#!/bin/sh
### BEGIN INIT INFO
# Provides:          ssd fs
# Required-Start:    after mountall (36)
# Required-Stop:     before mountall (36)
# Default-Start:     S
# Default-Stop:      0 1
# Short-Description: Avoid write access to SSD's
# Description:       Creates layer with unionfs ans tmpfs to catch all write operations
#                    and store it to a single ram-disk. On shutdown all written data is
#                    synchronised to disk.
# Hints:             - Some monts via --rbind beyond /var and /home AFTER start of ssdfs can cause
#                      system-crash on shutdown because of unionfs on umount. You have to ummount
#                      such things before you shotdown ssdfs
#                    - /var/log, /var/tmp, /tmp and /media are volatile and where not synchronised
#                      to disk on shutdown
# Installation:      cp ssdfs /etc/init.d
#                    chown root:root /etc/init.d/ssdfs
#                    chmod 755 /etc/init.d/ssdfs
#                    update-rc.d ssdfs start 36 S 6 0 .
### END INIT INFO

# Author: Tobias Tacke <mail@tobias-tacke.de>
# Copyright 2009 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)

### Configuration
# Size of writing-area in RAM
RAMDISK_SIZE="512M"
# set this to "yes" to enable asking to proceed...
DEBUG="no"
### END Configuration


#>>>>>>>>>>>>>>>>
#/etc/default/bootlogd BOOTLOGD_ENABLE=yes | wofür ist das gut?

#HINWEISE
#wenn unterhalb eines unionfs-verzeichnisses etwas NACH dem start gemoiuntet wird, muss es VOR dem stop ungemountet werden sonst hängt unionfs und daten gehen veerloren!
#deie mtab wird noch beim Start mit 45 schreiboperationen belegt (mount/umoount dirtied inode)
#beim Wiederaufwachendes systemes gibt es einige Schreiboperationen (dirtied+write), keine ahnung wo die hingehen (~50)
#durch das rsync beim stoppen kann das ausschalten länger dauern, wenn /var und /home viele inhalte haben
#tmp, var/tmp, var/log gehen komplett verloren. Dieser inhalt wird nur über die Ramdisk abgebildet und nicht gesynct (ist im script separiert und kann bei bedarf dort angepasst werden)
#>>>>>>>>>>>>

#TODO weitermachen,,,
#_additional_var_stuff()-#
# Das zeug auslagern
# dann var/log # var/tmp in /tmp verlinken und beim Start jeweils testen
# die daten in log dann neu erstellen
#################

PATH=/sbin:/usr/sbin:/bin:/usr/bin
DESC="SSD-FS"
NAME="ssdfs"
DAEMON=
DAEMON_ARGS=
PIDFILE=
SCRIPTNAME="/etc/init.d/$NAME"
. /lib/init/vars.sh
. /lib/lsb/init-functions

_ask() {
	while true
	do
		echo -n "  $1 (y/n): "
		read STDIN
		case $STDIN in
			y)
				return 0
			;;
			n)
				return 1;
			;;
		esac
	done
	return 1
}
_check_command() {
	case $1 in
		start|stop|status|force-umount|backup)
			return 0
		;;
		restart|reload|force-reload)
			_output_echo "Error: argument '$1' not supported", "err"
			return 1
		;;
		*)
			echo "Usage: $SCRIPTNAME {start|stop|status|force-umount|backup}" >&2
			return 1
		;;
	esac
	return 1
}
_mount_volatile() {
	_output_echo "     > $1"
	if [ ! -d /.ssdfs/volatile/sys.$2.volatile ] ; then
		mkdir /.ssdfs/volatile/sys.$2.volatile || return 1
	fi
	chmod 777 /.ssdfs/volatile/sys.$2.volatile
	mount --rbind /.ssdfs/volatile/sys.$2.volatile $1 || return 1
	_output_echo "      ...done"
	return 0
}
_bind_volatile_mtab() {
	_output_echo "  bind mtab to volatile content..."
# TODO mtab danach nochmal probieren
#	if [ "$DEBUG" = "no" ] || _ask "Bind mtab to volatile content?" ; then
#		cp /etc/mtab /.ssdfs/volatile/etc.mtab
#		mount --bind /.ssdfs/volatile/etc.mtab /etc/mtab
#		_output_echo "      ...done"
#	fi
}
_create_sys_content() {
	if [ ! -d /.ssdfs ] ; then
		mkdir /.ssdfs || return 1
	fi
	if [ ! -d /.ssdfs/volatile ] ; then
		mkdir /.ssdfs/volatile || return 1
	fi
	if [ ! -d /.ssdfs/changes ] ; then
		mkdir /.ssdfs/changes || return 1
	fi
	if [ ! -d /.ssdfs/backup ] ; then
		mkdir /.ssdfs/backup || return 1
	fi
	_output_echo "  mounting volatile disk with $RAMDISK_SIZE size..."
	mount -t tmpfs -o size=$RAMDISK_SIZE -o sync -o dirsync -o mode=1777 -o rw -o nosuid -o nodev ssdfs.volatile /.ssdfs/volatile || return 1
	
	_bind_volatile_mtab
	
	_output_echo "binding other system dirs to volatile disk..."
	if ! _mount_volatile "/tmp" "tmp" ; then
		return 1
	fi
	if ! _mount_volatile "/media" "media" ; then
		return 1
	fi
	
	_output_echo "  done"
	return 0
}
_remove_sys_content() {
	umount -l -t tmpfs ssdfs.volatile
}
_is_mount_complete() {
	grep "ssdfs.volatile /.ssdfs/volatile tmpfs " /etc/mtab 1> /dev/null || return 1
	grep "$1 /.ssdfs/volatile/$2.static none rw,bind " /etc/mtab 1> /dev/null || return 1
	grep "ssdfs.$2 $1 unionfs " /etc/mtab 1> /dev/null || return 1
	grep "ssdfs.$2.volatile.protector /.ssdfs/volatile/$2.volatile tmpfs " /etc/mtab 1> /dev/null || return 1
	grep "ssdfs.$2.static.protector /.ssdfs/volatile/$2.static tmpfs " /etc/mtab 1> /dev/null || return 1
	return 0
}
_is_skelett_complete() {
	[ -d /.ssdfs/volatile/$2.static ] || return 1
	[ -d /.ssdfs/volatile/$2.volatile ] || return 1
	return 0
}
_force_unmount() {
	umount -l -t tmpfs ssdfs.$2.protector
	umount -l /.ssdfs/changes
	umount -l -t tmpfs ssdfs.$2.static.protector
	umount -l -t tmpfs ssdfs.$2.volatile.protector
	umount -l -t unionfs ssdfs.$2
	umount -l /.ssdfs/volatile/$2.static
	umount -l -t tmpfs ssdfs.$2.volatile
	return 0
}
_mount() {
	chmod 777 /.ssdfs/volatile/$2.volatile || return 1
	mount --rbind $1 /.ssdfs/volatile/$2.static || return 1
	mount -t unionfs -o dirs=/.ssdfs/volatile/$2.volatile=rw:/.ssdfs/volatile/$2.static=ro ssdfs.$2 $1 || return 1
	mount -t tmpfs -o size=1k -o ro ssdfs.$2.volatile.protector /.ssdfs/volatile/$2.volatile || return 1
	mount -t tmpfs -o size=1k -o ro ssdfs.$2.static.protector /.ssdfs/volatile/$2.static || return 1
	return 0
}
_is_mount_remain() {
	grep "$1 /.ssdfs/volatile/$2.static none rw,bind " /etc/mtab 1> /dev/null && return 0
	grep "union.$2 $1 unionfs " /etc/mtab 1> /dev/null && return 0
	grep "ssdfs.$2.volatile.protector /.ssdfs/volatile/$2.volatile tmpfs " /etc/mtab 1> /dev/null && return 0
	grep "ssdfs.$2.static.protector /.ssdfs/volatile/$2.static tmpfs " /etc/mtab 1> /dev/null && return 0
	return 1
}
_create_skelett() {
	mkdir /.ssdfs/volatile/$2.static || return 1
	mkdir /.ssdfs/volatile/$2.volatile || return 1
	return 0
}
_remove_skelett() {
	[ -d /.ssdfs/volatile ] || return 0
	[ -d /.ssdfs/volatile/$2.static ] && rmdir /.ssdfs/volatile/$2.static/
	[ -d /.ssdfs/volatile/$2.volatile ] && rmdir /.ssdfs/volatile/$2.volatile/
	return 0
}
_unmount_prepare_save() {
#TODO Das hier ist "busy"
	if ! umount -t unionfs $1 ; then
		_output_echo "   warning: dir $1 is busy, umount in lazy mode...", "err"
		if ! umount -l -t unionfs $1 ; then
			_output_echo "   ... failed", "err"
			return 1
		fi
		_output_echo "   ... ok"
	fi
	mount -t tmpfs -o size=1k -o ro ssdfs.$2.protector $1 || return 1
	umount -l -t tmpfs ssdfs.$2.volatile.protector || return 1
	return 0
}
_read_rescue_backup() {
	[ -r /.ssdfs/backup/$2.backup ] || return 0
	_output_echo "	try read remaining rescue backup from disk..."
	if ! rsync --read-batch=/.ssdfs/backup/$2.backup -a -q --delete /.ssdfs/volatile/$2.static/ ; then
		if _ask "can't read backup file. Delete it?" ; then
			if [ -f /.ssdfs/backup/$2.backup.try ] ; then
				rm /.ssdfs/backup/$2.backup.try
			fi
			if [ -f /.ssdfs/backup/$2.backup ] ; then
				rm /.ssdfs/backup/$2.backup
			fi
			_output_echo "	done"
			return 0
		fi
		if _ask "Proceed with action?" ; then
			return 0
		fi
		return 1
	fi
	if [ -f /.ssdfs/backup/$2.backup.try ] ; then
		rm /.ssdfs/backup/$2.backup.try
	fi
	if [ -f /.ssdfs/backup/$2.backup ] ; then
		rm /.ssdfs/backup/$2.backup
	fi
	_output_echo "	done"
	return 0
}
_check_run_complete() {
	if ! _is_skelett_complete $1 $2 ; then
		_output_echo "Error: $2 - skelett is'n complete", "err"
		return 1
	fi
	if ! _is_mount_complete $1 $2 ; then
		_output_echo "Error: $2 mounts are incomplete", "err"
		return 1
	fi
	return 0
}
_check_not_run() {
	if _is_mount_remain $1 $2 ; then
		_output_echo "Error: some mounts for $2 still exists", "err"
		return 1
	fi
	return 0
}
_unmount() {
#TODO das wieder versuchen einzusetzen, das ist eigentlich wichtig!!!
	#unionctl $1 --mode /.ssdfs/volatile/$2.volatile ro || _output_echo "warning: can't remount $1 read-only", "err"
	mount -o remount,ro /.ssdfs/volatile/$2.volatile

	if grep "ssdfs.changes /.ssdfs/changes tmpfs " /etc/mtab 1> /dev/null ; then
		umount -l /.ssdfs/changes
	fi
	mount -t tmpfs -o size=$RAMDISK_SIZE -o sync -o dirsync -o mode=1777 -o rw -o nosuid -o nodev -o noauto ssdfs.changes /.ssdfs/changes || return 1
	umount -l -t tmpfs ssdfs.$2.static.protector || return 1
	rsync --only-write-batch=/.ssdfs/changes/$2.data -a -q --delete $1/ /.ssdfs/volatile/$2.static/ || return 1
	if ! _unmount_prepare_save $1 $2 ; then
		_output_echo "unclean unmount for $2: try saving backup-data to disk...", "err"
		cp /.ssdfs/changes/$2.data /.ssdfs/backup/$2.backup || return 1
		_output_echo "done"
		return 1
	fi
	_output_echo "try saving data on disk..."
	if ! rsync --read-batch=/.ssdfs/changes/$2.data -a -q --delete /.ssdfs/volatile/$2.static ; then
		if _ask "Can't write data to disk. Open a bash?" ; then
			_output_echo "Exit this shell to proceed...", "err"
			bash
		fi
		if _ask "Abort action?" ; then
			_output_echo "aborted!", "err"
			return 1
		fi
	fi
	_output_echo "done"
#TODO hier bleibt er haengen, wenn es in var normal weider geht
	umount -l /.ssdfs/volatile/$2.static || return 1
	umount -l -t tmpfs ssdfs.$2.protector || return 1
	umount -l -t tmpfs ssdfs.changes || return 1
	rm -rf /.ssdfs/volatile/$2.volatile
	return 0
}
_write_rescue_backup() {
	if ! _check_run_complete $1 $2 ; then
		if _ask "ssdfs is't correct initialised. Abort rescue backup?" ; then
			_output_echo "aborted!", "err"
			return 1
		fi
	fi
	
	umount -l -t tmpfs ssdfs.$2.static.protector || return 1
	rsync --only-write-batch=/.ssdfs/backup/$2.backup.try -a -q --delete $1/ /.ssdfs/volatile/$2.static/ || return 1
	mv /.ssdfs/backup/$2.backup.try /.ssdfs/backup/$2.backup || return 1
	mount -t tmpfs -o size=1k -o ro ssdfs.$2.static.protector /.ssdfs/volatile/$2.static || return 1
	return 0
}
_hint_manual_sync() {
	echo "how to rescue ssdfs RAM-disk-data for $1 in case of an error (only if ssdfs is running):"
	echo "	umount -l -t tmpfs ssdfs.$2.static.protector"
	echo "	rsync --only-write-batch=/root/ssdfs.$2.data -a -q --delete $1/ /.ssdfs/volatile/$2.static/"
	echo "--- in case of multiple dirs to rescue, do things above for all dirs before proceeding..."
	echo "	/etc/init.d/ssdfs force-umount"
	echo "	rsync --read-batch=/root/ssdfs.$2.data -a -q --delete $1"
}
_execute() {
	_output_echo "--- $1 for dir $3 ($4)"
	case $1 in
		status)
			if _is_mount_complete $3 $4 && _is_skelett_complete $3 $4 ; then
				_output_echo "started"
				return 0
			fi
			if ! _is_mount_remain $3 $4 ; then
				_output_echo "stopped"
				return 0
			fi
			_output_echo "corrupt"
			_hint_manual_sync $3 $4
			return 1
		;;
		backup)
			_output_echo "writing backup..."
			if ! _write_rescue_backup $3 $4 ; then
				_output_echo "Error: backup failed", "err"
				return 1
			fi
			_output_echo "done"
			return 0
		;;
		force-umount)
			if [ "$2" != 'do-it' ] ; then
				_output_echo "Warning: that will result in loss of data, make backups before!", "err"
				_output_echo "Say: '/etc/init.d/ssdfs force-umount do-it' to execute this", "err"
				_hint_manual_sync $3 $4
				return 0
			fi
			_force_unmount $3 $4
			return 0
		;;
		stop)
			if ! _is_mount_remain $3 $4 ; then
				_output_echo "Nothing to do. Still stopped"
				return 0
			fi
			if ! _check_run_complete $3 $4 ; then
				return 1
			fi
			if ! _handle_extras $3 "stop" ; then
				return 1
			fi
			if ! _unmount $3 $4 ; then
				_output_echo "Error: can't unmount", "err"
				_hint_manual_sync $3 $4
				return 1
			fi
			if ! _check_not_run $3 $4 ; then
				return 1
			fi
			_output_echo "stopped"
			return 0
		;;
		start)
			if _is_mount_complete $3 $4 && _is_skelett_complete $3 $4 ; then
				_output_echo "Nothing to do. Still started"
				return 0
			fi
			if ! _check_not_run $3 $4 ; then
				return 1
			fi
			if ! _is_skelett_complete $3 $4 ; then
				if ! _remove_skelett $3 $4 ; then
					_output_echo "Error: can't remove skelett", "err"
					return 1
				fi
				if ! _create_skelett $3 $4 ; then
					_output_echo "Error: can't create skelett", "err"
					exit 1
				fi
			fi
			if ! _read_rescue_backup $3 $4 ; then
				_output_echo "failed", "err"
				return 1
			fi
			if ! _mount $3 $4 ; then
				_output_echo "Error: can't mount", "err"
				return 1
			fi
			if ! _check_run_complete $3 $4 ; then
				return 1
			fi
			if ! _handle_extras $3 "start" ; then
				return 1
			fi
			_output_echo "started"
		;;
	esac
	return 0
}
_handle_extras() {
	if [ "$1" != "/var" ] ; then
		return 0
	fi
	
	if [ "$2" = "start" ] ; then
		_output_echo " ... bind volatile dirs ... "
		if ! _additional_var_stuff ; then
			_output_echo " ... failed", "err"
		fi
	else
		_output_echo " ... change volatile dirs to separate filesystems ... "
		umount -l /var/log
		mount -t tmpfs -o size=10M -o sync -o dirsync -o mode=1777 -o rw -o nosuid -o nodev ssdfs.shutdown.var.log /var/log
		umount -l /var/tmp
		mount -t tmpfs -o size=10M -o sync -o dirsync -o mode=1777 -o rw -o nosuid -o nodev ssdfs.shutdown.var.tmp /var/tmp
	fi
	_output_echo " done"
	return 0
}
_additional_var_stuff() {
	if ! _mount_volatile "/var/tmp" "var.tmp" ; then
		return 1
	fi
	if ! _mount_volatile "/var/log" "var.log" ; then
		return 1
	fi
	touch /var/log/dmesg
	touch /var/log/mail.warn
	touch /var/log/user.log
	touch /var/log/daemon.log
	touch /var/log/messages
	touch /var/log/debug
	touch /var/log/auth.log
	touch /var/log/mail.err
	touch /var/log/syslog
	touch /var/log/mail.log
	touch /var/log/kern.log
	touch /var/log/lpr.log
	touch /var/log/mail.info
	[ ! -d /var/log/news ] && mkdir /var/log/news
	touch /var/log/news/news.crit
	touch /var/log/news/news.err
	touch /var/log/news/news.notice
	return 0
}
_output_echo() {
	if [ "$2" == "err" ] || [ "$DEBUG" != "no" ] || [ "$VERBOSE" != "no" ] ; then
		echo "$1"
	fi
}
_run_ssdfs() {
	RESULT="0"
	if ! _check_command $1 ; then
		return 1
	fi
	_output_echo "[ ssdfs ... begin  ]"
	if [ "$1" = "start" ] ; then
		if ! _create_sys_content ; then
			RESULT="1"
		fi
	fi
	if [ "$1" = "start" ] ; then
		if _execute "$1" "$2" "/var" "var"; then
			_output_echo " < done >"
		else
			_output_echo " < failed >", "err"
			RESULT="1"
		fi
		if _execute "$1" "$2" "/home" "home"; then
		        _output_echo " < done >"
		else
		        _output_echo " < failed >", "err"
			RESULT="1"
		fi
	else
		if _execute "$1" "$2" "/home" "home"; then
		        _output_echo " < done >"
		else
		        _output_echo " < failed >", "err"
			RESULT="1"
		fi
		if _execute "$1" "$2" "/var" "var"; then
			_output_echo " < done >"
		else
			_output_echo " < failed >", "err"
			RESULT="1"
		fi
	fi
	if [ "$1" = "stop" ] ; then
		if ! _remove_sys_content ; then
			RESULT="1"
		fi
	fi
	_output_echo "[ ssdfs ...  end   ]"
	return "$RESULT"
}
# helper function to set the usplash timeout. https://launchpad.net/bugs/21617
usplash_timeout () {
        TIMEOUT=$1
        if [ -x /sbin/usplash_write ]; then
            /sbin/usplash_write "TIMEOUT $TIMEOUT" || true
        fi
}
######### package main; ##########

usplash_timeout 10
[ "$VERBOSE" != "no" ] && log_daemon_msg "$1 $DESC" "$NAME"
[ "$DEBUG" = "no" ] && log_action_begin_msg "$1 $NAME"

if [ "$DEBUG" = "yes" ] ; then
	if ! _ask "proceed?" ; then
		_output_echo "aborted!", "err"
		exit 0
	fi
fi
if [ "$1" = "status" ] ; then
	DEBUG="yes"
fi
_run_ssdfs $1
case "$?" in
	0)
		[ "$VERBOSE" != no ] && log_end_msg 0
		[ "$DEBUG" = "no" ] && log_action_end_msg 0
	;;
	1)
		[ "$VERBOSE" != no ] && log_end_msg 1
		[ "$DEBUG" = "no" ] && log_action_end_msg 1
	;;
esac

exit 0