#!/system/bin/sh
#
# RO2RW for any Android phone
#
# Makes /vendor, /system and /product read-write
# And converts /system from f2fs to ext4 if it's f2fs
#
# (c) Vitaliy Filippov 2023
#

set -e

resize_fs() {
  local path=$1
  local label=$2
  local partname=$3
  local percent=$4
  local convert_fs=$5
  local dm_block_ext4=$(df -t ext4 | grep "$path"'$' | cut -DF1)
  local dm_block_f2fs=$(df -t f2fs | grep "$path"'$' | cut -DF1)

  fs_size_mb=`du -sm $path | cut -f1`
  part_size_mb=`blockdev --getsize64 $dm_block_ext4 $dm_block_f2fs | awk '{print int($1 / 1048576)}'`
  super_free_mb=`lptools free | grep Free | awk '{print int($3 / 1048576)}'`
  new_fs_size_mb=`echo $fs_size_mb $super_free_mb $percent | awk '{print int($1 + $2 * $3 / 100)}'`
  if [[ "$new_fs_size_mb" -le "$part_size_mb" ]]; then
    # just in case if we resized the partition, but not the FS
    new_fs_size_mb=$part_size_mb
  fi
  new_fs_size=`echo $new_fs_size_mb | awk '{print $1 * 1048576}'`

  if [ "$dm_block_ext4" ]; then
    echo " - Unmounting $path..."
    umount $path
    echo " - Resizing partition $partname inside 'super' to $new_fs_size_mb MB using lptools"
    lptools resize $partname $new_fs_size
    lptools unmap $partname
    lptools map $partname
    echo " - Checking $path block partition before resizing..."
    e2fsck -f $dm_block_ext4
    echo " - Resizing the filesystem on $dm_block_ext4..."
    resize2fs $dm_block_ext4
    echo " - Make the $path partition R/W by unsharing its blocks..."
    e2fsck -E unshare_blocks $dm_block_ext4
  elif [ "$dm_block_f2fs" ]; then
    uuid=`toybox blkid $dm_block_f2fs | egrep '[0-9a-f]{8}-([0-9a-f]{4}-){3}[0-9a-f]{12}' -o`
    echo " - Create R/W $partname image..."
    truncate -s ${new_fs_size_mb}M /data/new-rw.img
    if [ "$convert_fs" = "ext4" ]; then
      mke2fs -t ext4 -U $uuid -L $label /data/new-rw.img
    else
      make_f2fs -g android -O project_quota,extra_attr,inode_checksum,sb_checksum,compression,flexible_inline_xattr,verity,inode_crtime -U $uuid -f -l $label /data/new-rw.img
    fi
    mkdir -p /data/new-rw
    mount /data/new-rw.img /data/new-rw
    echo " - Copy old R/O $partname files to our new created image..."
    cp -a --preserve=all $path/* /data/new-rw
    # Android's toybox `cp` is buggy: `cp -a --preserve=all` does NOT preserve selinux contexts
    # on directories and symlinks and you get a bootloop. So we need to restore selinux contexts...
    cd $path
    find . -type dl -exec ls -dZ {} \; | awk '{ print "chcon -h " $0 }' > /data/new-rw-chcon.sh
    cd /data/new-rw
    sh /data/new-rw-chcon.sh
    cd /
    umount $path
    umount /data/new-rw
    echo " - Checking $partname image before flashing..."
    if [ "$convert_fs" = "ext4" ]; then
      e2fsck -f /data/new-rw.img
    else
      fsck.f2fs -f /data/new-rw.img
    fi
    echo " - Resizing partition $partname inside 'super' to $new_fs_size_mb MB using lptools"
    lptools resize $partname $(stat -c '%s' /data/new-rw.img)
    lptools unmap $partname
    lptools map $partname
    echo " - Writing our new R/W $partname image, please wait..."
    dd if=/data/new-rw.img of=/dev/block/bootdevice/by-name/$partname bs=1M
    rm -rf /data/new-rw*
  fi
  echo " - Remounting $path..."
  mount $path -o rw
}

fs_free_size_check() {
  local path=$1
  local label=$2
  local partname=$3
  local percent=$4
  echo " - Checking $path free space..."
  if dd if=/dev/zero of=$path/test bs=1 count=1 2>/dev/null; then
    echo " -     ...succeeded."
    rm -f $path/test || true
  else
    echo " -     ...No free space on $path, attempting to resize it..."
    echo " "
    rm -f $path/test || true
    resize_fs "$path" "$label" "$partname" "$percent"
  fi
}

echo " "
echo "RO2RW"
echo " "

os=$(getprop ro.build.version.release)
major=${os%%.*}
dp=$(getprop ro.boot.dynamic_partitions)

if [ $major -lt 9 ]; then
  echo " - This software is incompatible with Android $major."
  echo " - Installation aborted."
  echo " "
  exit 1
fi

echo " - Mounting /data..."
mount /data || true
if ! mount | grep '/data ' >/dev/null; then
  echo " -   Mount failed. Aborting..."
  exit 3
fi

echo " - Mounting $ANDROID_ROOT..."
if ! mount | grep "$ANDROID_ROOT " >/dev/null; then
  mount -o rw $ANDROID_ROOT 2>/dev/null || true
  if ! mount | grep "$ANDROID_ROOT " >/dev/null; then
    ANDROID_ROOT=/system_root
    echo " -   Attempt failed. Mounting at $ANDROID_ROOT..."
    if ! mount | grep "$ANDROID_ROOT " >/dev/null; then
      mount -o rw $ANDROID_ROOT
      if ! mount | grep "$ANDROID_ROOT " >/dev/null; then
        echo " -   Even that attempt failed. Aborting..."
        exit 2
      fi
    fi
  fi
fi

echo " - Mounting /vendor..."
mount /vendor || true
mount -o remount,rw /vendor || true
if ! mount | grep '/vendor ' >/dev/null; then
  echo " -   Mount failed. Aborting..."
  exit 3
fi

echo " - Mounting /product..."
mount /product || true
mount -o remount,rw /product || true
if ! mount | grep '/product ' >/dev/null; then
  echo " -   Mount failed. Aborting..."
  exit 3
fi

slot=$(getprop ro.boot.slot_suffix)
fs_free_size_check $ANDROID_ROOT "/" system$slot 70 ext4
fs_free_size_check /vendor vendor vendor$slot 50
fs_free_size_check /product product product$slot 50

echo " - Unmounting /product..."
umount /product
echo " - Unmounting /vendor..."
umount /vendor
echo " - Unmounting $ANDROID_ROOT..."
umount $ANDROID_ROOT

echo " "
echo " - Finished."
echo " "

exit 0