perlsignalsevaldiecarp

How do you catch a buggy sig die handler if the mechanism to debug code that everyone uses overrides it?

Let's say you use a cpan (or otherwise external) module, like our fictional one here Stupid::CPAN::Module::OfSatan

package Stupid::CPAN::Module::OfSatan {
  BEGIN { $SIG{__DIE__} = sub { print STDERR "ERROR"; exit; }; }
}

Now later in your code you have something very innocent,

package main {
  eval { die 42 };
}

This is going to trigger your buggy signal handler. You're going to want to know where that buggy signal handler is defined, so you'll do something logical like insert a Carp::Always,

package main {
  use Carp::Always;
  eval { die 42 };
}

Carp::Always will then override the buggy signal handler, and your code will magically work. How can you debug where the code is that introduces a buggy signal handler?

Solution

  • Devel::Confess

    From mst on irc.freenode.net/#perl,

    < mst> EvanCarroll: Devel::Confess honours the old signal handlers
< mst> EvanCarroll: it's basically a better Carp::Always
< EvanCarroll> Cool cool, thanks for that tidbit.