Apparently not using local is enough to prevent the crashes. sigprocmask also solves the issue and I have been confused about the root cause of my problems.

It looks like the signal handler (essentially calling die) leaked out of the eval { } block. Or doesn't it?

This code: 

#!/usr/bin/perl

use warnings FATAL => qw( all );
use strict;

use Test::More tests => 1;
use POSIX qw( _exit );

sub wrap_sigs {
        my $signals = shift;
        my $coderef = shift;

        my $died;
        my %old_sighandlers;
        eval {
                for my $sig (keys %$signals) {
                        $old_sighandlers{$sig} = ($SIG{$sig} || 'DEFAU
+LT');
                        $SIG{$sig} =  sub { die ('SIG' . $sig . "\n") 
+};
                }

                $died = 1 unless eval { $coderef->(); 1 };

                for my $sig (keys %old_sighandlers) {
                        $SIG{$sig} = $old_sighandlers{$sig};
                }
        };

        return $died;
}

my $pid = fork;
if ($pid) {
        $SIG{ALRM} = sub { };
        my $timeout = time + 5;
        diag('parent entering wrap_sigs loop');
        while (time < $timeout) {
                wrap_sigs(
                        { ALRM => 1 },
                        sub { }
                );
        }
        diag('parent survived, killing child');
        kill TERM => $pid;
} else {
        sleep 1;
        diag('child starting signal storm');
        1 while kill ALRM => getppid;
        _exit(0);
}
ok(1, 'survived signal storm');

[download]
produces results like: 
1..1
# parent entering wrap_sigs loop
# child starting signal storm
SIGALRM
SIGALRM
END failed--call queue aborted.

[download]

Sorry for shifting the goalposts but have you got any ideas?

In reply to Re^2: Setting signal handlers considered unsafe? by gnosek
in thread Setting signal handlers considered unsafe? by gnosek

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