#!/bin/bash

# This script is supposed to be called from udev rules in order to open and mount a LUKS volume 
# (an encrypted volume) by using a key file in the user's home directory.

# see http://www.hauke-laging.de/software/homeextension/
# This software is licenced under the GPL version 3: http://www.gnu.org/licenses/gpl-3.0.html

# CHANGELOG
#
# 1.1, 2010-06-05, Hauke Laging, http://www.hauke-laging.de/software/homeextension/

# parameters from the udev rule call
dev=$1
mode=$2
user=$3

blockdev="/dev/${dev}"

# $user need not be an existing account but if it does not exist the 
# line "eval target_dir=..." has to be modified.

standard_action () {
	test -n "$target_dir" || exit 1
	cd "$target_dir" || exit 1
	if [ add = "$mode" ]
		then
		/sbin/cryptsetup isLuks "$blockdev" || exit 1
		uuid="$(/sbin/cryptsetup luksUUID "$blockdev")"
		if [ -z "$myuuid" -o "$myuuid" = "$uuid" ]
			then
			/usr/bin/test -f "$keyfile" || exit 1
			/sbin/cryptsetup --key-file "$keyfile" luksOpen "$blockdev" "$dm_name" &&
				/bin/mount -t ext2 -o ro /dev/mapper/"$dm_name" "$mountpoint" &&
				/bin/ln --symbolic --force --no-target-directory "$mountpoint" "$switch_dir"
		else
			exit 1
		fi
	fi
	if [ remove = "$mode" ]
		then
		/bin/umount /dev/mapper/"$dm_name"
		/sbin/cryptsetup luksClose "$dm_name"
		/bin/ln --symbolic --force --no-target-directory "$dummy_dir" "$switch_dir"
	fi
} # standard_action ()

case "$user" in
	specialuser)
		# these lines MAY be modified - BEGIN
		dm_name=homeextension-"$user"
		mountpoint=.homeextension
		switch_dir=homeextension
		dummy_dir=.homeextension.dummy
		keyfile=.homeextension.key
		eval target_dir="~$user" || exit 1 # eval is needed as ~ (tilde expansion) has 
			#	precedence over $user (parameter expansion)
		# these lines MAY be modified - END
		
		standard_action
	;;
	*)
		id "$user" &>/dev/null || exit 1
		dm_name=homeextension-"$user"
		mountpoint=.homeextension
		switch_dir=homeextension
		dummy_dir=.homeextension.dummy
		keyfile=.homeextension.key
		eval target_dir="~$user" || exit 1
		
		standard_action
	;;
esac