# Contribution Guidelines

[This text was composed based on 1.2. License section of curl/libcurl project.]

When contributing with code, you agree to put your changes and new code under the same license nghttp2 is already using unless stated and agreed otherwise.

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 nghttp2 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!

## Coding style

We use clang-format to format source code consistently. The clang-format configuration file .clang-format is located at the root directory. Since clang-format produces slightly different results between versions, we currently use clang-format-18.

To detect any violation to the coding style, we recommend to setup git pre-commit hook to check coding style of the changes you introduced. The pre-commit file is located at the root directory. Copy it under .git/hooks and make sure that it is executable. The pre-commit script uses clang-format-diff.py to detect any style errors. If it is not in your PATH or it exists under different name (e.g., clang-format-diff-18 in debian), either add it to PATH variable or add git option `clangformatdiff.binary` to point to the script.

For emacs users, integrating clang-format to emacs is very easy. clang-format.el should come with clang distribution. If it is not found, download it from here. And add these lines to your .emacs file:

    ;; From
    ;; https://code.google.com/p/chromium/wiki/Emacs#Use_Google's_C++_style!
    (load "/<path/to>/clang-format.el")
    (add-hook 'c-mode-common-hook
         (function (lambda () (local-set-key (kbd "TAB")
                                             'clang-format-region))))

You can find other editor integration in http://clang.llvm.org/docs/ClangFormat.html.