Intro

This project is a set of examples of FFI between Rust and C.
It uses CMake to build the C, and CMake to call Cargo to build the Rust.
This is not intended to be a Rust, C, or CMake tutorial, merely an example of using them together. That said, comments should explain to C programmers what the Rust code is doing.

Cargo, rustc, CMake, and a C compiler must be installed.
To install Rust (Cargo and rustc), follow the instructions at https://www.rust-lang.org/tools/install
Get CMake from https://cmake.org/download/ or your distribution's package manager (3.17+ needed) GCC (A C compiler) can also been used, and was used to test this project. It can be downloaded from https://gcc.gnu.org/
LLVM & Clang (a C compiler) can be downloaded from https://releases.llvm.org/download.html

To cross-compile, both a C and Rust cross-compiler are needed. For Rust, rustup target add <triple> where is a target from the list at https://doc.rust-lang.org/nightly/rustc/platform-support.html. For C, that's probably a cross-compiler and toolchain from your distro's package manager. CMake will need to define an appropriate Rust_CARGO_TARGET value, eg -DRust_CARGO_TARGET=armv7-unknown-linux-gnueabihf in addition to any C/C++ target flags needed. Adding cross-compiler support is not a goal of this project, and would require some extra scripts to call cmake with appropriate options.

NOTE: This has so far only been tested on Debian Bullseye. It should work for any Linux system, not sure about Mac or Windows.

Useful Links

Rust Documentation

The Rust Book
The Rust Reference
Reference chapter on build scripts
Rustdoc book

FFI tutorials and examples

https://jakegoulding.com/rust-ffi-omnibus/
https://github.com/alexcrichton/rust-ffi-examples
https://doc.rust-lang.org/nomicon/ffi.html

Binding generators

https://github.com/eqrion/cbindgen
https://github.com/eqrion/cbindgen/blob/master/docs.md
https://rust-lang.github.io/rust-bindgen/introduction.html

CMake helper for Cargo (Rust's build system)

https://github.com/AndrewGaspar/corrosion

Rust's Library repository

https://crates.io/

CMake documentation

https://cmake.org/cmake/help/v3.17/index.html

Cross compiling Rust

https://github.com/japaric/rust-cross https://rust-lang.github.io/rustup/cross-compilation.html

Helpful links for learning Rust

Rustlings provides small exercises, and is a good intro.

The Rust Book linked above as well, is comprehensive if theory-focused.

Rust-by-example is exactly what the title says.

Learning Rust with Entirely Too Many Linked Lists is all about linked lists. Linked lists aren't something you usually need to implement yourself, but they're the hardest of the data structures taught to undergraduates to implement safely.

Dancing Links in Rust provides an example of one of the rare algorithms that really needs a linked list. And two-dimensional linked list, at that!

https://ferrous-systems.com/blog/omg-wtf-rs-resources-to-help-you-get-started-with-rust/

The Rustonomicon: The Dark Arts of Unsafe Rust is a good reference to the use of Unsafe in Rust. Since C is wildly unsafe it's very common to need to make safe wrappers around unsafe C code.

The Embedded Rust Book is a guide to Rust on bare-metal (no OS, no standard library) development in Rust.