lockProcedure

#!/bin/bash
function sms ()
{
	echo $@
}
function setlock()
{
	echo $$ > $HOME/lock
	sms "Lock set, enjoy"
	return
}
function lock ()
{
	#si lock n'existe pas, le créer puis rendre la main
	test ! -f $HOME/lock && setlock && return
	#le fichier existe
	lockPID=$(cat $HOME/lock)
	sms "System locked by $lockPID, checking"
	if [ $lockPID -eq $$ ]
	then
		echo "What are you doing? Your lock is already set..."
		return
	fi
	#verification du pid utilise 
	ps uhp $lockPID >/dev/null
	ret=$?
	if [ $ret -ne 0 ]
	then
		#process not running, lock
		setlock
		return
	fi
	#est ce quon doit attendre
	if [ "x$1" != "x--wait" ]
	then
		sms "Still running and nowait. Exiting."
		exit
	else
	#loop (waitlock)
		ps uhp $lockPID >/dev/null
		ret=$?
		while [ $ret -eq 0 ]
		do
			sleepTime=$(($RANDOM%4+8))
			sms "Waiting $sleepTime seconds for pid $lockPID."
			sleep $sleepTime
			#re-read lock if there is two waitlock in the same time
			test -f $HOME/lock && lockPID=$(cat $HOME/lock)
			ps uhp $lockPID >/dev/null
			ret=$?
		done
		setlock
	fi

}

function waitlock ()
{
	lock --wait	
}
function unlock ()
{
	lockPID=$(cat $HOME/lock)
	if [ $lockPID -ne $$ ]
	then
		sms "refusing to unlock other task"
		return
	fi
	rm $HOME/lock
}
function forceunlock ()
{
	sms "/!\ Forcing unlock !"
	rm $HOME/lock
}