git/Documentation/SubmittingPatches

I started reading over the SubmittingPatches document for Linux
kernel, primarily because I wanted to have a document similar to
it for the core GIT to make sure people understand what they are
doing when they write "Signed-off-by" line.

But the patch submission requirements are a lot more relaxed
here, because the core GIT is thousand times smaller ;-).  So
here is only the relevant bits.


(1) Make separate commits for logically separate changes.

Unless your patch is really trivial, you should not be sending
out a patch that was generated between your working tree and
your commit head.  Instead, always make a commit with complete
commit message and generate a series of patches from your
repository.  It is a good discipline.

Describe the technical detail of the change(s).

If your description starts to get long, that's a sign that you
probably need to split up your commit to finer grained pieces.


(2) Generate your patch using git/cogito out of your commits.

git diff tools generate unidiff which is the preferred format.
You do not have to be afraid to use -M option to "git diff" or
"git format-patch", if your patch involves file renames.  The
receiving end can handle them just fine.

Please make sure your patch does not include any extra files
which do not belong in a patch submission.  Make sure to review
your patch after generating it, to ensure accuracy.  Before
sending out, please make sure it cleanly applies to the "master"
branch head.


(3) Sending your patches.

People on the git mailing list needs to be able to read and
comment on the changes you are submitting.  It is important for
a developer to be able to "quote" your changes, using standard
e-mail tools, so that they may comment on specific portions of
your code.  For this reason, all patches should be submitting
e-mail "inline".  WARNING: Be wary of your MUAs word-wrap
corrupting your patch.  Do not cut-n-paste your patch.

It is common convention to prefix your subject line with
[PATCH].  This lets people easily distinguish patches from other
e-mail discussions.

"git format-patch" command follows the best current practice to
format the body of an e-mail message.  At the beginning of the
patch should come your commit message, ending with the
Signed-off-by: lines, and a line that consists of three dashes,
followed by the diffstat information and the patch itself.  If
you are forwarding a patch from somebody else, optionally, at
the beginning of the e-mail message just before the commit
message starts, you can put a "From: " line to name that person.

You often want to add additional explanation about the patch,
other than the commit message itself.  Place such "cover letter"
material between the three dash lines and the diffstat.

Do not attach the patch as a MIME attachment, compressed or not.
Do not let your e-mail client send quoted-printable.  Many
popular e-mail applications will not always transmit a MIME
attachment as plain text, making it impossible to comment on
your code.  A MIME attachment also takes a bit more time to
process.  This does not decrease the likelihood of your
MIME-attached change being accepted, but it makes it more likely
that it will be postponed.

Exception:  If your mailer is mangling patches then someone may ask
you to re-send them using MIME.

Note that your maintainer does not subscribe to the git mailing
list (he reads it via mail-to-news gateway).  If your patch is
for discussion first, send it "To:" the mailing list, and
optoinally "cc:" him.  If it is trivially correct or after list
discussion reached consensus, send it "To:" the maintainer and
optionally "cc:" the list.


(6) Sign your work

To improve tracking of who did what, we've borrowed the
"sign-off" procedure from the Linux kernel project on patches
that are being emailed around.  Although core GIT is a lot
smaller project it is a good discipline to follow it.

The sign-off is a simple line at the end of the explanation for
the patch, which certifies that you wrote it or otherwise have
the right to pass it on as a open-source patch.  The rules are
pretty simple: if you can certify the below:

        Developer's Certificate of Origin 1.1

        By making a contribution to this project, I certify that:

        (a) The contribution was created in whole or in part by me and I
            have the right to submit it under the open source license
            indicated in the file; or

        (b) The contribution is based upon previous work that, to the best
            of my knowledge, is covered under an appropriate open source
            license and I have the right under that license to submit that
            work with modifications, whether created in whole or in part
            by me, under the same open source license (unless I am
            permitted to submit under a different license), as indicated
            in the file; or

        (c) The contribution was provided directly to me by some other
            person who certified (a), (b) or (c) and I have not modified
            it.

	(d) I understand and agree that this project and the contribution
	    are public and that a record of the contribution (including all
	    personal information I submit with it, including my sign-off) is
	    maintained indefinitely and may be redistributed consistent with
	    this project or the open source license(s) involved.

then you just add a line saying

	Signed-off-by: Random J Developer <random@developer.example.org>

Some people also put extra tags at the end.  They'll just be ignored for
now, but you can do this to mark internal company procedures or just
point out some special detail about the sign-off.