#!/bin/bash

# Mount home as an overlay filesystem

# Log stdout & stderr
exec > >(tee -i /tmp/gdm3_postlogin.log)
exec 2>&1

# Treat unset variables as an error when substituting.
set -u

# Exit immediately if a command exits with a non-zero status.
set -e

# Separate tokens on newlines only
IFS='
'

# The value of this parameter is expanded like PS1 and the expanded value is the
# prompt printed before the command line is echoed when the -x option is set
# (see The Set Builtin). The first character of the expanded value is replicated
# multiple times, as necessary, to indicate multiple levels of indirection.
# \D{%F %T} prints date like this : 2019-12-31 23:59:59
PS4='-\D{%F %T} '

# Print commands and their arguments as they are executed.
set -x

sleep 0.5

# Find the first removable F2FS partition
PART=$(lsblk -pro kname,partlabel | grep 01-home)

# Make sure the mountpoints are free
(
	lsof -t $HOME | xargs kill -9
	umount $HOME
	umount /mnt
) || true

if test "$PART"
then
	mount -o noatime "$PART" /mnt
else
	# No removable F2FS partition found, use the third local partition instead
	PART=$(lsblk -pro kname,partlabel | grep 01-tmp-home)

	if test -z "$PART"
	then
		# No local partition found, error
		exit 1
	fi

	# We don't care about data consistency since the partition is temporary
	/sbin/mke2fs -t ext4 -O ^has_journal -F "$PART"
	mount -o noatime,nobarrier "$PART" /mnt
fi

USER_PATH=/mnt/.01/$USER
TEMP_PATH=/mnt/.01/tmp

mkdir -p $USER_PATH $TEMP_PATH
chown -R $USER:$USER $USER_PATH $TEMP_PATH
mount -t overlay -o lowerdir=$HOME,upperdir=$USER_PATH,workdir=$TEMP_PATH overlay $HOME