#!/usr/bin/sh

# This script invalidates any stale swsusp and Software Suspend 2 images. It
# searches all swap partitions on your machine, as well as Suspend2's
# filewriter files (by way of the hibernate script telling it where to find
# it).
#
# It should be called on boot, after mounting filesystems, but before enabling
# swap or clearing out /var/run. Copy this into /etc/init.d/ (or the appropriate
# place on your system), then add a symlink at the appropriate point on boot.
# On a Debian system, you would do this:
#   update-rc.d hibernate-cleanup.sh start 31 S .
#
# On other SysV-based systems, you would do something like:
#   ln -s ../init.d/hibernate-cleanup.sh /etc/rcS.d/S31hibernate-cleanup.sh

HIBERNATE_FILEWRITER_TRAIL="/var/run/suspend2_filewriter_image_exists"

get_part_label() {
	local ID_FS_LABEL

	eval "$(vol_id -x $1 2> /dev/null)"
	echo "$ID_FS_LABEL"
}

get_part_uuid() {
	local ID_FS_UUID

	eval "$(vol_id -x $1 2> /dev/null)"
	echo "$ID_FS_UUID"
}

get_swap_id() {
	local line
	fdisk -l 2>/dev/null | while read line; do
		case "$line" in
			/*Linux\ [sS]wap*) echo "${line%% *}"
		esac
	done
}

clear_swap() {
	local where wason label uuid
	where=$1
	wason=
	test x"$2" = x || label="-L $2"
	test x"$3" = x || uuid="-U $3"
	swapoff $where 2>/dev/null && wason=yes
	mkswap $where $label $uuid > /dev/null || echo -n " (failed: $?)"
	[ -n "$wason" ] && swapon $where
}

check_swap_sig() {
	local part="$(get_swap_id)"
	local where what type rest p c dev label
	while read  where what type rest ; do
		test "$type" = "swap" || continue
		c=continue
		dev=
		label=
		for p in $part ; do
			case "$where" in
				LABEL=* )
					test x"$(get_part_label $p)" = x"${where#LABEL=}" &&  {
						c=:
						dev=$p
						label=${where#LABEL=}
					}
				;;
				UUID=* )
					test x"$(get_part_uuid $p)" = x"${where#UUID=}" &&  {
						c=:
						dev=$p
						uuid=${where#UUID=}
					}
				;;
				* )	
					test "$p" = "$where" && {
						c=:
						dev=$p
					}
				;;
			esac
		done
		$c
		case "$(dd if=$dev bs=1 count=6 skip=4086 2>/dev/null)" in
			ULSUSP|S1SUSP|S2SUSP|pmdisk|[zZ]*)
				echo -n "$dev"
				clear_swap $dev "$label" "$uuid"
				echo -n ", "
		esac
	done < /etc/fstab
}

check_filewriter_sig() {
	local target
	[ -f "$HIBERNATE_FILEWRITER_TRAIL" ] || return
	read target < $HIBERNATE_FILEWRITER_TRAIL
	[ -f "$target" ] || return
	case "`dd \"if=$target\" bs=8 count=1 2>/dev/null`" in
		HaveImag)
			/bin/echo -ne "Suspend2\n\0\0" | dd "of=$target" bs=11 count=1 conv=notrunc 2>/dev/null
			echo -n "$target, "
			rm -f $HIBERNATE_FILEWRITER_TRAIL
	esac
}

case "$1" in
start)
        echo -n "Invalidating stale software suspend images... "
        check_swap_sig
        check_filewriter_sig
        echo "done."
        ;;
stop|restart|force-reload)
        ;;
*)
        echo "Usage: /etc/init.d/hibernate {start|stop|restart|force-reload}"
esac

exit 0
