#!/sbin/sh
##########################################################################################
#
# Magisk Uninstaller
# by topjohnwu
# 
# This zip will remove all Magisk related files and revert boot image
#
##########################################################################################

INSTALLER=/tmp/uninstall

##########################################################################################
# Flashable update-binary preparation
##########################################################################################

OUTFD=$2
ZIP=$3

readlink /proc/$$/fd/$OUTFD 2>/dev/null | grep /tmp >/dev/null
if [ "$?" -eq "0" ]; then
  OUTFD=0

  for FD in `ls /proc/$$/fd`; do
    readlink /proc/$$/fd/$FD 2>/dev/null | grep pipe >/dev/null
    if [ "$?" -eq "0" ]; then
      ps | grep " 3 $FD " | grep -v grep >/dev/null
      if [ "$?" -eq "0" ]; then
        OUTFD=$FD
        break
      fi
    fi
  done
fi

mkdir -p $INSTALLER
cd $INSTALLER
unzip -o "$ZIP"

##########################################################################################
# Functions
##########################################################################################

ui_print() {
  echo -n -e "ui_print $1\n" >> /proc/self/fd/$OUTFD
  echo -n -e "ui_print\n" >> /proc/self/fd/$OUTFD
}

getvar() {
  local VARNAME=$1
  local VALUE=$(eval echo \$"$VARNAME");
  for FILE in /data/.magisk /cache/.magisk /system/.magisk; do
    if [ -z "$VALUE" ]; then
      LINE=$(cat $FILE 2>/dev/null | grep "$VARNAME=")
      if [ ! -z "$LINE" ]; then
        VALUE=${LINE#*=}
      fi
    fi
  done
  eval $VARNAME=\$VALUE
}

find_boot_image() {
  if [ -z "$BOOTIMAGE" ]; then
    for PARTITION in kern-a KERN-A android_boot ANDROID_BOOT kernel KERNEL boot BOOT lnx LNX; do
      BOOTIMAGE=$(readlink /dev/block/by-name/$PARTITION || readlink /dev/block/platform/*/by-name/$PARTITION || readlink /dev/block/platform/*/*/by-name/$PARTITION)
      if [ ! -z "$BOOTIMAGE" ]; then break; fi
    done
  fi
  if [ -z "$BOOTIMAGE" ]; then
    FSTAB="/etc/recovery.fstab"
    [ ! -f "$FSTAB" ] && FSTAB="/etc/recovery.fstab.bak"
    BOOTIMAGE=$(grep -E '\b/boot\b' "$FSTAB" | grep -oE '/dev/[a-zA-Z0-9_./-]*')
  fi
}

is_mounted() {
  if [ ! -z "$2" ]; then
    cat /proc/mounts | grep $1 | grep $2, >/dev/null
  else
    cat /proc/mounts | grep $1 >/dev/null
  fi
  return $?
}

grep_prop() {
  REGEX="s/^$1=//p"
  shift
  FILES=$@
  if [ -z "$FILES" ]; then
    FILES='/system/build.prop'
  fi
  cat $FILES 2>/dev/null | sed -n $REGEX | head -n 1
}

unpack_boot() {
  rm -rf $UNPACKDIR $RAMDISK 2>/dev/null
  mkdir -p $UNPACKDIR
  mkdir -p $RAMDISK
  cd $UNPACKDIR
  $BINDIR/bootimgtools --extract $1

  find $TMPDIR/boottmp -type d -exec chmod 755 {} \;
  find $TMPDIR/boottmp -type f -exec chmod 644 {} \;
  chmod 755 $(find $TMPDIR/boottmp -type d)
  chmod 644 $(find $TMPDIR/boottmp -type f)

  cd $RAMDISK
  gunzip -c < $UNPACKDIR/ramdisk.gz | cpio -i
}

repack_boot() {
  cd $RAMDISK
  find . | cpio -o -H newc 2>/dev/null | gzip -9 > $UNPACKDIR/ramdisk.gz
  cd $UNPACKDIR
  $BINDIR/bootimgtools --repack $ORIGBOOT
  if [ -f chromeos ]; then
    echo " " > config
    echo " " > bootloader
    $CHROMEDIR/futility vbutil_kernel --pack new-boot.img.signed --keyblock $CHROMEDIR/kernel.keyblock --signprivate $CHROMEDIR/kernel_data_key.vbprivk --version 1 --vmlinuz new-boot.img --config config --arch arm --bootloader bootloader --flags 0x1
    rm -f new-boot.img
    mv new-boot.img.signed new-boot.img
  fi
  if ($SAMSUNG); then
    SAMSUNG_CHECK=$(cat new-boot.img | grep SEANDROIDENFORCE)
    if [ $? -ne 0 ]; then
      echo -n "SEANDROIDENFORCE" >> new-boot.img
    fi
  fi
  mv new-boot.img $NEWBOOT
}

revert_boot() {
  rm -rf $TMPDIR/boottmp 2>/dev/null
  mkdir -p $TMPDIR/boottmp

  CHROMEDIR=$INSTALLER/chromeos
  ORIGBOOT=$TMPDIR/boottmp/boot.img
  NEWBOOT=$TMPDIR/boottmp/new-boot.img
  UNPACKDIR=$TMPDIR/boottmp/bootunpack
  RAMDISK=$TMPDIR/boottmp/ramdisk

  chmod 777 $CHROMEDIR/futility $BINDIR/*

  ui_print "- Dumping boot image"
  dd if=$BOOTIMAGE of=$ORIGBOOT

  ui_print "- Unpacking boot image"
  unpack_boot $ORIGBOOT

  if [ -d ".backup" ]; then
    ui_print "- Restoring ramdisk with backup"
    cp -af .backup/* .
    rm -rf magisk init.magisk.rc sbin/magic_mask.sh 2>/dev/null
    rm -rf .backup
  else
    ui_print "! No ramdisk backup found"
    ui_print "! Unable to revert completely"
    ui_print "! Will still remove Magisk additions"
    # Removing boot image modifications
    rm -rf magisk init.magisk.rc sbin/magic_mask.sh 2>/dev/null
  fi

  ui_print "- Repacking boot image"
  repack_boot
}

##########################################################################################
# Main
##########################################################################################

ui_print "*****************************"
ui_print "      Magisk Uninstaller     "
ui_print "*****************************"

if [ ! -d "$INSTALLER/arm" ]; then
  ui_print "! Failed: Unable to extract zip file!"
  exit 1
fi

ui_print "- Mounting /system(ro), /cache, /data"
mount -o ro /system 2>/dev/null
mount /cache 2>/dev/null
mount /data 2>/dev/null

if [ ! -f '/system/build.prop' ]; then
  ui_print "! Failed: /system could not be mounted!"
  exit 1
fi

API=$(grep_prop ro.build.version.sdk)
ABI=$(grep_prop ro.product.cpu.abi | cut -c-3)
ABI2=$(grep_prop ro.product.cpu.abi2 | cut -c-3)
ABILONG=$(grep_prop ro.product.cpu.abi)

ARCH=arm
IS64BIT=
if [ "$ABI" = "x86" ]; then ARCH=x86; fi;
if [ "$ABI2" = "x86" ]; then ARCH=x86; fi;
if [ "$ABILONG" = "arm64-v8a" ]; then ARCH=arm64; IS64BIT=1; fi;
if [ "$ABILONG" = "x86_64" ]; then ARCH=x64; IS64BIT=1; fi;

ui_print "- Device platform: $ARCH"

BINDIR=$INSTALLER/arm
if [ "$ARCH" = "x86" -o "$ARCH" = "x64" ]; then
  BINDIR=$INSTALLER/x86
fi

find_boot_image
if [ -z "$BOOTIMAGE" ]; then
  ui_print "! Unable to detect boot image"
  exit 1
fi

SAMSUNG=false
SAMSUNG_CHECK=$(cat /system/build.prop | grep "ro.build.fingerprint=" | grep -i "samsung")
if [ $? -eq 0 ]; then
  SAMSUNG=true
fi

##########################################################################################
# Detection all done, start installing
##########################################################################################

umount /magisk 2>/dev/null

if (is_mounted /data); then
  cp -af /data/stock_boot_*.gz /data/stock_boot.img.gz 2>/dev/null
  gzip -d /data/stock_boot.img.gz 2>/dev/null
  rm -rf /data/stock_boot.img.gz 2>/dev/null
  if [ -f "/data/stock_boot.img" ]; then
    ui_print "- Boot image backup found!"
    NEWBOOT=/data/stock_boot.img
  else
    ui_print "! Boot image backup unavalible, try using ramdisk backup"
    revert_boot
  fi
  ui_print "- Removing Magisk files"
  rm -rf /cache/magisk /cache/magisk_merge /cache/magisk.log /cache/last_magisk.log /cache/unblock /data/Magisk.apk /data/magisk.img /data/magisk_merge.img /data/busybox /data/magisk 2>/dev/null
else
  ui_print "! Data unavalible"
  ui_print "! Impossible to restore original boot image"
  ui_print "! Try using ramdisk backup"
  revert_boot
  ui_print "- Removing Magisk files"
  rm -rf /cache/magisk* /cache/last_magisk.log /cache/unblock 2>/dev/null
  ui_print "*****************************************"
  ui_print "     Magisk is not fully removed yet     "
  ui_print " Please manually remove /data/magisk.img "
  ui_print "*****************************************"
fi

if [ -L "$BOOTIMAGE" ]; then
  ui_print "- Block symlink detected!"
else
  dd if=/dev/zero of=$BOOTIMAGE bs=4096 2>/dev/null
fi
ui_print "- Flashing reverted image"
dd if=$NEWBOOT of=$BOOTIMAGE bs=4096

umount /system

ui_print "- Done"
exit 0