':status' => $status))->fetchField();
}

/**
 * Saves a file upload to a new location.
 *
 * The file will be added to the files table as a temporary file. Temporary
 * files are periodically cleaned. To make the file a permanent file call
 * assign the status and use hook_file_save() to save it.
 *
 * @param $source
 *   A string specifying the name of the upload field to save.
 * @param $validators
 *   An optional, associative array of callback functions used to validate the
 *   file. See @hook_file_validate for a full discussion of the array format.
 * @param $destination
 *   A string containing the directory $source should be copied to. If this is
 *   not provided or is not writable, the temporary directory will be used.
 * @param $replace
 *   A boolean indicating whether an existing file of the same name in the
 *   destination directory should overwritten. A false value will generate a
 *   new, unique filename in the destination directory.
 * @return
 *   An object containing the file information, or FALSE in the event of an
 *   error.
 */
function hook_file_save_upload($source, $validators = array(), $destination = FALSE, $replace = FILE_EXISTS_RENAME) {
  global $user;
  static $upload_cache;

  // Return cached objects without processing since the file will have
  // already been processed and the paths in _FILES will be invalid.
  if (isset($upload_cache[$source])) {
    return $upload_cache[$source];
  }

  // Add in our check of the the file name length.
  $validators['hook_file_validate_name_length'] = array();


  // If a file was uploaded, process it.
  if (isset($_FILES['files']['name'][$source]) && is_uploaded_file($_FILES['files']['tmp_name'][$source])) {
    // Check for file upload errors and return FALSE if a lower level system
    // error occurred.
    switch ($_FILES['files']['error'][$source]) {
      // @see http://php.net/manual/en/features.file-upload.errors.php
      case UPLOAD_ERR_OK:
        break;

      case UPLOAD_ERR_INI_SIZE:
      case UPLOAD_ERR_FORM_SIZE:
        drupal_set_message(t('The file %file could not be saved, because it exceeds %maxsize, the maximum allowed size for uploads.', array('%file' => $source, '%maxsize' => format_size(hook_file_upload_max_size()))), 'error');
        return FALSE;

      case UPLOAD_ERR_PARTIAL:
      case UPLOAD_ERR_NO_FILE:
        drupal_set_message(t('The file %file could not be saved, because the upload did not complete.', array('%file' => $source)), 'error');
        return FALSE;

        // Unknown error
      default:
        drupal_set_message(t('The file %file could not be saved. An unknown error has occurred.', array('%file' => $source)), 'error');
        return FALSE;
    }

    // Build the list of non-munged extensions.
    // @todo: this should not be here. we need to figure out the right place.
    $extensions = '';
    foreach ($user->roles as $rid => $name) {
      $extensions .= ' ' . variable_get("upload_extensions_$rid",
      variable_get('upload_extensions_default', 'jpg jpeg gif png txt html doc xls pdf ppt pps odt ods odp'));
    }

    // Begin building file object.
    $file = new stdClass();
    $file->uid      = $user->uid;
    $file->status   = FILE_STATUS_TEMPORARY;
    $file->filename = hook_file_munge_filename(trim(basename($_FILES['files']['name'][$source]), '.'), $extensions);
    $file->filepath = $_FILES['files']['tmp_name'][$source];
    $file->filemime = hook_file_get_mimetype($file->filename);
    $file->filesize = $_FILES['files']['size'][$source];

    // Rename potentially executable files, to help prevent exploits.
    if (preg_match('/\.(php|pl|py|cgi|asp|js)$/i', $file->filename) && (substr($file->filename, -4) != '.txt')) {
      $file->filemime = 'text/plain';
      $file->filepath .= '.txt';
      $file->filename .= '.txt';
    }

    // If the destination is not provided, or is not writable, then use the
    // temporary directory.
    if (empty($destination) || hook_file_check_path($destination) === FALSE) {
      $destination = hook_file_directory_temp();
    }

    $file->source = $source;
    $file->destination = hook_file_destination(hook_file_create_path($destination . '/' . $file->filename), $replace);

    // Call the validation functions specified by this function's caller.
    $errors = hook_file_validate($file, $validators);

    // Check for errors.
    if (!empty($errors)) {
      $message = t('The specified file %name could not be uploaded.', array('%name' => $file->filename));
      if (count($errors) > 1) {
        $message .= theme('item_list', $errors);
      }
      else {
        $message .= ' ' . array_pop($errors);
      }
      form_set_error($source, $message);
      return FALSE;
    }

    // Move uploaded files from PHP's upload_tmp_dir to Drupal's temporary
    // directory. This overcomes open_basedir restrictions for future file
    // operations.
    $file->filepath = $file->destination;
    if (!move_uploaded_file($_FILES['files']['tmp_name'][$source], $file->filepath)) {
      form_set_error($source, t('File upload error. Could not move uploaded file.'));
      watchdog('file', 'Upload error. Could not move uploaded file %file to destination %destination.', array('%file' => $file->filename, '%destination' => $file->filepath));
      return FALSE;
    }

    // If we made it this far it's safe to record this file in the database.
    if ($file = hook_file_save($file)) {
      // Add file to the cache.
      $upload_cache[$source] = $file;
      return $file;
    }
  }
  return FALSE;
}


/**
 * Check that a file meets the criteria specified by the validators.
 *
 * After executing the validator callbacks specified hook_hook_file_validate() will
 * also be called to allow other modules to report errors about the file.
 *
 * @param $file
 *   A Drupal file object.
 * @param $validators
 *   An optional, associative array of callback functions used to validate the
 *   file. The keys are function names and the values arrays of callback
 *   parameters which will be passed in after the user and file objects. The
 *   functions should return an array of error messages, an empty array
 *   indicates that the file passed validation. The functions will be called in
 *   the order specified.
 * @return
 *   An array contaning validation error messages.
 *
 * @see hook_hook_file_validate()
 */
function hook_file_validate(&$file, $validators = array()) {
  // Call the validation functions specified by this function's caller.
  $errors = array();
  foreach ($validators as $function => $args) {
    array_unshift($args, $file);
    $errors = array_merge($errors, call_user_func_array($function, $args));
  }

  // Let other modules perform validation on the new file.
  return array_merge($errors, module_invoke_all('hook_file_validate', $file));
}

/**
 * Check for files with names longer than we can store in the database.
 *
 * @param $file
 *   A Drupal file object.
 * @return
 *   An array. If the file name is too long, it will contain an error message.
 */
function hook_file_validate_name_length($file) {
  $errors = array();

  if (empty($file->filename)) {
    $errors[] = t("The file's name is empty. Please give a name to the file.");
  }
  if (strlen($file->filename) > 255) {
    $errors[] = t("The file's name exceeds the 255 characters limit. Please rename the file and try again.");
  }
  return $errors;
}

/**
 * Check that the filename ends with an allowed extension.
 *
 * @param $file
 *   A Drupal file object.
 * @param $extensions
 *   A string with a space separated
 * @return
 *   An array. If the file extension is not allowed, it will contain an error
 *   message.
 *
 * @see hook_hook_file_validate()
 */
function hook_file_validate_extensions($file, $extensions) {
  global $user;

  $errors = array();

  $regex = '/\.(' . preg_replace('/ +/', '|', preg_quote($extensions)) . ')$/i';
  if (!preg_match($regex, $file->filename)) {
    $errors[] = t('Only files with the following extensions are allowed: %files-allowed.', array('%files-allowed' => $extensions));
  }
  return $errors;
}

/**
 * Check that the file's size is below certain limits.
 *
 * This check is not enforced for the user #1.
 *
 * @param $file
 *   A Drupal file object.
 * @param $hook_file_limit
 *   An integer specifying the maximum file size in bytes. Zero indicates that
 *   no limit should be enforced.
 * @param $user_limit
 *   An integer specifying the maximum number of bytes the user is allowed.
 *   Zero indicates that no limit should be enforced.
 * @return
 *   An array. If the file size exceeds limits, it will contain an error
 *   message.
 *
 * @see hook_hook_file_validate()
 */
function hook_file_validate_size($file, $hook_file_limit = 0, $user_limit = 0) {
  global $user;

  $errors = array();

  // Bypass validation for uid  = 1.
  if ($user->uid != 1) {
    if ($hook_file_limit && $file->filesize > $hook_file_limit) {
      $errors[] = t('The file is %filesize exceeding the maximum file size of %maxsize.', array('%filesize' => format_size($file->filesize), '%maxsize' => format_size($hook_file_limit)));
    }

    if ($user_limit && (hook_file_space_used($user->uid) + $file->filesize) > $user_limit) {
      $errors[] = t('The file is %filesize which would exceed your disk quota of %quota.', array('%filesize' => format_size($file->filesize), '%quota' => format_size($user_limit)));
    }
  }
  return $errors;
}

/**
 * Check that the file is recognized by image_get_info() as an image.
 *
 * @param $file
 *   A Drupal file object.
 * @return
 *   An array. If the file is not an image, it will contain an error message.
 *
 * @see hook_hook_file_validate()
 */
function hook_file_validate_is_image(&$file) {
  $errors = array();

  $info = image_get_info($file->filepath);
  if (!$info || empty($info['extension'])) {
    $errors[] = t('Only JPEG, PNG and GIF images are allowed.');
  }

  return $errors;
}

/**
 * If the file is an image verify that its dimensions are within the specified
 * maximum and minimum dimensions.
 *
 * Non-image files will be ignored. If a image toolkit is available the image
 * will be scalled to fit within the desired maximum dimensions.
 *
 * @param $file
 *   A Drupal file object. This function may resize the file affecting its
 *   size.
 * @param $maximum_dimensions
 *   An optional string in the form WIDTHxHEIGHT e.g. '640x480' or '85x85'. If
 *   an image toolkit is installed the image will be resized down to these
 *   dimensions. A value of 0 indicates no restriction on size, so resizing
 *   will be attempted.
 * @param $minimum_dimensions
 *   An optional string in the form WIDTHxHEIGHT. This will check that the
 *   image meets a minimum size. A value of 0 indicates no restriction.
 * @return
 *   An array. If the file is an image and did not meet the requirements, it
 *   will contain an error message.
 *
 * @see hook_hook_file_validate()
 */
function hook_file_validate_image_resolution(&$file, $maximum_dimensions = 0, $minimum_dimensions = 0) {
  $errors = array();

  // Check first that the file is an image.
  if ($info = image_get_info($file->filepath)) {
    if ($maximum_dimensions) {
      // Check that it is smaller than the given dimensions.
      list($width, $height) = explode('x', $maximum_dimensions);
      if ($info['width'] > $width || $info['height'] > $height) {
        // Try to resize the image to fit the dimensions.
        if (image_get_toolkit() && image_scale($file->filepath, $file->filepath, $width, $height)) {
          drupal_set_message(t('The image was resized to fit within the maximum allowed dimensions of %dimensions pixels.', array('%dimensions' => $maximum_dimensions)));

          // Clear the cached filesize and refresh the image information.
          clearstatcache();
          $info = image_get_info($file->filepath);
          $file->filesize = $info['hook_file_size'];
        }
        else {
          $errors[] = t('The image is too large; the maximum dimensions are %dimensions pixels.', array('%dimensions' => $maximum_dimensions));
        }
      }
    }

    if ($minimum_dimensions) {
      // Check that it is larger than the given dimensions.
      list($width, $height) = explode('x', $minimum_dimensions);
      if ($info['width'] < $width || $info['height'] < $height) {
        $errors[] = t('The image is too small; the minimum dimensions are %dimensions pixels.', array('%dimensions' => $minimum_dimensions));
      }
    }
  }

  return $errors;
}

/**
 * Save a string to the specified destination and create a database file entry.
 *
 * @param $data
 *   A string containing the contents of the file.
 * @param $destination
 *   A string containing the destination location. If no value is provided
 *   then a randomly name will be generated and the file saved in Drupal's
 *   files directory.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *                          unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 * @return
 *   A file object, or FALSE on error.
 *
 * @see hook_file_unmanaged_save_data()
 */
function hook_file_save_data($data, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  global $user;

  if ($filepath = hook_file_unmanaged_save_data($data, $destination, $replace)) {
    // Create a file object.
    $file = new stdClass();
    $file->filepath = $filepath;
    $file->filename = basename($file->filepath);
    $file->filemime = hook_file_get_mimetype($file->filepath);
    $file->uid      = $user->uid;
    $file->status   = FILE_STATUS_PERMANENT;
    return hook_file_save($file);
  }
  return FALSE;
}

/**
 * Save a string to the specified destination without calling any hooks or
 * making any changes to the database.
 *
 * This function is identical to hook_file_save_data() except the file will not be
 * saved to the files table and none of the hook_file_* hooks will be called.
 *
 * @param $data
 *   A string containing the contents of the file.
 * @param $destination
 *   A string containing the destination location. If no value is provided
 *   then a randomly name will be generated and the file saved in Drupal's
 *   files directory.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *                          unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 * @return
 *   A string with the path of the resulting file, or FALSE on error.
 *
 * @see hook_file_save_data()
 */
function hook_file_unmanaged_save_data($data, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  // Write the data to a temporary file.
  $temp_name = tempnam(hook_file_directory_temp(), 'file');
  if (hook_file_put_contents($temp_name, $data) === FALSE) {
    drupal_set_message(t('The file could not be created.'), 'error');
    return FALSE;
  }

  // Move the file to its final destination.
  return hook_file_unmanaged_move($temp_name, $destination, $replace);
}

/**
 * Transfer file using HTTP to client. Pipes a file through Drupal to the
 * client.
 *
 * @param $source
 *   String specifying the file path to transfer.
 * @param $headers
 *   An array of HTTP headers to send along with file.
 */
function hook_file_transfer($source, $headers) {
  if (ob_get_level()) {
    ob_end_clean();
  }

  foreach ($headers as $header) {
    // To prevent HTTP header injection, we delete new lines that are
    // not followed by a space or a tab.
    // See http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
    $header = preg_replace('/\r?\n(?!\t| )/', '', $header);
    drupal_set_header($header);
  }

  $source = hook_file_create_path($source);

  // Transfer file in 1024 byte chunks to save memory usage.
  if ($fd = fopen($source, 'rb')) {
    while (!feof($fd)) {
      print fread($fd, 1024);
    }
    fclose($fd);
  }
  else {
    drupal_not_found();
  }
  exit();
}

/**
 * Menu handler for private file transfers.
 *
 * Call modules that implement hook_hook_file_download() to find out if a file is
 * accessible and what headers it should be transferred with. If a module
 * returns -1 drupal_access_denied() will be returned. If one or more modules
 * returned headers the download will start with the returned headers. If no
 * modules respond drupal_not_found() will be returned.
 *
 * @see hook_hook_file_download()
 */
function hook_file_download() {
  // Merge remainder of arguments from GET['q'], into relative file path.
  $args = func_get_args();
  $filepath = implode('/', $args);

  // Maintain compatibility with old ?file=paths saved in node bodies.
  if (isset($_GET['file'])) {
    $filepath =  $_GET['file'];
  }

  if (hook_file_exists(hook_file_create_path($filepath))) {
    // Let other modules provide headers and controls access to the file.
    $headers = module_invoke_all('hook_file_download', $filepath);
    if (in_array(-1, $headers)) {
      return drupal_access_denied();
    }
    if (count($headers)) {
      hook_file_transfer($filepath, $headers);
    }
  }
  return drupal_not_found();
}


/**
 * Finds all files that match a given mask in a given directory.
 *
 * Directories and files beginning with a period are excluded; this
 * prevents hidden files and directories (such as SVN working directories)
 * from being scanned.
 *
 * @param $dir
 *   The base directory for the scan, without trailing slash.
 * @param $mask
 *   The preg_match() regular expression of the files to find.
 * @param $nomask
 *   The preg_match() regular expression of the files to ignore.
 * @param $callback
 *   The callback function to call for each match.
 * @param $recurse
 *   When TRUE, the directory scan will recurse the entire tree
 *   starting at the provided directory.
 * @param $key
 *   The key to be used for the returned array of files. Possible
 *   values are "filename", for the path starting with $dir,
 *   "basename", for the basename of the file, and "name" for the name
 *   of the file without an extension.
 * @param $min_depth
 *   Minimum depth of directories to return files from.
 * @param $depth
 *   Current depth of recursion. This parameter is only used internally and
 *   should not be passed.
 * @return
 *   An associative array (keyed on the provided key) of objects with
 *   "path", "basename", and "name" members corresponding to the
 *   matching files.
 */
function hook_file_scan_directory($dir, $mask, $nomask = '/(\.\.?|CVS)$/', $callback = 0, $recurse = TRUE, $key = 'filename', $min_depth = 0, $depth = 0) {
  $key = (in_array($key, array('filename', 'basename', 'name')) ? $key : 'filename');
  $files = array();

  if (is_dir($dir) && $handle = opendir($dir)) {
    while (FALSE !== ($file = readdir($handle))) {
      if (!preg_match($nomask, $file) && $file[0] != '.') {
        if (is_dir("$dir/$file") && $recurse) {
          // Give priority to files in this folder by merging them in after any subdirectory files.
          $files = array_merge(hook_file_scan_directory("$dir/$file", $mask, $nomask, $callback, $recurse, $key, $min_depth, $depth + 1), $files);
        }
        elseif ($depth >= $min_depth && preg_match($mask, $file)) {
          // Always use this match over anything already set in $files with the
          // same $$key.
          $filename = "$dir/$file";
          $basename = basename($file);
          $name = substr($basename, 0, strrpos($basename, '.'));
          $files[$$key] = new stdClass();
          $files[$$key]->filename = $filename;
          $files[$$key]->basename = $basename;
          $files[$$key]->name = $name;
          if ($callback) {
            $callback($filename);
          }
        }
      }
    }

    closedir($handle);
  }

  return $files;
}

/**
 * Determine the default temporary directory.
 *
 * @return
 *   A string containing a temp directory.
 */
function hook_file_directory_temp() {
  $temporary_directory = variable_get('hook_file_directory_temp', NULL);

  if (is_null($temporary_directory)) {
    $directories = array();

    // Has PHP been set with an upload_tmp_dir?
    if (ini_get('upload_tmp_dir')) {
      $directories[] = ini_get('upload_tmp_dir');
    }

    // Operating system specific dirs.
    if (substr(PHP_OS, 0, 3) == 'WIN') {
      $directories[] = 'c:/windows/temp';
      $directories[] = 'c:/winnt/temp';
    }
    else {
      $directories[] = '/tmp';
    }

    foreach ($directories as $directory) {
      if (!$temporary_directory && is_dir($directory)) {
        $temporary_directory = $directory;
      }
    }

    // if a directory has been found, use it, otherwise default to 'files/tmp'
    $temporary_directory = $temporary_directory ? $temporary_directory : hook_file_directory_path() . '/tmp';
    variable_set('hook_file_directory_temp', $temporary_directory);
  }

  return $temporary_directory;
}

/**
 * Determine the default 'files' directory.
 *
 * @return
 *   A string containing the path to Drupal's 'files' directory.
 */
function hook_file_directory_path()