path: root/docs/CONTRIBUTE

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                        When Contributing Source Code

 This document is intended to offer guidelines that can be useful to keep in
 mind when you decide to contribute to the project. This concerns new features
 as well as corrections to existing flaws or bugs.

 1. Learning cURL
 1.1 Join the Community
 1.2 License
 1.3 What To Read

 2. cURL Coding Standards
 2.1 Naming
 2.2 Indenting
 2.3 Commenting
 2.4 Line Lengths
 2.5 General Style
 2.6 Non-clobbering All Over
 2.7 Platform Dependent Code
 2.8 Write Separate Patches
 2.9 Patch Against Recent Sources
 2.10 Document
 2.11 Test Cases

 3. Pushing Out Your Changes
 3.1 Write Access to git Repository
 3.2 How To Make a Patch with git
 3.3 How To Make a Patch without git
 3.4 How to get your changes into the main sources
 3.5 Write good commit messages
 3.6 About pull requests

==============================================================================

1. Learning cURL

1.1 Join the Community

 Skip over to http://curl.haxx.se/mail/ and join the appropriate mailing
 list(s).  Read up on details before you post questions. Read this file before
 you start sending patches! We prefer patches and discussions being held on
 the mailing list(s), not sent to individuals.

 Before posting to one of the curl mailing lists, please read up on the mailing
 list etiquette: http://curl.haxx.se/mail/etiquette.html

 We also hang out on IRC in #curl on irc.freenode.net

 If you're at all interested in the code side of things, consider clicking
 'watch' on the curl repo at github to get notified on pull requests and new
 issues posted there.

1.2. License

 When contributing with code, you agree to put your changes and new code under
 the same license curl and libcurl is already using unless stated and agreed
 otherwise.

 If you add a larger piece of code, you can opt to make that file or set of
 files to use a different license as long as they don't enforce any changes to
 the rest of the package and they make sense. Such "separate parts" can not be
 GPL licensed (as we don't want copyleft to affect users of libcurl) but they
 must use "GPL compatible" licenses (as we want to allow users to use libcurl
 properly in GPL licensed environments).

 When changing existing source code, you do not alter the copyright of the
 original file(s). The copyright will still be owned by the original
 creator(s) or those who have been assigned copyright by the original
 author(s).

 By submitting a patch to the curl project, you are assumed to have the right
 to the code and to be allowed by your employer or whatever to hand over that
 patch/code to us. We will credit you for your changes as far as possible, to
 give credit but also to keep a trace back to who made what changes. Please
 always provide us with your full real name when contributing!

1.3 What To Read

 Source code, the man pages, the INTERNALS document, TODO, KNOWN_BUGS and the
 most recent changes in the git log. Just lurking on the curl-library mailing
 list is gonna give you a lot of insights on what's going on right now. Asking
 there is a good idea too.

2. cURL Coding Standards

2.1 Naming

 Try using a non-confusing naming scheme for your new functions and variable
 names. It doesn't necessarily have to mean that you should use the same as in
 other places of the code, just that the names should be logical,
 understandable and be named according to what they're used for. File-local
 functions should be made static. We like lower case names.

 See the INTERNALS document on how we name non-exported library-global
 symbols.

2.2 Indenting

 Use the same indenting levels and bracing method as all the other code
 already does. It makes the source code easier to follow if all of it is
 written using the same style. We don't ask you to like it, we just ask you to
 follow the tradition! ;-) This mainly means: 2-level indents, using spaces
 only (no tabs) and having the opening brace ({) on the same line as the if()
 or while().

 Also note that we use if() and while() with no space before the parenthesis.

2.3 Commenting

 Comment your source code extensively using C comments (/* comment */), DO NOT
 use C++ comments (// this style). Commented code is quality code and enables
 future modifications much more. Uncommented code risk having to be completely
 replaced when someone wants to extend things, since other persons' source
 code can get quite hard to read.

2.4 Line Lengths

 We write source lines shorter than 80 columns.

2.5 General Style

 Keep your functions small. If they're small you avoid a lot of mistakes and
 you don't accidentally mix up variables etc.

2.6 Non-clobbering All Over

 When you write new functionality or fix bugs, it is important that you don't
 fiddle all over the source files and functions. Remember that it is likely
 that other people have done changes in the same source files as you have and
 possibly even in the same functions. If you bring completely new
 functionality, try writing it in a new source file. If you fix bugs, try to
 fix one bug at a time and send them as separate patches.

2.7 Platform Dependent Code

 Use #ifdef HAVE_FEATURE to do conditional code. We avoid checking for
 particular operating systems or hardware in the #ifdef lines. The
 HAVE_FEATURE shall be generated by the configure script for unix-like systems
 and they are hard-coded in the config-[system].h files for the others.

2.8 Write Separate Patches

 It is annoying when you get a huge patch from someone that is said to fix 511
 odd problems, but discussions and opinions don't agree with 510 of them - or
 509 of them were already fixed in a different way. Then the patcher needs to
 extract the single interesting patch from somewhere within the huge pile of
 source, and that gives a lot of extra work. Preferably, all fixes that
 correct different problems should be in their own patch with an attached
 description exactly what they correct so that all patches can be selectively
 applied by the maintainer or other interested parties.

 Also, separate patches enable bisecting much better when we track problems in
 the future.

2.9 Patch Against Recent Sources

 Please try to get the latest available sources to make your patches
 against. It makes the life of the developers so much easier. The very best is
 if you get the most up-to-date sources from the git repository, but the
 latest release archive is quite OK as well!

2.10 Document

 Writing docs is dead boring and one of the big problems with many open source
 projects. Someone's gotta do it. It makes it a lot easier if you submit a
 small description of your fix or your new features with every contribution so
 that it can be swiftly added to the package documentation.

 The documentation is always made in man pages (nroff formatted) or plain
 ASCII files. All HTML files on the web site and in the release archives are
 generated from the nroff/ASCII versions.

2.11 Test Cases

 Since the introduction of the test suite, we can quickly verify that the main
 features are working as they're supposed to. To maintain this situation and
 improve it, all new features and functions that are added need to be tested
 in the test suite. Every feature that is added should get at least one valid
 test case that verifies that it works as documented. If every submitter also
 posts a few test cases, it won't end up as a heavy burden on a single person!

 If you don't have test cases or perhaps you have done something that is very
 hard to write tests for, do explain exactly how you have otherwise tested and
 verified your changes.

3. Pushing Out Your Changes

3.1 Write Access to git Repository

 If you are a frequent contributor, or have another good reason, you can of
 course get write access to the git repository and then you'll be able to push
 your changes straight into the git repo instead of sending changes by mail as
 patches. Just ask if this is what you'd want. You will be required to have
 posted a few quality patches first, before you can be granted push access.

3.2 How To Make a Patch with git

 You need to first checkout the repository:

     git clone https://github.com/bagder/curl.git

 You then proceed and edit all the files you like and you commit them to your
 local repository:

     git commit [file]

 As usual, group your commits so that you commit all changes that at once that
 constitutes a logical change. See also section "3.5 Write good commit
 messages".

 Once you have done all your commits and you're happy with what you see, you
 can make patches out of your changes that are suitable for mailing:

     git format-patch remotes/origin/master

 This creates files in your local directory named NNNN-[name].patch for each
 commit.

 Now send those patches off to the curl-library list. You can of course opt to
 do that with the 'git send-email' command.

3.3 How To Make a Patch without git

 Keep a copy of the unmodified curl sources. Make your changes in a separate
 source tree. When you think you have something that you want to offer the
 curl community, use GNU diff to generate patches.

 If you have modified a single file, try something like:

     diff -u unmodified-file.c my-changed-one.c > my-fixes.diff

 If you have modified several files, possibly in different directories, you
 can use diff recursively:

     diff -ur curl-original-dir curl-modified-sources-dir > my-fixes.diff

 The GNU diff and GNU patch tools exist for virtually all platforms, including
 all kinds of Unixes and Windows:

 For unix-like operating systems:

     https://savannah.gnu.org/projects/patch/
     https://www.gnu.org/software/diffutils/

 For Windows:

     http://gnuwin32.sourceforge.net/packages/patch.htm
     http://gnuwin32.sourceforge.net/packages/diffutils.htm

3.4 How to get your changes into the main sources

 Submit your patch to the curl-library mailing list.

 Make the patch against as recent sources as possible.

 Make sure your patch adheres to the source indent and coding style of already
 existing source code. Failing to do so just adds more work for me.

 Respond to replies on the list about the patch and answer questions and/or
 fix nits/flaws. This is very important. I will take lack of replies as a sign
 that you're not very anxious to get your patch accepted and I tend to simply
 drop such patches from my TODO list.

 If you've followed the above paragraphs and your patch still hasn't been
 incorporated after some weeks, consider resubmitting it to the list.

3.5 Write good commit messages

 A short guide to how to do fine commit messages in the curl project.

      ---- start ----
      [area]: [short line describing the main effect]

      [separate the above single line from the rest with an empty line]

      [full description, no wider than 72 columns that describe as much as
      possible as to why this change is made, and possibly what things
      it fixes and everything else that is related]

      [Bug: link to source of the report or more related discussion]
      [Reported-by: John Doe - credit the reporter]
      [whatever-else-by: credit all helpers, finders, doers]
      ---- stop ----

 Don't forget to use commit --author="" if you commit someone else's work,
 and make sure that you have your own user and email setup correctly in git
 before you commit

3.6 About pull requests

 With git (and especially github) it is easy and tempting to send a pull
 request to the curl project to have changes merged this way instead of
 mailing patches to the curl-library mailing list.

 We used to dislike this but we're trying to change that and accept that this
 is a frictionless way for people to contribute to the project. We now welcome
 pull requests!

 We will continue to avoid using github's merge tools to make the history
 linear and to make sure commits follow our style guidelines.