Function accept

src/windows/libwinio.cpp:552–599

Future<Nothing> accept(const int_fd& fd, const int_fd& accepted_socket)
{
  process::initialize();

  Promise<Nothing>* promise = new Promise<Nothing>();
  Future<Nothing> future = promise->future();

  // We use a `std::shared_ptr`, so we can safely support canceling.
  auto overlapped = std::make_shared<IOOverlappedAccept>(
      IOOverlappedBase{OVERLAPPED{}, fd, IOType::ACCEPT}, promise);

  enable_cancellation(fd, future, overlapped);

  // The `overlapped->buf` passed into `::AcceptEx` will receive the first
  // data block sent, the local address of the server and the remote address
  // of the client. The (4th, 5th, 6th) arguments are
  // (0, sizeof(buf)/2 , sizeof(buf) / 2), since we ignore the first block,
  // and simply store the local and remote addresses. For more details, see
  // https://msdn.microsoft.com/en-us/library/windows/desktop/ms737524(v=vs.85).aspx // NOLINT(whitespace/line_length)
  DWORD bytes;
  const BOOL success = ::AcceptEx(
      fd,
      accepted_socket,
      overlapped->buf,
      0,
      sizeof(overlapped->buf) / 2,
      sizeof(overlapped->buf) / 2,
      &bytes,
      &overlapped->base.overlapped);

  const DWORD error = ::WSAGetLastError();

  // If the request is pending, then we return immediately and have the
  // callback free the promise and overlapped
  if (!success && error == WSA_IO_PENDING) {
    return future;
  }

  // In an error or immediate success, we have to manually set the promise
  // and free it.
  if (success) {
    promise->set(Nothing());
  } else {
    promise->fail("AcceptEx failed: " + WindowsError(error).message);
  }
  delete promise;
  return future;
}

// The MSDN docs state that `::ConnectEx` must be retrieved through
// `::WSAIoctl`. See the remarks section of the docs: