- Patch #227232 by dopry, c960657, jmstacey, pwolanin, aaron, drewish: added initial support for PHP file wrappers.

3 files changed, 845 insertions, 1 deletions

diff --git a/includes/common.inc b/includes/common.inc
index bca164c1f..c7104187f 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -3451,7 +3451,8 @@ function _drupal_bootstrap_full() {
   fix_gpc_magic();
   // Load all enabled modules
   module_load_all();
-
+  // Make sure all stream wrappers are registered.
+  file_get_stream_wrappers();
   // Let all modules take action before menu system handles the request
   // We do not want this while running update.php.
   if (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update') {
diff --git a/includes/file.inc b/includes/file.inc
index 5478e8748..2b94ae03d 100644
--- a/includes/file.inc
+++ b/includes/file.inc
@@ -7,6 +7,13 @@
  */
 
 /**
+ * Stream wrapper code is included here because there are cases where
+ * File API is needed before a bootstrap, or in an alternate order (e.g.
+ * maintenance theme).
+ */
+require_once DRUPAL_ROOT . '/includes/stream_wrappers.inc';
+
+/**
  * @defgroup file File interface
  * @{
  * Common file handling functions.
@@ -77,6 +84,221 @@ define('FILE_EXISTS_ERROR', 2);
 define('FILE_STATUS_PERMANENT', 1);
 
 /**
+ * Methods to manage a registry of stream wrappers.
+ */
+
+/**
+ * Drupal stream wrapper registry.
+ *
+ * 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.
+ *
+ * Provide a facility for managing and querying user-defined stream wrappers
+ * in PHP. PHP's internal stream_get_wrappers() doesn't return the class
+ * registered to handle a stream, which we need to be able to find the handler
+ * for class instantiation.
+ *
+ * If a module registers a scheme that is already registered with PHP, the
+ * existing scheme will be unregistered and replaced with the specified class.
+ *
+ * A stream is referenced as "scheme://target".
+ *
+ * @return
+ *   Returns the entire Drupal stream wrapper registry.
+ * @see hook_stream_wrappers()
+ * @see hook_stream_wrappers_alter()
+ */
+function file_get_stream_wrappers() {
+  $wrappers = &drupal_static(__FUNCTION__);
+
+  if (!isset($wrappers)) {
+    $wrappers = module_invoke_all('stream_wrappers');
+    drupal_alter('stream_wrappers', $wrappers);
+    $existing = stream_get_wrappers();
+    foreach ($wrappers as $scheme => $info) {
+      // We only register classes that implement our interface.
+      if (in_array('DrupalStreamWrapperInterface', class_implements($info['class']), TRUE)) {
+        // Record whether we are overriding an existing scheme.
+        if (in_array($scheme, $existing, TRUE)) {
+          $wrappers[$scheme]['override'] = TRUE;
+          stream_wrapper_unregister($scheme);
+        }
+        else {
+          $wrappers[$scheme]['override'] = FALSE;
+        }
+        stream_wrapper_register($scheme, $info['class']);
+      }
+    }
+  }
+  return $wrappers;
+}
+
+/**
+ * Returns the stream wrapper class name for a given scheme.
+ *
+ * @param $scheme
+ *   Stream scheme.
+ * @return
+ *   Return string if a scheme has a registered handler, or FALSE.
+ */
+function file_stream_wrapper_get_class($scheme) {
+  $wrappers = file_get_stream_wrappers();
+  return empty($wrappers[$scheme]) ? FALSE : $wrappers[$scheme]['class'];
+}
+
+/**
+ * Returns the scheme of a URI (e.g. a stream).
+ *
+ * @param $uri
+ *   A stream, referenced as "scheme://target".
+ * @return
+ *   A string containing the name of the scheme, or FALSE if none. For example,
+ *   the URI "public://example.txt" would return "public".
+ */
+function file_uri_scheme($uri) {
+  $data = explode('://', $uri, 2);
+
+  return count($data) == 2 ? $data[0] : FALSE;
+}
+
+/**
+ * Check that the scheme of a stream URI is valid.
+ *
+ * Confirms that there is a registered stream handler for the provided scheme
+ * and that it is callable. This is useful if you want to confirm a valid
+ * scheme without creating a new instance of the registered handler.
+ *
+ * @param $scheme
+ *   A URI scheme, a stream is referenced as "scheme://target".
+ * @return
+ *   Returns TRUE if the string is the name of a validated stream,
+ *   or FALSE if the scheme does not have a registered handler.
+ */
+function file_stream_wrapper_valid_scheme($scheme) {
+  // Does the scheme have a registered handler that is callable?
+  $class = file_stream_wrapper_get_class($scheme);
+  if (class_exists($class)) {
+    return TRUE;
+  }
+  else {
+    return FALSE;
+  }
+}
+
+/**
+ * Returns the target of a URI (e.g. a stream).
+ *
+ * @param $uri
+ *   A stream, referenced as "scheme://target".
+ * @return
+ *   A string containing the target (path), or FALSE if none.
+ *   For example, the URI "public://sample/test.txt" would return
+ *   "sample/test.txt".
+ */
+function file_uri_target($uri) {
+  $data = explode('://', $uri, 2);
+
+  if (count($data) != 2) {
+    return FALSE;
+  }
+
+  // Remove erroneous beginning forward slash.
+  $data[1] = ltrim($data[1], '\/');
+
+  return $data[1];
+}
+
+/**
+ * Normalizes a URI by making it syntactically correct.
+ *
+ * A stream is referenced as "scheme://target".
+ *
+ * The following actions are taken:
+ * - Remove all occurrences of the wrapper's directory path
+ * - Remove trailing slashes from target
+ * - Trim erroneous leading slashes from target. e.g. ":///" becomes "://".
+ *
+ * @param $uri
+ *   String reference containing the URI to normalize.
+ */
+function file_stream_wrapper_uri_normalize($uri) {
+  $scheme = file_uri_scheme($uri);
+
+  if ($scheme && file_stream_wrapper_valid_scheme($scheme)) {
+    $target = file_uri_target($uri);
+
+    // Remove all occurrences of the wrapper's directory path.
+    $directory_path = file_stream_wrapper_get_instance_by_scheme($scheme)->getDirectoryPath();
+    $target = str_replace($directory_path, '', $target);
+
+    // Trim trailing slashes from target.
+    $target = rtrim($target, '/');
+
+    // Trim erroneous leading slashes from target.
+    $uri = $scheme . '://' . ltrim($target, '/');
+  }
+  return $uri;
+}
+
+/**
+ * Returns a reference to the stream wrapper class responsible for a given URI (stream).
+ *
+ * The scheme determines the stream wrapper class that should be
+ * used by consulting the stream wrapper registry.
+ *
+ * @param $uri
+ *   A stream, referenced as "scheme://target".
+ * @return
+ *   Returns a new stream wrapper object appropriate for the given URI or FALSE
+ *   if no registered handler could be found. For example, a URI of
+ *   "private://example.txt" would return a new private stream wrapper object
+ *   (DrupalPrivateStreamWrapper).
+ */
+function file_stream_wrapper_get_instance_by_uri($uri) {
+  $scheme = file_uri_scheme($uri);
+  $class = file_stream_wrapper_get_class($scheme);
+  if (class_exists($class)) {
+    $instance = new $class;
+    $instance->setUri($uri);
+    return $instance;
+  }
+  else {
+    return FALSE;
+  }
+}
+
+/**
+ * Returns a reference to the stream wrapper class responsible for a given scheme.
+ *
+ * This helper method returns a stream instance using a scheme. That is, the
+ * passed string does not contain a "://". For example, "public" is a scheme
+ * but "public://" is a URI (stream). This is because the later contains both
+ * a scheme and target despite target being empty.
+ *
+ * Note: the instance URI will be initialized to "scheme://" so that you can
+ * make the customary method calls as if you had retrieved an instance by URI.
+ *
+ * @param $scheme
+ *   If the stream was "public://target", "public" would be the scheme.
+ * @return
+ *   Returns a new stream wrapper object appropriate for the given $scheme.
+ *   For example, for the public scheme a stream wrapper object
+ *   (DrupalPublicStreamWrapper).
+ *   FALSE is returned if no registered handler could be found.
+ */
+function file_stream_wrapper_get_instance_by_scheme($scheme) {
+  $class = file_stream_wrapper_get_class($scheme);
+  if (class_exists($class)) {
+    $instance = new $class;
+    $instance->setUri($scheme . '://');
+    return $instance;
+  }
+  else {
+    return FALSE;
+  }
+}
+
+/**
  * Create the download path to a file.
  *
  * @param $path A string containing the path of the file to generate URL for.
diff --git a/includes/stream_wrappers.inc b/includes/stream_wrappers.inc
new file mode 100644
index 000000000..4648536dc
--- /dev/null
+++ b/includes/stream_wrappers.inc
@@ -0,0 +1,621 @@
+<?php
+// $Id$
+
+/**
+ * @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 "://".  Becuase of this PHP limitation
+ * and for consistency Drupal will only accept URIs of form "scheme://target".
+ *
+ * @link http://www.faqs.org/rfcs/rfc3986.html
+ * @link http://bugs.php.net/bug.php?id=47070
+ */
+
+/**
+ * Generic PHP stream wrapper interface.
+ *
+ * @see http://www.php.net/manual/en/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 $uri
+   *   A string containing the URI that should be used for this instance.
+   */
+  function setUri($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();
+}
+
+
+/**
+ * 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 $uri;
+
+  /**
+   * Gets the path that the wrapper is responsible for.
+   *
+   * @return
+   *   String specifying the path.
+   */
+  abstract function getDirectoryPath();
+
+  /**
+   * Base implementation of setUri().
+   */
+  function setUri($uri) {
+    $this->uri = $uri;
+  }
+
+  /**
+   * Base implementation of getUri().
+   */
+  function getUri() {
+    return $this->uri;
+  }
+
+  /**
+   * Base implementation of getMimeType().
+   */
+  static function getMimeType($uri, $mapping = NULL) {
+    if (!isset($mapping)) {
+      $mapping = variable_get('mime_extension_mapping', NULL);
+      if (!isset($mapping) && drupal_function_exists('file_default_mimetype_mapping')) {
+        // The default file map, defined in file.mimetypes.inc is quite big.
+        // We only load it when necessary.
+        $mapping = file_default_mimetype_mapping();
+      }
+    }
+
+    $extension = '';
+    $file_parts = explode('.', basename($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) {
+    return @chmod($this->realpath(), $mode);
+  }
+
+  /**
+   * Base implementaiton of realpath().
+   */
+  function realpath() {
+    return @realpath($this->getDirectoryPath() . '/' . file_uri_target($this->uri));
+  }
+
+  /**
+   * Return the local filesystem path.
+   *
+   * @param $uri
+   *   Optional URI, supplied when doing a move or rename.
+   */
+  protected function getLocalPath($uri = NULL) {
+    if (!isset($uri)) {
+      $uri = $this->uri;
+    }
+    return $this->getDirectoryPath() . '/' . file_uri_target($uri);
+  }
+
+  /**
+   * Support for fopen(), file_get_contents(), file_put_contents() etc.
+   *
+   * @param $uri
+   *   A string containing the path 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/en/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_url = $path;
+    }
+
+    return (bool)$this->handle;
+  }
+
+  /**
+   * Support for flock().
+   *
+   * @param $operation
+   *   One of the following:
+   *   - LOCK_SH to acquire a shared lock (reader).
+   *   - LOCK_EX to acquire an exclusive lock (writer).
+   *   - LOCK_UN to release a lock (shared or exclusive).
+   *   - LOCK_NB if you don't want flock() to block while locking (not
+   *     supported on Windows).
+   * @return
+   *   Always returns TRUE at the present time.
+   * @see http://php.net/manual/en/streamwrapper.stream-lock.php
+   */
+  public function stream_lock($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 $count
+   *   Maximum number of bytes to be read.
+   * @return
+   *   The string that was read, or FALSE in case of an error.
+   * @see http://php.net/manual/en/streamwrapper.stream-read.php
+   */
+  public function stream_read($count) {
+    return fread($this->handle, $count);
+  }
+
+  /**
+   * Support for fwrite(), file_put_contents() etc.
+   *
+   * @param $data
+   *   The string to be written.
+   * @return
+   *   The number of bytes written (integer).
+   * @see http://php.net/manual/en/streamwrapper.stream-write.php
+   */
+  public function stream_write($data) {
+    return fwrite($this->handle, $data);
+  }
+
+  /**
+   * Support for feof().
+   *
+   * @return
+   *   TRUE if end-of-file has been reached.
+   * @see http://php.net/manual/en/streamwrapper.stream-eof.php
+   */
+  public function stream_eof() {
+    return feof($this->handle);
+  }
+
+  /**
+   * Support for fseek().
+   *
+   * @param $offset
+   *   The byte offset to got to.
+   * @param $whence
+   *   SEEK_SET, SEEK_CUR, or SEEK_END.
+   * @return
+   *   TRUE on success.
+   * @see http://php.net/manual/en/streamwrapper.stream-seek.php
+   */
+  public function stream_seek($offset, $whence) {
+    return fseek($this->handle, $offset, $whence);
+  }
+
+  /**
+   * Support for fflush().
+   *
+   * @return
+   *   TRUE if data was successfully stored (or there was no data to store).
+   * @see http://php.net/manual/en/streamwrapper.stream-flush.php
+   */
+  public function stream_flush() {
+    return fflush($this->handle);
+  }
+
+  /**
+   * Support for ftell().
+   *
+   * @return
+   *   The current offset in bytes from the beginning of file.
+   * @see http://php.net/manual/en/streamwrapper.stream-tell.php
+   */
+  public function stream_tell() {
+    return ftell($this->handle);
+  }
+
+  /**
+   * Support for fstat().
+   *
+   * @return
+   *   An array with file status, or FALSE in case of an error - see fstat()
+   *   for a description of this array.
+   * @see http://php.net/manual/en/streamwrapper.stream-stat.php
+   */
+  public function stream_stat() {
+    return fstat($this->handle);
+  }
+
+  /**
+   * Support for fclose().
+   *
+   * @return
+   *   TRUE if stream was successfully closed.
+   * @see http://php.net/manual/en/streamwrapper.stream-close.php
+   */
+  public function stream_close() {
+    return fclose($this->handle);
+  }
+
+  /**
+   * Support for unlink().
+   *
+   * @param $uri
+   *   A string containing the uri to the resource to delete.
+   * @return
+   *   TRUE if resource was successfully deleted.
+   * @see http://php.net/manual/en/streamwrapper.unlink.php
+   */
+  public function unlink($uri) {
+    $this->uri = $uri;
+    return unlink($this->getLocalPath());
+  }
+
+  /**
+   * Support for rename().
+   *
+   * @param $from_uri,
+   *   The uri to the file to rename.
+   * @param $to_uri
+   *   The new uri for file.
+   * @return
+   *   TRUE if file was successfully renamed.
+   * @see http://php.net/manual/en/streamwrapper.rename.php
+   */
+  public function rename($from_uri, $to_uri) {
+    return rename($this->getLocalPath($from_uri), $this->getLocalPath($to_uri));
+  }
+
+  /**
+   * Support for mkdir().
+   *
+   * @param $uri
+   *   A string containing the url to the directory to create.
+   * @param $mode
+   *   Permission flags - see mkdir().
+   * @param $options
+   *   A bit mask of STREAM_REPORT_ERRORS and STREAM_MKDIR_RECURSIVE.
+   * @return
+   *   TRUE if directory was successfully created.
+   * @see http://php.net/manual/en/streamwrapper.mkdir.php
+   */
+  public function mkdir($uri, $mode, $options) {
+    $this->uri = $uri;
+    $recursive = (bool)($options & STREAM_MKDIR_RECURSIVE);
+    if ($options & STREAM_REPORT_ERRORS) {
+      return mkdir($this->getLocalPath(), $mode, $recursive);
+    }
+    else {
+      return @mkdir($this->getLocalPath(), $mode, $recursive);
+    }
+  }
+
+  /**
+   * Support for rmdir().
+   *
+   * @param $uri
+   *   A string containing the url to the directory to delete.
+   * @param $options
+   *   A bit mask of STREAM_REPORT_ERRORS.
+   * @return
+   *   TRUE if directory was successfully removed.
+   * @see http://php.net/manual/en/streamwrapper.rmdir.php
+   */
+  public function rmdir($uri, $options) {
+    $this->uri = $uri;
+    if ($options & STREAM_REPORT_ERRORS) {
+      return rmdir($this->getLocalPath());
+    }
+    else {
+      return @rmdir($this->getLocalPath());
+    }
+  }
+
+  /**
+   * Support for stat().
+   *
+   * @param $uri
+   *   A string containing the url to get information about.
+   * @param $flags
+   *   A bit mask of STREAM_URL_STAT_LINK and STREAM_URL_STAT_QUIET.
+   * @return
+   *   An array with file status, or FALSE in case of an error - see fstat()
+   *   for a description of this array.
+   * @see http://php.net/manual/en/streamwrapper.url-stat.php
+   */
+  public function url_stat($uri, $flags) {
+    $this->uri = $uri;
+    if ($flags & STREAM_URL_STAT_QUIET) {
+      return @stat($this->getLocalPath());
+    }
+    else {
+      return stat($this->getLocalPath());
+    }
+  }
+
+  /**
+   * Support for opendir().
+   *
+   * @param $uri
+   *   A string containing the url to the directory to open.
+   * @param $options
+   *   Unknown (parameter is not documented in PHP Manual).
+   * @return
+   *   TRUE on success.
+   * @see http://php.net/manual/en/streamwrapper.dir-opendir.php
+   */
+  public function dir_opendir($uri, $options) {
+    $this->uri = $uri;
+    $this->handle = opendir($this->getLocalPath());
+
+    return (bool)$this->handle;
+  }
+
+  /**
+   * Support for readdir().
+   *
+   * @return
+   *   The next filename, or FALSE if there are no more files in the directory.
+   * @see http://php.net/manual/en/streamwrapper.dir-readdir.php
+   */
+  public function dir_readdir() {
+    return readdir($this->handle);
+  }
+
+  /**
+   * Support for rewinddir().
+   *
+   * @return
+   *   TRUE on success.
+   * @see http://php.net/manual/en/streamwrapper.dir-rewinddir.php
+   */
+  public function dir_rewinddir() {
+    return rewinddir($this->handle);
+  }
+
+  /**
+   * Support for closedir().
+   *
+   * @return
+   *   TRUE on success.
+   * @see http://php.net/manual/en/streamwrapper.dir-closedir.php
+   */
+  public function dir_closedir() {
+    return closedir($this->handle);
+  }
+}
+
+/**
+ * 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', 'sites/default/files');
+  }
+
+  /**
+   * Overrides getExternalUrl().
+   *
+   * Return the HTML URI of a public file.
+   */
+  function getExternalUrl() {
+    $path = str_replace('\\', '/', file_uri_target($this->uri));
+    return $GLOBALS['base_url'] . '/' . self::getDirectoryPath() . '/' . $path;
+  }
+}
+
+
+/**
+ * Drupal private (private://) stream wrapper class.
+ *
+ * Provides support for storing privately accessible files with the Drupal file
+ * interface.
+ *
+ * Extends DrupalPublicStreamWrapper.
+ */
+class DrupalPrivateStreamWrapper extends DrupalLocalStreamWrapper {
+  /**
+   * Implements abstract public function getDirectoryPath()
+   */
+  public function getDirectoryPath() {
+    return variable_get('file_private_path', 'sites/default/files-private');
+  }
+
+  /**
+   * Overrides getExternalUrl().
+   *
+   * Return the HTML URI of a private file.
+   */
+  function getExternalUrl() {
+    $path = str_replace('\\', '/', file_uri_target($this->uri));
+    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', '/tmp');
+  }
+
+  /**
+   * Overrides getExternalUrl().
+   */
+  public function getExternalUrl() {
+    return '';
+  }
+}