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Postings from July 2009
> Avar mailed p5p in
> 51dd1af80807190107h30b8626ct6d4d0a825abe4b3b@mail.gmail.com
> http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-07/msg00382.html
>
> perl 5.10 and blead will do various combinations of running of of
> memory, hanging or segfaulting when running on a program using
> XML::Parser::Lite, attached is a stripped down version of X::P::L
> which demonstrates the problem:
>
>
> Dave notes:
>
> possibly a 5.10.0 regression
>
Some more debugging (and trimming perl5db.pl to 19 lines) revealed the
problem.
In perl5db.pl in sub sub:
http://perl5.git.perl.org/perl.git/blob/85bdf03b25729816eedfea55a7f2c32c4bb80fba:/lib/perl5db.pl
3650 if ($sub =~ /^threads::new$/ && $ENV{PERL5DB_THREADED}) {
3651 print "creating new thread\n";
3652 }
The trimmed test case from some earlier debugging:
*c = sub {};
'' =~ m/(?{ c() })/;
What happens:
- c() is called inside a regex.
- DB::sub is called
- DB::sub starts a new regex
The end result is that a new regex is being executed inside a regex
and the regex engine can't handle that.
This also means it is reproduciable without the debugger:
#!/usr/bin/perl -l
print $];
*c = sub { "foo" =~ m/bar/ };
sub parse_re {
$_[0] =~ m{(?{ c() })};
}
parse_re();
__END__
5.011000
Segmentation fault
(Of course since it is a memory corruption it may not be reproducible
on every system).
I'll submit a patch and a test case later today.
Best regards,
Bram
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