Commits on Nov 1, 2022

1. Add support for Android versions 5-11. …

   **Configuration**
   
   We provide the following arguments to configure the Android version:
   - `ANDROID_NDK`
   - `ANDROID_SDK` (note that this is dependent on `ANDROID_VERSION)
   - `ANDROID_VERSION`
   - `ANDROID_SYSTEM_COMPLETE`: do a complete Android build
   - `ANDROID_SYSTEM_NONE`: do not build the Android system, disables runner support
   
   **Version Support**
   
   We now support NDK versions r10e-r25b, SDK versions 21-33, and Android versions 5.0, 5.1, 6.0, 7.0, 8.0, 8.1, 9.0, 10.0, and 11.0. We also validate that the NDK, SDK, and Android versions are compatible.
   
   For Android 12+, we do support using the NDK with the proper API level, allowing cross-compilation for the desired target, however, running or testing the generated binary is currently not supported without a complete build. Note that support for non-complete builds with Android versions 12+ is unlikely to ever occur, due to issues with APEX in the build system.
   
   **Implementation Details**
   
   Next, we've improved the removal of unittests during the build process, to ensure fast builds while maintaining compatibility with various newer Android versions. To do this, we've implemented a Python library and a script. The Python library contains a complete parser (correctly parses all valid input) for Soong blueprint files, using an LALR grammar, and a rudimentary parser for Makefiles.
   
   The Soong parser removes any `gtest` dependencies, as well as any subdirectories or scope names containing `test`. For example:
   
   ```go
   cc_library {
       name: "lib",
       srcs: ["lib.cc",],
   }
   cc_test {
       name: "test",
       defaults: ["target"],
       srcs: ["test.cc"],
   }
   ```
   
   Will become:
   
   ```go
   cc_library {
       name: "lib",
       srcs: ["lib.cc",],
   }
   ```
   
   The Makefile parser first splits the file based on conditional directives (`ifeq`, `endif`, etc.) to ensure any subsequent processing doesn't lead to unbalanced directives. Next, we split the text within each directive based on comment sections used in the Android source tree. For example:
   
   ```Makefile
   test_tags := tests
   
   include $(call subdir,$(LOCAL_PATH))
   
   c_flags := \
     -g \
     -Wall
   ```
   
   We can therefore remove the `Benchmarks` and `Unit tests` sections without removing the `Other section`.
   
   The Python library is reasonably performant (it adds no noticeable overhead to the build process) and is compact (in total, < 60KB). Also, it is much more resilient than a series of `sed` scripts.
   
   Finally, extensive unittests have been added for the Python library, for both code linting (`flake8`) and unittests (via `tox`). Since we cannot assume the presence of Python on the host machine, the tests can be optionally enabled via the `--python` flag (or `PYTHON` environment variable, to hook into the git hooks), and custom overrides for the `flake8` and `tox` commands are provided (since the user may wish to specify a specific Python version, such as `python3.7 -m flake8`).
   
   **Linker**
   
   For Android 10+, since we use a minimal Android build, we only support the bootstrap and ASAN linkers unless using a complete Android build. Supporting the APEX linker requires a nearly complete Android runtime, requiring 60+GB image sizes, slow builds, and other prohibitive factors.
   
   **Complete Builds**
   
   Complete builds are currently untested, for Androids version 12+ they exceed the default storage capacity of WSL2 images (250GB). They should work and properly install both the `/system` and `/apex` directories, however, the builds are slow and untested.

   

   Alexhuszagh committed Nov 1, 2022
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