#223 Windows: Excessive error reporting when polling (rcvmsg)

[Bernd Löhr]

Polling under Windows outputs an error message (EWOULDBLOCK) if no data available.
The error handling in function vos_sock.c:111 recvmsg() should be revised. E.g. WSAIoCtl() will probably never return WSAEWOULDBLOCK.

[Armin-Hagen Weiss]

recvmsg() in Windows vos_sock.c generates an error msg for WSAEWOULDBLOCK.
Instead of excluding WSAEMSGSIZE in line 137 WSAEWOULDBLOCK should be excluded for generating error messages.

[John Varghese]

It still outputs an error message if there is no data received by the function
it is outputing. "trdp_pdcom.c:972 PDframe size error (8))".
I feel that if WSARecvMsg is returning SOCKET_ERROR then numBytes will not be a valid value for our case.
So I suggest returning -1 if there is SOCKET_ERROR.

Could you please review if my suggestion will work?
else
{
pMessage->dwFlags = flags;
res = WSARecvMsg(sock, pMessage, &numBytes, NULL, NULL);
if (0 != res)
{
DWORD err = WSAGetLastError();
if (err != WSAEWOULDBLOCK)
{
vos_printLog(VOS_LOG_ERROR, "WSARecvMsg() failed (Err: %d)\n", err);
}
return -1;
}
}
return numBytes;
}

[Armin-Hagen Weiss]

recvmsg() needs to return SOCKET_ERROR also in case of WSAEWOULDBLOCK even the error message needs to be suppressed.