#!/usr/bin/perl

# safe - run a command but kill it after the given amount of time
# Steve Kinzler, kinzler@cs.indiana.edu, Jun 08
# ported/enhanced from safe(1) in C by Mike Blackwell, ihnp4!aicchi!mdb, Aug 86
# http://www.cs.indiana.edu/~kinzler/home.html#unix

# Tests:	./safe -d 3 /bin/csh -fc : && echo ok
#		./safe -d 3 sleep 1	   && echo ok
#		./safe -d 3 sleep 5	   || echo ok

# NOTE: This seems to mostly work, but I'm not entirely confident with it
#	since I've seen it fail strangely on occasion on RH9 and RHEL3.

$dflt_d = 60;

$usage = <<EOF;
usage: $0 [ -d seconds ] [ -w seconds ] [ -b ] [ -q ] [ -v ] command
	-d	seconds to delay before killing command (default $dflt_d)
	-w	seconds before killing to give a warning message
	-b	beep instead of printing the warning message
	-q	quiet mode, don't print the killing message
	-v	verbose mode, print a message if the command finishes itself
Also, signal INT is trapped and will kill the command.
EOF
require 'getopts.pl';
die $usage if ! &Getopts('d:w:bqvh') || $opt_h || $opt_d < 0 || $opt_w < 0;

$opt_d = $opt_d || $dflt_d;
warn("$0: delay ($opt_d) less than warning ($opt_w),"
   . " no warning will be given\n"), $opt_w = 0 if $opt_d < $opt_w;

###############################################################################

$pid = fork;
die "$0: aborting, cannot fork ($!)\n" unless defined $pid;
if ($pid == 0) {
	exec(@ARGV) || die "$0: cannot exec command ($!)\n";
} else {
	@SIG{'CHLD', 'INT'} = ('done', 'maim');
	sleep $opt_d - $opt_w;
	if ($opt_w > 0) {
		print STDERR "\a\a", $opt_b ? '' :
			     "$0: killing process $pid in $opt_w seconds\n";
		sleep $opt_w;
	}
	&maim();
}

sub maim {
	$SIG{'CHLD'} = 'IGNORE';
	kill(15, $pid);
	sleep(2)	if kill(0, $pid);
	kill( 9, $pid)	if kill(0, $pid);
	sleep(2)	if kill(0, $pid);
	if (kill(0, $pid)) {
		warn "$0: process $pid will not die\n";
	} else {
		warn "$0: process $pid killed\n" unless $opt_q;
	}
	exit 1;
}

sub done {
	warn "$0: process self-terminated\n" if $opt_v;
	exit 0;
}