[libvirt] [PATCH v3] util: systemd: Define MSG_NOSIGNAL if needed

[Daniel P. Berrange]

On Wed, Jul 20, 2016 at 03:11:51PM +0100, Justin Clift wrote:
> On 20 Jul 2016, at 14:46, Andrea Bolognani <abologna at redhat.com> wrote:
> > The symbol being missing has been reported as causing build
> > failures on OS X. If it's not already defined, define it to
> > zero so that it won't have any effect.
> > ---
> > Changes from v2:
> > 
> >  * define MSG_NOSIGNAL to zero if not already defined
> >    instead of conditionally compiling the code depending
> >    on it
> > 
> > src/util/virsystemd.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> > 
> > diff --git a/src/util/virsystemd.c b/src/util/virsystemd.c
> > index 969cd68..7d6985b 100644
> > --- a/src/util/virsystemd.c
> > +++ b/src/util/virsystemd.c
> > @@ -41,6 +41,10 @@
> > 
> > VIR_LOG_INIT("util.systemd");
> > 
> > +#ifndef MSG_NOSIGNAL
> > +# define MSG_NOSIGNAL 0
> > +#endif
> > +
> > static void virSystemdEscapeName(virBufferPtr buf,
> >                                  const char *name)
> > {
> > -- 
> > 2.7.4
> 
> This compiles fine on OSX too. :)
> 
> One niggle with it though... this is what is looks like in context:
> 
> *******************************************************************
> ...
> #include "virerror.h"
> #include "virfile.h"
> 
> #define VIR_FROM_THIS VIR_FROM_SYSTEMD
> 
> VIR_LOG_INIT("util.systemd");
> 
> #ifndef MSG_NOSIGNAL
> # define MSG_NOSIGNAL 0
> #endif
> 
> static void virSystemdEscapeName(virBufferPtr buf,
>                                  const char *name)
> {
>     static const char hextable[16] = "0123456789abcdef";
> 
> #define ESCAPE(c)
> ...
> *******************************************************************
> 
> Isn't it kind of crying out for a useful comment, so the next person
> looking through this code has a good chance to understand why it's
> there? ;)
> 
> Maybe something like:
> 
> /* OSX is missing MSG_NOSIGNAL, so we define it here to avoid
>  * failure during building.
>  */

Not really - it is pretty obvious what the code is doing so adding
such a comment doesn't really add much value.

Regards,
Daniel
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