Club Drupal

<?php

/**

 * @file

 * Drupal stream wrapper interface.

 *

 * Provides a Drupal interface and classes to implement PHP stream wrappers for

 * public, private, and temporary files.

 *

 * A stream wrapper is an abstraction of a file system that allows Drupal to

 * use the same set of methods to access both local files and remote resources.

 *

 * Note that PHP 5.2 fopen() only supports URIs of the form "scheme://target"

 * despite the fact that according to RFC 3986 a URI's scheme component

 * delimiter is in general just ":", not "://".  Because of this PHP limitation

 * and for consistency Drupal will only accept URIs of form "scheme://target".

 *

 * @see http://www.faqs.org/rfcs/rfc3986.html

 * @see http://bugs.php.net/bug.php?id=47070

 */

/**

 * Stream wrapper bit flags that are the basis for composite types.

 *

 * Note that 0x0002 is skipped, because it was the value of a constant that has

 * since been removed.

 */

/**

 * Stream wrapper bit flag -- a filter that matches all wrappers.

 */

define('STREAM_WRAPPERS_ALL', 0x0000);

/**

 * Stream wrapper bit flag -- refers to a local file system location.

 */

define('STREAM_WRAPPERS_LOCAL', 0x0001);

/**

 * Stream wrapper bit flag -- wrapper is readable (almost always true).

 */

define('STREAM_WRAPPERS_READ', 0x0004);

/**

 * Stream wrapper bit flag -- wrapper is writeable.

 */

define('STREAM_WRAPPERS_WRITE', 0x0008);

/**

 * Stream wrapper bit flag -- exposed in the UI and potentially web accessible.

 */

define('STREAM_WRAPPERS_VISIBLE', 0x0010);

/**

 * Composite stream wrapper bit flags that are usually used as the types.

 */

/**

 * Stream wrapper type flag -- not visible in the UI or accessible via web,

 * but readable and writable. E.g. the temporary directory for uploads.

 */

define('STREAM_WRAPPERS_HIDDEN', STREAM_WRAPPERS_READ | STREAM_WRAPPERS_WRITE);

/**

 * Stream wrapper type flag -- hidden, readable and writeable using local files.

 */

define('STREAM_WRAPPERS_LOCAL_HIDDEN', STREAM_WRAPPERS_LOCAL | STREAM_WRAPPERS_HIDDEN);

/**

 * Stream wrapper type flag -- visible, readable and writeable.

 */

define('STREAM_WRAPPERS_WRITE_VISIBLE', STREAM_WRAPPERS_READ | STREAM_WRAPPERS_WRITE | STREAM_WRAPPERS_VISIBLE);

/**

 * Stream wrapper type flag -- visible and read-only.

 */

define('STREAM_WRAPPERS_READ_VISIBLE', STREAM_WRAPPERS_READ | STREAM_WRAPPERS_VISIBLE);

/**

 * Stream wrapper type flag -- the default when 'type' is omitted from

 * hook_stream_wrappers(). This does not include STREAM_WRAPPERS_LOCAL,

 * because PHP grants a greater trust level to local files (for example, they

 * can be used in an "include" statement, regardless of the "allow_url_include"

 * setting), so stream wrappers need to explicitly opt-in to this.

 */

define('STREAM_WRAPPERS_NORMAL', STREAM_WRAPPERS_WRITE_VISIBLE);

/**

 * Stream wrapper type flag -- visible, readable and writeable using local files.

 */

define('STREAM_WRAPPERS_LOCAL_NORMAL', STREAM_WRAPPERS_LOCAL | STREAM_WRAPPERS_NORMAL);

/**

 * Generic PHP stream wrapper interface.

 *

 * @see http://www.php.net/manual/class.streamwrapper.php

 */

interface StreamWrapperInterface {

  public function stream_open($uri, $mode, $options, &$opened_url);

  public function stream_close();

  public function stream_lock($operation);

  public function stream_read($count);

  public function stream_write($data);

  public function stream_eof();

  public function stream_seek($offset, $whence);

  public function stream_flush();

  public function stream_tell();

  public function stream_stat();

  public function unlink($uri);

  public function rename($from_uri, $to_uri);

  public function mkdir($uri, $mode, $options);

  public function rmdir($uri, $options);

  public function url_stat($uri, $flags);

  public function dir_opendir($uri, $options);

  public function dir_readdir();

  public function dir_rewinddir();

  public function dir_closedir();

}

/**

 * Drupal stream wrapper extension.

 *

 * Extend the StreamWrapperInterface with methods expected by Drupal stream

 * wrapper classes.

 */

interface DrupalStreamWrapperInterface extends StreamWrapperInterface {

  /**

   * Set the absolute stream resource URI.

   *

   * This allows you to set the URI. Generally is only called by the factory

   * method.

   *

   * @param $uri

   *   A string containing the URI that should be used for this instance.

   */

  public function setUri($uri);

  /**

   * Returns the stream resource URI.

   *

   * @return

   *   Returns the current URI of the instance.

   */

  public function getUri();

  /**

   * Returns a web accessible URL for the resource.

   *

   * This function should return a URL that can be embedded in a web page

   * and accessed from a browser. For example, the external URL of

   * "youtube://xIpLd0WQKCY" might be

   * "http://www.youtube.com/watch?v=xIpLd0WQKCY".

   *

   * @return

   *   Returns a string containing a web accessible URL for the resource.

   */

  public function getExternalUrl();

  /**

   * Returns the MIME type of the resource.

   *

   * @param $uri

   *   The URI, path, or filename.

   * @param $mapping

   *   An optional map of extensions to their mimetypes, in the form:

   *    - 'mimetypes': a list of mimetypes, keyed by an identifier,

   *    - 'extensions': the mapping itself, an associative array in which

   *      the key is the extension and the value is the mimetype identifier.

   *

   * @return

   *   Returns a string containing the MIME type of the resource.

   */

  public static function getMimeType($uri, $mapping = NULL);

  /**

   * Changes permissions of the resource.

   *

   * PHP lacks this functionality and it is not part of the official stream

   * wrapper interface. This is a custom implementation for Drupal.

   *

   * @param $mode

   *   Integer value for the permissions. Consult PHP chmod() documentation

   *   for more information.

   *

   * @return

   *   Returns TRUE on success or FALSE on failure.

   */

  public function chmod($mode);

  /**

   * Returns canonical, absolute path of the resource.

   *

   * Implementation placeholder. PHP's realpath() does not support stream

   * wrappers. We provide this as a default so that individual wrappers may

   * implement their own solutions.

   *

   * @return

   *   Returns a string with absolute pathname on success (implemented

   *   by core wrappers), or FALSE on failure or if the registered

   *   wrapper does not provide an implementation.

   */

  public function realpath();

  /**

   * Gets the name of the directory from a given path.

   *

   * This method is usually accessed through drupal_dirname(), which wraps

   * around the normal PHP dirname() function, which does not support stream

   * wrappers.

   *

   * @param $uri

   *   An optional URI.

   *

   * @return

   *   A string containing the directory name, or FALSE if not applicable.

   *

   * @see drupal_dirname()

   */

  public function dirname($uri = NULL);

}

/**

 * Drupal stream wrapper base class for local files.

 *

 * This class provides a complete stream wrapper implementation. URIs such as

 * "public://example.txt" are expanded to a normal filesystem path such as

 * "sites/default/files/example.txt" and then PHP filesystem functions are

 * invoked.

 *

 * DrupalLocalStreamWrapper implementations need to implement at least the

 * getDirectoryPath() and getExternalUrl() methods.

 */

abstract class DrupalLocalStreamWrapper implements DrupalStreamWrapperInterface {

  /**

   * Stream context resource.

   *

   * @var Resource

   */

  public $context;

  /**

   * A generic resource handle.

   *

   * @var Resource

   */

  public $handle = NULL;

  /**

   * Instance URI (stream).

   *

   * A stream is referenced as "scheme://target".

   *

   * @var String

   */

  protected $uri;

  /**

   * Gets the path that the wrapper is responsible for.

   * @TODO: Review this method name in D8 per http://drupal.org/node/701358

   *

   * @return

   *   String specifying the path.

   */

  abstract function getDirectoryPath();

  /**

   * Base implementation of setUri().

   */

  function setUri($uri) {

    $this->uri = $uri;

  }

  /**

   * Base implementation of getUri().

   */

  function getUri() {

    return $this->uri;

  }

  /**

   * Returns the local writable target of the resource within the stream.

   *

   * This function should be used in place of calls to realpath() or similar

   * functions when attempting to determine the location of a file. While

   * functions like realpath() may return the location of a read-only file, this

   * method may return a URI or path suitable for writing that is completely

   * separate from the URI used for reading.

   *

   * @param $uri

   *   Optional URI.

   *

   * @return

   *   Returns a string representing a location suitable for writing of a file,

   *   or FALSE if unable to write to the file such as with read-only streams.

   */

  protected function getTarget($uri = NULL) {

    if (!isset($uri)) {

      $uri = $this->uri;

    }

    list($scheme, $target) = explode('://', $uri, 2);

    // Remove erroneous leading or trailing, forward-slashes and backslashes.

    return trim($target, '\/');

  }

  /**

   * Base implementation of getMimeType().

   */

  static function getMimeType($uri, $mapping = NULL) {

    if (!isset($mapping)) {

      // The default file map, defined in file.mimetypes.inc is quite big.

      // We only load it when necessary.

      include_once DRUPAL_ROOT . '/includes/file.mimetypes.inc';

      $mapping = file_mimetype_mapping();

    }

    $extension = '';

    $file_parts = explode('.', drupal_basename($uri));

    // Remove the first part: a full filename should not match an extension.

    array_shift($file_parts);

    // Iterate over the file parts, trying to find a match.

    // For my.awesome.image.jpeg, we try:

    //   - jpeg

    //   - image.jpeg, and

    //   - awesome.image.jpeg

    while ($additional_part = array_pop($file_parts)) {

      $extension = strtolower($additional_part . ($extension ? '.' . $extension : ''));

      if (isset($mapping['extensions'][$extension])) {

        return $mapping['mimetypes'][$mapping['extensions'][$extension]];

      }

    }

    return 'application/octet-stream';

  }

  /**

   * Base implementation of chmod().

   */

  function chmod($mode) {

    $output = @chmod($this->getLocalPath(), $mode);

    // We are modifying the underlying file here, so we have to clear the stat

    // cache so that PHP understands that URI has changed too.

    clearstatcache();

    return $output;

  }

  /**

   * Base implementation of realpath().

   */

  function realpath() {

    return $this->getLocalPath();

  }

  /**

   * Returns the canonical absolute path of the URI, if possible.

   *

   * @param string $uri

   *   (optional) The stream wrapper URI to be converted to a canonical

   *   absolute path. This may point to a directory or another type of file.

   *

   * @return string|false

   *   If $uri is not set, returns the canonical absolute path of the URI

   *   previously set by the DrupalStreamWrapperInterface::setUri() function.

   *   If $uri is set and valid for this class, returns its canonical absolute

   *   path, as determined by the realpath() function. If $uri is set but not

   *   valid, returns FALSE.

   */

  protected function getLocalPath($uri = NULL) {

    if (!isset($uri)) {

      $uri = $this->uri;

    }

    $path = $this->getDirectoryPath() . '/' . $this->getTarget($uri);

    $realpath = realpath($path);

    if (!$realpath) {

      // This file does not yet exist.

      $realpath = realpath(dirname($path)) . '/' . drupal_basename($path);

    }

    $directory = realpath($this->getDirectoryPath());

    if (!$realpath || !$directory || strpos($realpath, $directory) !== 0) {

      return FALSE;

    }

    return $realpath;

  }

  /**

   * Support for fopen(), file_get_contents(), file_put_contents() etc.

   *

   * @param $uri

   *   A string containing the URI to the file to open.

   * @param $mode

   *   The file mode ("r", "wb" etc.).

   * @param $options

   *   A bit mask of STREAM_USE_PATH and STREAM_REPORT_ERRORS.

   * @param $opened_path

   *   A string containing the path actually opened.

   *

   * @return

   *   Returns TRUE if file was opened successfully.

   *

   * @see http://php.net/manual/streamwrapper.stream-open.php

   */

  public function stream_open($uri, $mode, $options, &$opened_path) {

    $this->uri = $uri;

    $path = $this->getLocalPath();

    $this->handle = ($options & STREAM_REPORT_ERRORS) ? fopen($path, $mode) : @fopen($path, $mode);

    if ((bool) $this->handle && $options & STREAM_USE_PATH) {

      $opened_path = $path;

    }

    return (bool) $this->handle;

  }

  /**

   * Support for flock().

   *

   * @param $operation

   *   One of the following:

   *   - LOCK_SH to acquire a shared lock (reader).

   *   - LOCK_EX to acquire an exclusive lock (writer).

   *   - LOCK_UN to release a lock (shared or exclusive).

   *   - LOCK_NB if you don't want flock() to block while locking (not

   *     supported on Windows).

   *

   * @return

   *   Always returns TRUE at the present time.

   *

   * @see http://php.net/manual/streamwrapper.stream-lock.php

   */

  public function stream_lock($operation) {

    if (in_array($operation, array(LOCK_SH, LOCK_EX, LOCK_UN, LOCK_NB))) {

      return flock($this->handle, $operation);

    }

    return TRUE;

  }

  /**

   * Support for fread(), file_get_contents() etc.

   *

   * @param $count

   *   Maximum number of bytes to be read.

   *

   * @return

   *   The string that was read, or FALSE in case of an error.

   *

   * @see http://php.net/manual/streamwrapper.stream-read.php

   */

  public function stream_read($count) {

    return fread($this->handle, $count);

  }

  /**

   * Support for fwrite(), file_put_contents() etc.

   *

   * @param $data

   *   The string to be written.

   *

   * @return

   *   The number of bytes written (integer).

   *

   * @see http://php.net/manual/streamwrapper.stream-write.php

   */

  public function stream_write($data) {

    return fwrite($this->handle, $data);

  }

  /**

   * Support for feof().

   *

   * @return

   *   TRUE if end-of-file has been reached.

   *

   * @see http://php.net/manual/streamwrapper.stream-eof.php

   */

  public function stream_eof() {

    return feof($this->handle);

  }

  /**

   * Support for fseek().

   *

   * @param $offset

   *   The byte offset to got to.

   * @param $whence

   *   SEEK_SET, SEEK_CUR, or SEEK_END.

   *

   * @return

   *   TRUE on success.

   *

   * @see http://php.net/manual/streamwrapper.stream-seek.php

   */

  public function stream_seek($offset, $whence) {

    // fseek returns 0 on success and -1 on a failure.

    // stream_seek   1 on success and  0 on a failure.

    return !fseek($this->handle, $offset, $whence);

  }

  /**

   * Support for fflush().

   *

   * @return

   *   TRUE if data was successfully stored (or there was no data to store).

   *

   * @see http://php.net/manual/streamwrapper.stream-flush.php

   */

  public function stream_flush() {

    return fflush($this->handle);

  }

  /**

   * Support for ftell().

   *

   * @return

   *   The current offset in bytes from the beginning of file.

   *

   * @see http://php.net/manual/streamwrapper.stream-tell.php

   */

  public function stream_tell() {

    return ftell($this->handle);

  }

  /**

   * Support for fstat().

   *

   * @return

   *   An array with file status, or FALSE in case of an error - see fstat()

   *   for a description of this array.

   *

   * @see http://php.net/manual/streamwrapper.stream-stat.php

   */

  public function stream_stat() {

    return fstat($this->handle);

  }

  /**

   * Support for fclose().

   *

   * @return

   *   TRUE if stream was successfully closed.

   *

   * @see http://php.net/manual/streamwrapper.stream-close.php

   */

  public function stream_close() {

    return fclose($this->handle);

  }

  /**

   * Sets metadata on the stream.

   *

   * WARNING: Do not call this method directly! It will be called internally by

   * PHP itself when one of the following functions is called on a stream URL:

   *

   * @param string $uri

   *   A string containing the URI to the file to set metadata on.

   * @param int $option

   *   One of:

   *   - STREAM_META_TOUCH: The method was called in response to touch().

   *   - STREAM_META_OWNER_NAME: The method was called in response to chown()

   *     with string parameter.

   *   - STREAM_META_OWNER: The method was called in response to chown().

   *   - STREAM_META_GROUP_NAME: The method was called in response to chgrp().

   *   - STREAM_META_GROUP: The method was called in response to chgrp().

   *   - STREAM_META_ACCESS: The method was called in response to chmod().

   * @param mixed $value

   *   If option is:

   *   - STREAM_META_TOUCH: Array consisting of two arguments of the touch()

   *     function.

   *   - STREAM_META_OWNER_NAME or STREAM_META_GROUP_NAME: The name of the owner

   *     user/group as string.

   *   - STREAM_META_OWNER or STREAM_META_GROUP: The value of the owner

   *     user/group as integer.

   *   - STREAM_META_ACCESS: The argument of the chmod() as integer.

   *

   * @return bool

   *   Returns TRUE on success or FALSE on failure. If $option is not

   *   implemented, FALSE should be returned.

   *

   * @see touch()

   * @see chmod()

   * @see chown()

   * @see chgrp()

   * @link http://php.net/manual/streamwrapper.stream-metadata.php

   */

  public function stream_metadata($uri, $option, $value) {

    $target = $this->getLocalPath($uri);

    $return = FALSE;

    switch ($option) {

      case STREAM_META_TOUCH:

        if (!empty($value)) {

          $return = touch($target, $value[0], $value[1]);

        }

        else {

          $return = touch($target);

        }

        break;

      case STREAM_META_OWNER_NAME:

      case STREAM_META_OWNER:

        $return = chown($target, $value);

        break;

      case STREAM_META_GROUP_NAME:

      case STREAM_META_GROUP:

        $return = chgrp($target, $value);

        break;

      case STREAM_META_ACCESS:

        $return = chmod($target, $value);

        break;

    }

    if ($return) {

      // For convenience clear the file status cache of the underlying file,

      // since metadata operations are often followed by file status checks.

      clearstatcache(TRUE, $target);

    }

    return $return;

  }

  /**

   * Truncate stream.

   *

   * Will respond to truncation; e.g., through ftruncate().

   *

   * @param int $new_size

   *   The new size.

   *

   * @return bool

   *   TRUE on success, FALSE otherwise.

   */

  public function stream_truncate($new_size) {

    return ftruncate($this->handle, $new_size);

  }

  /**

   * Retrieve the underlying stream resource.

   *

   * This method is called in response to stream_select().

   *

   * @param int $cast_as

   *   Can be STREAM_CAST_FOR_SELECT when stream_select() is calling

   *   stream_cast() or STREAM_CAST_AS_STREAM when stream_cast() is called for

   *   other uses.

   *

   * @return resource|false

   *   The underlying stream resource or FALSE if stream_select() is not

   *   supported.

   *

   * @see stream_select()

   * @link http://php.net/manual/streamwrapper.stream-cast.php

   */

  public function stream_cast($cast_as) {

    return $this->handle ? $this->handle : FALSE;

  }

  /**

   * Change stream options.

   *

   * This method is called to set options on the stream.

   *

   * Since Windows systems do not allow it and it is not needed for most use

   * cases anyway, this method is not supported on local files and will trigger

   * an error and return false. If needed, custom subclasses can provide

   * OS-specific implementations for advanced use cases.

   *

   * @param int $option

   *   One of:

   *   - STREAM_OPTION_BLOCKING: The method was called in response to

   *     stream_set_blocking().

   *   - STREAM_OPTION_READ_TIMEOUT: The method was called in response to

   *     stream_set_timeout().

   *   - STREAM_OPTION_WRITE_BUFFER: The method was called in response to

   *     stream_set_write_buffer().

   * @param int $arg1

   *   If option is:

   *   - STREAM_OPTION_BLOCKING: The requested blocking mode:

   *     - 1 means blocking.

   *     - 0 means not blocking.

   *   - STREAM_OPTION_READ_TIMEOUT: The timeout in seconds.

   *   - STREAM_OPTION_WRITE_BUFFER: The buffer mode, STREAM_BUFFER_NONE or

   *     STREAM_BUFFER_FULL.

   * @param int $arg2

   *   If option is:

   *   - STREAM_OPTION_BLOCKING: This option is not set.

   *   - STREAM_OPTION_READ_TIMEOUT: The timeout in microseconds.

   *   - STREAM_OPTION_WRITE_BUFFER: The requested buffer size.

   *

   * @return bool

   *   TRUE on success, FALSE otherwise. If $option is not implemented, FALSE

   *   should be returned.

   */

  public function stream_set_option($option, $arg1, $arg2) {

    trigger_error('stream_set_option() not supported for local file based stream wrappers', E_USER_WARNING);

    return FALSE;

  }

  /**

   * Support for unlink().

   *

   * @param $uri

   *   A string containing the URI to the resource to delete.

   *

   * @return

   *   TRUE if resource was successfully deleted.

   *

   * @see http://php.net/manual/streamwrapper.unlink.php

   */

  public function unlink($uri) {

    $this->uri = $uri;

    return drupal_unlink($this->getLocalPath());

  }

  /**

   * Support for rename().

   *

   * @param $from_uri,

   *   The URI to the file to rename.

   * @param $to_uri

   *   The new URI for file.

   *

   * @return

   *   TRUE if file was successfully renamed.

   *

   * @see http://php.net/manual/streamwrapper.rename.php

   */

  public function rename($from_uri, $to_uri) {

    return rename($this->getLocalPath($from_uri), $this->getLocalPath($to_uri));

  }

  /**

   * Gets the name of the directory from a given path.

   *

   * This method is usually accessed through drupal_dirname(), which wraps

   * around the PHP dirname() function because it does not support stream

   * wrappers.

   *

   * @param $uri

   *   A URI or path.

   *

   * @return

   *   A string containing the directory name.

   *

   * @see drupal_dirname()

   */

  public function dirname($uri = NULL) {

    list($scheme, $target) = explode('://', $uri, 2);

    $target  = $this->getTarget($uri);

    $dirname = dirname($target);

    if ($dirname == '.') {

      $dirname = '';

    }

    return $scheme . '://' . $dirname;

  }

  /**

   * Support for mkdir().

   *

   * @param $uri

   *   A string containing the URI to the directory to create.

   * @param $mode

   *   Permission flags - see mkdir().

   * @param $options

   *   A bit mask of STREAM_REPORT_ERRORS and STREAM_MKDIR_RECURSIVE.

   *

   * @return

   *   TRUE if directory was successfully created.

   *

   * @see http://php.net/manual/streamwrapper.mkdir.php

   */

  public function mkdir($uri, $mode, $options) {

    $this->uri = $uri;

    $recursive = (bool) ($options & STREAM_MKDIR_RECURSIVE);

    if ($recursive) {

      // $this->getLocalPath() fails if $uri has multiple levels of directories

      // that do not yet exist.

      $localpath = $this->getDirectoryPath() . '/' . $this->getTarget($uri);

    }

    else {

      $localpath = $this->getLocalPath($uri);

    }

    if ($options & STREAM_REPORT_ERRORS) {

      return mkdir($localpath, $mode, $recursive);

    }

    else {

      return @mkdir($localpath, $mode, $recursive);

    }

  }

  /**

   * Support for rmdir().

   *

   * @param $uri

   *   A string containing the URI to the directory to delete.

   * @param $options

   *   A bit mask of STREAM_REPORT_ERRORS.

   *

   * @return

   *   TRUE if directory was successfully removed.

   *

   * @see http://php.net/manual/streamwrapper.rmdir.php

   */

  public function rmdir($uri, $options) {

    $this->uri = $uri;

    if ($options & STREAM_REPORT_ERRORS) {

      return drupal_rmdir($this->getLocalPath());

    }

    else {

      return @drupal_rmdir($this->getLocalPath());

    }

  }

  /**

   * Support for stat().

   *

   * @param $uri

   *   A string containing the URI to get information about.

   * @param $flags

   *   A bit mask of STREAM_URL_STAT_LINK and STREAM_URL_STAT_QUIET.

   *

   * @return

   *   An array with file status, or FALSE in case of an error - see fstat()

   *   for a description of this array.

   *

   * @see http://php.net/manual/streamwrapper.url-stat.php

   */

  public function url_stat($uri, $flags) {

    $this->uri = $uri;

    $path = $this->getLocalPath();

    // Suppress warnings if requested or if the file or directory does not

    // exist. This is consistent with PHP's plain filesystem stream wrapper.

    if ($flags & STREAM_URL_STAT_QUIET || !file_exists($path)) {

      return @stat($path);

    }

    else {

      return stat($path);

    }

  }

  /**

   * Support for opendir().

   *

   * @param $uri

   *   A string containing the URI to the directory to open.

   * @param $options

   *   Unknown (parameter is not documented in PHP Manual).

   *

   * @return

   *   TRUE on success.

   *

   * @see http://php.net/manual/streamwrapper.dir-opendir.php

   */

  public function dir_opendir($uri, $options) {

    $this->uri = $uri;

    $this->handle = opendir($this->getLocalPath());

    return (bool) $this->handle;

  }

  /**

   * Support for readdir().

   *

   * @return

   *   The next filename, or FALSE if there are no more files in the directory.

   *

   * @see http://php.net/manual/streamwrapper.dir-readdir.php

   */

  public function dir_readdir() {

    return readdir($this->handle);

  }

  /**

   * Support for rewinddir().

   *

   * @return

   *   TRUE on success.

   *

   * @see http://php.net/manual/streamwrapper.dir-rewinddir.php

   */

  public function dir_rewinddir() {

    rewinddir($this->handle);

    // We do not really have a way to signal a failure as rewinddir() does not

    // have a return value and there is no way to read a directory handler

    // without advancing to the next file.

    return TRUE;

  }

  /**

   * Support for closedir().

   *

   * @return

   *   TRUE on success.

   *

   * @see http://php.net/manual/streamwrapper.dir-closedir.php

   */

  public function dir_closedir() {

    closedir($this->handle);

    // We do not really have a way to signal a failure as closedir() does not

    // have a return value.

    return TRUE;

  }

}

/**

 * Drupal public (public://) stream wrapper class.

 *

 * Provides support for storing publicly accessible files with the Drupal file

 * interface.

 */

class DrupalPublicStreamWrapper extends DrupalLocalStreamWrapper {

  /**

   * Implements abstract public function getDirectoryPath()

   */

  public function getDirectoryPath() {

    return variable_get('file_public_path', conf_path() . '/files');

  }

  /**

   * Overrides getExternalUrl().

   *

   * Return the HTML URI of a public file.

   */

  function getExternalUrl() {

    $path = str_replace('\\', '/', $this->getTarget());

    return $GLOBALS['base_url'] . '/' . self::getDirectoryPath() . '/' . drupal_encode_path($path);

  }

}

/**

 * Drupal private (private://) stream wrapper class.

 *

 * Provides support for storing privately accessible files with the Drupal file

 * interface.

 */

class DrupalPrivateStreamWrapper extends DrupalLocalStreamWrapper {

  /**

   * Implements abstract public function getDirectoryPath()

   */

  public function getDirectoryPath() {

    return variable_get('file_private_path', '');

  }

  /**

   * Overrides getExternalUrl().

   *

   * Return the HTML URI of a private file.

   */

  function getExternalUrl() {

    $path = str_replace('\\', '/', $this->getTarget());

    return url('system/files/' . $path, array('absolute' => TRUE));

  }

}

/**

 * Drupal temporary (temporary://) stream wrapper class.

 *

 * Provides support for storing temporarily accessible files with the Drupal

 * file interface.

 *

 * Extends DrupalPublicStreamWrapper.

 */

class DrupalTemporaryStreamWrapper extends DrupalLocalStreamWrapper {

  /**

   * Implements abstract public function getDirectoryPath()

   */

  public function getDirectoryPath() {

    return variable_get('file_temporary_path', file_directory_temp());

  }

  /**

   * Overrides getExternalUrl().

   */

  public function getExternalUrl() {

    $path = str_replace('\\', '/', $this->getTarget());

    return url('system/temporary/' . $path, array('absolute' => TRUE));

  }

}