Function sendfile

src/http.cpp:1589–1653

Future<Nothing> sendfile(
    network::Socket socket,
    Response response,
    Request* request)
{
  CHECK(response.type == Response::PATH);

  // Make sure no body is sent (this is really an error and
  // should be reported and no response sent.
  response.body.clear();

  Try<int_fd> fd = os::open(response.path, O_CLOEXEC | O_NONBLOCK | O_RDONLY);

  if (fd.isError()) {
    const string body = "Failed to open '" + response.path + "': " + fd.error();
    // TODO(benh): VLOG(1)?
    // TODO(benh): Don't send error back as part of InternalServiceError?
    // TODO(benh): Copy headers from `response`?
    return send(socket, InternalServerError(body), request);
  }

  const Try<Bytes> size = os::stat::size(fd.get());
  if (size.isError()) {
    const string body =
      "Failed to fstat '" + response.path + "': " + size.error();
    // TODO(benh): VLOG(1)?
    // TODO(benh): Don't send error back as part of InternalServiceError?
    // TODO(benh): Copy headers from `response`?
    os::close(fd.get());
    return send(socket, InternalServerError(body), request);
  } else if (os::stat::isdir(fd.get())) {
    const string body = "'" + response.path + "' is a directory";
    // TODO(benh): VLOG(1)?
    // TODO(benh): Don't send error back as part of InternalServiceError?
    // TODO(benh): Copy headers from `response`?
    os::close(fd.get());
    return send(socket, InternalServerError(body), request);
  }

  // While the user is expected to properly set a 'Content-Type'
  // header, we'll fill in (or overwrite) 'Content-Length' header.
  response.headers["Content-Length"] = stringify(size->bytes());

  // TODO(benh): If this is a TCP socket consider turning on TCP_CORK
  // for both sends and then turning it off.
  Encoder* encoder = new HttpResponseEncoder(response, *request);

  return send(socket, encoder)
    .onAny([=](const Future<Nothing>& future) {
      delete encoder;

      // Close file descriptor if we aren't doing any more sending.
      if (future.isDiscarded() || future.isFailed()) {
        os::close(fd.get());
      }
    })
    .then([=]() mutable -> Future<Nothing> {
      // NOTE: the file descriptor gets closed by FileEncoder.