[COFF] Re: Conditions, AKA exceptions.

[Ralph Corderoy <ralph@inputplus.co.uk>]

Hi Ted,

> > >         cmd = aprintf("gdb -batch -ex backtrace '%s/bk' %u 1>&%d 2>&%d",
> > >             bin, getpid(), fileno(f), fileno(f));
...
> > It works surprisingly often, i.e. the process is healthy enough to
> > run system(3).
>
> On Linux (or some other system using glibc) a limited facility is
> built into the C library.  So you can just do somthing like this:
...
> 	       frames = backtrace(stack_syms, 32);
> 	       backtrace_symbols_fd(stack_syms, frames, 2);

Since ’99, yes.  :-)  backtrace(3) says glibc 2.1 added it.

> I use this for the fsck for ext4, and the nice thing is that even with
> a stripped binary.
>
> For example:

Yes, that is nice.

> https://github.com/tytso/e2fsprogs/blob/master/e2fsck/sigcatcher.c#L379

Thanks, I've made a note.

Do you ever find things are so messed up that stdio has trouble whereas
using write(2) with compile-time memory allocations for a buffer would
have a better chance of reaching the TTY?

-- 
Cheers, Ralph.