Re: [PATCH] util: In ASSERT(), use "fprintf(stderr, ...)" rather than err(...)

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Aug 06, 2024 at 11:27:40AM +0200, Laurent Vivier wrote:
> On 06/08/2024 02:27, David Gibson wrote:
> > On Mon, Aug 05, 2024 at 04:10:27PM +0200, Laurent Vivier wrote:
> > > We use our own implementation of assert() because the glic implementation
> > > uses syscalls that aren't in our seccomp filter, see 7a8ed9459dfe
> > > ("Make assertions actually useful"). And we replaced it by an err(),
> > > followed by an abort() (that is also catched by seccomp).
> > 
> > I think Stefano's said everything I would on the change itself, but..
> > 
> > > We don't have a coredump or a backtrace but we have at least the
> > > error message... only if logging is enabled.
> > 
> > Whether we get a coredump shouldn't be affected by our weird ASSERT()
> > here.  If coredumps are enabled (which they're not by default on
> > current distros, AFAICT), we should still get a coredump with the
> > SIGSYS here, just as we would for a SIGABRT.
> > 
> 
> I don't know what, but there is something that prevent passts to generate a core dump
> (I tried abort(), (char *)0 = 0, it works with a simple program, not with passt).
> 
> Moreover, if we use gdb it doesn't stop on the syscall but exit and we
> cannot locate the exit point. And as strace doesn't report the syscall that
> generates the SIGSYS, it makes hard to find which one it is.

Oh... that'll be the PR_SET_DUMPABLE.  That'll stop strace, gdb, core
dumps, ..

I routinely comment that out when debugging.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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