#!/bin/bash
# To turn on systemd debug:
# setenv bootargs "systemd.log_level=debug console=ttymxc0,115200 ubi.mtd=nandubi root=ubi0:rootfs rootfstype=ubifs ro
# rootflags=chk_data_crc mtdparts=gpmi-nand:4m(nandboot),-(nandubi)"

# Command to erase user data file system
# Modified for ubifs, secure boot (no U-Boot access)

MNT_USER="/mnt/user"
OVERLAY="$MNT_USER/overlay"
WORKDIR="$MNT_USER/work"
UPPERDIR="$MNT_USER/upper"
LOWERDIR="/"
USER_ORIG="$UPPERDIR/orig"
USER_PARTITION="ubi0:user-data"
DO_ERASE_USERDATA_FILE="/mnt/user/.persistent/mts_do_erase_userdata"
DO_CLEAR_USERDATA_FILE="/mnt/user/.persistent/mts_do_clear_userdata"

pid=$$
prefix="<3>overlayrootfs-generator[${pid}]: "
loginfo()  { echo "${prefix}$@" >/dev/kmsg ; }
logpipe() { cat <(echo -n "${prefix}") - >/dev/kmsg ; }

mnt_user() {
    mkdir -p $MNT_USER
    mount -t ubifs $USER_PARTITION $MNT_USER
}

fs="/run /dev /proc /sys /sys/kernel/security /dev/shm /dev/pts /run /sys/fs/cgroup /sys/fs/cgroup/unified
 /sys/fs/cgroup/systemd /sys/fs/cgroup/devices /sys/fs/cgroup/freezer /sys/fs/cgroup/pids /sys/fs/cgroup/memory
 /dev/mqueue /sys/kernel/debug /tmp /sys/fs/fuse/connections /sys/kernel/config /var/volatile"
 
my_switch_root() {
    NEW_ROOT=$1
    echo mountinfo >&2
    cat /proc/mounts >&2
    mount --make-rprivate /
    for f in $fs ; do
        mount -o noatime,move --bind $f $NEW_ROOT/$f
    done
    /sbin/pivot_root $NEW_ROOT $NEW_ROOT/orig
}

# remove old hidden and non-hidden files and folders
do_remove_old() {
    shopt -s dotglob
    rm -rf $MNT_USER/*.old
    shopt -u dotglob
}

# select files for deletion
do_select_old() {
    if [[ -f $DO_ERASE_USERDATA_FILE ]]; then
        # when "erase user data" is requested - mark all hidden and non-hidden files for deletion
        shopt -s dotglob
        trap  "shopt -u dotglob" RETURN
        loginfo "Erasing user data"
    else
        # when "clear user data" is requested - mark all non-hidden files for deletion
        loginfo "Clearing user data"
    fi

    for FILE_PATH in "$MNT_USER"/*; do
        FILE_NAME=$(basename "$FILE_PATH")
        # rename all files and folders that exist in /mnt/user
        mv "$FILE_PATH" "$MNT_USER/$FILE_NAME.old"
    done
}

do_rw_mount() {
    loginfo "Starting RW overlayfs"
    mount -t tmpfs inittemp /mnt
    mnt_user

    do_remove_old
    if [[ -f $DO_CLEAR_USERDATA_FILE ]] || [[ -f $DO_ERASE_USERDATA_FILE ]] ; then
        do_select_old
        do_remove_old
        rm -f $DO_CLEAR_USERDATA_FILE 
    fi

    mkdir -p $UPPERDIR $WORKDIR $OVERLAY $USER_ORIG ${MNT_USER}/.persistent
    loginfo "Mounting..."
    set -x
    mount -o noatime,lowerdir=$LOWERDIR,upperdir=$UPPERDIR,workdir=$WORKDIR,rw -t overlay overlay $OVERLAY
    loginfo "JAK: What does overlay look like in /proc/mounts?"
    cat /proc/mounts | grep overlay | logpipe

    mkdir -p ${OVERLAY}/var/persistent

    mount --bind ${MNT_USER}/.persistent ${OVERLAY}/var/persistent
    loginfo "Switch root to $OVERLAY"
    my_switch_root $OVERLAY
    cat /proc/mounts | grep overlay >&2
    mount -o remount,rw /
    cat /proc/mounts | grep overlay | logpipe
    cat /proc/mounts | grep tmp | logpipe
    umount -l /tmp
    umount -l /var/volatile
    cgroupmnts=$(sed -r -e 's/[^[:space:]]*[[:space:]]//'  -e 's/[[:space:]]+.*//g' /proc/mounts | grep '^/orig')
    for mp in ${cgroupmnts} ; do
        if [[ $mp != /orig ]] ; then
            umount -l $mp
        fi
    done
}

do_start() {
    do_rw_mount
}

case $1 in
start)
    do_start
;;
*)
    echo "Usage: $0 {start}"
;;
esac