openbsd-timemachine-backup.sh

#!/bin/sh

# Copyright (c) 2022 Matthias Schmidt <xhr@giessen.ccc.de>
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

# Mountpoint for the backup disk
MNTPOIN=/backup

# ------- Do not modify the following variables ----------
# DUID of the softraid container
OUTER_DUID=$1
# DUID of the disk within the decrypted container
INNER_DUID=$2
# Location to the file containing the passphrase
PASSFILE=$3
# Location to counter file
CNTF=${MNTPOIN}/.counter
# --------------------------------------------------------

# Wrong number of arguments
if [[ -z $OUTER_DUID || -z $INNER_DUID ]]; then
	logger -i -t error "$(basename $0): DUIDs missing. Abort"
	exit 1
fi

if [[ -z $PASSFILE ]]; then
	logger -i -t error "$(basename $0): No path to PASSFILE given. Abort"
	exit 1
else
	if [[ ! -f $PASSFILE ]]; then
		logger -i -t error "$(basename $0): Cannot open $PASSFILE. Abort"
		exit 1
	fi
fi

if [[ -n $(mount | grep ${MNTPOIN}) ]]; then
	logger -i -t error "$(basename $0): Mount point $MNTPOIN is not empty. Abort"
	exit 1
fi

bioctl -c C -p $PASSFILE -l ${OUTER_DUID}.a softraid0 > /dev/null || exit 1
logger "$(basename $0): Backup disk successfully bio-attached"

sync

mount -o noatime ${INNER_DUID}.i $MNTPOIN || exit 1
logger "$(basename $0): Backup disk mounted successfully to $MNTPOIN"

# First backup of its kind
if [[ ! -f ${CNTF} ]]; then
	echo "1" > $CNTF
fi

i=$(cat $CNTF)
if [ $((i%8)) -eq 0 ]; then
	logger "$(basename $0): Iteration ${i}, doing a gamma backup"
	rsnapshot -q gamma
elif [ $((i%4)) -eq 0 ]; then
	logger "$(basename $0): Iteration ${i}, doing a beta backup"
	rsnapshot -q beta
else
	logger "$(basename $0): Iteration ${i}, doing an alpha backup"
	rsnapshot -q alpha
fi
echo $((i+=1)) > $CNTF

sync

umount $MNTPOIN || exit 1

logger "$(basename $0): $MNTPOIN successfully unmounted"

bioctl -d $INNER_DUID || exit 1

logger "$(basename $0): disk successfully bio-detached"

exit $?