xref: /external/wayland/doc/Contributing

= Contributing to Wayland =

== Sending patches ==

Patches should be sent to wayland-devel@lists.freedesktop.org, using
git send-email. See git's documentation for help [1].

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 examples:

    protocol: Support scaled outputs and surfaces

and

    doc: generate server documentation from XML too

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

The body of the commit message should describe what the patch changes
and why, and also note any particular side effects. This shouldn't be
empty on most of the cases. It shouldn't take a lot of effort to write
a commit message for an obvious change, so an empty commit message
body is only acceptable if the questions "What?" and "Why?" are already
answered on the one-line summary.

The lines of the commit message should have at most 76 characters, to
cope with the way git log presents them.

See [2] for a recommended reading on writing commit messages.

Your patches should also include 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.

== Tracking patches and following up ==

Patchwork is used for tracking patches to Wayland and Weston:
http://patchwork.freedesktop.org/project/wayland/list/

Xwayland patches are tracked with the Xorg project, not here.

Libinput patches, even though they use the same mailing list as Wayland, are
not tracked in the Wayland Patchwork.

The following applies only to Wayland and Weston.

If a patch is not found in Patchwork, there is a high possibility for it to be
forgotten. Patches attached to bug reports or not arriving to the mailing list
because of e.g. subscription issues will not be in Patchwork because Patchwork
only collects patches sent to the list.

When you send a revised version of a patch, it would be very nice to mark your
old patch as superseded (or rejected, if that is applicable). You can change
the status of your own patches by registering to Patchwork - ownership is
identified by email address you use to register. Updating your patch status
appropriately will help maintainer work.

The following patch states are found in Patchwork:

  New
	Patches under discussion or not yet processed.

  Under review
	Mostly unused state.

  Accepted
	The patch is merged in the master branch upstream, as is or slightly
	modified.

  Rejected
	The idea or approach is rejected and cannot be fixed by revising
	the patch.

  RFC
	Request for comments, not meant to be merged as is.

  Not applicable
	The email was not actually a patch, or the patch is not for Wayland or
	Weston. Libinput patches are usually automatically ignored by Wayland
	Patchwork, but if they get through, they will be marked as Not
	applicable.

  Changes requested
	Reviewers determined that changes to the patch are needed. The
	submitter is expected to send a revised version. (You should
	not wait for your patch to be set to this state before revising,
	though.)

  Awaiting upstream
	Mostly unused as the patch is waiting for upstream actions but
	is not shown in the default list, which means it is easy to
	overlook.

  Superseded
	A revised version of the patch has been submitted.

  Deferred
	Used mostly during freeze periods before releases, to temporarily
	hide patches that cannot be merged during a freeze.

Note, that in the default listing, only patches in New or Under review are
shown.

There is also a command line interface to Patchwork called 'pwclient', see
http://patchwork.freedesktop.org/project/wayland/
for links where to get it and the sample .pwclientrc for Wayland/Weston.


== Coding style ==

You should follow the style of the file you're editing. In general, we
try to follow the rules below.

- indent with tabs, and a tab is always 8 characters wide
- opening braces are on the same line as the if statement;
- no braces in an if-body with just one statement;
- if one of the branches of an if-else condition has braces, then the
  other branch should also have braces;
- there is always an empty line between variable declarations and the
  code;

static int
my_function(void)
{
	int a = 0;

	if (a)
		b();
	else
		c();

	if (a) {
		b();
		c();
	} else {
		d();
	}
}

- lines should be less than 80 characters wide;
- when breaking lines with functions calls, the parameters are aligned
  with the opening parentheses;
- when assigning a variable with the result of a function call, if the
  line would be longer we break it around the equal '=' sign if it makes
  sense;

	long_variable_name =
		function_with_a_really_long_name(parameter1, parameter2,
						 parameter3, parameter4);

	x = function_with_a_really_long_name(parameter1, parameter2,
					     parameter3, parameter4);

== Licensing ==

Wayland is licensed with the intention to be usable anywhere X.org is.
Originally, X.org was covered under the MIT X11 license, but changed to
the MIT Expat license.  Similarly, Wayland was covered initially as MIT
X11 licensed, but changed to the MIT Expat license, following in X.org's
footsteps.  Other than wording, the two licenses are substantially the
same, with the exception of a no-advertising clause in X11 not included
in Expat.

New source code files should specify the MIT Expat license in their
boilerplate, as part of the copyright statement.

== References ==

	[1] http://git-scm.com/documentation

	[2] http://who-t.blogspot.de/2009/12/on-commit-messages.html