#!/bin/sh

. /etc/rc.conf
. /etc/rc.d/functions

# 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"

clear_swap() {
	local where wason
	where=$1
	wason=
	swapoff $where 2>/dev/null && wason=yes
	mkswap $where > /dev/null || stat_append " (failed: $?)"
	[ -n "$wason" ] && swapon $where
}

check_swap_sig() {
	local where what type rest p c
	while read  where what type rest ; do
		test "$type" = "swap" || continue
		case "$(dd if=$where bs=1 count=6 skip=4086 2>/dev/null)" in
			S1SUSP|S2SUSP|ULSUSP|pmdisk|[zZ]*)
				stat_append "$where"
				clear_swap $where
				stat_append ", "
		esac
	done < /etc/fstab
}

check_filewriter_sig() {
	local target
	[ -f "$HIBERNATE_FILEWRITER_TRAIL" ] || return 0
	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
			stat_append -n "$target, "
			rm -f $HIBERNATE_FILEWRITER_TRAIL
	esac
}

case "$1" in
start)
	stat_busy "Invalidating stale software suspend images... "
	check_swap_sig
	check_filewriter_sig
	stat_done
	;;
stop)
	;;
*)
	echo "Usage: $0 {start|stop}"
esac