path: root/SUBMITTING_PATCHES

Short Version:

 - Make small logical changes.
 - Provide a meaningful commit message.

 - Include your Signed-Off-By line to note you agree with the
   Developer's Certificate of Origin (see below).
 - Make sure all code is under the proper license:

      3-clause BSD

 - Use a subject prefix of "[PATCH JGIT ...]"  when sending any
   patches directly by email.

 - Send by email to the maintainers, cc'ing the git mailing list
   which is currently used for both Git and JGit:

   maintainers   : "Shawn O. Pearce" <spearce@spearce.org>
                   Robin Rosenberg <robin.rosenberg@dewire.com>

   git list      : git@vger.kernel.org

   git list info : http://vger.kernel.org/vger-lists.html#git    

Long Version:

I wanted a file describing how to submit patches for JGit,
so I started with the one found in the core Git distribution
(Documentation/SubmittingPatches), which itself was based on the
patch submission guidelines for the Linux kernel.

However there are some differences, so please review and familiarize
yourself with the following 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 too long, that's a sign that you
probably need to split up your commit to finer grained pieces.

I am very picky about formatting.  Make sure your final version
of every file was formatted using the Eclipse code formatter
using the project specific settings (Properties->Java Code
Style->Formatter->"Java Conventions [built-in]").


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

git based diff tools (git, and StGIT included) generate unidiff,
which is the only acceptable 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 need 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 submitted "inline".  WARNING: Be wary
of your MUAs word-wrap corrupting your patch.  Do not cut-n-paste
your patch; you can lose tabs that way if you are not careful.

It is a 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.  Do not let your
e-mail client send format=flowed which would destroy whitespaces
in your patches. 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, that is OK.

Do not PGP sign your patch, at least for now.  Most likely, your
maintainer or other people on the list would not have your PGP
key and would not bother obtaining it anyway.  Your patch is not
judged by who you are; a good patch from an unknown origin has a
far better chance of being accepted than a patch from a known,
respected origin that is done poorly or does incorrect things.

If you really really really really want to do a PGP signed
patch, format it as "multipart/signed", not a text/plain message
that starts with '-----BEGIN PGP SIGNED MESSAGE-----'.  That is
not a text/plain, it's something else.

Note that your maintainer does not necessarily read everything
on the git mailing list.  If your patch is for discussion first,
send it "To:" the mailing list, and optionally "cc:" him.  If it
is trivially correct or after the list reached a consensus, send it
"To:" the maintainer and optionally "cc:" the list.


(4) Check the license

JGit is licensed under the 3-clause (new-style) BSD.

Because of this licensing model *every* file within the project
*must* list which license covers it in the header of the file.
Any new contributions to an existing file *must* be submitted under
the current license of that file.  Any new files *must* clearly
indicate which license they are provided under in the file header.

Please verify that you are legally allowed and willing to submit your
changes under the license covering each file *prior* to submitting
your patch.  It is virtually impossible to remove a patch once it
has been applied and pushed out.


(5) 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 JGit 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>

This line can be automatically added by git if you run the git-commit
command with the -s option.

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.


------------------------------------------------
MUA specific hints

Some of patches I receive or pick up from the list share common
patterns of breakage.  Please make sure your MUA is set up
properly not to corrupt whitespaces.  Here are two common ones
I have seen:

* Empty context lines that do not have _any_ whitespace.

* Non empty context lines that have one extra whitespace at the
  beginning.

One test you could do yourself if your MUA is set up correctly is:

* Send the patch to yourself, exactly the way you would, except
  To: and Cc: lines, which would not contain the list and
  maintainer address.

* Save that patch to a file in UNIX mailbox format.  Call it say
  a.patch.

* Try to apply to the tip of the "master" branch from the
  egit.git public repository:

    $ git fetch git://repo.or.cz/egit.git master:test-apply
    $ git checkout test-apply
    $ git reset --hard
    $ git am a.patch

If it does not apply correctly, there can be various reasons.

* Your patch itself does not apply cleanly.  That is _bad_ but
  does not have much to do with your MUA.  Please rebase the
  patch appropriately.

* Your MUA corrupted your patch; applymbox would complain that
  the patch does not apply.  Look at .dotest/ subdirectory and
  see what 'patch' file contains and check for the common
  corruption patterns mentioned above.

* While you are at it, check what are in 'info' and
  'final-commit' files as well.  If what is in 'final-commit' is
  not exactly what you would want to see in the commit log
  message, it is very likely that your maintainer would end up
  hand editing the log message when he applies your patch.
  Things like "Hi, this is my first patch.\n", if you really
  want to put in the patch e-mail, should come after the
  three-dash line that signals the end of the commit message.


Pine
----

(Johannes Schindelin)

I don't know how many people still use pine, but for those poor
souls it may be good to mention that the quell-flowed-text is
needed for recent versions.

... the "no-strip-whitespace-before-send" option, too. AFAIK it
was introduced in 4.60.

(Linus Torvalds)

And 4.58 needs at least this.

---
diff-tree 8326dd8350be64ac7fc805f6563a1d61ad10d32c (from e886a61f76edf5410573e92e38ce22974f9c40f1)
Author: Linus Torvalds <torvalds@g5.osdl.org>
Date:   Mon Aug 15 17:23:51 2005 -0700

    Fix pine whitespace-corruption bug

    There's no excuse for unconditionally removing whitespace from
    the pico buffers on close.

diff --git a/pico/pico.c b/pico/pico.c
--- a/pico/pico.c
+++ b/pico/pico.c
@@ -219,7 +219,9 @@ PICO *pm;
 	    switch(pico_all_done){	/* prepare for/handle final events */
 	      case COMP_EXIT :		/* already confirmed */
 		packheader();
+#if 0
 		stripwhitespace();
+#endif
 		c |= COMP_EXIT;
 		break;
 

(Daniel Barkalow)

> A patch to SubmittingPatches, MUA specific help section for
> users of Pine 4.63 would be very much appreciated.

Ah, it looks like a recent version changed the default behavior to do the
right thing, and inverted the sense of the configuration option. (Either
that or Gentoo did it.) So you need to set the
"no-strip-whitespace-before-send" option, unless the option you have is
"strip-whitespace-before-send", in which case you should avoid checking
it.


Thunderbird
-----------

(A Large Angry SCM)

Here are some hints on how to successfully submit patches inline using
Thunderbird.

This recipe appears to work with the current [*1*] Thunderbird from Suse.

The following Thunderbird extensions are needed:
	AboutConfig 0.5
		http://aboutconfig.mozdev.org/
	External Editor 0.7.2
		http://globs.org/articles.php?lng=en&pg=8

1) Prepare the patch as a text file using your method of choice.

2) Before opening a compose window, use Edit->Account Settings to
uncheck the "Compose messages in HTML format" setting in the
"Composition & Addressing" panel of the account to be used to send the
patch. [*2*]

3) In the main Thunderbird window, _before_ you open the compose window
for the patch, use Tools->about:config to set the following to the
indicated values:
	mailnews.send_plaintext_flowed	=> false
	mailnews.wraplength		=> 0

4) Open a compose window and click the external editor icon.

5) In the external editor window, read in the patch file and exit the
editor normally.

6) Back in the compose window: Add whatever other text you wish to the
message, complete the addressing and subject fields, and press send.

7) Optionally, undo the about:config/account settings changes made in
steps 2 & 3.


[Footnotes]
*1* Version 1.0 (20041207) from the MozillaThunderbird-1.0-5 rpm of Suse
9.3 professional updates.

*2* It may be possible to do this with about:config and the following
settings but I haven't tried, yet.
	mail.html_compose			=> false
	mail.identity.default.compose_html	=> false
	mail.identity.id?.compose_html		=> false



Gnus
----

'|' in the *Summary* buffer can be used to pipe the current
message to an external program, and this is a handy way to drive
"git am".  However, if the message is MIME encoded, what is
piped into the program is the representation you see in your
*Article* buffer after unwrapping MIME.  This is often not what
you would want for two reasons.  It tends to screw up non ASCII
characters (most notably in people's names), and also
whitespaces (fatal in patches).  Running 'C-u g' to display the
message in raw form before using '|' to run the pipe can work
this problem around.