Proc::Background::Win32 - Interface to process mangement on Win32 systems

# Proc::Background::Win32 Windows interface to background process management.
#
# Copyright (C) 1998-2005 Blair Zajac.  All rights reserved.

package Proc::Background::Win32;

require 5.004_04;

use strict;
use Exporter;
use Carp;

use vars qw(@ISA $VERSION);
@ISA     = qw(Exporter);
$VERSION = sprintf '%d.%02d', '$Revision: 1.10 $' =~ /(\d+)\.(\d+)/;

BEGIN {
  eval "use Win32";
  $@ and die "Proc::Background::Win32 needs Win32 from libwin32-?.??.zip to run.\n";
  eval "use Win32::Process";
  $@ and die "Proc::Background::Win32 needs Win32::Process from libwin32-?.??.zip to run.\n";
}

sub _new {
  my $class = shift;

  unless (@_ > 0) {
    confess "Proc::Background::Win32::_new called with insufficient number of arguments";
  }

  return unless defined $_[0];

  # If there is only one element in the @_ array, then just split the
  # argument by whitespace.  If there is more than one element in @_,
  # then assume that each argument should be properly protected from
  # the shell so that whitespace and special characters are passed
  # properly to the program, just as it would be in a Unix
  # environment.  This will ensure that a single argument with
  # whitespace will not be split into multiple arguments by the time
  # the program is run.  Make sure that any arguments that are already
  # protected stay protected.  Then convert unquoted "'s into \"'s.
  # Finally, check for whitespace and protect it.
  my @args;
  if (@_ == 1) {
    @args = split(' ', $_[0]);
  } else {
    @args = @_;
    for (my $i=1; $i<@args; ++$i) {
      my $arg = $args[$i];
      $arg =~ s#\\\\#\200#g;
      $arg =~ s#\\"#\201#g;
      $arg =~ s#"#\\"#g;
      $arg =~ s#\200#\\\\#g;
      $arg =~ s#\201#\\"#g;
      if (length($arg) == 0 or $arg =~ /\s/) {
        $arg = "\"$arg\"";
      }
      $args[$i] = $arg;
    }
  }

  # Find the absolute path to the program.  If it cannot be found,
  # then return.  To work around a problem where
  # Win32::Process::Create cannot start a process when the full
  # pathname has a space in it, convert the full pathname to the
  # Windows short 8.3 format which contains no spaces.
  $args[0] = Proc::Background::_resolve_path($args[0]) or return;
  $args[0] = Win32::GetShortPathName($args[0]);

  my $self = bless {}, $class;

  # Perl 5.004_04 cannot run Win32::Process::Create on a nonexistant
  # hash key.
  my $os_obj = 0;

  # Create the process.
  if (Win32::Process::Create($os_obj,
			     $args[0],
			     "@args",
			     0,
			     NORMAL_PRIORITY_CLASS,
			     '.')) {
    $self->{_pid}    = $os_obj->GetProcessID;
    $self->{_os_obj} = $os_obj;
    return $self;
  } else {
    return;
  }
}

# Reap the child.
sub _waitpid {
  my ($self, $timeout) = @_;

  # Try to wait on the process.
  my $result = $self->{_os_obj}->Wait($timeout ? INFINITE : 0);
  # Process finished.  Grab the exit value.
  if ($result == 1) {
    my $_exit_status;
    $self->{_os_obj}->GetExitCode($_exit_status);
    return (0, $_exit_status<<8);
  }
  # Process still running.
  elsif ($result == 0) {
    return (2, 0);
  }
  # If we reach here, then something odd happened.
  return (0, 1<<8);
}

sub _die {
  my $self = shift;

  # Try the kill the process several times.  Calling alive() will
  # collect the exit status of the program.
  my $count = 5;
  while ($count and $self->alive) {
    --$count;
    $self->{_os_obj}->Kill(1<<8);
    last unless $self->alive;
    sleep 1;
  }
}

1;

__END__