1# Contributing to the curl project 2 3This document is intended to offer guidelines on how to best contribute to the 4curl project. This concerns new features as well as corrections to existing 5flaws or bugs. 6 7## Learning curl 8 9### Join the Community 10 11Skip over to [https://curl.haxx.se/mail/](https://curl.haxx.se/mail/) and join 12the appropriate mailing list(s). Read up on details before you post 13questions. Read this file before you start sending patches! We prefer 14questions sent to and discussions being held on the mailing list(s), not sent 15to individuals. 16 17Before posting to one of the curl mailing lists, please read up on the 18[mailing list etiquette](https://curl.haxx.se/mail/etiquette.html). 19 20We also hang out on IRC in #curl on irc.freenode.net 21 22If you're at all interested in the code side of things, consider clicking 23'watch' on the [curl repo on github](https://github.com/curl/curl) to be 24notified of pull requests and new issues posted there. 25 26### License and copyright 27 28When contributing with code, you agree to put your changes and new code under 29the same license curl and libcurl is already using unless stated and agreed 30otherwise. 31 32If you add a larger piece of code, you can opt to make that file or set of 33files to use a different license as long as they don't enforce any changes to 34the rest of the package and they make sense. Such "separate parts" can not be 35GPL licensed (as we don't want copyleft to affect users of libcurl) but they 36must use "GPL compatible" licenses (as we want to allow users to use libcurl 37properly in GPL licensed environments). 38 39When changing existing source code, you do not alter the copyright of the 40original file(s). The copyright will still be owned by the original creator(s) 41or those who have been assigned copyright by the original author(s). 42 43By submitting a patch to the curl project, you are assumed to have the right 44to the code and to be allowed by your employer or whatever to hand over that 45patch/code to us. We will credit you for your changes as far as possible, to 46give credit but also to keep a trace back to who made what changes. Please 47always provide us with your full real name when contributing! 48 49### What To Read 50 51Source code, the man pages, the [INTERNALS 52document](https://curl.haxx.se/dev/internals.html), 53[TODO](https://curl.haxx.se/docs/todo.html), 54[KNOWN_BUGS](https://curl.haxx.se/docs/knownbugs.html) and the [most recent 55changes](https://curl.haxx.se/dev/sourceactivity.html) in git. Just lurking on 56the [curl-library mailing 57list](https://curl.haxx.se/mail/list.cgi?list=curl-library) will give you a 58lot of insights on what's going on right now. Asking there is a good idea too. 59 60## Write a good patch 61 62### Follow code style 63 64When writing C code, follow the 65[CODE_STYLE](https://curl.haxx.se/dev/code-style.html) already established in 66the project. Consistent style makes code easier to read and mistakes less 67likely to happen. Run `make checksrc` before you submit anything, to make sure 68you follow the basic style. That script doesn't verify everything, but if it 69complains you know you have work to do. 70 71### Non-clobbering All Over 72 73When you write new functionality or fix bugs, it is important that you don't 74fiddle all over the source files and functions. Remember that it is likely 75that other people have done changes in the same source files as you have and 76possibly even in the same functions. If you bring completely new 77functionality, try writing it in a new source file. If you fix bugs, try to 78fix one bug at a time and send them as separate patches. 79 80### Write Separate Changes 81 82It is annoying when you get a huge patch from someone that is said to fix 511 83odd problems, but discussions and opinions don't agree with 510 of them - or 84509 of them were already fixed in a different way. Then the person merging 85this change needs to extract the single interesting patch from somewhere 86within the huge pile of source, and that creates a lot of extra work. 87 88Preferably, each fix that corrects a problem should be in its own patch/commit 89with its own description/commit message stating exactly what they correct so 90that all changes can be selectively applied by the maintainer or other 91interested parties. 92 93Also, separate changes enable bisecting much better for tracking problems 94and regression in the future. 95 96### Patch Against Recent Sources 97 98Please try to get the latest available sources to make your patches against. 99It makes the lives of the developers so much easier. The very best is if you 100get the most up-to-date sources from the git repository, but the latest 101release archive is quite OK as well! 102 103### Documentation 104 105Writing docs is dead boring and one of the big problems with many open source 106projects. But someone's gotta do it! It makes things a lot easier if you 107submit a small description of your fix or your new features with every 108contribution so that it can be swiftly added to the package documentation. 109 110The documentation is always made in man pages (nroff formatted) or plain 111ASCII files. All HTML files on the web site and in the release archives are 112generated from the nroff/ASCII versions. 113 114### Test Cases 115 116Since the introduction of the test suite, we can quickly verify that the main 117features are working as they're supposed to. To maintain this situation and 118improve it, all new features and functions that are added need to be tested 119in the test suite. Every feature that is added should get at least one valid 120test case that verifies that it works as documented. If every submitter also 121posts a few test cases, it won't end up as a heavy burden on a single person! 122 123If you don't have test cases or perhaps you have done something that is very 124hard to write tests for, do explain exactly how you have otherwise tested and 125verified your changes. 126 127## Sharing Your Changes 128 129### How to get your changes into the main sources 130 131Ideally you file a [pull request on 132github](https://github.com/curl/curl/pulls), but you can also send your plain 133patch to [the curl-library mailing 134list](https://curl.haxx.se/mail/list.cgi?list=curl-library). 135 136Either way, your change will be reviewed and discussed there and you will be 137expected to correct flaws pointed out and update accordingly, or the change 138risks stalling and eventually just getting deleted without action. As a 139submitter of a change, you are the owner of that change until it has been merged. 140 141Respond on the list or on github about the change and answer questions and/or 142fix nits/flaws. This is very important. We will take lack of replies as a 143sign that you're not very anxious to get your patch accepted and we tend to 144simply drop such changes. 145 146### About pull requests 147 148With github it is easy to send a [pull 149request](https://github.com/curl/curl/pulls) to the curl project to have 150changes merged. 151 152We strongly prefer pull requests to mailed patches, as it makes it a proper 153git commit that is easy to merge and they are easy to track and not that easy 154to loose in the flood of many emails, like they sometimes do on the mailing 155lists. 156 157Every pull request submitted will automatically be tested in several different 158ways. Every pull request is verified for each of the following: 159 160 - ... it still builds, warning-free, on Linux and macOS, with both 161 clang and gcc 162 - ... it still builds fine on Windows with several MSVC versions 163 - ... it still builds with cmake on Linux, with gcc and clang 164 - ... it follows rudimentary code style rules 165 - ... the test suite still runs 100% fine 166 - ... the release tarball (the "dist") still works 167 - ... it builds fine in-tree as well as out-of-tree 168 - ... code coverage doesn't shrink drastically 169 170If the pull-request fails one of these tests, it will show up as a red X and 171you are expected to fix the problem. If you don't understand when the issue is 172or have other problems to fix the complaint, just ask and other project 173members will likely be able to help out. 174 175When you adjust your pull requests after review, consider squashing the 176commits so that we can review the full updated version more easily. 177 178### Making quality patches 179 180Make the patch against as recent source versions as possible. 181 182If you've followed the tips in this document and your patch still hasn't been 183incorporated or responded to after some weeks, consider resubmitting it to the 184list or better yet: change it to a pull request. 185 186### Write good commit messages 187 188A short guide to how to write commit messages in the curl project. 189 190 ---- start ---- 191 [area]: [short line describing the main effect] 192 -- empty line -- 193 [full description, no wider than 72 columns that describe as much as 194 possible as to why this change is made, and possibly what things 195 it fixes and everything else that is related] 196 -- empty line -- 197 [Closes/Fixes #1234 - if this closes or fixes a github issue] 198 [Bug: URL to source of the report or more related discussion] 199 [Reported-by: John Doe - credit the reporter] 200 [whatever-else-by: credit all helpers, finders, doers] 201 ---- stop ---- 202 203Don't forget to use commit --author="" if you commit someone else's work, and 204make sure that you have your own user and email setup correctly in git before 205you commit 206 207### Write Access to git Repository 208 209If you are a very frequent contributor, you may be given push access to the 210git repository and then you'll be able to push your changes straight into the 211git repo instead of sending changes as pull requests or by mail as patches. 212 213Just ask if this is what you'd want. You will be required to have posted 214several high quality patches first, before you can be granted push access. 215 216### How To Make a Patch with git 217 218You need to first checkout the repository: 219 220 git clone https://github.com/curl/curl.git 221 222You then proceed and edit all the files you like and you commit them to your 223local repository: 224 225 git commit [file] 226 227As usual, group your commits so that you commit all changes at once that 228constitute a logical change. 229 230Once you have done all your commits and you're happy with what you see, you 231can make patches out of your changes that are suitable for mailing: 232 233 git format-patch remotes/origin/master 234 235This creates files in your local directory named NNNN-[name].patch for each 236commit. 237 238Now send those patches off to the curl-library list. You can of course opt to 239do that with the 'git send-email' command. 240 241### How To Make a Patch without git 242 243Keep a copy of the unmodified curl sources. Make your changes in a separate 244source tree. When you think you have something that you want to offer the 245curl community, use GNU diff to generate patches. 246 247If you have modified a single file, try something like: 248 249 diff -u unmodified-file.c my-changed-one.c > my-fixes.diff 250 251If you have modified several files, possibly in different directories, you 252can use diff recursively: 253 254 diff -ur curl-original-dir curl-modified-sources-dir > my-fixes.diff 255 256The GNU diff and GNU patch tools exist for virtually all platforms, including 257all kinds of Unixes and Windows: 258 259For unix-like operating systems: 260 261 - [https://savannah.gnu.org/projects/patch/](https://savannah.gnu.org/projects/patch/) 262 - [https://www.gnu.org/software/diffutils/](https://www.gnu.org/software/diffutils/) 263 264For Windows: 265 266 - [https://gnuwin32.sourceforge.io/packages/patch.htm](https://gnuwin32.sourceforge.io/packages/patch.htm) 267 - [https://gnuwin32.sourceforge.io/packages/diffutils.htm](https://gnuwin32.sourceforge.io/packages/diffutils.htm) 268