pbot/PBot/ProcessManager.pm

# File: ProcessManager.pm
# Author: pragma_
#
# Purpose: Handles forking and execution of module/subroutine processes

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

package PBot::ProcessManager;
use parent 'PBot::Class';

use warnings; use strict;
use feature 'unicode_strings';

use POSIX qw(WNOHANG);
use JSON;

# automatically reap children processes in background
$SIG{CHLD} = sub { while (waitpid(-1, WNOHANG) > 0) {} };

sub initialize {
  my ($self, %conf) = @_;
  $self->{pbot}->{commands}->register(sub { $self->ps_cmd(@_)   }, 'ps',   0);
  $self->{pbot}->{commands}->register(sub { $self->kill_cmd(@_) }, 'kill', 1);
  $self->{pbot}->{capabilities}->add('admin', 'can-kill');
  $self->{processes} = {};
}

sub ps_cmd {
  my ($self, $from, $nick, $user, $host, $arguments, $stuff) = @_;
  my @processes;
  foreach my $pid (sort keys %{$self->{processes}}) {
    push @processes, "$pid: $self->{processes}->{$pid}->{commands}->[0]";
  }
  if (@processes) {
    return "Running processes: "  . join '; ', @processes;
  } else {
    return "No running processes.";
  }
}

sub kill_cmd {
  my ($self, $from, $nick, $user, $host, $arguments, $stuff) = @_;
  my $usage = "Usage: kill <pids...>";
  my @pids;
  while (1) {
    my $pid = $self->{pbot}->{interpreter}->shift_arg($stuff->{arglist}) // last;
    return "No such pid $pid." if not exists $self->{processes}->{$pid};
    push @pids, $pid;
  }
  return $usage if not @pids;
  kill 'INT', @pids;
  return "Killed.";
}

sub add_process {
  my ($self, $pid, $stuff) = @_;
  $self->{processes}->{$pid} = $stuff;
}

sub remove_process {
  my ($self, $pid) = @_;
  delete $self->{processes}->{$pid};
}

sub execute_process {
  my ($self, $stuff, $subref, $timeout) = @_;
  $timeout //= 30;

  if (not exists $stuff->{commands}) {
    $stuff->{commands} = [ $stuff->{command} ];
  }

  pipe(my $reader, my $writer);
  $stuff->{pid} = fork;

  if (not defined $stuff->{pid}) {
    $self->{pbot}->{logger}->log("Could not fork process: $!\n");
    close $reader;
    close $writer;
    $stuff->{checkflood} = 1;
    $self->{pbot}->{interpreter}->handle_result($stuff, "/me groans loudly.\n");
    return;
  }

  if ($stuff->{pid} == 0) {
    # child
    close $reader;

    # don't quit the IRC client when the child dies
    no warnings;
    *PBot::IRC::Connection::DESTROY = sub { return; };
    use warnings;

    # execute the provided subroutine, results are stored in $stuff
    eval {
      local $SIG{ALRM} = sub { die "PBot::Process `$stuff->{commands}->[0]` timed-out" };
      alarm $timeout;
      $subref->($stuff);
      die if $@;
    };
    alarm 0;

    # check for errors
    if ($@) {
      $stuff->{result} = $@;
      $stuff->{result} =~ s/ at PBot.*$//ms;
      $self->{pbot}->{logger}->log("Error executing process: $stuff->{result}\n");
    }

    # print $stuff to pipe
    my $json = encode_json $stuff;
    print $writer "$json\n";

   # end child
    exit 0;
 } else {
   # parent
   close $writer;
   $self->add_process($stuff->{pid}, $stuff);
   $self->{pbot}->{select_handler}->add_reader($reader, sub { $self->process_pipe_reader($stuff->{pid}, @_) });
   # return empty string since reader will handle the output when child is finished
   return "";
 }
}

sub process_pipe_reader {
  my ($self, $pid, $buf) = @_;
  $self->remove_process($pid);
  my $stuff = decode_json $buf or do {
    $self->{pbot}->{logger}->log("Failed to decode bad json: [$buf]\n");
    return;
  };

  if (not defined $stuff->{result} or not length $stuff->{result}) {
    $self->{pbot}->{logger}->log("No result from process.\n");
    return;
  }

  if ($stuff->{referenced}) {
    return if $stuff->{result} =~ m/(?:no results)/i;
  }

  if (exists $stuff->{special} and $stuff->{special} eq 'code-factoid') {
    $stuff->{result} =~ s/\s+$//g;
    $self->{pbot}->{logger}->log("No text result from code-factoid.\n") and return if not length $stuff->{result};
    $stuff->{original_keyword} = $stuff->{root_keyword};
    $stuff->{result} = $self->{pbot}->{factoids}->handle_action($stuff, $stuff->{result});
  }

  $stuff->{checkflood} = 0;

  if (defined $stuff->{nickoverride}) {
    $self->{pbot}->{interpreter}->handle_result($stuff, $stuff->{result});
  } else {
    # don't override nick if already set
    if (exists $stuff->{special} and $stuff->{special} ne 'code-factoid' and $self->{pbot}->{factoids}->{factoids}->exists($stuff->{channel}, $stuff->{trigger}, 'add_nick') and $self->{pbot}->{factoids}->{factoids}->get_data($stuff->{channel}, $stuff->{trigger}, 'add_nick') != 0) {
      $stuff->{nickoverride} = $stuff->{nick};
      $stuff->{no_nickoverride} = 0;
      $stuff->{force_nickoverride} = 1;
    } else {
      # extract nick-like thing from module result
      if ($stuff->{result} =~ s/^(\S+): //) {
        my $nick = $1;
        if (lc $nick eq "usage") {
          # put it back on result if it's a usage message
          $stuff->{result} = "$nick: $stuff->{result}";
        } else {
          my $present = $self->{pbot}->{nicklist}->is_present($stuff->{channel}, $nick);
          if ($present) {
            # nick is present in channel
            $stuff->{nickoverride} = $present;
          } else {
            # nick not present, put it back on result
            $stuff->{result} = "$nick: $stuff->{result}";
          }
        }
      }
    }
    $self->{pbot}->{interpreter}->handle_result($stuff, $stuff->{result});
  }

  my $text = $self->{pbot}->{interpreter}->truncate_result($stuff->{channel}, $self->{pbot}->{registry}->get_value('irc', 'botnick'), 'undef', $stuff->{result}, $stuff->{result}, 0);
  $self->{pbot}->{antiflood}->check_flood($stuff->{from}, $self->{pbot}->{registry}->get_value('irc', 'botnick'), $self->{pbot}->{registry}->get_value('irc', 'username'), 'pbot', $text, 0, 0, 0);
}

1;