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Postings from March 2003
On Fri, Mar 21, 2003 at 12:29:18AM +0000, hv@crypt.org wrote:
> It hasn't been established yet precisely what is going wrong, but it
> seems likely based on available evidence that #18533 was either wrong
> or insufficient. In particular, given that the symptom is a hard loop
> in intuit_start, it seems unlikely that P::RD is to blame. I'll be
> looking to discover more detail as soon as a tuit presents itself.
>
> Hugo
The faulty regexp in RecDescent.pm is this, at line 1856
elsif ($grammar =~ m/(?=$ACTION)/gco
The second time the _generate method runs, fbm_instr() will be called
at regexec.c:622 with a random pointer as it second argument, pointer
generated with some small adjustments from that prog->subbeg -
if (s && RX_MATCH_COPIED(prog))
s = prog->subbeg + (s - SvPVX(sv));
(the stale pointer from the first run, I guess (?) - notice
that the grammar string in the example is a mortal, returned
by a sub, i.e. it is each time a different pointer )
If that pointer happens to be behind 't', an infinite loop happens.
P::RD could be easily 'fixed' <:( by removing the 'study $grammar'
at line 1829.
Regards
Adi