Repository files navigation

The C libffi library provides two main facilities: assembling callsto functions dynamically, and creating closures that can be calledas ordinary C functions. In Rust, the latter means that we can turna Rust lambda (or any object implementingFn/FnMut) into anordinary C function pointer that we can pass as a callback to C.

This repository is a Cargo workspace containing bothlibffi andlibffi-sys.

Buildinglibffi will buildlifbffi-sys, which will in turn build thelibffi C libraryfrom github, whichrequires that you have a working make, C compiler, automake, andautoconf first. It’son crates.io, soyou can add

[dependencies]libffi ="4.1.1"

to yourCargo.toml.

This crate depends onthelibffi-sys crate, which by defaultattempts to build its own version of the C libffi library. In order touse your system’s C libffi instead, enable this crate’ssystemfeature in yourCargo.toml:

[features]libffi = {version ="4.1.1",features = ["system"] }

Seethelibffi-sys documentation for more information about how itfinds C libffi.

This crate supports Rust version 1.78 and later.

In this example, we convert a Rust lambda containing a free variableinto an ordinary C code pointer. The type offun below isextern "C" fn(u64, u64) -> u64.

use libffi::high::Closure2;fnmain(){let x =5u64;let f = |y:u64,z:u64| x + y + z;let closure =Closure2::new(&f);let fun = closure.code_ptr();assert_eq!(18, fun(6,7));}

More examples are available in theexamples folder.