Alright, it's week 2 and I've got some updates. This week I learnt the different nuances and difficulties that comes while trying to compile a project for a new target. In my case it was WebAssemebly.

Parts of Falco, which will be used for the web application is completely written in C and C++. So, we'll be using the emscripten toolchain to compile the C/C++ code into wasm.

Compiling Falco to Wasm 😱

So, Falco's core logic is inside the libs repository.

We need to filter out libraries that won't be used and can't be compiled to wasm i.e kubernetes, grpc etc. There were a lot of modifications done, most of which are pre-processor checks for emscripten. Emscripten provies tools like emcmake and emmake to work with projects that are integrated using cmake build system. After that we wrote a github workflow that can sucessfully compile libs to wasm. It looks something like this.

 build-libs-emscripten:
    name: build-libs-emscripten 
    runs-on: ubuntu-latest
    steps:
      - name: Install deps 
        run: |
          sudo apt update
          sudo apt install -y --no-install-recommends ca-certificates cmake build-essential clang-14 llvm-14 git pkg-config autoconf automake libtool libelf-dev libcap-dev linux-headers-$(uname -r) emscripten          

      - name: Checkout Libs 
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Git safe directory
        run: |
                    git config --global --add safe.directory $GITHUB_WORKSPACE

      - name: Build and test 
        run: |
          mkdir -p build
          cd build && emcmake cmake -DUSE_BUNDLED_DEPS=True ../
          KERNELDIR=/lib/modules/$(ls /lib/modules)/build emmake make run-unit-tests -j4          

You can find more information about the PR here.

Testing the shiny new Wasm build 😎

During the final steps of compilation, the c++ exceutable will be converted to a .js file with a .wasm file linked to it. I loaded the wasm module with the help of a fancy react hook provied by my mentor, Jason and to my suprise! it worked without any additional configurations.

The above image contains the help funtion of a CLI interface. This is a simple std::cout<< statement that logs the entire string into the console.

Conclusions

Overall, This week was super productive and informative for me. For the next week, I'm looking into adding parsers for the syscalls that I added previous week. Also we'll be supporting wasm build for Falco's main repository, which looks very exciting!

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