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file.inc

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  • David Rothstein's avatar
    Issue #1815930 by slashrsm, gbrands, amontero: Fixed Update watchdog message...
    David Rothstein authored
    Issue #1815930 by slashrsm, gbrands, amontero: Fixed Update watchdog message in file_unmanaged_copy() with correct string/variable replacement values.
    286deb81
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    file.inc 86.65 KiB
    <?php
    
    /**
     * @file
     * API for handling file uploads and server file management.
     */
    
    /**
     * Manually include stream wrapper code.
     *
     * 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.
     *
     * 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.
     * - uri: URI of the file.
     * - 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 first 8
     *   bits are reserved for Drupal core. The least significant bit indicates
     *   temporary (0) or permanent (1). Temporary files older than
     *   DRUPAL_MAXIMUM_TEMP_FILE_AGE will be removed during cron runs.
     * - timestamp: UNIX timestamp for the date the file was added to the database.
     */
    
    /**
     * Flag used by file_prepare_directory() -- create directory if not present.
     */
    define('FILE_CREATE_DIRECTORY', 1);
    
    /**
     * Flag used by file_prepare_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);
    
    /**
     * Indicates that the file is permanent and should not be deleted.
     *
     * Temporary files older than DRUPAL_MAXIMUM_TEMP_FILE_AGE will be removed
     * during cron runs, but permanent files will not be removed during the file
     * garbage collection process.
     */
    define('FILE_STATUS_PERMANENT', 1);
    
    /**
     * Provides 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".
     *
     * The optional $filter parameter can be used to retrieve only the stream
     * wrappers that are appropriate for particular usage. For example, this returns
     * only stream wrappers that use local file storage:
     * @code
     *   $local_stream_wrappers = file_get_stream_wrappers(STREAM_WRAPPERS_LOCAL);
     * @endcode
     *
     * The $filter parameter can only filter to types containing a particular flag.
     * In some cases, you may want to filter to types that do not contain a
     * particular flag. For example, you may want to retrieve all stream wrappers
     * that are not writable, or all stream wrappers that are not local. PHP's
     * array_diff_key() function can be used to help with this. For example, this
     * returns only stream wrappers that do not use local file storage:
     * @code
     *   $remote_stream_wrappers = array_diff_key(file_get_stream_wrappers(STREAM_WRAPPERS_ALL), file_get_stream_wrappers(STREAM_WRAPPERS_LOCAL));
     * @endcode
     *
     * @param $filter
     *   (Optional) Filters out all types except those with an on bit for each on
     *   bit in $filter. For example, if $filter is STREAM_WRAPPERS_WRITE_VISIBLE,
     *   which is equal to (STREAM_WRAPPERS_READ | STREAM_WRAPPERS_WRITE |
     *   STREAM_WRAPPERS_VISIBLE), then only stream wrappers with all three of these
     *   bits set are returned. Defaults to STREAM_WRAPPERS_ALL, which returns all
     *   registered stream wrappers.
     *
     * @return
     *   An array keyed by scheme, with values containing an array of information
     *   about the stream wrapper, as returned by hook_stream_wrappers(). If $filter
     *   is omitted or set to STREAM_WRAPPERS_ALL, the entire Drupal stream wrapper
     *   registry is returned. Otherwise only the stream wrappers whose 'type'
     *   bitmask has an on bit for each bit specified in $filter are returned.
     *
     * @see hook_stream_wrappers()
     * @see hook_stream_wrappers_alter()
     */
    function file_get_stream_wrappers($filter = STREAM_WRAPPERS_ALL) {
      $wrappers_storage = &drupal_static(__FUNCTION__);
    
      if (!isset($wrappers_storage)) {
        $wrappers = module_invoke_all('stream_wrappers');
        foreach ($wrappers as $scheme => $info) {
          // Add defaults.
          $wrappers[$scheme] += array('type' => STREAM_WRAPPERS_NORMAL);
        }
        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;
            }
            if (($info['type'] & STREAM_WRAPPERS_LOCAL) == STREAM_WRAPPERS_LOCAL) {
              stream_wrapper_register($scheme, $info['class']);
            }
            else {
              stream_wrapper_register($scheme, $info['class'], STREAM_IS_URL);
            }
          }
          // Pre-populate the static cache with the filters most typically used.
          $wrappers_storage[STREAM_WRAPPERS_ALL][$scheme] = $wrappers[$scheme];
          if (($info['type'] & STREAM_WRAPPERS_WRITE_VISIBLE) == STREAM_WRAPPERS_WRITE_VISIBLE) {
            $wrappers_storage[STREAM_WRAPPERS_WRITE_VISIBLE][$scheme] = $wrappers[$scheme];
          }
        }
      }
    
      if (!isset($wrappers_storage[$filter])) {
        $wrappers_storage[$filter] = array();
        foreach ($wrappers_storage[STREAM_WRAPPERS_ALL] as $scheme => $info) {
          // Bit-wise filter.
          if (($info['type'] & $filter) == $filter) {
            $wrappers_storage[$filter][$scheme] = $info;
          }
        }
      }
    
      return $wrappers_storage[$filter];
    }
    
    /**
     * 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 $uri
     *   A stream, referenced as "scheme://target".
     *
     * @return
     *   A string containing the name of the scheme, or FALSE if none. For example,
     *   the URI "public://example.txt" would return "public".
     *
     * @see file_uri_target()
     */
    function file_uri_scheme($uri) {
      $position = strpos($uri, '://');
      return $position ? substr($uri, 0, $position) : FALSE;
    }
    
    /**
     * Checks 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 part of a URI after the schema.
     *
     * @param $uri
     *   A stream, referenced as "scheme://target".
     *
     * @return
     *   A string containing the target (path), or FALSE if none.
     *   For example, the URI "public://sample/test.txt" would return
     *   "sample/test.txt".
     *
     * @see file_uri_scheme()
     */
    function file_uri_target($uri) {
      $data = explode('://', $uri, 2);
    
      // Remove erroneous leading or trailing, forward-slashes and backslashes.
      return count($data) == 2 ? trim($data[1], '\/') : FALSE;
    }
    
    /**
     * Gets the default file stream implementation.
     *
     * @return
     *   'public', 'private' or any other file scheme defined as the default.
     */
    function file_default_scheme() {
      return variable_get('file_default_scheme', 'public');
    }
    
    /**
     * Normalizes a URI by making it syntactically correct.
     *
     * A stream is referenced as "scheme://target".
     *
     * The following actions are taken:
     * - Remove trailing slashes from target
     * - Trim erroneous leading slashes from target. e.g. ":///" becomes "://".
     *
     * @param $uri
     *   String reference containing the URI to normalize.
     *
     * @return
     *   The normalized URI.
     */
    function file_stream_wrapper_uri_normalize($uri) {
      $scheme = file_uri_scheme($uri);
    
      if ($scheme && file_stream_wrapper_valid_scheme($scheme)) {
        $target = file_uri_target($uri);
    
        if ($target !== FALSE) {
          $uri = $scheme . '://' . $target;
        }
      }
      else {
        // The default scheme is file://
        $url = 'file://' . $uri;
      }
      return $uri;
    }
    
    /**
     * Returns a reference to the stream wrapper class responsible for a given URI.
     *
     * 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 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;
      }
    }
    
    /**
     * Creates a web-accessible URL for a stream to an external or local file.
     *
     * Compatibility: normal paths and stream wrappers.
     *
     * There are two kinds of local files:
     * - "managed files", i.e. those stored by a Drupal-compatible stream wrapper.
     *   These are files that have either been uploaded by users or were generated
     *   automatically (for example through CSS aggregation).
     * - "shipped files", i.e. those outside of the files directory, which ship as
     *   part of Drupal core or contributed modules or themes.
     *
     * @param $uri
     *   The URI to a file for which we need an external URL, or the path to a
     *   shipped file.
     *
     * @return
     *   A string containing a URL that may be used to access the file.
     *   If the provided string already contains a preceding 'http', 'https', or
     *   '/', nothing is done and the same string is returned. If a stream wrapper
     *   could not be found to generate an external URL, then FALSE is returned.
     *
     * @see http://drupal.org/node/515192
     */
    function file_create_url($uri) {
      // Allow the URI to be altered, e.g. to serve a file from a CDN or static
      // file server.
      drupal_alter('file_url', $uri);
    
      $scheme = file_uri_scheme($uri);
    
      if (!$scheme) {
        // Allow for:
        // - root-relative URIs (e.g. /foo.jpg in http://example.com/foo.jpg)
        // - protocol-relative URIs (e.g. //bar.jpg, which is expanded to
        //   http://example.com/bar.jpg by the browser when viewing a page over
        //   HTTP and to https://example.com/bar.jpg when viewing a HTTPS page)
        // Both types of relative URIs are characterized by a leading slash, hence
        // we can use a single check.
        if (drupal_substr($uri, 0, 1) == '/') {
          return $uri;
        }
        else {
          // If this is not a properly formatted stream, then it is a shipped file.
          // Therefore, return the urlencoded URI with the base URL prepended.
          return $GLOBALS['base_url'] . '/' . drupal_encode_path($uri);
        }
      }
      elseif ($scheme == 'http' || $scheme == 'https') {
        // Check for HTTP so that we don't have to implement getExternalUrl() for
        // the HTTP wrapper.
        return $uri;
      }
      else {
        // Attempt to return an external URL using the appropriate wrapper.
        if ($wrapper = file_stream_wrapper_get_instance_by_uri($uri)) {
          return $wrapper->getExternalUrl();
        }
        else {
          return FALSE;
        }
      }
    }
    
    /**
     * Checks 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 reference containing the name of a directory path or URI. A
     *   trailing slash will be trimmed from a path.
     * @param $options
     *   A bitmask to indicate if the directory should be created if it does
     *   not exist (FILE_CREATE_DIRECTORY) or made writable if it is read-only
     *   (FILE_MODIFY_PERMISSIONS).
     *
     * @return
     *   TRUE if the directory exists (or was created) and is writable. FALSE
     *   otherwise.
     */
    function file_prepare_directory(&$directory, $options = FILE_MODIFY_PERMISSIONS) {
      if (!file_stream_wrapper_valid_scheme(file_uri_scheme($directory))) {
        // Only trim if we're not dealing with a stream.
        $directory = rtrim($directory, '/\\');
      }
    
      // Check if directory exists.
      if (!is_dir($directory)) {
        // Let mkdir() recursively create directories and use the default directory
        // permissions.
        if (($options & FILE_CREATE_DIRECTORY) && @drupal_mkdir($directory, NULL, TRUE)) {
          return drupal_chmod($directory);
        }
        return FALSE;
      }
      // The directory exists, so check to see if it is writable.
      $writable = is_writable($directory);
      if (!$writable && ($options & FILE_MODIFY_PERMISSIONS)) {
        return drupal_chmod($directory);
      }
    
      return $writable;
    }
    
    /**
     * Creates a .htaccess file in each Drupal files directory if it is missing.
     */
    function file_ensure_htaccess() {
      file_create_htaccess('public://', FALSE);
      if (variable_get('file_private_path', FALSE)) {
        file_create_htaccess('private://', TRUE);
      }
      file_create_htaccess('temporary://', TRUE);
    }
    
    /**
     * Creates a .htaccess file in the given directory.
     *
     * @param $directory
     *   The directory.
     * @param $private
     *   FALSE indicates that $directory should be an open and public directory.
     *   The default is TRUE which indicates a private and protected directory.
     */
    function file_create_htaccess($directory, $private = TRUE) {
      if (file_uri_scheme($directory)) {
        $directory = file_stream_wrapper_uri_normalize($directory);
      }
      else {
        $directory = rtrim($directory, '/\\');
      }
      $htaccess_path =  $directory . '/.htaccess';
    
      if (file_exists($htaccess_path)) {
        // Short circuit if the .htaccess file already exists.
        return;
      }
    
      if ($private) {
        // Private .htaccess file.
        $htaccess_lines = "SetHandler Drupal_Security_Do_Not_Remove_See_SA_2006_006\nDeny from all\nOptions None\nOptions +FollowSymLinks";
      }
      else {
        // Public .htaccess file.
        $htaccess_lines = "SetHandler Drupal_Security_Do_Not_Remove_See_SA_2006_006\nOptions None\nOptions +FollowSymLinks";
      }
    
      // Write the .htaccess file.
      if (file_put_contents($htaccess_path, $htaccess_lines)) {
        drupal_chmod($htaccess_path, 0444);
      }
      else {
        $variables = array('%directory' => $directory, '!htaccess' => '<br />' . nl2br(check_plain($htaccess_lines)));
        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);
      }
    }
    
    /**
     * Loads file objects from the database.
     *
     * @param $fids
     *   An array of file IDs.
     * @param $conditions
     *   (deprecated) An associative array of conditions on the {file_managed}
     *   table, where the keys are the database fields and the values are the
     *   values those fields must have. Instead, it is preferable to use
     *   EntityFieldQuery to retrieve a list of entity IDs loadable by
     *   this function.
     *
     * @return
     *   An array of file objects, indexed by fid.
     *
     * @todo Remove $conditions in Drupal 8.
     *
     * @see hook_file_load()
     * @see file_load()
     * @see entity_load()
     * @see EntityFieldQuery
     */
    function file_load_multiple($fids = array(), $conditions = array()) {
      return entity_load('file', $fids, $conditions);
    }
    
    /**
     * Loads a single file object from the database.
     *
     * @param $fid
     *   A file ID.
     *
     * @return
     *   An object representing the file, or FALSE if the file was not found.
     *
     * @see hook_file_load()
     * @see file_load_multiple()
     */
    function file_load($fid) {
      $files = file_load_multiple(array($fid), array());
      return reset($files);
    }
    
    /**
     * Saves a file object to the database.
     *
     * If the $file->fid is not set a new record will be added.
     *
     * @param $file
     *   A file object returned by file_load().
     *
     * @return
     *   The updated file object.
     *
     * @see hook_file_insert()
     * @see hook_file_update()
     */
    function file_save(stdClass $file) {
      $file->timestamp = REQUEST_TIME;
      $file->filesize = filesize($file->uri);
    
      // Load the stored entity, if any.
      if (!empty($file->fid) && !isset($file->original)) {
        $file->original = entity_load_unchanged('file', $file->fid);
      }
    
      module_invoke_all('file_presave', $file);
      module_invoke_all('entity_presave', $file, 'file');
    
      if (empty($file->fid)) {
        drupal_write_record('file_managed', $file);
        // Inform modules about the newly added file.
        module_invoke_all('file_insert', $file);
        module_invoke_all('entity_insert', $file, 'file');
      }
      else {
        drupal_write_record('file_managed', $file, 'fid');
        // Inform modules that the file has been updated.
        module_invoke_all('file_update', $file);
        module_invoke_all('entity_update', $file, 'file');
      }
    
      unset($file->original);
      return $file;
    }
    
    /**
     * Determines where a file is used.
     *
     * @param $file
     *   A file object.
     *
     * @return
     *   A nested array with usage data. The first level is keyed by module name,
     *   the second by object type and the third by the object id. The value
     *   of the third level contains the usage count.
     *
     * @see file_usage_add()
     * @see file_usage_delete()
     */
    function file_usage_list(stdClass $file) {
      $result = db_select('file_usage', 'f')
        ->fields('f', array('module', 'type', 'id', 'count'))
        ->condition('fid', $file->fid)
        ->condition('count', 0, '>')
        ->execute();
      $references = array();
      foreach ($result as $usage) {
        $references[$usage->module][$usage->type][$usage->id] = $usage->count;
      }
      return $references;
    }
    
    /**
     * Records that a module is using a file.
     *
     * This usage information will be queried during file_delete() to ensure that
     * a file is not in use before it is physically removed from disk.
     *
     * Examples:
     * - A module that associates files with nodes, so $type would be
     *   'node' and $id would be the node's nid. Files for all revisions are stored
     *   within a single nid.
     * - The User module associates an image with a user, so $type would be 'user'
     *   and the $id would be the user's uid.
     *
     * @param $file
     *   A file object.
     * @param $module
     *   The name of the module using the file.
     * @param $type
     *   The type of the object that contains the referenced file.
     * @param $id
     *   The unique, numeric ID of the object containing the referenced file.
     * @param $count
     *   (optional) The number of references to add to the object. Defaults to 1.
     *
     * @see file_usage_list()
     * @see file_usage_delete()
     */
    function file_usage_add(stdClass $file, $module, $type, $id, $count = 1) {
      db_merge('file_usage')
        ->key(array(
          'fid' => $file->fid,
          'module' => $module,
          'type' => $type,
          'id' => $id,
        ))
        ->fields(array('count' => $count))
        ->expression('count', 'count + :count', array(':count' => $count))
        ->execute();
    }
    
    /**
     * Removes a record to indicate that a module is no longer using a file.
     *
     * The file_delete() function is typically called after removing a file usage
     * to remove the record from the file_managed table and delete the file itself.
     *
     * @param $file
     *   A file object.
     * @param $module
     *   The name of the module using the file.
     * @param $type
     *   (optional) The type of the object that contains the referenced file. May
     *   be omitted if all module references to a file are being deleted.
     * @param $id
     *   (optional) The unique, numeric ID of the object containing the referenced
     *   file. May be omitted if all module references to a file are being deleted.
     * @param $count
     *   (optional) The number of references to delete from the object. Defaults to
     *   1. 0 may be specified to delete all references to the file within a
     *   specific object.
     *
     * @see file_usage_add()
     * @see file_usage_list()
     * @see file_delete()
     */
    function file_usage_delete(stdClass $file, $module, $type = NULL, $id = NULL, $count = 1) {
      // Delete rows that have a exact or less value to prevent empty rows.
      $query = db_delete('file_usage')
        ->condition('module', $module)
        ->condition('fid', $file->fid);
      if ($type && $id) {
        $query
          ->condition('type', $type)
          ->condition('id', $id);
      }
      if ($count) {
        $query->condition('count', $count, '<=');
      }
      $result = $query->execute();
    
      // If the row has more than the specified count decrement it by that number.
      if (!$result && $count > 0) {
        $query = db_update('file_usage')
          ->condition('module', $module)
          ->condition('fid', $file->fid);
        if ($type && $id) {
          $query
            ->condition('type', $type)
            ->condition('id', $id);
        }
        $query->expression('count', 'count - :count', array(':count' => $count));
        $query->execute();
      }
    }
    
    /**
     * Copies 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
     *   file_save_upload() for details on temporary files.
     *
     * @param $source
     *   A file object.
     * @param $destination
     *   A string containing the destination that $source should be copied to.
     *   This must be a stream wrapper URI.
     * @param $replace
     *   Replace behavior when the destination file already exists:
     *   - FILE_EXISTS_REPLACE - Replace the existing file. If a managed file with
     *       the destination name exists then its database entry will be updated. If
     *       no database entry is found then a new one will be created.
     *   - 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 file_unmanaged_copy()
     * @see hook_file_copy()
     */
    function file_copy(stdClass $source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
      if (!file_valid_uri($destination)) {
        if (($realpath = drupal_realpath($source->uri)) !== FALSE) {
          watchdog('file', 'File %file (%realpath) could not be copied, because the destination %destination is invalid. This is often caused by improper use of file_copy() or a missing stream wrapper.', array('%file' => $source->uri, '%realpath' => $realpath, '%destination' => $destination));
        }
        else {
          watchdog('file', 'File %file could not be copied, because the destination %destination is invalid. This is often caused by improper use of file_copy() or a missing stream wrapper.', array('%file' => $source->uri, '%destination' => $destination));
        }
        drupal_set_message(t('The specified file %file could not be copied, because the destination is invalid. More information is available in the system log.', array('%file' => $source->uri)), 'error');
        return FALSE;
      }
    
      if ($uri = file_unmanaged_copy($source->uri, $destination, $replace)) {
        $file = clone $source;
        $file->fid = NULL;
        $file->uri = $uri;
        $file->filename = drupal_basename($uri);
        // If we are replacing an existing file re-use its database record.
        if ($replace == FILE_EXISTS_REPLACE) {
          $existing_files = file_load_multiple(array(), array('uri' => $uri));
          if (count($existing_files)) {
            $existing = reset($existing_files);
            $file->fid = $existing->fid;
            $file->filename = $existing->filename;
          }
        }
        // If we are renaming around an existing file (rather than a directory),
        // use its basename for the filename.
        elseif ($replace == FILE_EXISTS_RENAME && is_file($destination)) {
          $file->filename = drupal_basename($destination);
        }
    
        $file = file_save($file);
    
        // Inform modules that the file has been copied.
        module_invoke_all('file_copy', $file, $source);
    
        return $file;
      }
      return FALSE;
    }
    
    /**
     * Determines whether the URI has a valid scheme for file API operations.
     *
     * There must be a scheme and it must be a Drupal-provided scheme like
     * 'public', 'private', 'temporary', or an extension provided with
     * hook_stream_wrappers().
     *
     * @param $uri
     *   The URI to be tested.
     *
     * @return
     *   TRUE if the URI is allowed.
     */
    function file_valid_uri($uri) {
      // Assert that the URI has an allowed scheme. Barepaths are not allowed.
      $uri_scheme = file_uri_scheme($uri);
      if (empty($uri_scheme) || !file_stream_wrapper_valid_scheme($uri_scheme)) {
        return FALSE;
      }
      return TRUE;
    }
    
    /**
     * Copies a file to a new location without invoking the file API.
     *
     * 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.
     * - Provides a fallback using realpaths if the move fails using stream
     *   wrappers. This can occur because PHP's copy() function does not properly
     *   support streams if safe_mode or open_basedir are enabled. See
     *   https://bugs.php.net/bug.php?id=60456
     *
     * @param $source
     *   A string specifying the filepath or URI of the source file.
     * @param $destination
     *   A URI containing the destination that $source should be copied to. The
     *   URI may be a bare filepath (without a scheme) and in that case the default
     *   scheme (file://) will be used. If this value is omitted, Drupal's default
     *   files scheme will be used, usually "public://".
     * @param $replace
     *   Replace behavior when the destination file already exists:
     *   - FILE_EXISTS_REPLACE - Replace the existing file.
     *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
     *       unique.
     *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
     *
     * @return
     *   The path to the new file, or FALSE in the event of an error.
     *
     * @see file_copy()
     */
    function file_unmanaged_copy($source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
      $original_source = $source;
      $original_destination = $destination;
    
      // Assert that the source file actually exists.
      if (!file_exists($source)) {
        // @todo Replace drupal_set_message() calls with exceptions instead.
        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' => $original_source)), 'error');
        if (($realpath = drupal_realpath($original_source)) !== FALSE) {
          watchdog('file', 'File %file (%realpath) could not be copied because it does not exist.', array('%file' => $original_source, '%realpath' => $realpath));
        }
        else {
          watchdog('file', 'File %file could not be copied because it does not exist.', array('%file' => $original_source));
        }
        return FALSE;
      }
    
      // Build a destination URI if necessary.
      if (!isset($destination)) {
        $destination = file_build_uri(drupal_basename($source));
      }
    
    
      // Prepare the destination directory.
      if (file_prepare_directory($destination)) {
        // The destination is already a directory, so append the source basename.
        $destination = file_stream_wrapper_uri_normalize($destination . '/' . drupal_basename($source));
      }
      else {
        // Perhaps $destination is a dir/file?
        $dirname = drupal_dirname($destination);
        if (!file_prepare_directory($dirname)) {
          // The destination is not valid.
          watchdog('file', 'File %file could not be copied, because the destination directory %destination is not configured correctly.', array('%file' => $original_source, '%destination' => $dirname));
          drupal_set_message(t('The specified file %file could not be copied, because the destination directory is not properly configured. This may be caused by a problem with file or directory permissions. More information is available in the system log.', array('%file' => $original_source)), 'error');
          return FALSE;
        }
      }
    
      // Determine whether we can perform this operation based on overwrite rules.
      $destination = file_destination($destination, $replace);
      if ($destination === FALSE) {
        drupal_set_message(t('The file %file could not be copied because a file by that name already exists in the destination directory.', array('%file' => $original_source)), 'error');
        watchdog('file', 'File %file could not be copied because a file by that name already exists in the destination directory (%directory)', array('%file' => $original_source, '%directory' => $destination));
        return FALSE;
      }
    
      // Assert that the source and destination filenames are not the same.
      $real_source = drupal_realpath($source);
      $real_destination = drupal_realpath($destination);
      if ($source == $destination || ($real_source !== FALSE) && ($real_source == $real_destination)) {
        drupal_set_message(t('The specified file %file was not copied because it would overwrite itself.', array('%file' => $source)), 'error');
        watchdog('file', 'File %file could not be copied because it would overwrite itself.', array('%file' => $source));
        return FALSE;
      }
      // Make sure the .htaccess files are present.
      file_ensure_htaccess();
      // Perform the copy operation.
      if (!@copy($source, $destination)) {
        // If the copy failed and realpaths exist, retry the operation using them
        // instead.
        if ($real_source === FALSE || $real_destination === FALSE || !@copy($real_source, $real_destination)) {
          watchdog('file', 'The specified file %file could not be copied to %destination.', array('%file' => $source, '%destination' => $destination), WATCHDOG_ERROR);
          return FALSE;
        }
      }
    
      // Set the permissions on the new file.
      drupal_chmod($destination);
    
      return $destination;
    }
    
    /**
     * Constructs a URI to Drupal's default files location given a relative path.
     */
    function file_build_uri($path) {
      $uri = file_default_scheme() . '://' . $path;
      return file_stream_wrapper_uri_normalize($uri);
    }
    
    /**
     * Determines the destination path for a file.
     *
     * @param $destination
     *   A string specifying the desired final URI or filepath.
     * @param $replace
     *   Replace behavior when the destination file already exists.
     *   - FILE_EXISTS_REPLACE - Replace the existing file.
     *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
     *       unique.
     *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
     *
     * @return
     *   The destination filepath, or FALSE if the file already exists
     *   and FILE_EXISTS_ERROR is specified.
     */
    function file_destination($destination, $replace) {
      if (file_exists($destination)) {
        switch ($replace) {
          case FILE_EXISTS_REPLACE:
            // Do nothing here, we want to overwrite the existing file.
            break;
    
          case FILE_EXISTS_RENAME:
            $basename = drupal_basename($destination);
            $directory = drupal_dirname($destination);
            $destination = file_create_filename($basename, $directory);
            break;
    
          case FILE_EXISTS_ERROR:
            // Error reporting handled by calling function.
            return FALSE;
        }
      }
      return $destination;
    }
    
    /**
     * Moves 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 destination that $source should be moved to.
     *   This must be a stream wrapper URI.
     * @param $replace
     *   Replace behavior when the destination file already exists:
     *   - FILE_EXISTS_REPLACE - Replace the existing file. If a managed file with
     *       the destination name exists then its database entry will be updated and
     *       file_delete() called on the source file after hook_file_move is called.
     *       If no database entry is found then the source files record will be
     *       updated.
     *   - 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 file_unmanaged_move()
     * @see hook_file_move()
     */
    function file_move(stdClass $source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
      if (!file_valid_uri($destination)) {
        if (($realpath = drupal_realpath($source->uri)) !== FALSE) {
          watchdog('file', 'File %file (%realpath) could not be moved, because the destination %destination is invalid. This may be caused by improper use of file_move() or a missing stream wrapper.', array('%file' => $source->uri, '%realpath' => $realpath, '%destination' => $destination));
        }
        else {
          watchdog('file', 'File %file could not be moved, because the destination %destination is invalid. This may be caused by improper use of file_move() or a missing stream wrapper.', array('%file' => $source->uri, '%destination' => $destination));
        }
        drupal_set_message(t('The specified file %file could not be moved, because the destination is invalid. More information is available in the system log.', array('%file' => $source->uri)), 'error');
        return FALSE;
      }
    
      if ($uri = file_unmanaged_move($source->uri, $destination, $replace)) {
        $delete_source = FALSE;
    
        $file = clone $source;
        $file->uri = $uri;
        // If we are replacing an existing file re-use its database record.
        if ($replace == FILE_EXISTS_REPLACE) {
          $existing_files = file_load_multiple(array(), array('uri' => $uri));
          if (count($existing_files)) {
            $existing = reset($existing_files);
            $delete_source = TRUE;
            $file->fid = $existing->fid;
          }
        }
        // If we are renaming around an existing file (rather than a directory),
        // use its basename for the filename.
        elseif ($replace == FILE_EXISTS_RENAME && is_file($destination)) {
          $file->filename = drupal_basename($destination);
        }
    
        $file = file_save($file);
    
        // Inform modules that the file has been moved.
        module_invoke_all('file_move', $file, $source);
    
        if ($delete_source) {
          // Try a soft delete to remove original if it's not in use elsewhere.
          file_delete($source);
        }
    
        return $file;
      }
      return FALSE;
    }
    
    /**
     * Moves a file to a new location without database changes or hook invocation.
     *
     * @param $source
     *   A string specifying the filepath or URI of the original file.
     * @param $destination
     *   A string containing the destination that $source should be moved to.
     *   This must be a stream wrapper URI. If this value is omitted, Drupal's
     *   default files scheme will be used, usually "public://".
     * @param $replace
     *   Replace behavior when the destination file already exists:
     *   - FILE_EXISTS_REPLACE - Replace the existing file.
     *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
     *       unique.
     *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
     *
     * @return
     *   The URI of the moved file, or FALSE in the event of an error.
     *
     * @see file_move()
     */
    function file_unmanaged_move($source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
      $filepath = file_unmanaged_copy($source, $destination, $replace);
      if ($filepath == FALSE || file_unmanaged_delete($source) == FALSE) {
        return FALSE;
      }
      return $filepath;
    }
    
    /**
     * Modifies a filename as needed for security purposes.
     *
     * Munging a file name prevents unknown file extensions from masking exploit
     * files. When web servers such as Apache decide how to process a URL request,
     * they use the file extension. If the extension is not recognized, Apache
     * skips that extension and uses the previous file extension. For example, if
     * the file being requested is exploit.php.pps, and Apache does not recognize
     * the '.pps' extension, it treats the file as PHP and executes it. To make
     * this file name safe for Apache and prevent it from executing as PHP, the
     * .php extension is "munged" into .php_, making the safe file name
     * exploit.php_.pps.
     *
     * Specifically, this function adds an underscore to all extensions that are
     * between 2 and 5 characters in length, internal to the file name, and not
     * included in $extensions.
     *
     * Function behavior is also controlled by the Drupal variable
     * 'allow_insecure_uploads'. If 'allow_insecure_uploads' evaluates to TRUE, no
     * alterations will be made, if it evaluates to FALSE, the filename is 'munged'.
     *
     * @param $filename
     *   File name to modify.
     * @param $extensions
     *   A space-separated list of extensions that should not be altered.
     * @param $alerts
     *   If TRUE, drupal_set_message() will be called to display a message if the
     *   file name was changed.
     *
     * @return
     *   The potentially modified $filename.
     */
    function file_munge_filename($filename, $extensions, $alerts = TRUE) {
      $original = $filename;
    
      // Allow potentially insecure uploads for very savvy users and admin
      if (!variable_get('allow_insecure_uploads', 0)) {
        // Remove any null bytes. See http://php.net/manual/en/security.filesystem.nullbytes.php
        $filename = str_replace(chr(0), '', $filename);
    
        $whitelist = array_unique(explode(' ', trim($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;
    }
    
    /**
     * Undoes the effect of file_munge_filename().
     *
     * @param $filename
     *   String with the filename to be unmunged.
     *
     * @return
     *   An unmunged filename string.
     */
    function file_unmunge_filename($filename) {
      return str_replace('_.', '.', $filename);
    }
    
    /**
     * Creates 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 containing the directory or parent URI.
     *
     * @return
     *   File path consisting of $directory and a unique filename based off
     *   of $basename.
     */
    function file_create_filename($basename, $directory) {
      // Strip control characters (ASCII value < 32). Though these are allowed in
      // some filesystems, not many applications handle them well.
      $basename = preg_replace('/[\x00-\x1F]/u', '_', $basename);
      if (substr(PHP_OS, 0, 3) == 'WIN') {
        // These characters are not allowed in Windows filenames
        $basename = str_replace(array(':', '*', '?', '"', '<', '>', '|'), '_', $basename);
      }
    
      // A URI or path may already have a trailing slash or look like "public://".
      if (substr($directory, -1) == '/') {
        $separator = '';
      }
      else {
        $separator = '/';
      }
    
      $destination = $directory . $separator . $basename;
    
      if (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 . $separator . $name . '_' . $counter++ . $ext;
        } while (file_exists($destination));
      }
    
      return $destination;
    }
    
    /**
     * Deletes a file and its database record.
     *
     * If the $force parameter is not TRUE, file_usage_list() will be called to
     * determine if the file is being used by any modules. If the file is being
     * used the delete will be canceled.
     *
     * @param $file
     *   A file object.
     * @param $force
     *   Boolean indicating that the file should be deleted even if the file is
     *   reported as in use by the file_usage table.
     *
     * @return mixed
     *   TRUE for success, FALSE in the event of an error, or an array if the file
     *   is being used by any modules.
     *
     * @see file_unmanaged_delete()
     * @see file_usage_list()
     * @see file_usage_delete()
     * @see hook_file_delete()
     */
    function file_delete(stdClass $file, $force = FALSE) {
      if (!file_valid_uri($file->uri)) {
        if (($realpath = drupal_realpath($file->uri)) !== FALSE) {
          watchdog('file', 'File %file (%realpath) could not be deleted because it is not a valid URI. This may be caused by improper use of file_delete() or a missing stream wrapper.', array('%file' => $file->uri, '%realpath' => $realpath));
        }
        else {
          watchdog('file', 'File %file could not be deleted because it is not a valid URI. This may be caused by improper use of file_delete() or a missing stream wrapper.', array('%file' => $file->uri));
        }
        drupal_set_message(t('The specified file %file could not be deleted, because it is not a valid URI. More information is available in the system log.', array('%file' => $file->uri)), 'error');
        return FALSE;
      }
    
      // If any module still has a usage entry in the file_usage table, the file
      // will not be deleted, but file_delete() will return a populated array
      // that tests as TRUE.
      if (!$force && ($references = file_usage_list($file))) {
        return $references;
      }
    
      // Let other modules clean up any references to the deleted file.
      module_invoke_all('file_delete', $file);
      module_invoke_all('entity_delete', $file, '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 (file_unmanaged_delete($file->uri)) {
        db_delete('file_managed')->condition('fid', $file->fid)->execute();
        db_delete('file_usage')->condition('fid', $file->fid)->execute();
        return TRUE;
      }
      return FALSE;
    }
    
    /**
     * Deletes a file without database changes or hook invocations.
     *
     * This function should be used when the file to be deleted does not have an
     * entry recorded in the files table.
     *
     * @param $path
     *   A string containing a file path or (streamwrapper) URI.
     *
     * @return
     *   TRUE for success or path does not exist, or FALSE in the event of an
     *   error.
     *
     * @see file_delete()
     * @see file_unmanaged_delete_recursive()
     */
    function file_unmanaged_delete($path) {
      if (is_dir($path)) {
        watchdog('file', '%path is a directory and cannot be removed using file_unmanaged_delete().', array('%path' => $path), WATCHDOG_ERROR);
        return FALSE;
      }
      if (is_file($path)) {
        return drupal_unlink($path);
      }
      // Return TRUE for non-existent file, but log that nothing was actually
      // deleted, as the current state is the intended result.
      if (!file_exists($path)) {
        watchdog('file', 'The file %path was not deleted, because it does not exist.', array('%path' => $path), WATCHDOG_NOTICE);
        return TRUE;
      }
      // We cannot handle anything other than files and directories. Log an error
      // for everything else (sockets, symbolic links, etc).
      watchdog('file', 'The file %path is not of a recognized type so it was not deleted.', array('%path' => $path), WATCHDOG_ERROR);
      return FALSE;
    }
    
    /**
     * Deletes all files and directories in the specified filepath recursively.
     *
     * If the specified path is a directory then the function will call itself
     * recursively to process the contents. Once the contents have been removed the
     * directory will also be removed.
     *
     * If the specified path is a file then it will be passed to
     * file_unmanaged_delete().
     *
     * Note that this only deletes visible files with write permission.
     *
     * @param $path
     *   A string containing either an URI or a file or directory path.
     *
     * @return
     *   TRUE for success or if path does not exist, FALSE in the event of an
     *   error.
     *
     * @see file_unmanaged_delete()
     */
    function file_unmanaged_delete_recursive($path) {
      if (is_dir($path)) {
        $dir = dir($path);
        while (($entry = $dir->read()) !== FALSE) {
          if ($entry == '.' || $entry == '..') {
            continue;
          }
          $entry_path = $path . '/' . $entry;
          file_unmanaged_delete_recursive($entry_path);
        }
        $dir->close();
    
        return drupal_rmdir($path);
      }
      return file_unmanaged_delete($path);
    }
    
    /**
     * Determines 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 $status
     *   Optional. The file status to consider. The default is to only
     *   consider files in status FILE_STATUS_PERMANENT.
     *
     * @return
     *   An integer containing the number of bytes used.
     */
    function file_space_used($uid = NULL, $status = FILE_STATUS_PERMANENT) {
      $query = db_select('file_managed', 'f');
      $query->condition('f.status', $status);
      $query->addExpression('SUM(f.filesize)', 'filesize');
      if (isset($uid)) {
        $query->condition('f.uid', $uid);
      }
      return $query->execute()->fetchField();
    }
    
    /**
     * Saves a file upload to a new location.
     *
     * The file will be added to the {file_managed} table as a temporary file.
     * Temporary files are periodically cleaned. To make the file a permanent file,
     * assign the status and use file_save() to save the changes.
     *
     * @param $source
     *   A string specifying the filepath or URI of the uploaded file to save.
     * @param $validators
     *   An optional, associative array of callback functions used to validate the
     *   file. See file_validate() for a full discussion of the array format.
     *   If no extension validator is provided it will default to a limited safe
     *   list of extensions which is as follows: "jpg jpeg gif png txt
     *   doc xls pdf ppt pps odt ods odp". To allow all extensions you must
     *   explicitly set the 'file_validate_extensions' validator to an empty array
     *   (Beware: this is not safe and should only be allowed for trusted users, if
     *   at all).
     * @param $destination
     *   A string containing the URI $source should be copied to.
     *   This must be a stream wrapper URI. If this value is omitted, Drupal's
     *   temporary files scheme will be used ("temporary://").
     * @param $replace
     *   Replace behavior when the destination file already exists:
     *   - FILE_EXISTS_REPLACE: Replace the existing file.
     *   - FILE_EXISTS_RENAME: Append _{incrementing number} until the filename is
     *     unique.
     *   - FILE_EXISTS_ERROR: Do nothing and return FALSE.
     *
     * @return
     *   An object containing the file information if the upload succeeded, FALSE
     *   in the event of an error, or NULL if no file was uploaded. The
     *   documentation for the "File interface" group, which you can find under
     *   Related topics, or the header at the top of this file, documents the
     *   components of a file object. In addition to the standard components,
     *   this function adds:
     *   - source: Path to the file before it is moved.
     *   - destination: Path to the file after it is moved (same as 'uri').
     */
    function file_save_upload($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];
      }
    
      // Make sure there's an upload to process.
      if (empty($_FILES['files']['name'][$source])) {
        return NULL;
      }
    
      // Check for file upload errors and return FALSE if a lower level system
      // error occurred. For a complete list of errors:
      // See http://php.net/manual/en/features.file-upload.errors.php.
      switch ($_FILES['files']['error'][$source]) {
        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' => $_FILES['files']['name'][$source], '%maxsize' => format_size(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' => $_FILES['files']['name'][$source])), 'error');
          return FALSE;
    
        case UPLOAD_ERR_OK:
          // Final check that this is a valid upload, if it isn't, use the
          // default error handler.
          if (is_uploaded_file($_FILES['files']['tmp_name'][$source])) {
            break;
          }
    
        // Unknown error
        default:
          drupal_set_message(t('The file %file could not be saved. An unknown error has occurred.', array('%file' => $_FILES['files']['name'][$source])), 'error');
          return FALSE;
      }
    
      // Begin building file object.
      $file = new stdClass();
      $file->uid      = $user->uid;
      $file->status   = 0;
      $file->filename = trim(drupal_basename($_FILES['files']['name'][$source]), '.');
      $file->uri      = $_FILES['files']['tmp_name'][$source];
      $file->filemime = file_get_mimetype($file->filename);
      $file->filesize = $_FILES['files']['size'][$source];
    
      $extensions = '';
      if (isset($validators['file_validate_extensions'])) {
        if (isset($validators['file_validate_extensions'][0])) {
          // Build the list of non-munged extensions if the caller provided them.
          $extensions = $validators['file_validate_extensions'][0];
        }
        else {
          // If 'file_validate_extensions' is set and the list is empty then the
          // caller wants to allow any extension. In this case we have to remove the
          // validator or else it will reject all extensions.
          unset($validators['file_validate_extensions']);
        }
      }
      else {
        // No validator was provided, so add one using the default list.
        // Build a default non-munged safe list for file_munge_filename().
        $extensions = 'jpg jpeg gif png txt doc xls pdf ppt pps odt ods odp';
        $validators['file_validate_extensions'] = array();
        $validators['file_validate_extensions'][0] = $extensions;
      }
    
      if (!empty($extensions)) {
        // Munge the filename to protect against possible malicious extension hiding
        // within an unknown file type (ie: filename.html.foo).
        $file->filename = file_munge_filename($file->filename, $extensions);
      }
    
      // Rename potentially executable files, to help prevent exploits (i.e. will
      // rename filename.php.foo and filename.php to filename.php.foo.txt and
      // filename.php.txt, respectively). Don't rename if 'allow_insecure_uploads'
      // evaluates to TRUE.
      if (!variable_get('allow_insecure_uploads', 0) && preg_match('/\.(php|pl|py|cgi|asp|js)(\.|$)/i', $file->filename) && (substr($file->filename, -4) != '.txt')) {
        $file->filemime = 'text/plain';
        $file->uri .= '.txt';
        $file->filename .= '.txt';
        // The .txt extension may not be in the allowed list of extensions. We have
        // to add it here or else the file upload will fail.
        if (!empty($extensions)) {
          $validators['file_validate_extensions'][0] .= ' txt';
          drupal_set_message(t('For security reasons, your upload has been renamed to %filename.', array('%filename' => $file->filename)));
        }
      }
    
      // If the destination is not provided, use the temporary directory.
      if (empty($destination)) {
        $destination = 'temporary://';
      }
    
      // Assert that the destination contains a valid stream.
      $destination_scheme = file_uri_scheme($destination);
      if (!$destination_scheme || !file_stream_wrapper_valid_scheme($destination_scheme)) {
        drupal_set_message(t('The file could not be uploaded, because the destination %destination is invalid.', array('%destination' => $destination)), 'error');
        return FALSE;
      }
    
      $file->source = $source;
      // A URI may already have a trailing slash or look like "public://".
      if (substr($destination, -1) != '/') {
        $destination .= '/';
      }
      $file->destination = file_destination($destination . $file->filename, $replace);
      // If file_destination() returns FALSE then $replace == FILE_EXISTS_ERROR and
      // there's an existing file so we need to bail.
      if ($file->destination === FALSE) {
        drupal_set_message(t('The file %source could not be uploaded because a file by that name already exists in the destination %directory.', array('%source' => $source, '%directory' => $destination)), 'error');
        return FALSE;
      }
    
      // Add in our check of the the file name length.
      $validators['file_validate_name_length'] = array();
    
      // Call the validation functions specified by this function's caller.
      $errors = file_validate($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', array('items' => $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->uri = $file->destination;
      if (!drupal_move_uploaded_file($_FILES['files']['tmp_name'][$source], $file->uri)) {
        form_set_error($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->uri));
        return FALSE;
      }
    
      // Set the permissions on the new file.
      drupal_chmod($file->uri);
    
      // If we are replacing an existing file re-use its database record.
      if ($replace == FILE_EXISTS_REPLACE) {
        $existing_files = file_load_multiple(array(), array('uri' => $file->uri));
        if (count($existing_files)) {
          $existing = reset($existing_files);
          $file->fid = $existing->fid;
        }
      }
    
      // If we made it this far it's safe to record this file in the database.
      if ($file = file_save($file)) {
        // Add file to the cache.
        $upload_cache[$source] = $file;
        return $file;
      }
      return FALSE;
    }
    
    /**
     * Moves an uploaded file to a new location.
     *
     * PHP's move_uploaded_file() does not properly support streams if safe_mode
     * or open_basedir are enabled, so this function fills that gap.
     *
     * Compatibility: normal paths and stream wrappers.
     *
     * @param $filename
     *   The filename of the uploaded file.
     * @param $uri
     *   A string containing the destination URI of the file.
     *
     * @return
     *   TRUE on success, or FALSE on failure.
     *
     * @see move_uploaded_file()
     * @see http://drupal.org/node/515192
     * @ingroup php_wrappers
     */
    function drupal_move_uploaded_file($filename, $uri) {
      $result = @move_uploaded_file($filename, $uri);
      // PHP's move_uploaded_file() does not properly support streams if safe_mode
      // or open_basedir are enabled so if the move failed, try finding a real path
      // and retry the move operation.
      if (!$result) {
        if ($realpath = drupal_realpath($uri)) {
          $result = move_uploaded_file($filename, $realpath);
        }
        else {
          $result = move_uploaded_file($filename, $uri);
        }
      }
    
      return $result;
    }
    
    /**
     * Checks that a file meets the criteria specified by the validators.
     *
     * After executing the validator callbacks specified hook_file_validate() will
     * also be called to allow other modules to report errors about the file.
     *
     * @param $file
     *   A Drupal file object.
     * @param $validators
     *   An optional, associative array of callback functions used to validate the
     *   file. The keys are function names and the values arrays of callback
     *   parameters which will be passed in after the file object. The
     *   functions should return an array of error messages; an empty array
     *   indicates that the file passed validation. The functions will be called in
     *   the order specified.
     *
     * @return
     *   An array containing validation error messages.
     *
     * @see hook_file_validate()
     */
    function file_validate(stdClass &$file, $validators = array()) {
      // Call the validation functions specified by this function's caller.
      $errors = array();
      foreach ($validators as $function => $args) {
        if (function_exists($function)) {
          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('file_validate', $file));
    }
    
    /**
     * Checks 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 file_validate_name_length(stdClass $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) > 240) {
        $errors[] = t("The file's name exceeds the 240 characters limit. Please rename the file and try again.");
      }
      return $errors;
    }
    
    /**
     * Checks that the filename ends with an allowed extension.
     *
     * @param $file
     *   A Drupal file object.
     * @param $extensions
     *   A string with a space separated list of allowed extensions.
     *
     * @return
     *   An array. If the file extension is not allowed, it will contain an error
     *   message.
     *
     * @see hook_file_validate()
     */
    function file_validate_extensions(stdClass $file, $extensions) {
      $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;
    }
    
    /**
     * Checks 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 $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_file_validate()
     */
    function file_validate_size(stdClass $file, $file_limit = 0, $user_limit = 0) {
      global $user;
    
      $errors = array();
    
      // Bypass validation for uid  = 1.
      if ($user->uid != 1) {
        if ($file_limit && $file->filesize > $file_limit) {
          $errors[] = t('The file is %filesize exceeding the maximum file size of %maxsize.', array('%filesize' => format_size($file->filesize), '%maxsize' => format_size($file_limit)));
        }
    
        // Save a query by only calling file_space_used() when a limit is provided.
        if ($user_limit && (file_space_used($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;
    }
    
    /**
     * Checks 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_file_validate()
     */
    function file_validate_is_image(stdClass $file) {
      $errors = array();
    
      $info = image_get_info($file->uri);
      if (!$info || empty($info['extension'])) {
        $errors[] = t('Only JPEG, PNG and GIF images are allowed.');
      }
    
      return $errors;
    }
    
    /**
     * Verifies that image dimensions are within the specified maximum and minimum.
     *
     * Non-image files will be ignored. If a image toolkit is available the image
     * will be scaled 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_file_validate()
     */
    function file_validate_image_resolution(stdClass $file, $maximum_dimensions = 0, $minimum_dimensions = 0) {
      $errors = array();
    
      // Check first that the file is an image.
      if ($info = image_get_info($file->uri)) {
        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 = image_load($file->uri)) {
              image_scale($image, $width, $height);
              image_save($image);
              $file->filesize = $image->info['file_size'];
              drupal_set_message(t('The image was resized to fit within the maximum allowed dimensions of %dimensions pixels.', array('%dimensions' => $maximum_dimensions)));
            }
            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;
    }
    
    /**
     * Saves a file to the specified destination and creates a database entry.
     *
     * @param $data
     *   A string containing the contents of the file.
     * @param $destination
     *   A string containing the destination URI. This must be a stream wrapper URI.
     *   If no value is provided, a randomized name will be generated and the file
     *   will be saved using Drupal's default files scheme, usually "public://".
     * @param $replace
     *   Replace behavior when the destination file already exists:
     *   - FILE_EXISTS_REPLACE - Replace the existing file. If a managed file with
     *       the destination name exists then its database entry will be updated. If
     *       no database entry is found then a new one will be created.
     *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
     *       unique.
     *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
     *
     * @return
     *   A file object, or FALSE on error.
     *
     * @see file_unmanaged_save_data()
     */
    function file_save_data($data, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
      global $user;
    
      if (empty($destination)) {
        $destination = file_default_scheme() . '://';
      }
      if (!file_valid_uri($destination)) {
        watchdog('file', 'The data could not be saved because the destination %destination is invalid. This may be caused by improper use of file_save_data() or a missing stream wrapper.', array('%destination' => $destination));
        drupal_set_message(t('The data could not be saved, because the destination is invalid. More information is available in the system log.'), 'error');
        return FALSE;
      }
    
      if ($uri = file_unmanaged_save_data($data, $destination, $replace)) {
        // Create a file object.
        $file = new stdClass();
        $file->fid = NULL;
        $file->uri = $uri;
        $file->filename = drupal_basename($uri);
        $file->filemime = file_get_mimetype($file->uri);
        $file->uid      = $user->uid;
        $file->status   = FILE_STATUS_PERMANENT;
        // If we are replacing an existing file re-use its database record.
        if ($replace == FILE_EXISTS_REPLACE) {
          $existing_files = file_load_multiple(array(), array('uri' => $uri));
          if (count($existing_files)) {
            $existing = reset($existing_files);
            $file->fid = $existing->fid;
            $file->filename = $existing->filename;
          }
        }
        // If we are renaming around an existing file (rather than a directory),
        // use its basename for the filename.
        elseif ($replace == FILE_EXISTS_RENAME && is_file($destination)) {
          $file->filename = drupal_basename($destination);
        }
    
        return file_save($file);
      }
      return FALSE;
    }
    
    /**
     * Saves a string to the specified destination without invoking file API.
     *
     * This function is identical to file_save_data() except the file will not be
     * saved to the {file_managed} table and none of the file_* hooks will be
     * called.
     *
     * @param $data
     *   A string containing the contents of the file.
     * @param $destination
     *   A string containing the destination location. This must be a stream wrapper
     *   URI. If no value is provided, a randomized name will be generated and the
     *   file will be saved using Drupal's default files scheme, usually
     *   "public://".
     * @param $replace
     *   Replace behavior when the destination file already exists:
     *   - FILE_EXISTS_REPLACE - Replace the existing file.
     *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
     *                          unique.
     *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
     *
     * @return
     *   A string with the path of the resulting file, or FALSE on error.
     *
     * @see file_save_data()
     */
    function file_unmanaged_save_data($data, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
      // Write the data to a temporary file.
      $temp_name = drupal_tempnam('temporary://', 'file');
      if (file_put_contents($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 file_unmanaged_move($temp_name, $destination, $replace);
    }
    
    /**
     * Transfers a file to the client using HTTP.
     *
     * Pipes a file through Drupal to the client.
     *
     * @param $uri
     *   String specifying the file URI to transfer.
     * @param $headers
     *   An array of HTTP headers to send along with file.
     */
    function file_transfer($uri, $headers) {
      if (ob_get_level()) {
        ob_end_clean();
      }
    
      foreach ($headers as $name => $value) {
        drupal_add_http_header($name, $value);
      }
      drupal_send_headers();
      $scheme = file_uri_scheme($uri);
      // Transfer file in 1024 byte chunks to save memory usage.
      if ($scheme && file_stream_wrapper_valid_scheme($scheme) && $fd = fopen($uri, 'rb')) {
        while (!feof($fd)) {
          print fread($fd, 1024);
        }
        fclose($fd);
      }
      else {
        drupal_not_found();
      }
      drupal_exit();
    }
    
    /**
     * Menu handler for private file transfers.
     *
     * Call modules that implement hook_file_download() to find out if a file is
     * accessible and what headers it should be transferred with. If one or more
     * modules returned headers the download will start with the returned headers.
     * If a module returns -1 drupal_access_denied() will be returned. If the file
     * exists but no modules responded drupal_access_denied() will be returned.
     * If the file does not exist drupal_not_found() will be returned.
     *
     * @see system_menu()
     */
    function file_download() {
      // Merge remainder of arguments from GET['q'], into relative file path.
      $args = func_get_args();
      $scheme = array_shift($args);
      $target = implode('/', $args);
      $uri = $scheme . '://' . $target;
      if (file_stream_wrapper_valid_scheme($scheme) && file_exists($uri)) {
        // Let other modules provide headers and controls access to the file.
        // module_invoke_all() uses array_merge_recursive() which merges header
        // values into a new array. To avoid that and allow modules to override
        // headers instead, use array_merge() to merge the returned arrays.
        $headers = array();
        foreach (module_implements('file_download') as $module) {
          $function = $module . '_file_download';
          $result = $function($uri);
          if ($result == -1) {
            // Throw away the headers received so far.
            $headers = array();
            break;
          }
          if (isset($result) && is_array($result)) {
            $headers = array_merge($headers, $result);
          }
        }
        if (count($headers)) {
          file_transfer($uri, $headers);
        }
        drupal_access_denied();
      }
      else {
        drupal_not_found();
      }
      drupal_exit();
    }
    
    
    /**
     * 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 or URI to scan, without trailing slash.
     * @param $mask
     *   The preg_match() regular expression of the files to find.
     * @param $options
     *   An associative array of additional options, with the following elements:
     *   - 'nomask': The preg_match() regular expression of the files to ignore.
     *     Defaults to '/(\.\.?|CVS)$/'.
     *   - 'callback': The callback function to call for each match. There is no
     *     default callback.
     *   - 'recurse': When TRUE, the directory scan will recurse the entire tree
     *     starting at the provided directory. Defaults to TRUE.
     *   - 'key': The key to be used for the returned associative array of files.
     *     Possible values are 'uri', for the file's URI; 'filename', for the
     *     basename of the file; and 'name' for the name of the file without the
     *     extension. Defaults to 'uri'.
     *   - 'min_depth': Minimum depth of directories to return files from. Defaults
     *     to 0.
     * @param $depth
     *   Current depth of recursion. This parameter is only used internally and
     *   should not be passed in.
     *
     * @return
     *   An associative array (keyed on the chosen key) of objects with 'uri',
     *   'filename', and 'name' members corresponding to the matching files.
     */
    function file_scan_directory($dir, $mask, $options = array(), $depth = 0) {
      // Merge in defaults.
      $options += array(
        'nomask' => '/(\.\.?|CVS)$/',
        'callback' => 0,
        'recurse' => TRUE,
        'key' => 'uri',
        'min_depth' => 0,
      );
    
      $options['key'] = in_array($options['key'], array('uri', 'filename', 'name')) ? $options['key'] : 'uri';
      $files = array();
      if (is_dir($dir) && $handle = opendir($dir)) {
        while (FALSE !== ($filename = readdir($handle))) {
          if (!preg_match($options['nomask'], $filename) && $filename[0] != '.') {
            $uri = "$dir/$filename";
            $uri = file_stream_wrapper_uri_normalize($uri);
            if (is_dir($uri) && $options['recurse']) {
              // Give priority to files in this folder by merging them in after any subdirectory files.
              $files = array_merge(file_scan_directory($uri, $mask, $options, $depth + 1), $files);
            }
            elseif ($depth >= $options['min_depth'] && preg_match($mask, $filename)) {
              // Always use this match over anything already set in $files with the
              // same $$options['key'].
              $file = new stdClass();
              $file->uri = $uri;
              $file->filename = $filename;
              $file->name = pathinfo($filename, PATHINFO_FILENAME);
              $key = $options['key'];
              $files[$file->$key] = $file;
              if ($options['callback']) {
                $options['callback']($uri);
              }
            }
          }
        }
    
        closedir($handle);
      }
    
      return $files;
    }
    
    /**
     * Determines the maximum file upload size by querying the PHP settings.
     *
     * @return
     *   A file size limit in bytes based on the PHP upload_max_filesize and
     *   post_max_size
     */
    function file_upload_max_size() {
      static $max_size = -1;
    
      if ($max_size < 0) {
        // Start with post_max_size.
        $max_size = parse_size(ini_get('post_max_size'));
    
        // If upload_max_size is less, then reduce. Except if upload_max_size is
        // zero, which indicates no limit.
        $upload_max = parse_size(ini_get('upload_max_filesize'));
        if ($upload_max > 0 && $upload_max < $max_size) {
          $max_size = $upload_max;
        }
      }
      return $max_size;
    }
    
    /**
     * Determines an Internet Media Type or MIME type from a filename.
     *
     * @param $uri
     *   A string containing 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 (lowercase) and the value is the mimetype
     *      identifier. If $mapping is NULL file_mimetype_mapping() is called.
     *
     * @return
     *   The internet media type registered for the extension or
     *   application/octet-stream for unknown extensions.
     *
     * @see file_default_mimetype_mapping()
     */
    function file_get_mimetype($uri, $mapping = NULL) {
      if ($wrapper = file_stream_wrapper_get_instance_by_uri($uri)) {
        return $wrapper->getMimeType($uri, $mapping);
      }
      else {
        // getMimeType() is not implementation specific, so we can directly
        // call it without an instance.
        return DrupalLocalStreamWrapper::getMimeType($uri, $mapping);
      }
    }
    
    /**
     * Sets the permissions on a file or directory.
     *
     * This function will use the 'file_chmod_directory' and 'file_chmod_file'
     * variables for the default modes for directories and uploaded/generated
     * files. By default these will give everyone read access so that users
     * accessing the files with a user account without the webserver group (e.g.
     * via FTP) can read these files, and give group write permissions so webserver
     * group members (e.g. a vhost account) can alter files uploaded and owned by
     * the webserver.
     *
     * PHP's chmod does not support stream wrappers so we use our wrapper
     * implementation which interfaces with chmod() by default. Contrib wrappers
     * may override this behavior in their implementations as needed.
     *
     * @param $uri
     *   A string containing a URI file, or directory path.
     * @param $mode
     *   Integer value for the permissions. Consult PHP chmod() documentation for
     *   more information.
     *
     * @return
     *   TRUE for success, FALSE in the event of an error.
     *
     * @ingroup php_wrappers
     */
    function drupal_chmod($uri, $mode = NULL) {
      if (!isset($mode)) {
        if (is_dir($uri)) {
          $mode = variable_get('file_chmod_directory', 0775);
        }
        else {
          $mode = variable_get('file_chmod_file', 0664);
        }
      }
    
      // If this URI is a stream, pass it off to the appropriate stream wrapper.
      // Otherwise, attempt PHP's chmod. This allows use of drupal_chmod even
      // for unmanaged files outside of the stream wrapper interface.
      if ($wrapper = file_stream_wrapper_get_instance_by_uri($uri)) {
        if ($wrapper->chmod($mode)) {
          return TRUE;
        }
      }
      else {
        if (@chmod($uri, $mode)) {
          return TRUE;
        }
      }
    
      watchdog('file', 'The file permissions could not be set on %uri.', array('%uri' => $uri), WATCHDOG_ERROR);
      return FALSE;
    }
    
    /**
     * Deletes a file.
     *
     * PHP's unlink() is broken on Windows, as it can fail to remove a file
     * when it has a read-only flag set.
     *
     * @param $uri
     *   A URI or pathname.
     * @param $context
     *   Refer to http://php.net/manual/en/ref.stream.php
     *
     * @return
     *   Boolean TRUE on success, or FALSE on failure.
     *
     * @see unlink()
     * @ingroup php_wrappers
     */
    function drupal_unlink($uri, $context = NULL) {
      $scheme = file_uri_scheme($uri);
      if ((!$scheme || !file_stream_wrapper_valid_scheme($scheme)) && (substr(PHP_OS, 0, 3) == 'WIN')) {
        chmod($uri, 0600);
      }
      if ($context) {
        return unlink($uri, $context);
      }
      else {
        return unlink($uri);
      }
    }
    
    /**
     * Returns the absolute local filesystem path of a stream URI.
     *
     * This function was originally written to ease the conversion of 6.x code to
     * use 7.x stream wrappers. However, it assumes that every URI may be resolved
     * to an absolute local filesystem path, and this assumption fails when stream
     * wrappers are used to support remote file storage. Remote stream wrappers
     * may implement the realpath method by always returning FALSE. The use of
     * drupal_realpath() is discouraged, and is slowly being removed from core
     * functions where possible.
     *
     * Only use this function if you know that the stream wrapper in the URI uses
     * the local file system, and you need to pass an absolute path to a function
     * that is incompatible with stream URIs.
     *
     * @param $uri
     *   A stream wrapper URI or a filesystem path, possibly including one or more
     *   symbolic links.
     *
     * @return
     *   The absolute local filesystem path (with no symbolic links), or FALSE on
     *   failure.
     *
     * @todo This function is deprecated, and should be removed wherever possible.
     *
     * @see DrupalStreamWrapperInterface::realpath()
     * @see http://php.net/manual/function.realpath.php
     * @ingroup php_wrappers
     */
    function drupal_realpath($uri) {
      // If this URI is a stream, pass it off to the appropriate stream wrapper.
      // Otherwise, attempt PHP's realpath. This allows use of drupal_realpath even
      // for unmanaged files outside of the stream wrapper interface.
      if ($wrapper = file_stream_wrapper_get_instance_by_uri($uri)) {
        return $wrapper->realpath();
      }
      // Check that the URI has a value. There is a bug in PHP 5.2 on *BSD systems
      // that makes realpath not return FALSE as expected when passing an empty
      // variable.
      // @todo Remove when Drupal drops support for PHP 5.2.
      elseif (!empty($uri)) {
        return realpath($uri);
      }
      return FALSE;
    }
    
    /**
     * Gets the name of the directory from a given path.
     *
     * PHP's dirname() does not properly pass streams, so this function fills
     * that gap. It is backwards compatible with normal paths and will use
     * PHP's dirname() as a fallback.
     *
     * Compatibility: normal paths and stream wrappers.
     *
     * @param $uri
     *   A URI or path.
     *
     * @return
     *   A string containing the directory name.
     *
     * @see dirname()
     * @see http://drupal.org/node/515192
     * @ingroup php_wrappers
     */
    function drupal_dirname($uri) {
      $scheme = file_uri_scheme($uri);
    
      if ($scheme && file_stream_wrapper_valid_scheme($scheme)) {
        return file_stream_wrapper_get_instance_by_scheme($scheme)->dirname($uri);
      }
      else {
        return dirname($uri);
      }
    }
    
    /**
     * Gets the filename from a given path.
     *
     * PHP's basename() does not properly support streams or filenames beginning
     * with a non-US-ASCII character.
     *
     * @see http://bugs.php.net/bug.php?id=37738
     * @see basename()
     *
     * @ingroup php_wrappers
     */
    function drupal_basename($uri, $suffix = NULL) {
      $separators = '/';
      if (DIRECTORY_SEPARATOR != '/') {
        // For Windows OS add special separator.
        $separators .= DIRECTORY_SEPARATOR;
      }
      // Remove right-most slashes when $uri points to directory.
      $uri = rtrim($uri, $separators);
      // Returns the trailing part of the $uri starting after one of the directory
      // separators.
      $filename = preg_match('@[^' . preg_quote($separators, '@') . ']+$@', $uri, $matches) ? $matches[0] : '';
      // Cuts off a suffix from the filename.
      if ($suffix) {
        $filename = preg_replace('@' . preg_quote($suffix, '@') . '$@', '', $filename);
      }
      return $filename;
    }
    
    /**
     * Creates a directory using Drupal's default mode.
     *
     * PHP's mkdir() does not respect Drupal's default permissions mode. If a mode
     * is not provided, this function will make sure that Drupal's is used.
     *
     * Compatibility: normal paths and stream wrappers.
     *
     * @param $uri
     *   A URI or pathname.
     * @param $mode
     *   By default the Drupal mode is used.
     * @param $recursive
     *   Default to FALSE.
     * @param $context
     *   Refer to http://php.net/manual/en/ref.stream.php
     *
     * @return
     *   Boolean TRUE on success, or FALSE on failure.
     *
     * @see mkdir()
     * @see http://drupal.org/node/515192
     * @ingroup php_wrappers
     */
    function drupal_mkdir($uri, $mode = NULL, $recursive = FALSE, $context = NULL) {
      if (!isset($mode)) {
        $mode = variable_get('file_chmod_directory', 0775);
      }
    
      if (!isset($context)) {
        return mkdir($uri, $mode, $recursive);
      }
      else {
        return mkdir($uri, $mode, $recursive, $context);
      }
    }
    
    /**
     * Removes a directory.
     *
     * PHP's rmdir() is broken on Windows, as it can fail to remove a directory
     * when it has a read-only flag set.
     *
     * @param $uri
     *   A URI or pathname.
     * @param $context
     *   Refer to http://php.net/manual/en/ref.stream.php
     *
     * @return
     *   Boolean TRUE on success, or FALSE on failure.
     *
     * @see rmdir()
     * @ingroup php_wrappers
     */
    function drupal_rmdir($uri, $context = NULL) {
      $scheme = file_uri_scheme($uri);
      if ((!$scheme || !file_stream_wrapper_valid_scheme($scheme)) && (substr(PHP_OS, 0, 3) == 'WIN')) {
        chmod($uri, 0700);
      }
      if ($context) {
        return rmdir($uri, $context);
      }
      else {
        return rmdir($uri);
      }
    }
    
    /**
     * Creates a file with a unique filename in the specified directory.
     *
     * PHP's tempnam() does not return a URI like we want. This function
     * will return a URI if given a URI, or it will return a filepath if
     * given a filepath.
     *
     * Compatibility: normal paths and stream wrappers.
     *
     * @param $directory
     *   The directory where the temporary filename will be created.
     * @param $prefix
     *   The prefix of the generated temporary filename.
     *   Note: Windows uses only the first three characters of prefix.
     *
     * @return
     *   The new temporary filename, or FALSE on failure.
     *
     * @see tempnam()
     * @see http://drupal.org/node/515192
     * @ingroup php_wrappers
     */
    function drupal_tempnam($directory, $prefix) {
      $scheme = file_uri_scheme($directory);
    
      if ($scheme && file_stream_wrapper_valid_scheme($scheme)) {
        $wrapper = file_stream_wrapper_get_instance_by_scheme($scheme);
    
        if ($filename = tempnam($wrapper->getDirectoryPath(), $prefix)) {
          return $scheme . '://' . drupal_basename($filename);
        }
        else {
          return FALSE;
        }
      }
      else {
        // Handle as a normal tempnam() call.
        return tempnam($directory, $prefix);
      }
    }
    
    /**
     * Gets the path of system-appropriate temporary directory.
     */
    function file_directory_temp() {
      $temporary_directory = variable_get('file_temporary_path', NULL);
    
      if (empty($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';
        }
        // PHP may be able to find an alternative tmp directory.
        // This function exists in PHP 5 >= 5.2.1, but Drupal
        // requires PHP 5 >= 5.2.0, so we check for it.
        if (function_exists('sys_get_temp_dir')) {
          $directories[] = sys_get_temp_dir();
        }
    
        foreach ($directories as $directory) {
          if (is_dir($directory) && is_writable($directory)) {
            $temporary_directory = $directory;
            break;
          }
        }
    
        if (empty($temporary_directory)) {
          // If no directory has been found default to 'files/tmp'.
          $temporary_directory = variable_get('file_public_path', conf_path() . '/files') . '/tmp';
    
          // Windows accepts paths with either slash (/) or backslash (\), but will
          // not accept a path which contains both a slash and a backslash. Since
          // the 'file_public_path' variable may have either format, we sanitize
          // everything to use slash which is supported on all platforms.
          $temporary_directory = str_replace('\\', '/', $temporary_directory);
        }
        // Save the path of the discovered directory.
        variable_set('file_temporary_path', $temporary_directory);
      }
    
      return $temporary_directory;
    }
    
    /**
     * Examines a file object and returns appropriate content headers for download.
     *
     * @param $file
     *   A file object.
     *
     * @return
     *   An associative array of headers, as expected by file_transfer().
     */
    function file_get_content_headers($file) {
      $name = mime_header_encode($file->filename);
      $type = mime_header_encode($file->filemime);
      // Serve images, text, and flash content for display rather than download.
      $inline_types = variable_get('file_inline_types', array('^text/', '^image/', 'flash$'));
      $disposition = 'attachment';
      foreach ($inline_types as $inline_type) {
        // Exclamation marks are used as delimiters to avoid escaping slashes.
        if (preg_match('!' . $inline_type . '!', $file->filemime)) {
          $disposition = 'inline';
        }
      }
    
      return array(
        'Content-Type' => $type,
        'Content-Length' => $file->filesize,
        'Content-Disposition' => $disposition . '; filename="' . $name . '"',
        'Cache-Control' => 'private',
      );
    }
    
    /**
     * @} End of "defgroup file".
     */