package Debug::DumpCore;
use 5.00503;
use strict;
#use warnings;
use Debug::FaultAutoBT (); # The C/XS code is in that module's .so object
$Debug::DumpCore::VERSION = '0.01';
1;
__END__
=head1 NAME
Debug::DumpCore - Generate a SegFault
=head1 SYNOPSIS
use Debug::DumpCore;
Debug::DumpCore::segv();
=head1 DESCRIPTION
This module implements a buggy C function which tries to dereference a
NULL pointer, which generates a SEGFAULT. It is used to test the
C<Debug::FaultAutoBT> module that attempts to automatically generate a
backtrace when some fatal signal is delivered, without needing the
core file.
Notice that you could use Perl's C<CORE::dump> to achieve the same
goal, but dump()'s backtrace is not very useful for teaching purposes.
C<Debug::DumpCore::segv()> calls another proper C function which
finally calls a buggy C function, which causes a SEGFAULT. So you get
a long trace. For example this is the backtrace generated on my
machine:
#0 0x402b979b in crash_now_for_real (
suicide_message=0x402ba040 "Cannot stand this life anymore")
at DumpCore.xs:246
#1 0x402b97bd in crash_now (
suicide_message=0x402ba040 "Cannot stand this life anymore",
attempt_num=42) at FaultAutoBT.xs:253
#2 0x402b983e in XS_Debug__DumpCore_segv (cv=0x81751e4)
at FaultAutoBT.xs:262
#3 0x400851ec in Perl_pp_entersub ()
from /usr/lib/perl5/5.6.1/i386-linux/CORE/libperl.so
And the corresponding C code around line 246 is:
7: crash_now_for_real(char *suicide_message)
8: {
9: int *p = NULL;
10: printf("%d", *p); /* cause a segfault */
=head1 EXPORT
None.
=head1 AUTHOR
Stas Bekman E<lt>stas@stason.orgE<gt>
=head1 SEE ALSO
perl(3), C<Debug::FaultAutoBT(3)>.
=cut