# libffi-sys-rs: Low-level Rust bindings for [libffi]

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The C libffi library provides two main facilities: assembling calls
to functions dynamically, and creating closures that can be called
as ordinary C functions. This is an undocumented wrapper, generated
by bindgen, intended as the basis for higher-level bindings.

If you clone this repository in order to build the library and you do
not plan to enable the `system` Cargo feature to build against your
system’s C libffi, then you should do a recursive clone, by default this
library builds C libffi from a Git submodule.

See [the `libffi` crate] for a higher-level API.

## Usage

`libffi-sys` can either build its own copy of the libffi C library [from
github][libffi github] or it can link against your
system’s C libffi. By default it builds its own because many systems
ship with an old C libffi; this requires that you have a working make,
C compiler, automake, and autoconf first. If your system libffi
is new enough (v3.2.1 as of October 2019), you can instead enable the
`system` feature flag to use that. If you want this crate to build
a C libffi for you, add

```toml
[dependencies]
libffi-sys = "2.3.0"
```

to your `Cargo.toml`. If you want to use your system C libffi, then

```toml
[dependencies.libffi-sys]
version = "2.3.0"
features = ["system"]
```

to your `Cargo.toml` instead.

This crate supports Rust version 1.32 and later.

[the `libffi` crate]: https://crates.io/crates/libffi/
[libffi]: https://sourceware.org/libffi/
[libffi github]: https://github.com/libffi/libffi