The libudev-sys crate provides declarations and linkage for the libudev C library. Following the *-sys package conventions, the libudev-sys crate does not define higher-level abstractions over the native libudev library functions.

In order to use the libudev-sys crate, you must have a Linux system with the libudev library installed where it can be found by pkg-config. To install libudev on Debian-based Linux distributions, execute the following command:

sudo apt-get install libudev-dev

For Red Hat distributions (e.g. Fedora):

sudo dnf install systemd-devel

libudev is a Linux-specific package. It is not available for Windows, OSX, or other operating systems.

To link to a cross-compiled version of the native libudev library, it's necessary to set several environment variables to configure pkg-config to work with a cross-compiler's sysroot. Autotools Mythbuster has a good explanation of supporting cross-compilation with pkg-config.

However, Rust's pkg-config build helper doesn't support calling a $CHOST-prefixed pkg-config. It will always call pkg-config without a prefix. To cross-compile libudev-sys with the pkg-config build helper, one must define the environment variables PKG_CONFIG_DIR, PKG_CONFIG_LIBDIR, and PKG_CONFIG_SYSROOT_DIR for the default pkg-config. It's also necessary to set PKG_CONFIG_ALLOW_CROSS to tell Rust's pkg-config helper that it's okay to proceed with a cross-compile.

To adapt the pkg-config wrapper in the Autotools Mythbuster guide so that it works with Rust, one will end up with a script similar to the following:

#!/bin/sh

SYSROOT=/build/root

export PKG_CONFIG_DIR=
export PKG_CONFIG_LIBDIR=${SYSROOT}/usr/lib/pkgconfig:${SYSROOT}/usr/share/pkgconfig
export PKG_CONFIG_SYSROOT_DIR=${SYSROOT}
export PKG_CONFIG_ALLOW_CROSS=1

cargo build

Add libudev-sys as a dependency in Cargo.toml:

[dependencies]
libudev-sys = "0.1"

Import the libudev_sys crate and use the functions as they're defined in the native libudev library. See the libudev API documention for more usage information.

extern crate libudev_sys as ffi;

The libudev-sys build script detects the presence of native libudev functions and exports the functions found to exist. libudev-sys exports this information from its build script, which Cargo will provide to the build scripts of dependent packages in the form of environment variables:

• DEP_LIBUDEV_HWDB={true,false}: The native libudev library has udev_hwdb_* functions. They will be exported by libudev-sys.

Since libudev-sys does nothing more than export symbols from the native libudev library, the best source for help is the information already available for the native libudev:

• API Documentation

Copyright © 2015 David Cuddeback

Distributed under the MIT License.