protected function serveFile($filename, $displayName, Request $request, $asAttachment = false)
{
$lastModified = new \DateTime();
$lastModified->setTimestamp(filemtime($filename));
$ifModifiedSince = $request->headers->has('If-Modified-Since') ? new \DateTime($request->headers->get('If-Modified-Since')) : false;
$finfo = finfo_open(FILEINFO_MIME_TYPE);
$mimeType = finfo_file($finfo, $filename);
$response = new BinaryFileResponse($filename);
$response->setMaxAge(10);
$response->headers->addCacheControlDirective('must-revalidate');
$response->headers->set('Content-Type', $mimeType);
$response->setLastModified($lastModified);
$response->setContentDisposition($asAttachment ? ResponseHeaderBag::DISPOSITION_ATTACHMENT : ResponseHeaderBag::DISPOSITION_INLINE, $displayName, mb_convert_encoding($displayName, "ASCII", "UTF-8"));
$response->prepare($request);
if ($ifModifiedSince && $ifModifiedSince <= $lastModified) {
$response->setStatusCode(304);
}
return $response;
}