class GzipDownloader

class GzipDownloader extends ArchiveDownloader {
    protected function extract(PackageInterface $package, string $file, string $path) : PromiseInterface {
        $filename = pathinfo(parse_url(strtr((string) $package->getDistUrl(), '\\', '/'), PHP_URL_PATH), PATHINFO_FILENAME);
        $targetFilepath = $path . DIRECTORY_SEPARATOR . $filename;
        // Try to use gunzip on *nix
        if (!Platform::isWindows()) {
            $command = [
                'sh',
                '-c',
                'gzip -cd -- "$0" > "$1"',
                $file,
                $targetFilepath,
            ];
            if (0 === $this->process
                ->execute($command, $ignoredOutput)) {
                return \React\Promise\resolve(null);
            }
            if (extension_loaded('zlib')) {
                // Fallback to using the PHP extension.
                $this->extractUsingExt($file, $targetFilepath);
                return \React\Promise\resolve(null);
            }
            $processError = 'Failed to execute ' . implode(' ', $command) . "\n\n" . $this->process
                ->getErrorOutput();
            throw new \RuntimeException($processError);
        }
        // Windows version of PHP has built-in support of gzip functions
        $this->extractUsingExt($file, $targetFilepath);
        return \React\Promise\resolve(null);
    }
    private function extractUsingExt(string $file, string $targetFilepath) : void {
        $archiveFile = gzopen($file, 'rb');
        $targetFile = fopen($targetFilepath, 'wb');
        while ($string = gzread($archiveFile, 4096)) {
            fwrite($targetFile, $string, Platform::strlen($string));
        }
        gzclose($archiveFile);
        fclose($targetFile);
    }

}