class BinaryFileResponseTestController

class BinaryFileResponseTestController {
  
  /**
   * Download the file set in the relative_file_url query parameter.
   *
   * @return \Symfony\Component\HttpFoundation\BinaryFileResponse
   *   The response wrapping the file content.
   */
  public function download(Request $request) {
    if (!$request->query
      ->has('relative_file_url')) {
      throw new BadRequestHttpException();
    }
    $relative_file_url = $request->query
      ->get('relative_file_url');
    // A relative URL for a file contains '%20' instead of spaces. A relative
    // file path contains spaces.
    $relative_file_path = rawurldecode($relative_file_url);
    // Ensure the file path does not start with a slash to prevent exploring
    // the file system root.
    $relative_file_path = ltrim($relative_file_path, '/');
    return new BinaryFileResponse($relative_file_path);
  }

}