xchroot

#!/bin/sh -e
# xchroot DIR [CMD...] - chroot into a Void (or other Linux) installation

fail() {
	printf '%s\n' "$1" >&2
	exit 1
}

if [ "$(id -u)" -ne 0 ]; then
	fail 'xchroot needs to run as root'
fi

CHROOT=$1; shift

[ -d "$CHROOT" ] || fail 'not a directory'
[ -d "$CHROOT/dev" ] || fail 'no /dev in chroot'
[ -d "$CHROOT/proc" ] || fail 'no /proc in chroot'
[ -d "$CHROOT/sys" ] || fail 'no /sys in chroot'

for _fs in dev proc sys; do
	mount --rbind "/$_fs" "$CHROOT/$_fs"
	mount --make-rslave "$CHROOT/$_fs"
done

touch "$CHROOT/etc/resolv.conf"
mount --bind /etc/resolv.conf "$CHROOT/etc/resolv.conf"

cleanup() {
	umount -R "$CHROOT/dev" "$CHROOT/proc" "$CHROOT/sys" "$CHROOT/etc/resolv.conf"
}

trap cleanup EXIT INT

if [ -x "$CHROOT/$SHELL" ]; then
	INNER_SHELL="$SHELL"
elif [ -x "$CHROOT/bin/bash" ]; then
	INNER_SHELL="/bin/bash"
else
	INNER_SHELL="/bin/sh"
fi

printf "\033[1m=> Entering chroot $CHROOT\033[m\n"
export PS1="[xchroot $CHROOT] $PS1"
chroot "$CHROOT" "${@:-$INNER_SHELL}"
STATUS=$?
if [ $STATUS -ne 0 ]; then
	printf "\033[1m=> Exited chroot $CHROOT\033[m\n"
else
	printf "\033[1m=> Exited chroot $CHROOT with status $STATUS\033[m\n"
fi
exit $STATUS