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Contributing to libfprint


Although the library uses GLib internally, libfprint is designed to provide a completely neutral interface to its application users. So, the public APIs should never return GLib data types.

License clarification

Although this library's license could allow for shims that hook up into proprietary blobs to add driver support for some unsupported devices, the intent of the original authors, and of current maintainers of the library, was for this license to allow integration into proprietary stacks, not integration of proprietary code in the library.

As such, no code to integrate proprietary drivers will be accepted in libfprint upstream. Proprietary drivers would make it impossible to debug problems in libfprint, as we wouldn't know what the proprietary driver does behind the library's back. The closed source nature of drivers is usually used to hide parts of the hardware setup, such as encryption keys, or protocols, in order to protect the hardware's integrity. Unfortunately, this is only security through obscurity.

We however encourage potential contributors to take advantage of libfprint's source availability to create such shims to make it easier to reverse-engineer proprietary drivers in order to create new free software drivers, to the extent permitted by local laws.


Like any decent library, this one is designed to provide a stable and documented API to its users: applications. Clear distinction is made between data available internally in the library, and data/functions available to the applications.

This library is confused a little by the fact that there is another 'interface' at hand: the internal interface provided to drivers. So, we effectively end up with 2 APIs:

  1. The external-facing API for applications
  2. The internal API for fingerprint drivers

Non-static functions which are intended for internal use only are prepended with the "fpi_" prefix.


All additions of public API functions must be accompanied with gtk-doc comments.

All changes which potentially change the behaviour of the public API must be reflected by updating the appropriate gtk-doc comments.


Patches should be sent as merge requests to the gitlab page:

Drivers are not usually written by libfprint developers, but when they are, we require:

  • 3 stand-alone devices. Not in a laptop or another embedded device, as space is scarce, unless the device has special integration with that hardware.
  • specifications of the protocol.

If you are an end-user, you can file a feature request with the "Driver Request" tag on libfprint's issue page, or subscribe to an existing feature request there.

If you are an enterprising hacker, please file a new merge request with the driver patches integrated.