rules_libusb

A small wrapper Bazel module that builds libusb from sources. Supports Windows, macOS, and Linux.

This wrapper is maintained by Pigweed. Please file bug reports at https://issues.pigweed.dev/.

Getting Started

At this time, rules_libusb only supports bzlmod projects. Legacy WORKSPACE projects are not explicitly supported.

bzlmod

Add rules_libusb to your MODULE.bazel file:

bazel_dep(name = "rules_libusb", version = "0.1.0")

libusb = use_extension("@rules_libusb//:extensions.bzl", "libusb")
# Versioning constraints are optional.
libusb.source_release(min_version = "1.0.30")
use_repo(libusb, "libusb")

Note: source_release constraints follow bzlmod behavior of minimal version selection.

If you need to use a libusb release that is not yet listed in versions.json, any module can supply additional version-to-SHA-256 mappings on libusb.source_release() via versions (a dictionary mapping version strings to SHA-256 digests) or versions_file (a JSON file with the same format as versions.json). All supplied mappings across modules are merged before the selected version is resolved:

libusb.source_release(
    min_version = "1.0.30",
    versions = {
        "1.0.30": "fea36f34f9156400209595e300840767ab1a385ede1dc7ee893015aea9c6dbaf",
    },
)

Then add to the tool that requires libusb:

cc_binary(
    name = "my_tool",
    srcs = ["main.cc"],
    deps = ["@libusb//:libusb"],
)

Linking libusb

The libusb build file offers two targets to help guide link behavior:

//:libusb: The generic cc_library for libusb. Most build targets should just use this.
//:libusb_dynamic: The actual libusb dynamic/shared library (e.g. libusb-1.0.so).

By default, @libusb//:libusb will always dynamically link. This can be disabled by toggling the flag that controls this:

bazelisk build //... --@rules_libusb//:force_dynamic_linkage=False

When @rules_libusb//:force_dynamic_linkage is disabled, the link behavior is fully controlled by your build system, and can be controlled on a per-binary basis by specifying dynamic_deps on build targets that require dynamic linkage of libusb:

cc_binary(
    name = "my_tool",
    srcs = ["main.cc"],
    deps = ["@libusb//:libusb"],
    dynamic_deps = ["@libusb//:libusb_dynamic"],
)

Building and testing this repo

To build the libusb shared library directly, run:

bazelisk build @libusb//:libusb_dynamic

To build and run the example test in examples/basic_usage, run:

cd examples/basic_usage
bazelisk test //...

Updating libusb versions

Release versions and SHA-256 digests are stored in versions.json. To fetch new releases from GitHub and generate an updated versions.json, run:

bazelisk run //tools:update_versions

Then run the cp command printed in the output to update versions.json in the workspace.

Creating a new release

(Googlers only) If you are a Googler making a release, see http://go/pwi-cookbook#bcr.

Branches