private static function init_listingDirectories()
 {
     if (MainWPSecurity::$listingDirectories == null) {
         $wp_upload_dir = wp_upload_dir();
         MainWPSecurity::$listingDirectories = array(WP_CONTENT_DIR, WP_PLUGIN_DIR, get_theme_root(), $wp_upload_dir['basedir']);
     }
 }