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      6 
      7                         When Contributing Source Code
      8 
      9  This document is intended to offer guidelines that can be useful to keep in
     10  mind when you decide to contribute to the project. This concerns new features
     11  as well as corrections to existing flaws or bugs.
     12 
     13  1. Learning cURL
     14  1.1 Join the Community
     15  1.2 License
     16  1.3 What To Read
     17 
     18  2. cURL Coding Standards
     19  2.1 Naming
     20  2.2 Indenting
     21  2.3 Commenting
     22  2.4 Line Lengths
     23  2.5 General Style
     24  2.6 Non-clobbering All Over
     25  2.7 Platform Dependent Code
     26  2.8 Write Separate Patches
     27  2.9 Patch Against Recent Sources
     28  2.10 Document
     29  2.11 Test Cases
     30 
     31  3. Pushing Out Your Changes
     32  3.1 Write Access to git Repository
     33  3.2 How To Make a Patch with git
     34  3.3 How To Make a Patch without git
     35  3.4 How to get your changes into the main sources
     36  3.5 Write good commit messages
     37  3.6 About pull requests
     38 
     39 ==============================================================================
     40 
     41 1. Learning cURL
     42 
     43 1.1 Join the Community
     44 
     45  Skip over to http://curl.haxx.se/mail/ and join the appropriate mailing
     46  list(s).  Read up on details before you post questions. Read this file before
     47  you start sending patches! We prefer patches and discussions being held on
     48  the mailing list(s), not sent to individuals.
     49 
     50  Before posting to one of the curl mailing lists, please read up on the mailing
     51  list etiquette: http://curl.haxx.se/mail/etiquette.html
     52 
     53  We also hang out on IRC in #curl on irc.freenode.net
     54 
     55  If you're at all interested in the code side of things, consider clicking
     56  'watch' on the curl repo at github to get notified on pull requests and new
     57  issues posted there.
     58 
     59 1.2. License
     60 
     61  When contributing with code, you agree to put your changes and new code under
     62  the same license curl and libcurl is already using unless stated and agreed
     63  otherwise.
     64 
     65  If you add a larger piece of code, you can opt to make that file or set of
     66  files to use a different license as long as they don't enforce any changes to
     67  the rest of the package and they make sense. Such "separate parts" can not be
     68  GPL licensed (as we don't want copyleft to affect users of libcurl) but they
     69  must use "GPL compatible" licenses (as we want to allow users to use libcurl
     70  properly in GPL licensed environments).
     71 
     72  When changing existing source code, you do not alter the copyright of the
     73  original file(s). The copyright will still be owned by the original
     74  creator(s) or those who have been assigned copyright by the original
     75  author(s).
     76 
     77  By submitting a patch to the curl project, you are assumed to have the right
     78  to the code and to be allowed by your employer or whatever to hand over that
     79  patch/code to us. We will credit you for your changes as far as possible, to
     80  give credit but also to keep a trace back to who made what changes. Please
     81  always provide us with your full real name when contributing!
     82 
     83 1.3 What To Read
     84 
     85  Source code, the man pages, the INTERNALS document, TODO, KNOWN_BUGS and the
     86  most recent changes in the git log. Just lurking on the curl-library mailing
     87  list is gonna give you a lot of insights on what's going on right now. Asking
     88  there is a good idea too.
     89 
     90 2. cURL Coding Standards
     91 
     92 2.1 Naming
     93 
     94  Try using a non-confusing naming scheme for your new functions and variable
     95  names. It doesn't necessarily have to mean that you should use the same as in
     96  other places of the code, just that the names should be logical,
     97  understandable and be named according to what they're used for. File-local
     98  functions should be made static. We like lower case names.
     99 
    100  See the INTERNALS document on how we name non-exported library-global
    101  symbols.
    102 
    103 2.2 Indenting
    104 
    105  Use the same indenting levels and bracing method as all the other code
    106  already does. It makes the source code easier to follow if all of it is
    107  written using the same style. We don't ask you to like it, we just ask you to
    108  follow the tradition! ;-) This mainly means: 2-level indents, using spaces
    109  only (no tabs) and having the opening brace ({) on the same line as the if()
    110  or while().
    111 
    112  Also note that we use if() and while() with no space before the parenthesis.
    113 
    114 2.3 Commenting
    115 
    116  Comment your source code extensively using C comments (/* comment */), DO NOT
    117  use C++ comments (// this style). Commented code is quality code and enables
    118  future modifications much more. Uncommented code risk having to be completely
    119  replaced when someone wants to extend things, since other persons' source
    120  code can get quite hard to read.
    121 
    122 2.4 Line Lengths
    123 
    124  We write source lines shorter than 80 columns.
    125 
    126 2.5 General Style
    127 
    128  Keep your functions small. If they're small you avoid a lot of mistakes and
    129  you don't accidentally mix up variables etc.
    130 
    131 2.6 Non-clobbering All Over
    132 
    133  When you write new functionality or fix bugs, it is important that you don't
    134  fiddle all over the source files and functions. Remember that it is likely
    135  that other people have done changes in the same source files as you have and
    136  possibly even in the same functions. If you bring completely new
    137  functionality, try writing it in a new source file. If you fix bugs, try to
    138  fix one bug at a time and send them as separate patches.
    139 
    140 2.7 Platform Dependent Code
    141 
    142  Use #ifdef HAVE_FEATURE to do conditional code. We avoid checking for
    143  particular operating systems or hardware in the #ifdef lines. The
    144  HAVE_FEATURE shall be generated by the configure script for unix-like systems
    145  and they are hard-coded in the config-[system].h files for the others.
    146 
    147 2.8 Write Separate Patches
    148 
    149  It is annoying when you get a huge patch from someone that is said to fix 511
    150  odd problems, but discussions and opinions don't agree with 510 of them - or
    151  509 of them were already fixed in a different way. Then the patcher needs to
    152  extract the single interesting patch from somewhere within the huge pile of
    153  source, and that gives a lot of extra work. Preferably, all fixes that
    154  correct different problems should be in their own patch with an attached
    155  description exactly what they correct so that all patches can be selectively
    156  applied by the maintainer or other interested parties.
    157 
    158  Also, separate patches enable bisecting much better when we track problems in
    159  the future.
    160 
    161 2.9 Patch Against Recent Sources
    162 
    163  Please try to get the latest available sources to make your patches
    164  against. It makes the life of the developers so much easier. The very best is
    165  if you get the most up-to-date sources from the git repository, but the
    166  latest release archive is quite OK as well!
    167 
    168 2.10 Document
    169 
    170  Writing docs is dead boring and one of the big problems with many open source
    171  projects. Someone's gotta do it. It makes it a lot easier if you submit a
    172  small description of your fix or your new features with every contribution so
    173  that it can be swiftly added to the package documentation.
    174 
    175  The documentation is always made in man pages (nroff formatted) or plain
    176  ASCII files. All HTML files on the web site and in the release archives are
    177  generated from the nroff/ASCII versions.
    178 
    179 2.11 Test Cases
    180 
    181  Since the introduction of the test suite, we can quickly verify that the main
    182  features are working as they're supposed to. To maintain this situation and
    183  improve it, all new features and functions that are added need to be tested
    184  in the test suite. Every feature that is added should get at least one valid
    185  test case that verifies that it works as documented. If every submitter also
    186  posts a few test cases, it won't end up as a heavy burden on a single person!
    187 
    188  If you don't have test cases or perhaps you have done something that is very
    189  hard to write tests for, do explain exactly how you have otherwise tested and
    190  verified your changes.
    191 
    192 3. Pushing Out Your Changes
    193 
    194 3.1 Write Access to git Repository
    195 
    196  If you are a frequent contributor, or have another good reason, you can of
    197  course get write access to the git repository and then you'll be able to push
    198  your changes straight into the git repo instead of sending changes by mail as
    199  patches. Just ask if this is what you'd want. You will be required to have
    200  posted a few quality patches first, before you can be granted push access.
    201 
    202 3.2 How To Make a Patch with git
    203 
    204  You need to first checkout the repository:
    205 
    206      git clone https://github.com/bagder/curl.git
    207 
    208  You then proceed and edit all the files you like and you commit them to your
    209  local repository:
    210 
    211      git commit [file]
    212 
    213  As usual, group your commits so that you commit all changes that at once that
    214  constitutes a logical change. See also section "3.5 Write good commit
    215  messages".
    216 
    217  Once you have done all your commits and you're happy with what you see, you
    218  can make patches out of your changes that are suitable for mailing:
    219 
    220      git format-patch remotes/origin/master
    221 
    222  This creates files in your local directory named NNNN-[name].patch for each
    223  commit.
    224 
    225  Now send those patches off to the curl-library list. You can of course opt to
    226  do that with the 'git send-email' command.
    227 
    228 3.3 How To Make a Patch without git
    229 
    230  Keep a copy of the unmodified curl sources. Make your changes in a separate
    231  source tree. When you think you have something that you want to offer the
    232  curl community, use GNU diff to generate patches.
    233 
    234  If you have modified a single file, try something like:
    235 
    236      diff -u unmodified-file.c my-changed-one.c > my-fixes.diff
    237 
    238  If you have modified several files, possibly in different directories, you
    239  can use diff recursively:
    240 
    241      diff -ur curl-original-dir curl-modified-sources-dir > my-fixes.diff
    242 
    243  The GNU diff and GNU patch tools exist for virtually all platforms, including
    244  all kinds of Unixes and Windows:
    245 
    246  For unix-like operating systems:
    247 
    248      https://savannah.gnu.org/projects/patch/
    249      https://www.gnu.org/software/diffutils/
    250 
    251  For Windows:
    252 
    253      http://gnuwin32.sourceforge.net/packages/patch.htm
    254      http://gnuwin32.sourceforge.net/packages/diffutils.htm
    255 
    256 3.4 How to get your changes into the main sources
    257 
    258  Submit your patch to the curl-library mailing list.
    259 
    260  Make the patch against as recent sources as possible.
    261 
    262  Make sure your patch adheres to the source indent and coding style of already
    263  existing source code. Failing to do so just adds more work for me.
    264 
    265  Respond to replies on the list about the patch and answer questions and/or
    266  fix nits/flaws. This is very important. I will take lack of replies as a sign
    267  that you're not very anxious to get your patch accepted and I tend to simply
    268  drop such patches from my TODO list.
    269 
    270  If you've followed the above paragraphs and your patch still hasn't been
    271  incorporated after some weeks, consider resubmitting it to the list.
    272 
    273 3.5 Write good commit messages
    274 
    275  A short guide to how to do fine commit messages in the curl project.
    276 
    277       ---- start ----
    278       [area]: [short line describing the main effect]
    279 
    280       [separate the above single line from the rest with an empty line]
    281 
    282       [full description, no wider than 72 columns that describe as much as
    283       possible as to why this change is made, and possibly what things
    284       it fixes and everything else that is related]
    285 
    286       [Bug: link to source of the report or more related discussion]
    287       [Reported-by: John Doe - credit the reporter]
    288       [whatever-else-by: credit all helpers, finders, doers]
    289       ---- stop ----
    290 
    291  Don't forget to use commit --author="" if you commit someone else's work,
    292  and make sure that you have your own user and email setup correctly in git
    293  before you commit
    294 
    295 3.6 About pull requests
    296 
    297  With git (and especially github) it is easy and tempting to send a pull
    298  request to the curl project to have changes merged this way instead of
    299  mailing patches to the curl-library mailing list.
    300 
    301  We used to dislike this but we're trying to change that and accept that this
    302  is a frictionless way for people to contribute to the project. We now welcome
    303  pull requests!
    304 
    305  We will continue to avoid using github's merge tools to make the history
    306  linear and to make sure commits follow our style guidelines.
    307