rust-clib

An example project that uses Rust to create a library with C API.

Build rust lib and run C tests

(cd mylib && cargo build)
make test

successful output looks like this:

   Compiling add v0.2.0 (~/src/rust/clib/mylib)
    Finished dev [unoptimized + debuginfo] target(s) in 4.21s
cp mylib/target/debug/libmylib.a .
gcc  libmylib.a -o test test.o libmylib.a 
./test
PASSED
Tests run: 4

Docs I found helpful

• Rust Embedded book: A little Rust with your C
• https://svartalf.info/posts/2019-03-01-exposing-ffi-from-the-rust-library/
• Cargo book: build scripts

The Rust part

in the my directory is a Rust crate, which has tests along with a very simple example that calls a function from Rust (that is also callable from C)

cd mylib
cargo test                  # test that we can call the function in Rust
cargo run --example stdin   # interactive example

references that might be helpful

• https://doc.rust-lang.org/nomicon/ffi.html
• https://karroffel.gitlab.io/post/2019-05-15-rust/
• https://www.greyblake.com/blog/2017-08-10-exposing-rust-library-to-c/
• https://www.joshmatthews.net/blog/2015/10/creating-a-c-api-for-a-rust-library/
• https://www.reddit.com/r/rust/comments/6u7y3q/rust_wrappers_and_c_callbacks/
• https://users.rust-lang.org/t/stubbing-extern-c-functions-for-tests/15976/2

Changelog

• v0.1: exporting a Rust function that can be called from C, generating C header (blog post)
• v0.2: export struct, functions that create/destroy, call functions that accept struct with C callback function