What are the legal considerations when forking a BSD-licensed project?

Question

I'm interested in forking a project released under a two-clause BSD license:

Copyright (c) 2010 {copyright holder} All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

(1) Redistributions of source code must retain the above copyright notice, this list of conditions and the disclaimer at the end. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

(2) Neither the name of {copyright holder} nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

DISCLAIMER

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

I've never forked a project before, but this project is very similar to something that I need/want. However, I'm not sure how far I'll get, so my plan is to pull the latest from their repository and start working. Maybe, eventually, I'll get it to where I want it, and be able to release it. Is this the right approach?

How, exactly, does this impact forking of the project? How do I track who owns what components or sections (what's copyright me, what's copyright the original creators, once I start stomping over their code base)? Can I fork this project? What must I do prior to releasing, and when/if I decide to release the software derived from this BSD-licensed work?

Answer 1

To answer your questions:

Is this the right approach? Maybe, if your changes are generally useful I would attempt to contribute to the project instead of forking.

Can I fork this project? Yes. The BSD license allows you to fork it. You don't need to ask permission to fork.

How to track changes...? Add your name to the copyright notice for the files you changed. And make sure it is in files you add. If you want more details your SCM tool will keep track of who changed what.

What must I do before releasing...? If you are releasing the source the copyright notices in the source is enough if you are releasing binaries make sure the original copyright notice is in your supporting documentation.

Answer 2

The common thing I see to handle this is basically using some kind of version control and when a file is changed by a large amount, adding a copyright header.

For instance, in OpenBSD I believe they follow a convention like this:

--top of file--
[copyright header of recent "major" editor]

[copyright header of previous major editor]

[copyright header of creator]

(where copyright header is BSD license or whatever)

This handles the copyright issue for the most part. Basically anytime a major edit is done on a file, a copyright header will be added. Major is subjective, but usually involves more than trivial refactoring or porting.

Answer 3

Clearly people are misunderstanding what I said so here is a re-phrase: I am not giving you legal advise. If that is what you want please seek legal advise from a lawyer and not from this site. That said, what follows is my understanding of forking a project:

In general, as I understand it, you must leave the comments and not claim that any code they wrote is yours. I would create new files for your code and try not to touch theirs -- unless to extend and bug fix. I would contact the other developers before you fork and see if your contributions can be added to the main code. If not, then fork and re-name but keep notices and attribute credit where credit is due.