void-minecraft-usb/opt/backup-fs

#!/usr/bin/env bash

# used to work around cases where stdin is unavailable or not a terminal
if bash -c ': > /dev/tty' > /dev/null 2>&1; then
  TTY_OR_CONSOLE="/dev/tty"
else
  TTY_OR_CONSOLE="/dev/console"
fi


function yesno {
  unset DISCARD_ME
  while [ -z "$DISCARD_ME" ]; do
    read -p "[y/n] " -n1 DISCARD_ME < $TTY_OR_CONSOLE
    case "$DISCARD_ME" in
      y)
        return 0
        ;;
      n)
        return 1
        ;;
      *)
        echo " Please enter y for yes or n for no."
        unset DISCARD_ME
        ;;
    esac
  done
}

# Overlay should still be mounted, right?

cat /proc/mounts

read -p "
press any key" -n1 DISCARD_ME < $TTY_OR_CONSOLE

# And no services running?

ps aux | grep -vF "[kworker"

read -p "
press any key" -n1 DISCARD_ME < $TTY_OR_CONSOLE

#TODO: remove above debugging sanity checks

#TODO: refuse to run if system is running

#TODO: add a way to tell the system whether to back up before shutting down

#TODO: colors
echo "Back up system changes to disk?

This only affects things outside the /home directory.
Backing up the system will take some time.
"

if yesno; then
  echo "Backing up..."
  #TODO: fiddle with squashfs parameters to find optimal settings
  #TODO: exclude /tmp
  mksquashfs / /run/void-usb/container/new_squashfs.img -b 1M -comp xz -one-file-system -progress -noappend -e /var/cache/xbps
  #TODO: check if enough disk space
  # yes -> create new image next to old image
  # no  -> create new image in RAM
  #TODO: figure out when appending to existing squashfs is a good idea
  mv /run/void-usb/container/new_squashfs.img /run/void-usb/container/squashfs.img
else
  echo ""
  echo "Not backing up."
fi