Contributing to libinput

Contributions to libinput are always welcome. Please see the steps below for details on how to create merge requests, correct git formatting and other topics:

Questions regarding this process can be asked on #wayland-devel on freenode or on the wayland-devel@lists.freedesktop.org mailing list.

Submitting Code

Any patches should be sent via a Merge Request (see the GitLab docs) in the libinput GitLab instance hosted by freedesktop.org.

To submit a merge request, you need to

• Register an account in the freedesktop.org GitLab instance.

• Fork libinput into your username’s namespace

• Get libinput’s main repository:

  git clone https://gitlab.freedesktop.org/libinput/libinput.git
  

• Add the forked git repository to your remotes (replace USERNAME with your username):

  cd /path/to/libinput.git
  git remote add gitlab git@gitlab.freedesktop.org:USERNAME/libinput.git
  git fetch gitlab
  

• Push your changes to your fork:

  git push gitlab BRANCHNAME
  

• Submit a merge request. The URL for a merge request is:

  https://gitlab.freedesktop.org/USERNAME/libinput/merge_requests
  

  Select your branch name to merge and libinput/libinput master as target branch.

Commit History

libinput strives to have a linear, ‘recipe’ style history This means that every commit should be small, digestible, stand-alone, and functional. Rather than a purely chronological commit history like this:

doc: final docs for view transforms
fix tests when disabled, redo broken doc formatting
better transformed-view iteration (thanks Hannah!)
try to catch more cases in tests
tests: add new spline test
fix compilation on splines
doc: notes on reticulating splines
compositor: add spline reticulation for view transforms

We aim to have a clean history which only reflects the final state, broken up into functional groupings:

compositor: add spline reticulation for view transforms
compositor: new iterator for view transforms
tests: add view-transform correctness tests
doc: fix Doxygen formatting for view transforms

This ensures that the final patch series only contains the final state, without the changes and missteps taken along the development process.

The first line of a commit message should contain a prefix indicating what part is affected by the patch followed by one sentence that describes the change. For example:

touchpad: add software button behavior
fallback: disable button debouncing on device foo

If in doubt what prefix to use, look at other commits that change the same file(s) as the patch being sent.

Commit Messages

Read on commit messages as a general guideline on what commit messages should contain.

Commit messages should contain a Signed-off-by line with your name and email address. If you’re not the patch’s original author, you should also gather S-o-b’s by them (and/or whomever gave the patch to you.) The significance of this is that it certifies that you created the patch, that it was created under an appropriate open source license, or provided to you under those terms. This lets us indicate a chain of responsibility for the copyright status of the code.

We won’t reject patches that lack S-o-b, but it is strongly recommended.

When you re-send patches, revised or not, it would be very good to document the changes compared to the previous revision in the commit message and/or the merge request. If you have already received Reviewed-by or Acked-by tags, you should evaluate whether they still apply and include them in the respective commit messages. Otherwise the tags may be lost, reviewers miss the credit they deserve, and the patches may cause redundant review effort.

Coding Style

Please see the CODING_STYLE.md document in the source tree.

Tracking patches and follow-ups

Once submitted to GitLab, your patches will be reviewed by the libinput development team on GitLab. Review may be entirely positive and result in your code landing instantly, in which case, great! You’re done. However, we may ask you to make some revisions: fixing some bugs we’ve noticed, working to a slightly different design, or adding documentation and tests.

If you do get asked to revise the patches, please bear in mind the notes above. You should use git rebase -i to make revisions, so that your patches follow the clear linear split documented above. Following that split makes it easier for reviewers to understand your work, and to verify that the code you’re submitting is correct.

A common request is to split single large patch into multiple patches. This can happen, for example, if when adding a new feature you notice a bug in libinput’s core which you need to fix to progress. Separating these changes into separate commits will allow us to verify and land the bugfix quickly, pushing part of your work for the good of everyone, whilst revision and discussion continues on the larger feature part. It also allows us to direct you towards reviewers who best understand the different areas you are working on.

When you have made any requested changes, please rebase the commits, verify that they still individually look good, then force-push your new branch to GitLab. This will update the merge request and notify everyone subscribed to your merge request, so they can review it again.

There are also many GitLab CLI clients, if you prefer to avoid the web interface. It may be difficult to follow review comments without using the web interface though, so we do recommend using this to go through the review process, even if you use other clients to track the list of available patches.

Code of Conduct

As a freedesktop.org project, libinput follows the freedesktop.org Contributor Covenant.

Please conduct yourself in a respectful and civilised manner when interacting with community members on mailing lists, IRC, or bug trackers. The community represents the project as a whole, and abusive or bullying behaviour is not tolerated by the project.