Magisk/native

Native Development

Prerequisite

Install the NDK required to build and develop Magisk with ./build.py ndk. The NDK will be installed to $ANDROID_SDK_ROOT/ndk/magisk. You don't need to manually install a Rust toolchain with rustup, as the NDK installed already has a Rust toolchain bundled.

Code Paths

• jni: Magisk's code in C++
• jni/external: external dependencies, mostly submodules
• rust: Magisk's code in Rust
• src: irrelevant, only exists to setup a native Android Studio project

Build Configs

All C/C++ code and its dependencies are built with ndk-build and configured with several *.mk files scatterred in many places.

The rust folder is a proper Cargo workspace, and all Rust code is built with cargo just like any other Rust projects.

Rust + C/C++

To reduce complexity involved in linking, all Rust code is built as staticlib and linked to C++ targets to ensure our final product is built with an officially supported NDK build system. Each C++ target can at most link to one Rust staticlib or else multiple definitions error will occur.

We use the cxx project for interop between Rust and C++. Although cxx supports interop in both directions, for Magisk, it is strongly advised to avoid calling C++ functions in Rust; if some functionality required in Rust is already implemented in C++, the desired solution is to port the C++ implementation into Rust and export the migrated function back to C++.

Development / IDE

All C++ code should be recognized and properly indexed by Android Studio out of the box. For Rust:

• Install the Rust plugin in Android Studio
• In Preferences > Languages & Frameworks > Rust, set $ANDROID_SDK_ROOT/ndk/magisk/toolchains/rust/bin as the toolchain location
• Open native/rust/Cargo.toml, and select "Attach" in the "No Cargo projects found" banner

Note: run ./build.py binary before developing to make sure generated code is created.