[libvirt] [PATCH] configure: Check for MSG_NOSIGNAL availability

[Ján Tomko]

On Tue, Jul 19, 2016 at 04:00:25PM +0200, Andrea Bolognani wrote:
>The symbol being missing has been reported as causing build
>failures on OS X. Check for its availability before using it.
>---
>See https://www.redhat.com/archives/libvir-list/2016-July/msg00613.html
>
> configure.ac          | 4 ++++
> src/util/virsystemd.c | 4 ++--
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
>diff --git a/configure.ac b/configure.ac
>index 2c81c95..af5d2f8 100644
>--- a/configure.ac
>+++ b/configure.ac
>@@ -402,6 +402,10 @@ AC_CHECK_TYPE([struct sockpeercred],
>   [], [[#include <sys/socket.h>
>   ]])
>
>+AC_CHECK_DECLS([MSG_NOSIGNAL],
>+  [], [], [[#include <sys/socket.h>
>+  ]])
>+
> AC_CHECK_DECLS([ETH_FLAG_TXVLAN, ETH_FLAG_NTUPLE, ETH_FLAG_RXHASH, ETH_FLAG_LRO,
>                 ETHTOOL_GGSO, ETHTOOL_GGRO, ETHTOOL_GFLAGS, ETHTOOL_GFEATURES],
>   [], [], [[#include <linux/ethtool.h>
>diff --git a/src/util/virsystemd.c b/src/util/virsystemd.c
>index 969cd68..d2f4bfb 100644
>--- a/src/util/virsystemd.c
>+++ b/src/util/virsystemd.c
>@@ -482,7 +482,7 @@ int virSystemdTerminateMachine(const char *name)
> void
> virSystemdNotifyStartup(void)
> {
>-#ifdef HAVE_SYS_UN_H
>+#if defined(HAVE_SYS_UN_H) && defined(HAVE_MSG_NOSIGNAL)

What are the benefits of checking this at configure-time?

Seems to me we could just as well use defined(MSG_NOSIGNAL) without
slowing configure down even more if we aren't going to base other
configure-time decisions on it.

Jan