libffi 0.1.9

Rust bindings for libffi
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libffi-rs: Rust bindings for libffi

Build Status Crates.io

The C libffi library provides two main facilities: assembling calls to functions dynamically, and creating closures that can be called as ordinary C functions. In Rust, the latter means that we can turn a Rust lambda (or any object implementing Fn/FnMut) into an ordinary C function pointer that we can pass as a callback to C.

The easiest way to use this library is via the high layer module, but more flexibility (and less checking) is provided by the middle and low layers.

Usage

It’s on crates.io, so it can be used by adding libffi to the dependencies in your project’s Cargo.toml:

[dependencies]
libffi = "0.1"

It is necessary to have C libffi installed first. (We’ve tested with libffi version 3.2.1.)

Example

In this example, we convert a Rust lambda containing a free variable into an ordinary C code pointer. The type of fun below is extern "C" fn(u64, u64) -> u64.

use libffi::high::Closure2;

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));

Building

I’m writing this section to document my build process.

  • Installed pkg-config: brew install pkg-config

  • Installed libffi 3.2.1 (rather than OS X system libffi, which is old)

    • brew install autoconf automake

  • Installed bindgen 0.18.0