dchroot

#!/bin/bash
#
# Chroot script
#

#
# You can make a directory tree in ${HOME}/.dchroot/rc.d/ containing files named for chroots.  These
# will be sourced,  allowing you to make local, persistant modifications.  The most useful
# things to do here are:
#
# Set USER_MOUNT_DIRS to an array of <source,dest> pairs of directories to mount
#	declare -A USER_MOUNT_DIRS=(["/opt/home/dang"]="/home/dang" ["/share"]="/share")

# Set BASEDIR to some other base directory
# Set NOPORTAGE, NOSCREEN, AUTOSTOP, DETACHED, or OVERLAYS to avoid having to
# use command line options
# Set USER_PRE_COMMAND to some command to run before chroot, say "linux32"

BASEDIR="/home/chroots"

# Set usage output
USAGE="[-h |--help] [-a | --autostop] [-d | --detached] [-o | --overlays] [-p | --noportage] [-s | --noscreen ] [-b <basedir> | --basedir=<basedir>] <chrootname> start | stop | join | run"
LONGUSAGE="\t-h, --help\n\t\tPrint this help message
\t-a, --autostop\n\t\tAutomatically stop when screen exits
\t-d, --detached\n\t\tStart screen detached (ignored for noscreen or autostop)
\t-o, --overlays\n\t\tMount overlays too
\t-p, --noportage\n\t\tDon't mount portage directories
\t-s, --noscreen\n\t\tDon't start screen
\t-b <basedir>, --basedir=<basedir>\n\t\tSet the base directory for chroots
\t<chrootname>\n\t\tName of the chroot
\tstart | stop | join | run\n\t\tStart, stop, or join the chroot, or run a command in it"

# Standard functions
source ${SCRIPTS}/functions.sh

# Script name
ME=$(basename $0)

# Parse arguments
ARGS=`getopt -o hadopsb: --long help,autostop,detached,overlays,noportage,noscreen,basedir: -n "${ME}" -- "$@"`

if [ $? != 0 ] ; then
	usage 
fi
eval set -- "$ARGS"

while true ; do
	case "$1" in
		-h|--help) usage; shift ;;
		-a|--autostop) AUTOSTOP="yes"; shift ;;
		-d|--detached) DETACHED="yes"; shift ;;
		-o|--overlays) OVERLAYS="yes"; shift ;;
		-p|--noportage) NOPORTAGE="yes"; shift ;;
		-s|--noscreen) NOSCREEN="yes"; shift ;;
		-b|--basedir) BASEDIR=$2 ; shift 2 ;;
		--) shift ; break ;;
		* ) usage "Invalid argument $1";;
	esac
done

if [ -z "${1}" ]; then
	usage "Must give chrootname"
fi
CHROOTNAME=${1}

if [ -z "${2}" ]; then
	usage "Must give start, stop, or join"
fi
CMD=${2}

# We want parameters for run
shift 2

SYS_MOUNT_DIRS="/proc /dev /sys /dev/pts"

if [ -f ${HOME}/.dchroot/rc.d/${CHROOTNAME} ]; then
	source ${HOME}/.dchroot/rc.d/${CHROOTNAME}
fi

if [ -z "${CHROOTDIR}" ]; then
	CHROOTDIR="${BASEDIR}/${CHROOTNAME}"
fi
if [ ! -d ${CHROOTDIR} ]; then
	usage "${CHROOTDIR} does't exist"
fi

if [ -z "${NOPORTAGE}" ]; then
	portage_setup ${CHROOTDIR}

	# Re-source after portage stuff, so that it can override
	if [ -f ${HOME}/.dchroot.rc.d/${CHROOTNAME} ]; then
		source ${HOME}/.dchroot.rc.d/${CHROOTNAME}
	fi
	
	SYS_MOUNT_DIRS="${SYS_MOUNT_DIRS} ${PORTDIR}"
	SYS_MOUNT_DIRS="${SYS_MOUNT_DIRS} ${PORTAGE_TMPDIR}"
	SYS_MOUNT_DIRS="${SYS_MOUNT_DIRS} ${DISTDIR}"

	if [ -n "${OVERLAYS}" ]; then
		for dir in ${PORTDIR_OVERLAY}; do
			SYS_MOUNT_DIRS="${SYS_MOUNT_DIRS} ${dir}"
		done
	fi
fi

if [ -z "${NOSCREEN}" ]; then
	SCREEN="screen -S ${CHROOTNAME} -t ${CHROOTNAME}"
	if [ -z "${AUTOSTOP}" ]; then
		if [ -n "${DETACHED}" ]; then
			SCREEN="${SCREEN} -d -m"
		fi
	fi
fi

function start() 
{
	# Mount system directories
	for dir in ${SYS_MOUNT_DIRS}; do
		sudo mount -o bind ${dir} ${CHROOTDIR}/${dir} || die "Mount of ${dir} failed"
	done
	# Mount user directories
	for dir in ${!USER_MOUNT_DIRS[@]}; do
		destdir=${CHROOTDIR}/${USER_MOUNT_DIRS[$dir]}
		if [[ "${dir}" == "0" ]]; then
			dir=${USER_MOUNT_DIRS[$dir]}
		fi
		sudo mount -o bind ${dir} ${destdir} || die "Mount of ${dir} failed"
	done
	sudo cp /etc/resolv.conf ${CHROOTDIR}/etc || die "Couldn't cp /etc/resolv.conf"
	
	# Now, start screen and chroot
	cd ${BUILDDIR}
	${SCREEN} ${USER_PRE_COMMAND} sudo -H chroot ${CHROOTDIR} /bin/bash -l

	if [ -n "${AUTOSTOP}" ]; then
		stop
	fi
}

function stop() 
{
	SCREENUP=$(screen -ls | grep -e "\.${CHROOTNAME}[[:space:]]" | awk '{print $1}')
	if [ -n "${SCREENUP}" ]; then
		screen -S ${SCREENUP} -X quit
	fi
	# Unmount system directories
	for dir in ${SYS_MOUNT_DIRS}; do
		UMOUNT_DIRS="${UMOUNT_DIRS} ${CHROOTDIR}/${dir}"
	done
	# Mount user directories
	for dir in ${USER_MOUNT_DIRS}; do
		destdir=${CHROOTDIR}/${USER_MOUNT_DIRS[$dir]}
		UMOUNT_DIRS="${UMOUNT_DIRS} ${destdir}"
	done
	sudo umount ${UMOUNT_DIRS} > /dev/null 2>&1

	# catchall
	UMOUNT_DIRS=""
	DIRS=$(grep ${CHROOTDIR} /proc/mounts | awk '{print $2}' | sort -r)
	for i in ${DIRS}; do
		if [ "${i}" != "${CHROOTDIR}"  ]; then
			UMOUNT_DIRS="${UMOUNT_DIRS} ${i}"
		fi
	done
	sudo umount ${UMOUNT_DIRS}
}

function join()
{
	if [ -z "$(grep ${CHROOTDIR} /proc/mounts)" ]; then
		die "${ME} ${BASENAME} is not running; use \"start\" rather than \"join\""
	fi

	# Now, start screen and chroot
	cd ${BUILDDIR}
	${SCREEN} sudo -H chroot ${CHROOTDIR} /bin/bash -l
}

function run()
{
	if [ -z "$(grep ${CHROOTDIR} /proc/mounts)" ]; then
		die "${ME} ${BASENAME} is not running; \"start\" must be run before \"run\""
	fi

	# Now, run the command in the chroot
	cd ${BUILDDIR}
	sudo -H chroot ${CHROOTDIR} /bin/bash -l -c "$*"
}

case "${CMD}" in
	start)
		start
		;;
	stop)
		stop
		;;
	join)
		join
		;;
	run)
		run $@
		;;
	*)
		usage "unknown command ${CMD}"
		;;
esac