Function wait_until_socket_is_ready

dependencies/httplib/httplib.h:2325–2380

}

inline Error wait_until_socket_is_ready(socket_t sock, time_t sec,
                                        time_t usec) {
#ifdef CPPHTTPLIB_USE_POLL
  struct pollfd pfd_read;
  pfd_read.fd = sock;
  pfd_read.events = POLLIN | POLLOUT;

  auto timeout = static_cast<int>(sec * 1000 + usec / 1000);

  auto poll_res = handle_EINTR([&]() { return poll(&pfd_read, 1, timeout); });

  if (poll_res == 0) { return Error::ConnectionTimeout; }

  if (poll_res > 0 && pfd_read.revents & (POLLIN | POLLOUT)) {
    int error = 0;
    socklen_t len = sizeof(error);
    auto res = getsockopt(sock, SOL_SOCKET, SO_ERROR,
                          reinterpret_cast<char *>(&error), &len);
    auto successful = res >= 0 && !error;
    return successful ? Error::Success : Error::Connection;
  }

  return Error::Connection;
#else
#ifndef _WIN32
  if (sock >= FD_SETSIZE) { return Error::Connection; }
#endif

  fd_set fdsr;
  FD_ZERO(&fdsr);
  FD_SET(sock, &fdsr);

  auto fdsw = fdsr;
  auto fdse = fdsr;

  timeval tv;
  tv.tv_sec = static_cast<long>(sec);
  tv.tv_usec = static_cast<decltype(tv.tv_usec)>(usec);

  auto ret = handle_EINTR([&]() {
    return select(static_cast<int>(sock + 1), &fdsr, &fdsw, &fdse, &tv);
  });

  if (ret == 0) { return Error::ConnectionTimeout; }

  if (ret > 0 && (FD_ISSET(sock, &fdsr) || FD_ISSET(sock, &fdsw))) {
    int error = 0;
    socklen_t len = sizeof(error);
    auto res = getsockopt(sock, SOL_SOCKET, SO_ERROR,
                          reinterpret_cast<char *>(&error), &len);
    auto successful = res >= 0 && !error;
    return successful ? Error::Success : Error::Connection;
  }
  return Error::Connection;
#endif
}

inline bool is_socket_alive(socket_t sock) {