Libc6 malloc bites?

David Murn davey at
Sat Sep 1 19:36:28 EST 2001

On Sat, 1 Sep 2001 jeremy at wrote:

> I've got a perl program segfaulting.  This problem got my interest
> because I couldn't nail down where it blew out.  I was iterating over an
> array, and the act of adding debugging prints would move which array
> element would cause the segfault.  I also can't localise it to a certain
> statement.

If you're under deban, install libc6-dbg package, type:

export LD_LIBRARY_PATH=/usr/lib/debug

Then gdb it again.  That is a libc compiled with -g which lets you see
exactly what line in libc is causing the segfault.

> And if it is libc, how can I get more information on how malloc was
> called?  I've tried reading the gdb docos but I'm not a C coder.  It
> seems gdb can track variables, but that doesn't help because Perl isn't
> going to tag a SV with a name so I can track it with gdb.

I think this could be an interesting talk sometime, how to use gdb at
least the basics.  I basically learnt the hard way from manpages and trial
and error.  I think possibly even little groups in corners talking about
gdb would, bof's in a way.  Ive learnt a fair bit about gdb from other
users, just little tips and tricks.


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