[PATCH 1/4] connection: Fix sendmsg() on BSD systems

[Karsten Otto]

From: Philip Withnall <philip at tecnocode.co.uk>

BSD systems expect all unused fields in the msghdr struct to be
initialized to 0 and NULL respectively, and returns EINVAL otherwise.
It can't hurt to be tidy about things on other platforms either though.

[KAO: Make comments refer to all BSD-like systems]
---
 src/connection.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/connection.c b/src/connection.c
index f292853..e728fd8 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -287,10 +287,16 @@ wl_connection_flush(struct wl_connection *connection)
 		msg.msg_namelen = 0;
 		msg.msg_iov = iov;
 		msg.msg_iovlen = count;
-		msg.msg_control = cmsg;
-		msg.msg_controllen = clen;
+		msg.msg_control = NULL;
+		msg.msg_controllen = 0;
 		msg.msg_flags = 0;
 
+		/* Only set msg_control when sending ancillary data */
+		if (clen > 0) {
+			msg.msg_controllen = clen;
+			msg.msg_control = cmsg;
+		}
+
 		do {
 			len = sendmsg(connection->fd, &msg,
 				      MSG_NOSIGNAL | MSG_DONTWAIT);
-- 
1.9.1