Test backup solution for bit-rot detection

btrfs-bitrot-backups-test.sh

#!/usr/bin/env bash

### Run this script in an otherwise empty directory. It currently tests rsync and restic on btrfs. ###
### Tested on Debian Buster with restic 0.9.2, rsync 3.1.2, and btrfs-progs 4.17. ###

if [ "x$(sudo whoami)" != "xroot" ]; then
	echo "No root, cannot use (u)mount."
	exit 1
fi

if [ -d mnt ]; then
	echo "Directory ./mnt/ exists. Please run me in an empty directory.";
	exit 2
fi

export RESTIC_PASSWORD_FILE=resticpassword

set -x

rm -r backuprestic backuprsync
mkdir backuprestic backuprsync mnt

echo -n oopsie > resticpassword
restic -r backuprestic init

dd if=/dev/zero of=fs.btrfs bs=4096 count=$((1024*1024*109/4096))
mkfs.btrfs fs.btrfs

sudo mount fs.btrfs mnt
sudo chmod 0777 mnt
yes "Hello World!" | head -1000 | tr -d \\n > mnt/testfile
rsync --delete -a mnt/ backuprsync/
restic -r backuprestic backup mnt
sudo umount mnt

hd fs.btrfs > /tmp/a
strings -t d fs.btrfs | grep Hello | awk '{print $1}' | while read offset; do
	echo -n Y | dd of=fs.btrfs count=1 seek=$offset bs=1 conv=notrunc 2>/dev/null
done
hd fs.btrfs > /tmp/b
git diff --color=always /tmp/{a,b} | grep -e + -e '-'

sudo mount fs.btrfs mnt
touch mnt/testfile
rsync --delete -a mnt/ backuprsync/
echo "Rsync exit status: $?"
restic -v -r backuprestic backup mnt
echo "Restic exit status: $?"
sudo umount mnt

set +x

echo "Expected result: testfile"
echo "Actual result for backuprsync:  $(ls backuprsync | grep testfile)"
echo "Actual result for backuprestic: $(restic -r backuprestic ls latest | grep testfile)"

rmdir mnt