pack to gz and return archive file download

function pack($dir){
  $dir = realpath($dir);

  $phar = new PharData($dir.'.tar');
  $phar->buildFromDirectory($dir);

  $phar->compress(Phar::GZ);

  header('Content-Type: application/x-gzip');
  header('Content-Disposition: attachment; filename="'.pathinfo($dir.'.tar.gz', PATHINFO_BASENAME).'"');
  echo file_get_contents($dir.'.tar.gz');
}