SCardCancel(): return SCARD_S_SUCCESS even if the client already fini…

…shed

In some cases SCardCancel() is called exactly at the same time
SCardGetStatusChange() exits with SCARD_E_TIMEOUT.

In that case the SCardGetStatusChange() client disapears in the middle
of SCardCancel() processing. If the client is found but can't be
contacted then we return SCARD_S_SUCCESS instead of
SCARD_E_INVALID_HANDLE.

Thanks to Jakub Janků for the bug report
Closes: #160
"Concurrency issue with SCardCancel and SCardGetStatusChange timeout #160"

src/winscard_svc.c

@@ -621,6 +621,8 @@ static void * ContextThread(LPVOID newContext)
 					/* signal the client only if it was still waiting */
 					if (SCARD_S_SUCCESS == rv)
 						caStr.rv = MSGSignalClient(fd, SCARD_E_CANCELLED);
+					else
+						caStr.rv = SCARD_S_SUCCESS;
 				}
 
 				WRITE_BODY(caStr);