#!/bin/sh

# casper-snapshot - utility to do Debian Live systems snapshots
#
#   This program mount a /tmpfs under ~/Desktop and save the /cow
#   filesystem in it for reusing in another session.
#
# Copyright (C) 2006 Marco Amadori <marco.amadori@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
# On Debian systems, the complete text of the GNU General Public License
# can be found in /usr/share/common-licenses/GPL file.

PROGRAM="`basename ${1}`"
VERSION=0.0.1

# Source casper conf
if [ -e /etc/casper.conf ]; then
	. /etc/casper.conf
else
	USERNAME=`cat /etc/passwd | grep "999" | cut -f1 -d ':'`
fi

Header ()
{
	echo "${PROGRAM} - utility to do Debian Live snapshots"
	echo
	echo "Usage: ${PROGRAM} [-c|--cow DIRECTORY] [-d|--dest DIRECTORY] [-o|--output FILE] [-t|--type TYPE]"
	echo "Usage: ${PROGRAM} [-h|--help]"
	echo "Usage: ${PROGRAM} [-u|--usage]"
	echo "Usage: ${PROGRAM} [-v|--version]"
}

Usage ()
{
	MESSAGE=${1}
	Header
	echo
	echo "Try \"${PROGRAM} --help\" for more information."
	if [ ! -z "${MESSAGE}" ]; then
		echo -e "${MESSAGE}"
		exit 1
	else
		exit 0
	fi
}

Help ()
{
	Header
	echo
	echo "Options:"
	echo "  -c, --cow: specifies the copy on write directory (default: /cow)."
	echo "  -d, --destination: specifies the output snapshot directory (default: /home/\$USERNAME/Desktop/casper-snapshot)."
	echo "  -o, --output: specifies the output image file (default: $type dependent)."
	echo "  -t,--type: specifies the snapshot type between \'squashfs\', \'ext2\' or \'cpio\'.gz archive (default: cpio)"
	exit 0
}

Version ()
{
	echo "${PROGRAM}, version ${VERSION}"
	echo
	echo "Copyright (C) 2006 Marco Amadori <marco.amadori@gmail.com>"
	echo
	echo "This program is free software; you can redistribute it and/or modify"
	echo "it under the terms of the GNU General Public License as published by"
	echo "the Free Software Foundation; either version 2 of the License, or"
	echo "(at your option) any later version."
	echo
	echo "This program is distributed in the hope that it will be useful,"
	echo "but WITHOUT ANY WARRANTY; without even the implied warranty of"
	echo "MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the"
	echo "GNU General Public License for more details."
	echo
	echo "You should have received a copy of the GNU General Public License"
	echo "along with this program; if not, write to the Free Software"
	echo "Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA"
	echo
	echo "On Debian systems, the complete text of the GNU General Public License"
	echo "can be found in /usr/share/common-licenses/GPL file."
	echo
	echo "Homepage: <http://live.debian.net/>"
	exit 0
}

Do_snapshot ()
{
	case "${TYPE}" in
		squashfs)
			mksquashfs "${COW}" "${DEST}" || exit 1
			;;
		cpio)
			(cd "${COW}" && find . | cpio --quiet -o -H newc | gzip -9 > "${DEST}") || exit 1
			;;
		ext2)
			DU_DIM="`du -ks ${COW} | cut -f1`"
			REAL_DIM="`expr ${DU_DIM} + ${DU_DIM} / 20`" # Just 5% more to be sure, need something more sophistcated here...
			genext2fs --size-in-blocks=${REAL_DIM} --reserved-blocks=0 --root="${COW}" "${DEST}" || exit 1
			;;
		*)
			echo "Internal error."
			exit 1
			;;
	esac
}

Lastline()
{
	while read lines ; do
		line=${lines}
	done
	echo "${line}"
}

Base_path ()
{
	testpath="${1}"
	mounts="`awk '{print $2}' /proc/mounts`"
	testpath="`realpath ${testpath}`"

	while true ; do
		if echo "${mounts}" | grep -qs "^${testpath}" ; then
			set -- `echo "${mounts}" | grep "^${testpath}" | Lastline`
			echo ${1}
			break
		else
			testpath=`dirname $testpath`
		fi
	done
}

Is_same_mount ()
{
	dir1="`Base_path ${1}`"
	dir2="`Base_path ${2}`"
	if [ "${dir1}" == "${dir2}" ]; then
		return 0
	else
		return 1
	fi
}

Parse_args ()
{
	# Parse command line
	ARGUMENTS="`getopt --longoptions cow:,destination:,output:,type:,help,usage,version --name=${PROGRAM} --options c:d:o:t:,h,u,v --shell sh -- ${@}`"

	if [ "${?}" != "0" ]; then
		echo "Terminating." >&2
		exit 1
	fi

	eval set -- "${ARGUMENTS}"

	while true; do
		case "${1}" in
			-c|--cow)
				SNAP_COW="${2}"; shift 2 ;;
			-d|--destination)
				SNAP_DEST="${2}"; shift 2 ;;
			-o|--output)
				SNAP_OUTPUT="${2}"; shift 2 ;;
			-t|--type)
				SNAP_TYPE="${2}"; shift 2 ;;
			-h|--help)
				Help; shift ;;
			-u|--usage)
				Usage ; shift ;;
			-v|--version)
				Version; shift ;;
			--)
				shift; break ;;
			*)
				echo "Internal error."; exit 1 ;;
		esac
	done
}

Defaults ()
{
	DEF_COW="/cow"

	# Bad options handling
	if [ -z "${SNAP_COW}" ]; then
		COW="${DEF_COW}"
	else
		COW="${SNAP_COW}"
	fi
	if [ ! -d "${COW}" ]; then
		Usage "Error: ${COW} is not a directory\nMaybe you booted with \"hide-cow\" as kernel parameter?"
	fi

	case "${SNAP_TYPE}" in
		"cpio"|"squashfs"|"ext2")
			TYPE="${SNAP_TYPE}"
			;;
		"")
			TYPE="cpio" ;;
		*)
			Usage "Error: unrecognized snapshot type"
			;;
	esac
}

Main ()
{
	Parse_args "${@}"
	Defaults
	Do_snapshot
}

Main "${@}"