Submitting Patches

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Wine patch submission guidelines

In order to review code better and use established lines of communication, the Wine project accepts code in the form of merge requests on the WineHQ Gitlab. The process may seem a little complicated at first, but it will probably become very natural after just one or two submissions.

Can I submit patches?

Not everyone can contribute code to Wine, primarily because doing so would violate the Clean Room Guidelines. If you have studied the Microsoft Windows source code, even if you aren't under a non-disclosure agreement, your patches probably won't be accepted. This is to ensure that the Wine project does not violate any copyrights belonging to Microsoft. Some more notes related to this can be found in the Developer FAQ.

Check your Git setup

It is important to make sure the author and email settings for your Git repo are configured correctly.

git config --global user.name "Your Name"
git config --global user.email "me@example.com"

The Git Wine Tutorial has more details, but the key point is to use your real name. This isn't just for developers to show a stronger commitment and establish trust, but also helps discourage irresponsible programmers from submitting unacceptable code (such as dissassembled Microsoft components).

Please also use your real name in your Gitlab profile, so that it can be matched to your commits.

Finally, there's always a chance that someone has recently changed the same code you are working on. To make sure your code hasn't been superseded, be sure to update your Git repo before submitting your merge request.

git pull --rebase

If you prefer to manage your work in separate Git branches, remember that the above command will only update your current branch and all of your branches need to be up-to-date. Keeping your "master" branch in sync with WineHQ's repository and creating branches (and rebasing them on "master") for your own changes might be a good idea. Again, the Git Wine Tutorial page goes into much more detail on using Git to manage your work.

Making your changes

Code guidelines

See also Wine Developer's Guide/Coding Practice#Some notes about style

If you are making changes to the Wine program itself, there are some basic rules your code should follow to pass review:

  • When changing existing code, try to follow the style of the old code but keep in mind the rules for new code
  • Copy and pasting old code is considered adding new code!
  • When adding new code:
    • Use spaces instead of tabs
    • Use underscores instead of camelCase, except if the Windows API requires it
    • Avoid type names that start with LP (e.g. write DWORD * instead of LPDWORD)
    • Don't use Hungarian notation (e.g. write char *important_buffer instead of char *pImportantBuffer)
  • Where possible, use only portable, C89-compliant code
  • Use a consistent style in your own changes (e.g. don't write int* foo in one place and int *foo in another)
  • Limit type casts as much as possible (e.g. don't cast a VOID * to a DWORD *)
  • Remove trailing whitespace from your changes, but don't change whitespace in other lines
  • Avoid very long lines (there is no hard limit, the preferred length is 100, but 120 or 80 chars are fine too)

As a general rule, only the simplest code possible is accepted into Wine. Spend some time looking over your changes and think about whether there is a more concise or straightforward way to do what you want.

Patch guidelines

In order to make your patches as easy to check as possible, try to keep them small, clear, and atomic:

  • Only include closely related changes in one commit
  • If you've written a fix and a lot of new conformance tests for an issue, add the tests as a separate commit before the fix
  • Limit a commit to changing a single file or component unless that would break something somewhere else
  • Limit a merge requests to only a few commits (no more than 5 is a good guideline)

These rules make the merge request easier to review, and also make it easier to find regressions, and help prevent new bugs from slipping through.

You can also look at the accepted merge requests to see the requests that have been submitted and committed recently. Try to imitate the style of the successful merge requests.

Related parts of the Wine project, such as the website, may have slightly looser requirements on patches, but it is still important to keep patches clear and simple, bundle related changes together, and not break anything.

Testing for problems

Be sure to run the conformance tests on an unchanged branch of Wine (or before you make any changes) to see where your system is OK. Then run the tests again after you make your changes to verify that they don't break anything new. If you've added or modified any of the conformance tests, be sure to check that they work properly by using the make test command, then submitting the resulting executable to the Wine Test Bot.

Also, make note of any significant compiler warnings that come up when building your modified version of Wine and fix the underlying cause before submitting your patch.

The commit message

In the first line of the commit message, write the name of the component you changed, followed by a colon, one sentence in the imperative mood that will appear in the release notes, and a period. Be brief: the first line should ideally not be more than 72 characters in length.

After the first line, you may add explanatory paragraphs that tell what the patch accomplishes. Describe your changes in the imperative mood, as if you are giving orders to the codebase to change its behavior, e.g. Make xyzzy do frotz. instead of This patch makes xyzzy do frotz. or Changed xyzzy to do frotz. Try to make sure your explanation can be understood without external resources. Instead of giving a URL to a mailing list archive, summarize the relevant points of the discussion. Describe how the patch works and why it is needed, but do not repeat what the diff already shows. Wrap all paragraph lines to 72 characters.

If your patch is related to a bug, it's recommended to include a Wine-Bug line with a URL to Bugzilla (see the example below). Do not include the bug number in the first line.

You can include any extra information that you do not want included in the commit log beneath three dashes (---), though it's usually better to add that information in the Description field when creating the merge request on the website.

A complete example:

gdiplus: Avoid calling GdipFillPath() with an empty path.

There is no point filling an empty path, and an empty
path will cause SelectClipPath() used in brush_fill_path()
to return an error.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=987654
---
v2: Fix test breakage.

Submitting your changes

Quality check

It never hurts to check through your changes one last time:

  • Look at each line of the patch, make sure there are no unintentional or unrelated changes
  • Did your fix pass all related tests? If it wasn't covered by a test, have you written a test of your own?

Sending the merge request

The Git Wine Tutorial includes more details about sending merge requests. In general you should push your changes to a temporary branch in your fork on Gitlab:

git push origin master:my-awesome-fix

and then go to the link that is displayed to finish the creation of the merge request.

Managing your submission

After you've submitted your merge request, a reviewer will be assigned to it, if someone is responsible for that area of code. You can also assign a reviewer yourself if you know who the right person is. If a reviewer gives some feedback or a critique, carefully think about what they say and fix your patch before resubmitting. If others point out a few flaws in your patch, it's safe to assume that they missed some too so try to check the whole patch and fix other flaws before resubmitting.

When updating your changes, don't simply push the fixes as a new commit on top of your merge request. You need to actually modify and recreate the existing commits to make it look as if you got everything right on the first try. You can then update your merge request by force pushing to its branch:

git push --force origin master:my-awesome-fix

If your merge request remains in the queue for several weeks without being committed and without feedback, improving it (perhaps by adding more tests) and resubmitting it (after rebasing to the current tip) may help. You can also ask for suggestions on the IRC channel or the wine-devel mailing list. If you have patches rejected multiple times, don't be discouraged. You might consider finding a mentor willing to pre-review your changes before you submit them (see https://www.winehq.org/pipermail/wine-devel/2010-August/086207.html for a discussion of this)

Reviewing merge requests

If you are asked to review a merge request, and find things that need to be improved, you should add a comment to the merge request from the Gitlab UI. If you prefer to use email, you can reply to the Gitlab notification (if you are subscribed to these), or to the mails that were sent to the wine-gitlab mailing list (if you are following that).

You can also fix things up yourself and force-push updated commits to the original branch. At the moment this requires the submitter to explicitly give you access (we are hoping to lift that restriction).

If you think that the merge request is good to go in, you should mark it approved in Gitlab. As a rule, a merge request won't be committed until all reviewers have approved it. If you have been assigned as a reviewer but feel that you cannot meaningfully review the changes, feel free to unassign yourself, and maybe re-assign it to someone more knowledgeable in that area.

Special situations

Submitting patches written by somebody else

Occasionally, the author of a useful patch stops working on it, and somebody else has to pick it up and continue. In this case, commit the author's original patch file to your local branch (git am), making sure that the Author: field of the commit is set to the original author, and submit a merge request. You'll be asked to approve the merge request to show that you have checked the original author's work.

Coauthored patches

If someone else has made a significant contribution to the patch, first try to split up the patch so that each patch has only one author. If that is impractical, explain in the commit message who you collaborated with on the patch, but keep yourself as the author.

Multiple outstanding merge requests

Alexandre says you should concentrate on one thing and get it in before trying others. He may ignore some of your merge requests if he feels you have too many balls in the air.