protected function readbytes($length)
    {
        if ($this->comptype === Archive::COMPRESS_GZIP) {
            return @gzread($this->fh, $length);
        } elseif ($this->comptype === Archive::COMPRESS_BZIP) {
            return @bzread($this->fh, $length);
        } else {
            return @fread($this->fh, $length);
        }
    }