public function get_handled_file_types($module) {
        $types = array();
        foreach ($this->filehandlers as $handler) {
            if ($handler->module == $module) {
                if ($handler->extension == '*') {
                    return '*';
                } else {
                    // Prepending '.' as otherwise mimeinfo fails.
                    $types[] = '.'.$handler->extension;
                }
            }
        }
        return $types;
    }