#!/usr/bin/perl

use warnings;
use strict;

use Carp;
use Time::HiRes;
use POSIX 'setsid';

my $child_pid;
my $child_proc;
my $cmd = "./aprogram.exe";
my $debug = 1;

start_child();
sleep(5.0);
stop_child();

sub start_child
{
  die "cannot execute cmd: $cmd" unless -x $cmd;
  if ($^O eq 'MSWin32') # Windows
  {
    require Win32::Process;
    Win32::Process::Create($child_proc, $cmd, $cmd, 0, 0, ".") || confess "Could not spawn child: $!";
    $child_pid = $child_proc->GetProcessID();
  }
  else # Unix
  {
    $SIG{CHLD} = 'IGNORE';
    $child_pid = fork();
    unless (defined $child_pid)
    {
      confess "Could not spawn child (Unix): $!";
    }
    if ($child_pid == 0 ) # child
    {
      unless ($debug)
      {
         open STDIN, "<", "/dev/null"   or die "Can't read /dev/null: $!";
         open STDOUT, ">", "/dev/null"  or die "Can't write /dev/null: $!";
      }
      setsid or warn "setsid cannot start a new session: $!";
      unless ($debug)
      {
         open STDERR, '>&STDOUT'  or die "Can't dup stdout: $!";
      }
      local $| = 1;
      unless (exec($cmd))
      {
        confess "Could not start child: $cmd: $!";
        CORE::exit(0);
      }
    }
    # parent
    $SIG{CHLD} = 'DEFAULT';
  }
  # catch early child exit, e.g. if program path is incorrect
  sleep(1.0);
  POSIX::waitpid(-1, POSIX::WNOHANG()); # clean up any defunct child process
  if (kill(0,$child_pid))
  {
    print "Started child process id $child_pid\n";
  }
  else
  {
    warn "Child process exited quickly: $cmd: process $child_pid";
  }
}

sub stop_child
{
    if ($^O eq 'MSWin32') # Windows
    {
      Win32::Process::KillProcess($child_pid,0);
    }
    else # Unix
    {
      kill 9, $child_pid || warn "could not kill process $child_pid: $!";
    }
    print "Stopped child process id $child_pid\n";
}