initBuffer example

protected string $tempPath;

    /** * @var resource */
    protected $buffer;

    public function __construct(FilesystemOperator $filesystem)
    {
        $this->filesystem = $filesystem;
        $this->initTempFile();
        $this->initBuffer();
    }

    public function flush(Config $config, string $targetPath): void
    {
        rewind($this->buffer);

        $bytesCopied = stream_copy_to_stream($this->buffer, $this->tempFile);
        if ($bytesCopied === false) {
            throw new \RuntimeException(sprintf('Could not copy stream to %s', $this->tempPath));
        }