#!/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin

#constants
START_PORT=10000
PORTS_PER_UML=1000
VOLUMEGROUP=vg1
BACKUPBLOCKSIZE=16M
UML_HOME_BASE=/var/local
KERNEL=/opt/uml/bin/linux

if [ "$1" = "--nice" ]; then
	NICE="nice"
	shift
else
	NICE=""
fi
UMLUSER=$1
IP_LAST_NR=$2
MEM=$3
DISKSPACE=$4
OP=$5
UMLIP=192.168.3.$IP_LAST_NR
SSHPORT=$(($START_PORT + $IP_LAST_NR * $PORTS_PER_UML + 22))
TAPDEV=tap$IP_LAST_NR
UMLHOME=$UML_HOME_BASE/$UMLUSER
PARTITION=/dev/mapper/$VOLUMEGROUP-$UMLUSER

NAME=UML-$UMLUSER
dESC="UML $UMLIP Instanz"
MEMORY="mem=$MEM"
UMID="umid=$UMLUSER"
NETWORK="eth0=tuntap,$TAPDEV"
DISKS="ubd0=$PARTITION"
CONSOLES='con0=fd:0,fd:1 con=pts'

set -e
case "$OP" in
	start)
		echo -n "starting $DESC $NAME"
		# Speicher Masterseitig auf Max 1 GB setzen.
		echo 262144 > /proc/sys/vm/max_map_count
		test -d $UMLHOME || mkdir $UMLHOME
		test -d $UMLHOME/tmp || mkdir $UMLHOME/tmp
		mount -t tmpfs -o mode=1777,size=$((`echo $MEM | tr M ' '`*2))M none $UMLHOME/tmp
		chown $UMLUSER $UMLHOME
		tunctl -u $UMLUSER -t $TAPDEV > /dev/null
		ifconfig $TAPDEV up
		brctl addif br0 $TAPDEV || echo creation of $TAPDEV failed
		chown $UMLUSER $PARTITION
		/usr/bin/screen -d -m -- su -c "HOME=$UMLHOME TMP=$UMLHOME/tmp $NICE $KERNEL $MEMORY $UMID $NETWORK $DISKS $CONSOLES" $UMLUSER
		#ip-forwarding einschalten
		echo 1 > /proc/sys/net/ipv4/ip_forward
		iptables -t nat -A POSTROUTING -o eth0 -s $UMLIP -j MASQUERADE
		iptables -t nat -A PREROUTING -p tcp --dport $SSHPORT -j DNAT --to-destination $UMLIP:22
		echo "."
	;;
	stop)
		echo -n "stopping $DESC $NAME "
		su -c "HOME=$UMLHOME /usr/bin/uml_mconsole $UMLUSER cad" $UMLUSER
		# wait doesn't wait for foreign childs 
		#that's why the following doesn't work:
		#wait `cat $UMLHOME/.uml/$UMLUSER/pid`
		#instead we loop 10 times to check whether the process terminated
		TESTCMD="ps `cat $UMLHOME/.uml/$UMLUSER/pid`"
		for ((i=1; i <= 120 ; i++)) do
			$TESTCMD > /dev/null && sleep 1
		done
		if $TESTCMD > /dev/null ; then 
			echo UML instance did not terminate. To kill it type
			echo su -c \"HOME=$UMLHOME /usr/bin/uml_mconsole $UMLUSER halt\" $UMLUSER
			exit 1
		fi
		iptables -t nat -D POSTROUTING -o eth0 -s $UMLIP -j MASQUERADE
		iptables -t nat -D PREROUTING -p tcp --dport $SSHPORT -j DNAT --to-destination $UMLIP:22
		brctl delif br0 $TAPDEV
		ifconfig $TAPDEV down
		tunctl -d $TAPDEV > /dev/null
		umount $UMLHOME/tmp
		#rmdir $UMLHOME
		echo "."
	;;
        restart)
                $0 $NICE $1 $2 $3 stop
                delay 100
                $0 $NICE $1 $2 $3 start
        ;;
	backup)
                if [ -b /dev/$VOLUMEGROUP/$UMLUSER-backup ]; then
			echo "backup-partition already exists. Please rename/delete it first" >&2
			exit 1
		fi
		su -c "HOME=$UMLHOME /usr/bin/uml_mconsole $UMLUSER stop" $UMLUSER
		su -c "HOME=$UMLHOME /usr/bin/uml_mconsole $UMLUSER sysrq s" $UMLUSER
                # Snapshotting is not working properly in 2.6 kernels
                #lvcreate -L $DISKSPACE -s -n $UMLUSER-backup /dev/$VOLUMEGROUP/$UMLUSER || echo backup of /dev/$VOLUMEGROUP/$UMLUSER failed
                (lvcreate -L $DISKSPACE -n $UMLUSER-backup $VOLUMEGROUP && dd if=/dev/$VOLUMEGROUP/$UMLUSERof=/dev/$VOLUMEGROUP/$UMLUSER-backup bs=$BACKUPBLOCKSIZE) || echo backup of /dev/$VOLUMEGROUP/$UMLUSER failed
		su -c "HOME=$UMLHOME /usr/bin/uml_mconsole $UMLUSER go" $UMLUSER
	;;
	*)
		N=/etc/init.d/$NAME
		echo "Usage: $N {start|stop|restart|backup}" >&2
		exit 1
	;;
esac
exit 0