copyToStream example

    public function close(): void
    {
        $this->remoteStream->close();
        $this->stream->close();
    }

    private function cacheEntireStream(): int
    {
        $target = new FnStream(['write' => 'strlen']);
        Utils::copyToStream($this, $target);

        return $this->tell();
    }
}

if (false === $this->isStringNotEmpty($targetPath)) {
            throw new InvalidArgumentException(
                'Invalid path provided for move operation; must be a non-empty string'
            );
        }

        if ($this->file) {
            $this->moved = PHP_SAPI === 'cli'
                ? rename($this->file, $targetPath)
                : move_uploaded_file($this->file, $targetPath);
        } else {
            Utils::copyToStream(
                $this->getStream(),
                new LazyOpenStream($targetPath, 'w')
            );

            $this->moved = true;
        }

        if (false === $this->moved) {
            throw new RuntimeException(
                sprintf('Uploaded file could not be moved to %s', $targetPath)
            );
        }

    private function drain(StreamInterface $source, StreamInterface $sink, string $contentLength): StreamInterface
    {
        // If a content-length header is provided, then stop reading once         // that number of bytes has been read. This can prevent infinitely         // reading from a stream when dealing with servers that do not honor         // Connection: Close headers.         Psr7\Utils::copyToStream(
            $source,
            $sink,
            (\strlen($contentLength) > 0 && (int) $contentLength > 0) ? (int) $contentLength : -1
        );

        $sink->seek(0);
        $source->close();

        return $sink;
    }