mohrezaei · March 27, 2022 18:02 · Mar 27, 2022
diff --git a/Calyx3-Magisk.md b/Calyx3-Magisk.md
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+# CalyxOS 3.x (Android 12) with Magisk with working signed images and AVB Verity
+
+This idea was inspired by this post https://github.com/topjohnwu/Magisk/issues/509#issuecomment-911720167
+
+I got this working with CalyxOS 3.3.1 (Android 12) with full AVB Verity enabled and was able to lock the bootloader after flashing and still have su.
+The OTA update zip generated was also tested against the Calyx 2.11.0 version (with Magisk) and it works well.
+
+### Create a working build
+First, make sure you can build and sign a proper CalyxOS for your device. This is probably the hardest part.
+
+### Prepare Magisk files for rooting
+Second, prepare a magisk directory outside your build directory as follows:
+```
+mkdir magisk24304
+cd magisk24304/
+wget https://cdn.jsdelivr.net/gh/topjohnwu/magisk-files@a17271415ec0b3b34fbb5715d92893a1f8c529d0/app-debug.apk
+unzip app-debug.apk
+```
+
+Replace the apk URL with whatever version is latest or works best for you. For Android 12, v24+ is a must.
+The URL for the latest version can be found in the Magisk files repo. https://github.com/topjohnwu/magisk-files
+
+We then need a few helper scripts in the same directory. 
+`cat > root-img.sh`
+```shell
+#!/bin/bash
+
+SCRIPT_DIR="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+
+export PATH=$PATH:$SCRIPT_DIR
+
+export BOOTMODE=true
+export KEEPVERITY=true
+
+cp $SCRIPT_DIR/lib/x86/libmagiskboot.so $SCRIPT_DIR/assets/magiskboot
+cp $SCRIPT_DIR/lib/arm64-v8a/libmagisk64.so $SCRIPT_DIR/assets/magisk64
+cp $SCRIPT_DIR/lib/armeabi-v7a/libmagisk32.so $SCRIPT_DIR/assets/magisk32
+cp $SCRIPT_DIR/lib/arm64-v8a/libmagiskinit.so $SCRIPT_DIR/assets/magiskinit
+
+. $SCRIPT_DIR/assets/boot_patch.sh $*
+```
+`chmod 755 root-img.sh`
+
+Make sure magiskinit is correct for your target in `root-img.sh`.
+
+`cat > dos2unix`
+```shell
+#!/bin/bash
+cat $*
+```
+chmod 755 dos2unix
+
+cat > getprop
+```shell
+#!/bin/bash
+echo $*
+```
+`chmod 755 getprop`
+
+That's all for preparing magisk. 
+
+### Prepare signing step
+Now we need to intercept `avbtool` to root the `boot.img` file just before it's hashed/signed.
+
+In the last step of building the OS, the target files are zipped up and moved into a signing directory, along with the signing keys and binaries. In the `bin` directory, you should find `avbtool` which will be used during signing. We're going to replace it with a script that detects boot images, roots them and then continues with the real `avbtool`.
+
+```shell
+cd bin
+mv avbtool avbtool.real
+```
+`cat > avbtool`
+```shell
+#!/bin/bash
+
+# change this to whereever you created the magisk directory:
+MAGISK_DIR=/media/work/magisk24304
+
+echo "%%%%%%%%%%" `date` Running avbtool with "$*" >> $MAGISK_DIR/avbtool-invokes.txt
+
+SCRIPT_DIR="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+IMG_NAME=`realpath $3`
+
+if [[ $1 == add_hash_footer ]] && [[ $7 == boot ]] ;
+then
+        echo starting to root $3 >> $MAGISK_DIR/rooting.txt
+        $MAGISK_DIR/root-img.sh $IMG_NAME >> $MAGISK_DIR/rooting.txt 2>&1
+        cp $MAGISK_DIR/assets/new-boot.img $IMG_NAME
+fi
+
+$SCRIPT_DIR/avbtool.real $*
+```
+`chmod 755 avbtool`
+
+We'll do something similar for `toybox` to avoid an error in the build.
+
+```
+mv toybox toybox.real
+```
+`cat > toybox`
+```shell
+#!/bin/bash
+
+SCRIPT_DIR="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+echo "%%%%%%%%%%" `date` Running toybox with "$*" >> $SCRIPT_DIR/toybox-invokes.txt
+
+if [[ $1 == cpio ]] && [[ $2 == -F ]] ;
+then
+        echo ignoring toybox error >> $SCRIPT_DIR/toybox-invokes.txt
+        $SCRIPT_DIR/toybox.real $* >> $SCRIPT_DIR/toybox-invokes.txt 2>&1
+        exit 0
+fi
+
+$SCRIPT_DIR/toybox.real $*
+```
+`chmod 755 toybox`
+
+Now, sign the target files again.
+If all goes well, that should create a rooted `boot.img` with the correct signatures. You can check the `avbtool-invokes.txt` and `rooting.txt` files to see if everything went well.
+You can apply the factory image (which will wipe the phone), or the OTA update (no wipe) if you have a previous OS with the same keys.
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