public function toStream()
    {
        if (!\is_resource($this->process)) {
            $this->process = \proc_open('/usr/bin/env tar c .', [['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']], $pipes, $this->directory);
            $this->stream = $pipes[1];
        }

        return $this->stream;
    }