Running a program through gdb without "interfering"

[Gary Jennejohn]

On Fri, 9 Oct 2009 01:16:59 +0200
Mel Flynn <mel.flynn+fbsd.hackers at mailing.thruhere.net> wrote:

> On Friday 09 October 2009 00:38:32 Paul B Mahol wrote:
> > On 10/9/09, Mel Flynn <mel.flynn+fbsd.hackers at mailing.thruhere.net> wrote:
> > > Hi,
> > >
> > > is there a way to have a program run through gdb and gdb only record a
> > > segfault, but otherwise let the program run?
> > >
> > > Why I'd like this is the following:
> > > I've got a i386 jail on an amd64 box, running 7.2-p4. UNAME_p and UNAME_m
> > > have
> > > been set to i386 as well as ARCH in /etc/make.conf. Running portmaster[1]
> > > to build ports under my uid and PM_SU_CMD, sudo *sometimes* segfaults.
> > > It's only
> > > sudo, so at present I don't have a reason to doubt memory. However, it
> > > doesn't
> > > dump core, so I'm at a loss what the culprit could be.
> > 
> > Tried 'sysctl kern.sugid_coredump=1' ?
> 
> Hmm, no. Enabled now and waiting for the next segfault.
> I actually looked at the sysctl -d, but it didn't register that this could be 
> the main cause.
> Perhaps that sentence could be more clear:
> -kern.sugid_coredump: Enable coredumping set user/group ID processes
> +kenr.sugid_coredump: Allow setuid/setgid processes to dump core
> 

See the info file for gdb, section 5.3 Signals.  It's possible to tell
gdb how to handle signals, e.g. stop vs. nostop, etc.

---
Gary Jennejohn