#!/bin/bash
# distributed by cfengine
# Copyright 1999-2010 Gentoo Foundation
# Distributed under the beerware license
# Author: Robin H. Johnson <robbat2@gentoo.org>
# Servers: stork
# Path on server: /usr/local/bin/
# Permissions: -rwxr-xr-x root root
# Comments: 
# 

function debug() {
	if [[ $DEBUG -eq 1 ]];
	then
		echo "DEBUG: pidlock: ${*}"
	fi
}

while getopts ":l:s:d" opt;
do
	case $opt in
		l)
			PIDDIR=$OPTARG
			;;
		s)
			MYSUFFIX=$OPTARG
			;;
		d)
			DEBUG=1
			;;
		:)
			echo "Option '-${OPTARG}' requires an argument." 1>&2
			exit 1
			;;
		\?)
			echo "Usage: ${0}: [-l PIDDIR] [-s PIDFILE_SUFFIX] [-d] -- args"
			exit 0
			;;
		*)
			continue
			;;
	esac
done
shift $(($OPTIND - 1))

if [[ -z "${PIDDIR}" ]]; then
	if [ -z "${USER}" ]; then
		if [ -n "${LOGNAME}" ]; then
			USER="${LOGNAME}"
		else
			echo "\$USER is not set!" 1>&2
			exit 2
		fi
	fi

	PIDDIR=/tmp/${USER}
	/bin/mkdir -p ${PIDDIR}
	ERR=$?
	/bin/chmod 700 ${PIDDIR}
	ERR=$((${ERR}+$?))
	if [ "${ERR}" -gt 0 ]; then
		echo "Some error in creating the PIDDIR!" 1>&2
		exit 3
	fi
fi

if [[ ! -d "${PIDDIR}" ]]; then
	echo "Error: '${PIDDIR}' does not exist!" 1>&2
	exit 3
fi

if [ -z "${1}" ]; then
	echo "Error! You need to specify a command to run!" 1>&2
	exit 1
fi

MYPID=$$
MYNAME=`/bin/basename $0`-`/bin/basename $1`
CMD="${*}"

if [[ -n "${MYSUFFIX}" ]]; then
	PIDFILE=${PIDDIR}/${MYNAME}-${MYSUFFIX}.pid
else
	PIDFILE=${PIDDIR}/${MYNAME}.pid
fi

if [ -f "${PIDFILE}" ]; then
	OLDPID=$(< ${PIDFILE})
	if [[ -d "/proc/${OLDPID}/" ]]; then
		OLDCMD=$(/usr/bin/tr '\000' ' ' < /proc/${OLDPID}/cmdline | /bin/grep -o "${0} ${CMD}")
		if [[ -n "${OLDCMD}" ]]; then
			echo "Error! '${MYNAME}' is running already!" 1>&2
			exit 4
		else
			echo "Error: A running process with the pid '${OLDPID}' taken from '${PIDFILE}' has been found!" 1>&2
			exit 4
		fi
	fi

	debug "Stale pidfile detected. Removing"
	/bin/rm -f ${PIDFILE}
fi

debug "Not running already, putting PID in pidfile"
echo ${MYPID} >${PIDFILE}
debug "Doing something (${CMD})"
eval ${CMD}
debug "Cleaning up ${PIDFILE}"
/bin/rm -f ${PIDFILE}