p5pRT
commented
16 years ago From nagler@bivio.biz
Created by nagler@bivio.biz
From: Rob Nagler \nagler@​bivio\.biz To: boulder-pm@pm.org Subject: Re: [Boulder.pm] mod_perl package lexicals becoming corrupt Date: Wed\, 20 Feb 2008 12:49:32 -0700
Found the bug. Here's what demonstrates it:
package T1; use strict; sub s1 {}
package T2; use base 'T1'; use strict;
package main; T2->s1; print("ok\n"); \&T2::s1; print("not reached\n"); T2->s1;
The \&T2:s1 autovivifies something in the package hash\, which is "nasty"\, and actually ends up corrupting the package hash so that lexicals disappear. We had a function called super_for_method\, which did this:
foreach my $a (@{$proto->inheritance_ancestors}) { my($sub) = \&{$a . '::' . $method}; next unless defined(&$sub); return ($sub\, $a); }
The fact that \&{} seems to autovivify an invalid package hash entry is the problem. You can implement the above this way:
foreach my $a (@{$proto->inheritance_ancestors}) { my($sub) = $a . '::' . $method; do { no strict 'refs'; next unless defined(&$sub); }; return (\&$sub\, $a); }
The above code does not corrupt the the package hash. Both pieces of code autovivify the glob for $sub\, but in the former case\, the autovivification has a dangerous side effect of corrupting the entire symbol table (in a subtle way\, of course\, which is why I got confused by the number of lexicals).
Rob
Migrated from rt.perl.org#51072 (status was 'rejected')
Searchable as RT51072$