Gopher Interface Devices (USB HID)

The hid package is a cross platform library for accessing and communicating with USB Human Interface Devices (HID). It is an alternative package to gousb for use cases where devices support this ligher mode of operation (e.g. input devices, hardware crypto wallets).

The package wraps hidapi for accessing OS specific USB HID APIs directly instead of using low level USB constructs, which might have permission issues on some platforms. On Linux the package uses either libusb (default) or hidraw as backend. All of these dependencies are vendored directly into the repository and wrapped using CGO, making the hid package self-contained and go-gettable.

Supported platforms at the moment are Linux, macOS and Windows (exclude constraints are also specified for Android and iOS to allow smoother vendoring into cross platform projects).

Libusb backend selection (linux only)

If nothing is specified, libusb is used as backend for hidapi. To use the hidraw backend, build it with

go build -tags hidraw

Cross-compiling

Using go get the embedded C library is compiled into the binary format of your host OS. Cross compiling to a different platform or architecture entails disabling CGO by default in Go, causing device enumeration hid.Enumerate() to yield no results.

To cross compile a functional version of this library, you'll need to enable CGO during cross compilation via CGO_ENABLED=1 and you'll need to install and set a cross compilation enabled C toolkit via CC=your-cross-gcc.

Acknowledgements

Although the hid package is an implementation from scratch, it was heavily inspired by the existing go.hid library, which seems abandoned since 2015; is incompatible with Go 1.6+; and has various external dependencies. Given its inspirational roots, I thought it important to give credit to the author of said package too.

Wide character support in the hid package is done via the gowchar library, unmaintained since 2013; non buildable with a modern Go release and failing go vet checks. As such, gowchar was also vendored in inline (copyright headers and origins preserved).

License

The components of hid are licensed as such:

• hidapi is released under the GNU LGPL 3/3-clause BSD/HIDAPI license.
• libusb is released under the GNU LGPL 2.1 license.
• go.hid is released under the 2-clause BSD license.
• gowchar is released under the 3-clause BSD license.

Given the above, hid is licensed under GNU LGPL 2.1 or later on Linux and 3-clause BSD on other platforms.