file_prepare_directory() doesn't do what it should when fed a drupal URI

API page: http://api.drupal.org/api/drupal/includes%21file.inc/function/file_prepa...

Enter a descriptive title (above) relating to file_prepare_directory, then describe the problem you have found:

I don't think this function works with Drupal URIs (although I might be missing something). If you pass in "public://info/55", it should create files/info/55 and then succeed. The is_dir() returns false, so it runs the drupal_mkdir() part, so creates the directories, but then returns false.

The $directory variable taken as input can be either a URI or a pathname. However, if it's a URI, it is never converted to an actual path, so the is_dir() check will always fail for URIs. If you pass it an actual filesystem path, it works correctly.

I haven't tested this, but I think the code should be something like:

function file_prepare_directory(&$directory, $options = FILE_MODIFY_PERMISSIONS) {
  $real_path = $directory;
  if (!file_stream_wrapper_valid_scheme(file_uri_scheme($directory))) {
    // Only trim if we're not dealing with a stream.
    $directory = rtrim($directory, '/\\');
  } else {
    $real_path = drupal_realpath($directory);
  }

  // Check if directory exists.
  if (!is_dir($real_path)) {
    // Let mkdir() recursively create directories and use the default directory
    // permissions.
    if (($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;
}

Note: drupal_realpath() is apparently deprecated, although I'm not sure what is supposed to replace it.