daemon: ignore ENOTSOCK from setsockopt

In inetd mode, we are not guaranteed stdin or stdout is a
socket; callers could filter the data through a pipe
or be testing with regular files.

This prevents t5802 from polluting syslog.

Signed-off-by: Eric Wong <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Eric Wong

daemon.c

@@ -673,9 +673,11 @@ static void set_keep_alive(int sockfd)
 {
 	int ka = 1;
 
-	if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
-		logerror("unable to set SO_KEEPALIVE on socket: %s",
-			strerror(errno));
+	if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
+		if (errno != ENOTSOCK)
+			logerror("unable to set SO_KEEPALIVE on socket: %s",
+				strerror(errno));
+	}
 }
 
 static int execute(void)