Slash Boxes
NOTE: use Perl; is on undef hiatus. You can read content, but you can't post it. More info will be forthcoming forthcomingly.

All the Perl that's Practical to Extract and Report

use Perl Log In

Log In

[ Create a new account ]

Matts (1087)

  (email not shown publicly)

I work for MessageLabs [] in Toronto, ON, Canada. I write spam filters, MTA software, high performance network software, string matching algorithms, and other cool stuff mostly in Perl and C.

Journal of Matts (1087)

Monday November 03, 2008
03:39 PM

Perl Unsafe Signals

[ #37798 ]

This is just to document (and place in google) how to do unsafe signals in recent perls without loading a non-core library to do it:

    use POSIX qw(SIGALRM);
    my $timeout = 30;
    my $sigset = POSIX::SigSet->new(SIGALRM);
    my $action = POSIX::SigAction->new(
        sub {
            # re-install alarm in case we were in an internal eval{} block
            die "timeout working on: " . (caller(1))[1] . "\n";
        &POSIX::SA_NODEFER, # turns off safe signals
    POSIX::sigaction(SIGALRM, $action);
    my $prev_alarm = alarm($timeout);
    eval {
        # long running code here
    my $err = $@;
    if ($err) {
        if ($err !~ /timeout working on:/) {
            die $err; # propogate this error
        # process the timeout

This is written for alarms, which TBH is probably where you really need it, since the regexp engine can get its knickers in a twist and not fire your alarm until the heat death of the universe, but the code will work for other types of signals too.

And yes, I know there are modules on CPAN for this, such as the excellent and very simple Perl::Unsafe::Signals, but sometimes another module isn't an option. I also know the code is a bit flawed in that the second installation of the alarm doesn't do the right thing (it should install at as $timeout - (time - $start_time)), so feel free to fix it yourself.

The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
More | Login | Reply
Loading... please wait.