Perl extension to use libutempter's helper binary

[Thomas Guyot-Sionnest]

Hi,

I work in an environment where rxvt-unicode isn't installed setgid (and 
I can't easily change that) but the utempter binary (libutempter's 
helper) has the right permissions.

The only caveat is that it requires access to the pty master to run. 
When I realized it was available as urxvt::term->pty_fd I wrote a plugin 
to use it instead, so others can see when I'm logged on a system (I'm 
running it remotely without any TTY...).

It's my first rxvt-unicode plugin, I tested all possible failures and it 
seems to behave well in all circumstances, but please let me know if I 
should be doing anything differently.

Regards,

--
Thomas#! perl

# Copyright (C) 2025 Thomas Guyot-Sionnest <tgu...@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

#:META:RESOURCE:utempter-bin:string:path to utempter helper binary

=head1 NAME

utempter - Update utmp / wtmp login records using libutempter

=head1 DESCRIPTION

Uses the utempter helper script from libutempter to update utmp / wtmp
login records. It adds and removes entries for each terminal if using a
tab manager. The default utempter path, /usr/libexec/utempter/utempter,
can be overridden in the C<URxvt.utempter-bin> resource.

This plugin can be useful if you cannot get the urxvt binary setgid, but
have a working libutempter installation.

=cut

use POSIX ();

sub utempter_helper {
   my $self = shift;

   my $utempter = $self->x_resource ('utempter-bin') // 
'/usr/libexec/utempter/utempter';
   my $fileno = $self->pty_fd;

   if (!(defined $fileno)) {
      warn "utempter: urxvt::term->pty_fd is not set, is it compiled with 
--enable-frills?";
      return;
   }

   # Use fork/exec, other methods mess up badly with urxvt
   my $pid = fork;
   if (!(defined $pid)) {
      warn "utempter: fork failed ($!)";
   } elsif ($pid == 0) {
      open STDIN, "<&$fileno";
      exec $utempter, @_ or warn "$utempter: exec failed ($!)";
      # On exec failure skip destructors as with exec!
      POSIX::_exit(1);
   }
} 

sub on_start {
   my ($self) = @_;

   $self->utempter_helper ('add', $ENV{'DISPLAY'});

   ()
}

sub on_destroy {
   my ($self) = @_;

   $self->utempter_helper ('del');

   ()
}
_______________________________________________
rxvt-unicode mailing list
rxvt-unicode@lists.schmorp.de
http://lists.schmorp.de/mailman/listinfo/rxvt-unicode