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

[Andrea Bolognani]

On Tue, 2016-07-19 at 16:23 +0200, Ján Tomko wrote:
> 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.

You're of course right. I'm not quite sure what I was thinking
when I added the configure check.

-- 
Andrea Bolognani / Red Hat / Virtualization