From 5e8d7527afc9dd1113ec6fbdcb091d87c6e32c1c Mon Sep 17 00:00:00 2001
From: Corinna Vinschen <corinna@vinschen.de>
Date: Tue, 22 Sep 2009 14:27:57 +0000
Subject: [PATCH] 	* autoload.cc (WSARecv): Define. 	*
 fhandler_socket.cc (fhandler_socket::recv_internal): Call WSARecv 
 instead of WSARecvFrom if no name parameter is given.  Explain why.

---
 winsup/cygwin/ChangeLog          |  6 ++++++
 winsup/cygwin/autoload.cc        |  1 +
 winsup/cygwin/fhandler_socket.cc | 28 ++++++++++++++++++++++------
 3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 9752abe5e..b09bf6fa7 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,9 @@
+2009-09-22  Corinna Vinschen  <corinna@vinschen.de>
+
+	* autoload.cc (WSARecv): Define.
+	* fhandler_socket.cc (fhandler_socket::recv_internal): Call WSARecv
+	instead of WSARecvFrom if no name parameter is given.  Explain why.
+
 2009-09-22  Eric Blake  <ebb9@byu.net>
 
 	* syscalls.cc (faccessat): Fix typo, reject bad flags.
diff --git a/winsup/cygwin/autoload.cc b/winsup/cygwin/autoload.cc
index afe6028a5..942891303 100644
--- a/winsup/cygwin/autoload.cc
+++ b/winsup/cygwin/autoload.cc
@@ -391,6 +391,7 @@ LoadDLLfunc (WSAEnumNetworkEvents, 12, ws2_32)
 LoadDLLfunc (WSAEventSelect, 12, ws2_32)
 LoadDLLfunc (WSAGetLastError, 0, ws2_32)
 LoadDLLfunc (WSAIoctl, 36, ws2_32)
+LoadDLLfunc (WSARecv, 28, ws2_32)
 LoadDLLfunc (WSARecvFrom, 36, ws2_32)
 LoadDLLfunc (WSASendMsg, 24, ws2_32)
 LoadDLLfunc (WSASendTo, 36, ws2_32)
diff --git a/winsup/cygwin/fhandler_socket.cc b/winsup/cygwin/fhandler_socket.cc
index 52d03ed07..3e218347d 100644
--- a/winsup/cygwin/fhandler_socket.cc
+++ b/winsup/cygwin/fhandler_socket.cc
@@ -1379,14 +1379,30 @@ fhandler_socket::recv_internal (LPWSAMSG wsamsg)
     {
       if (use_recvmsg)
 	res = WSARecvMsg (get_socket (), wsamsg, &wret, NULL, NULL);
+      /* This is working around a really weird problem in WinSock.
+
+         Assume you create a socket, fork the process (thus duplicating
+	 the socket), connect the socket in the child, then call recv
+	 on the original socket handle in the parent process.
+	 In this scenario, calls to WinSock's recvfrom and WSARecvFrom
+	 in the parent will fail with WSAEINVAL, regardless whether both
+	 address parameters, name and namelen, are NULL or point to valid
+	 storage.  However, calls to recv and WSARecv succeed as expected.
+	 Per MSDN, WSAEINVAL in the context of recv means  "The socket has not
+	 been bound".  It is as if the recvfrom functions test if the socket
+	 is bound locally, but in the parent process, WinSock doesn't know
+	 about that and fails, while the same test is omitted in the recv
+	 functions.
+	 
+	 This also covers another weird case: Winsock returns WSAEFAULT if
+	 namelen is a valid pointer while name is NULL.  Both parameters are
+	 ignored for TCP sockets, so this only occurs when using UDP socket. */
+      else if (!wsamsg->name)
+	res = WSARecv (get_socket (), wsabuf, wsacnt, &wret, &wsamsg->dwFlags,
+		       NULL, NULL);
       else
 	res = WSARecvFrom (get_socket (), wsabuf, wsacnt, &wret,
-			   &wsamsg->dwFlags, wsamsg->name,
-			   /* Winsock returns WSAEFAULT if namelen is a valid
-			      pointer while name is NULL.  Both parameters are
-			      ignored for TCP sockets, so this only occurs when
-			      using UDP socket. */
-			   wsamsg->name ? &wsamsg->namelen : NULL,
+			   &wsamsg->dwFlags, wsamsg->name, &wsamsg->namelen,
 			   NULL, NULL);
       if (!res)
 	{