// validate query parameter

    if ( is_array($parsed_url) && array_key_exists('query', $parsed_url) && $parsed_url['query']) {

      parse_str($parsed_url['query'], $parsed_query_arr);

      // validate

      $parsed_query_arr = $this->clear_system_vars($parsed_query_arr);

      // in error_document $_GET is empty, so set them at this line

      $_GET = $parsed_query_arr ? $parsed_query_arr : array();

    }

    static function parse_str($query)

    {

        if ($query === null) {

            return null;

        }



        $parts = explode('&', $query);



        $new_parts = array();

        for ($i = 0; $i < count($parts); $i++) {

            $pair = explode('=', $parts[$i]);



            if (count($pair) != 2) {

                continue;

            }



            list($key, $value) = $pair;

            $new_parts[urldecode($key)] = urldecode($value);

        }



        return $new_parts;

    }