libc 0.2.144

Raw FFI bindings to platform libraries like libc.

libc - Raw FFI bindings to platforms' system libraries

GHA Status Cirrus CI Status Latest Version Documentation License

libc provides all of the definitions necessary to easily interoperate with C code (or "C-like" code) on each of the platforms that Rust supports. This includes type definitions (e.g. c_int), constants (e.g. EINVAL) as well as function headers (e.g. malloc).

This crate exports all underlying platform types, functions, and constants under the crate root, so all items are accessible as libc::foo. The types and values of all the exported APIs match the platform that libc is compiled for.

More detailed information about the design of this library can be found in its associated RFC.


Add the following to your Cargo.toml:

libc = "0.2"


  • std: by default libc links to the standard library. Disable this feature to remove this dependency and be able to use libc in #![no_std] crates.

  • extra_traits: all structs implemented in libc are Copy and Clone. This feature derives Debug, Eq, Hash, and PartialEq.

  • const-extern-fn: Changes some extern fns into const extern fns. If you use Rust >= 1.62, this feature is implicitly enabled. Otherwise it requires a nightly rustc.

  • deprecated: use_std is deprecated, and is equivalent to std.

Rust version support

The minimum supported Rust toolchain version is currently Rust 1.13.0. (libc does not currently have any policy regarding changes to the minimum supported Rust version; such policy is a work in progress.) APIs requiring newer Rust features are only available on newer Rust toolchains:

Feature Version
union 1.19.0
const mem::size_of 1.24.0
repr(align) 1.25.0
extra_traits 1.25.0
core::ffi::c_void 1.30.0
repr(packed(N)) 1.33.0
cfg(target_vendor) 1.33.0
const-extern-fn 1.62.0

Platform support

Platform-specific documentation (master branch).

See ci/ for the platforms on which libc is guaranteed to build for each Rust toolchain. The test-matrix at GitHub Actions and Cirrus CI show the platforms in which libc tests are run.


This project is licensed under either of

at your option.


We welcome all people who want to contribute. Please see the contributing instructions for more information.

Contributions in any form (issues, pull requests, etc.) to this project must adhere to Rust's Code of Conduct.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in libc by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.