bssl-sys
============

A low-level binding crate for Rust that moves in lockstop with BoringSSL.

### How it works
`bssl-sys` uses `bindgen` as part of the cmake build process to generate Rust compatibility shims for the targeted platform. It is important to generate it for the correct platform because `bindgen` uses LLVM information for alignment which varies depending on architecture.

### To Use
1. Build `boringssl` with `-DRUST_BINDINGS=<rust-triple>`, which should match the [Rust target triple](https://doc.rust-lang.org/nightly/rustc/platform-support.html) when building `bssl-sys`. For example, to build on 64-bit Linux:

       cmake -GNinja -B build -DRUST_BINDINGS=x86_64-unknown-linux-gnu
       ninja -C build

2. Install `bindgen`.
3. Install [`cargo-deny`](https://github.com/EmbarkStudios/cargo-deny).
4. In case you have passed `-DBORINGSSL_PREFIX=foo` to `cmake`, run `export BORINGSSL_PREFIX=foo` prior to calling `cargo`.

After that, the `bssl-sys` crate can be built via `cargo`. By default, it looks for `bindgen` output and BoringSSL static libraries in the `build` directory. This can be reconfigured with `BORINGSSL_BUILD_DIR` environment variable. Note the environment variable is evaluated relative to `rust/bssl-sys/src`, so using an absolute path may be more convenient.