#!/bin/sh -e
# Copyright 2008 Tobias Tacke, all rights reserved.
# This program is free software; you can redistribute it and/or modify it under the GPL-terms (http://dev.perl.org/licenses/gpl1.html)

_assert_not_run() {
	if _is_mount_remain ; then
		echo "Error: some mounts still exists"
		exit 1
	fi
	if _is_skelett_remain ; then
		echo "Error: some parts of /.disk2ram - skelett still exists"
		exit 1
	fi
	return 0
}
_assert_run_complete() {
	if ! _is_skelett_complete ; then
		echo "Error: /.disk2ram - skelett is'n complete"
		exit 1
	fi
	if ! _is_mount_complete ; then
		echo "Error: mounts are incomplete"
		exit 1
	fi
	return 0
}
_sync_to_state() {
	rsync -xcav --delete --exclude=/lib/dpkg --exclude=/lib/apt --exclude=/cache --exclude=/run --exclude=/lock /.disk2ram/var.volatile/ /.disk2ram/var.state/ || return 1
	rsync -xcav --delete /.disk2ram/tmp.volatile/ /.disk2ram/tmp.state/ || return 1
	return 0
}
_sync_to_volatile() {
	rsync -xa --exclude=/lib/dpkg --exclude=/lib/apt --exclude=/cache --exclude=/run --exclude=/lock /.disk2ram/var.state/ /.disk2ram/var.volatile/ || return 1
	mkdir /.disk2ram/var.volatile/run || return 1
	mkdir /.disk2ram/var.volatile/lock || return 1
	rsync -xa /.disk2ram/tmp.state/ /.disk2ram/tmp.volatile/ || return 1
	return 0
}
_mount() {
	mount -t tmpfs -o size=256M -o sync -o dirsync -o mode=0755 -o rw -o nosuid -o nodev -o noauto disk2ram.var /.disk2ram/var.volatile || return 1
	mount -t tmpfs -o size=128M -o sync -o dirsync -o mode=1777 -o rw -o nosuid -o nodev -o noauto disk2ram.tmp /.disk2ram/tmp.volatile || return 1
	
	mount -o bind /var /.disk2ram/var.state || return 1
	mount -o bind /tmp /.disk2ram/tmp.state || return 1

	_sync_to_volatile || return 1

	mount -o bind /var/run /.disk2ram/var.state/run || return 1
	mount -o bind /var/lock /.disk2ram/var.state/lock || return 1
	umount -l /var/run || return 1
	umount -l /var/lock || return 1
	
	ln -s /.disk2ram/var.state/cache/ /.disk2ram/var.volatile/cache || return 1
	ln -s /.disk2ram/var.state/lib/apt/ /.disk2ram/var.volatile/lib/apt || return 1
	ln -s /.disk2ram/var.state/lib/dpkg/ /.disk2ram/var.volatile/lib/dpkg || return 1
	
	mount -o bind /.disk2ram/var.volatile /var || return 1
	mount -o bind /.disk2ram/var.state/run /var/run || return 1
	mount -o bind /.disk2ram/var.state/lock /var/lock || return 1
	
	mount -o bind /.disk2ram/tmp.volatile /tmp || return 1
	
	return 0
}
_force_unmount() {
	umount -l /tmp
	umount -l /.disk2ram/tmp.state
	umount -l /.disk2ram/tmp.volatile
	umount -l /var
	umount -l /.disk2ram/var.state
	umount -l /.disk2ram/var.volatile
}
_unmount() {
	_sync_to_state || return 1
	
	umount -l /var/run || return 1
	umount -l /var/lock || return 1
	umount -l /var || return 1
	
	mount -o bind /.disk2ram/var.state/run /var/run || return 1
	mount -o bind /.disk2ram/var.state/lock /var/lock || return 1
	
	umount -l /.disk2ram/var.state/run || return 1
	umount -l /.disk2ram/var.state/lock || return 1
	umount -l /.disk2ram/var.state || return 1
	umount -l /.disk2ram/var.volatile || return 1
	
	umount -l /tmp || return 1
	umount -l /.disk2ram/tmp.state || return 1
	umount -l /.disk2ram/tmp.volatile || return 1
	return 0
}
_create_skelett() {
	mkdir /.disk2ram || return
	mkdir /.disk2ram/var.state || return 1
	mkdir /.disk2ram/var.volatile || return 1
	mkdir /.disk2ram/tmp.state || return 1
	mkdir /.disk2ram/tmp.volatile || return 1
	return 0
}
_remove_skelett() {
	rmdir /.disk2ram/var.state/ || return 1
	rmdir /.disk2ram/var.volatile/ || return 1
	rmdir /.disk2ram/tmp.state/ || return 1
	rmdir /.disk2ram/tmp.volatile/ || return 1
	rmdir /.disk2ram/ || return 1
	return 0
}
_force_remove_skelett() {
	rmdir /.disk2ram/var.state/
	rmdir /.disk2ram/var.volatile/
	rmdir /.disk2ram/tmp.state/
	rmdir /.disk2ram/tmp.volatile/
	rmdir /.disk2ram/
	return 0
}
_is_mount_complete() {
	grep 'disk2ram.var /.disk2ram/var.volatile tmpfs ' /etc/mtab 1> /dev/null || return 1
	grep '/var /.disk2ram/var.state none ' /etc/mtab 1> /dev/null || return 1
	grep '/.disk2ram/var.volatile /var none ' /etc/mtab 1> /dev/null || return 1
	
	grep 'disk2ram.tmp /.disk2ram/tmp.volatile tmpfs ' /etc/mtab 1> /dev/null || return 1
	grep '/tmp /.disk2ram/tmp.state none ' /etc/mtab 1> /dev/null || return 1
	grep '/.disk2ram/tmp.volatile /tmp none ' /etc/mtab 1> /dev/null || return 1
	
	return 0
}
_is_mount_remain() {
	grep 'disk2ram.var /.disk2ram/var.volatile tmpfs ' /etc/mtab 1> /dev/null && return 0
	grep '/var /.disk2ram/var.state none ' /etc/mtab 1> /dev/null && return 0
	grep '/.disk2ram/var.volatile /var none ' /etc/mtab 1> /dev/null && return 0
	
	grep 'disk2ram.tmp /.disk2ram/tmp.volatile tmpfs ' /etc/mtab 1> /dev/null && return 0
	grep '/tmp /.disk2ram/tmp.state none ' /etc/mtab 1> /dev/null && return 0
	grep '/.disk2ram/tmp.volatile /tmp none ' /etc/mtab 1> /dev/null && return 0
	
    return 1
}
_is_skelett_complete() {
    [ -d /.disk2ram ] || return 1
    [ -d /.disk2ram/var.state ] || return 1
    [ -d /.disk2ram/var.volatile ] || return 1
    [ -d /.disk2ram/tmp.state ] || return 1
    [ -d /.disk2ram/tmp.volatile ] || return 1
    return 0
}
_is_skelett_remain() {
    [ -d /.disk2ram ] && return 0
    [ -d /.disk2ram/var.state ] && return 0
    [ -d /.disk2ram/var.volatile ] && return 0
    [ -d /.disk2ram/tmp.state ] && return 0
    [ -d /.disk2ram/tmp.volatile ] && return 0
    return 1
}
_restart_process() {
	echo "Restart all processes..."
	perl -e "
		use strict;
		use warnings;
		my \$KERNEL = {syslogd => 1, klogd => 1, cron => 1};
		\$| = 1;
		open(FH, '-|', 'lsof|grep \' /var\'');
			my \$process = {};
			while(my \$line = <FH>) {
			my @line = split(/\W/, \$line);
			\$process->{\$line[0]} = 1;
		}
		close(FH);
		foreach my \$p (keys(%\$process)) {
			next if(\$KERNEL->{\$p});
			my \$daemon = (-x(\"/etc/init.d/\$p\") ? 1 : 0);
			print \" - try restart \$p with \" . (\$daemon ? 'init.d-script' : 'SIGHUP') . \"...\n\";
			(\$daemon ? system(\"/etc/init.d/\$p restart\") : system(\"killall -SIGHUP \$p\"));
		}
	"
	/etc/init.d/klogd restart
	/etc/init.d/sysklogd restart
	/etc/init.d/cron restart
	echo "...done"
	return 0
}

echo "disk2ram $1 ..."
case $1 in
	status)
		if _is_mount_complete && _is_skelett_complete ; then
			echo "started"
			exit 0
		fi
		if ! _is_skelett_remain && ! _is_mount_remain ; then
			echo "stopped"
			exit 0
		fi
		echo "corrupt"
		exit 1
	;;
	start)
		if _is_mount_complete && _is_skelett_complete ; then
			echo "Nothing to do. Still started"
			exit 0
		fi
		_assert_not_run
		if ! _create_skelett ; then
			echo "Error: can't create skelett"
			exit 1
		fi
		if ! _mount ; then
			echo "Error: can't mount"
			exit 1
		fi
		_assert_run_complete
		_restart_process
		echo "started"
	;;
	sync)
		if ! _is_mount_complete || ! _is_skelett_complete ; then
			echo "Error: disk2ram is not correct running. Sync without correct state is dangerous! Perform manual sync if you like (remove option '-n' to execute)"
			echo "	rsync -xcav -n --delete --exclude=/lib/dpkg --exclude=/lib/apt --exclude=/cache --exclude=/run --exclude=/lock /.disk2ram/var.volatile/ /.disk2ram/var.state/"
			echo "	rsync -xcav -n --delete /.disk2ram/tmp.volatile/ /.disk2ram/tmp.state/"
			exit 1
		fi
		_sync_to_state
	;;
	stop)
		if ! _is_skelett_remain && ! _is_mount_remain ; then
			echo "Nothing to do. Still stopped"
			exit 0
		fi
		_assert_run_complete
		_sync_to_state
		if ! _unmount ; then
			echo "Error: can't unmount"
			exit 1
		fi
		if ! _remove_skelett ; then
			echo "Error: can't remove skelett"
			exit 1
		fi
		_assert_not_run
		_restart_process
		echo "stopped"
	;;
	restart|reload|force-reload)
		echo "Error: argument '$1' not supported"
		exit 3
	;;
	force-umount)
		if [ "$2" != 'do-it' ] ; then
			echo "Warning: that will result in loss of data! Say: '/etc/init.d/disk2ram force-umount do-it' to execute this"
			exit 3
		fi
		_force_unmount
	;;
	force-remove_skelett)
		if [ "$2" != 'do-it' ] ; then
			echo "Warning: that will result in loss of data! Say: '/etc/init.d/disk2ram force-remove_skelett do-it' to execute this"
			exit 3
		fi
		_force_remove_skelett
	;;

	*)
		echo "Usage: /etc/init.d/disk2ram {start|stop|status|sync|force-remove_skelett|force-umount}"
		exit 3
	;;
esac
exit 0