krishnakumar4a4 / ble-poc

Kickstarter for the re-usable shared lib based on rust to be used in android and iOS

• Install Rust curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

• Run the command mkdir android ios flutter rust

  • create sub-directories for each codebase

• Change directory to rust directory and run the following command cargo init --name rustylib --lib

• Add the following android target distributions for rust compilations being in rust sub-directory rustup target add aarch64-linux-android armv7-linux-androideabi i686-linux-android x86_64-linux-android

• Add the following iOS target distributions for rust compilation rustup target add aarch64-apple-ios armv7-apple-ios armv7s-apple-ios x86_64-apple-ios i386-apple-ios

  • On my machine mac book pro - intel based machine, I got error for adding the targets armv7-apple-ios, armv7s-apple-ios, and i386-apple-ios

Install tools for iOS,

• run following commands

  xcode-select --install

• This cargo subcommand will help you create a universal library for use with iOS. cargo install cargo-lipo

• This tool will let you automatically create the C/C++11 headers of the library. cargo install cbindgen

Install tools for Android

• Install Android Studio

• Install additional SDK tools from Android Studio

  Open Preferences -> System Settings -> Android SDK -> SDK Tools -> Select NDK (side by side), CMake, Android SDK Command Line Tools, Android SDK Platform Tools

• Set ANDROID_HOME, and NDK_HOME echo "ANDROID_HOME=$HOME/Library/Android/sdk" >> ~/.zshrc echo "NDK_HOME=$HOME/Library/Android/sdk/ndk/25.1.8937393" >> ~/.zshrc

• Install rustup targets rustup target add aarch64-linux-android armv7-linux-androideabi i686-linux-android x86_64-linux-android

• Install cargo-ndk cargo install cargo-ndk

Compile for android

• And setup ANDROID_NDK_HOME for cargo ndk to work properly ANDROID_NDK_HOME=/Users/<username>/Library/Android/sdk/ndk/25.1.8937393

• Create cargo config in ~/.cargo/config with following contents

[target.x86_64-linux-android]
linker = "/Users/<username>/Library/Android/sdk/ndk/25.1.8937393/toolchains/llvm/prebuilt/darwin-x86_64/bin/x86_64-linux-android28-clang"

[target.aarch64-linux-android]
linker = "/Users/<username>/Library/Android/sdk/ndk/25.1.8937393/toolchains/llvm/prebuilt/darwin-x86_64/bin/aarch64-linux-android28-clang"

[target.armv7-linux-androideabi]
linker = "/Users/<username>/Library/Android/sdk/ndk/25.1.8937393/toolchains/llvm/prebuilt/darwin-x86_64/bin/armv7a-linux-androideabi28-clang"

[target.i686-linux-android]
linker = "/Users/<username>/Library/Android/sdk/ndk/25.1.8937393/toolchains/llvm/prebuilt/darwin-x86_64/bin/i686-linux-android28-clang"

• Build for different android targets

make build_android_shared_lib_x86_64
make build_android_shared_lib_armv7
make build_android_shared_lib_aarch64
make build_android_shared_lib_i686

Obsolete Approach

• Setup toolchains for android

mkdir ~/.NDK

$(ANDROID_HOME)/ndk-bundle/build/tools/make_standalone_toolchain.py --api 26 --arch arm64 --install-dir ~/.NDK/arm64;
$(ANDROID_HOME)/ndk-bundle/build/tools/make_standalone_toolchain.py --api 26 --arch arm --install-dir ~/.NDK/arm;
$(ANDROID_HOME)/ndk-bundle/build/tools/make_standalone_toolchain.py --api 26 --arch x86 --install-dir ~/.NDK/x86;

• If you are using NDK > v22.0, they use lunwind and migrated from libgcc. Without this fix, the NDK toolchain still uses libgcc. Make the following change. Create a file called libgcc.a in the lib directory of the target ndk and redirect to libunwind. Do this for every target. The solution is given at(https://stackoverflow.com/questions/68873570/how-do-i-fix-ld-error-unable-to-find-library-lgcc-when-cross-compiling-rust)

echo "INPUT(-lunwind)" > /Users/<username>/.NDK/x86_64/lib64/clang/14.0.6/lib/linux/x86_64/libgcc.a echo "INPUT(-lunwind)" > /Users/<username>/.NDK/arm64/lib64/clang/14.0.6/lib/linux/aarch64/libgcc.a echo "INPUT(-lunwind)" > /Users/<username>/.NDK/arm64/lib64/clang/14.0.6/lib/linux/aarch64/libgcc.a

• To build android libs for all environments

cargo ndk -t x86_64-linux-android -t aarch64-linux-android -o ./jniLibs build --release