# C-friendly FFI Design

This document is a guide for authoring Rust libraries that expose a C-friendly FFI
and distributing them as ordinary CMake/pkg-config packages. It covers how to design
C-friendly FFI signatures, how to pass primitive types, enums, strings and
Rust-specific constructs such as `Option` and `Result` across the boundary, and how
to write the accompanying C/C++ header files.

## Contents

- [FFI Function Signatures](ffi-function-signatures.md)
- [Allowed Data Types](allowed-data-types.md)
- [C/C++ Headers](c-cpp-headers.md)