[Freeswitch-users] DockStar compile failure, with possible fix

[Tom C]

I thought the whole point of the va_start, va_end, va_arg and va_copy macros
was to make variadic functions portable.  (At least that's what it done said
on that there inter-web thingy.)  It's really sad if it doesn't actually
work that way.  :-)

I ran it for a little while with if(1), and it seemed to work fine, but that
was with a very mundane scenario.


On Mon, Dec 13, 2010 at 9:30 AM, Anthony Minessale <
anthony.minessale at gmail.com> wrote:

> va_copy is not portable either =D welcome to C
>
> I think this code has evolved to the point at which i don't think its
> even possible for this to happen anyway.
> I am going to try running it without the test at all.
>
> commit dfecc914876b164ce64c53c4f048aa38ed65d9c5
> Author: Anthony Minessale <anthm at freeswitch.org>
> Date:   Mon Dec 13 11:20:12 2010 -0600
>
>
> On Mon, Dec 13, 2010 at 1:10 AM, Tom C <mel0torme at gmail.com> wrote:
> > I was attempting to build FreeSwitch on a Dockstar running Debian
> Squeeze,
> > and ran into the sofia.c logger() compile problem as described here:
> > http://jira.freeswitch.org/browse/FS-802
> >
> > The offered solution was to downgrade GCC, but being a Linux newbie, I
> > didn't know how to do that. So I decided to figure out what the problem
> > really is.
> >
> > After learning waaaay too much about va_list, I see that the logger()
> > function in sofia.c assumes that va_list will always be a pointer.  But
> on
> > different platforms, va_list can be an array or a struct.  On the
> Dockstar
> > (with Debian Squeeze and GCC 4.4), va_list is apparently a struct.
> >
> > I made the following modifications to logger() to make it truly portable,
> > and it compiles and runs fine on my DockStar, my Debian Lenny x86.  (My
> > Windows build is having bigger problems.)  But I'm no C guru, so someone
> > needs to thoroughly examine my code before anyone else takes it as
> gospel.
> > Am I actually checking what needs to be checked with the va_arg() macro?
> > Changing it to if(1) worked too, after all.
> >
> >
> > ORIGINAL logger() in sofia.c, to make it easy to see what I changed.
> > static void logger(void *logarg, char const *fmt, va_list ap)
> > {
> > /* gcc 4.4 gets mad at us for testing if (ap) so let's try to work around
> > it....*/
> > void *ap_ptr = (void *) (intptr_t) ap;  //Error now occurs here, because
> ap
> > is a struct.
> > if (!fmt) return;
> > if (ap_ptr) {  //Error used to occur here, before attempted fix above.
> >    switch_log_vprintf(SWITCH_CHANNEL_LOG_CLEAN,
> > mod_sofia_globals.tracelevel, fmt, ap);
> > } else {
> >    switch_log_printf(SWITCH_CHANNEL_LOG_CLEAN,
> mod_sofia_globals.tracelevel,
> > "%s", fmt);
> > }
> > }
> >
> >
> > My MODIFIED logger() function, additions and changes labelled with
> DOCKSTAR:
> >
> > static
> >
> > void logger(void *logarg, char const *fmt, va_list ap)
> > {
> > va_list temp_ap;  //DOCKSTAR: Added line (replacing previous ap_ptr
> cast).
> >
> > if (!fmt) return;
> >
> > va_copy(temp_ap, ap); //DOCKSTAR: Added Line. Make copy of "ap" so
> va_arg()
> > macro doesn't move pointer.
> >
> > if (va_arg(temp_ap, int)) {  //DOCKSTAR: Modified, get first argument
> from
> > ap, check non-null.
> >      switch_log_vprintf(SWITCH_CHANNEL_LOG_CLEAN,
> > mod_sofia_globals.tracelevel, fmt, ap);
> > } else {
> >      switch_log_printf(SWITCH_CHANNEL_LOG_CLEAN,
> > mod_sofia_globals.tracelevel, "%s", fmt);
> > }
> >
> > va_end(temp_ap);  //DOCKSTAR: Added line.  Release our copy of "ap".
> > }
> >
> > _______________________________________________
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> >
> >
>
>
>
> --
> Anthony Minessale II
>
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