Use of open source software in commercial applications

Question

It is possible to include open source software in commercial applications and when the license is GPL the distributor is required to "open source" also its proprietary source code. However these two points are not completely clear to me:

• Is the distributor required to "open source" also other assets that are not in source form? For example icons, images, graphics, sound and in general other resource files that are linked in the program but cannot be considered source code.
• Is The distributor allowed to change the license of its derived work when he releases the code? Take this as an example: http://pocketcas.com/?Download. The software is derived from open source software, the source is released but with a new license that forbids commercial use.

Thanks, Luca

Answer 1

1. This is fuzzy.
2. They cannot change the license of the third-party portion as they do not own the copyright to it. They could change their application to a GPL-compatible license with that clause, but it would not apply to the entire codebase.

Answer 2

As a rule of thumb (you should check with a lawyer if you're serious about this), you can create commercial application with GPL but you have to made available the source code of your application under the terms of the GPL. At least this is mandated for any software that links to the GPL original code.

Other licenses (like BSD and MIT) allows you to change the terms of the derivative works.

I suggest to check the Open SOurce Initiative where all Open Source licenses are available

Answer 3

Can you generate, install, and run the application without those binary assets? If not, then it's considered corresponding source code under the GPL. In this context, "source code" refers to the preferred format for modifying something, which might be a text file containing commands in a programming language, or might be a jpeg file. If you have a photoshop .psd file you use to make all your modifications, but export it as a jpeg for the application, the .psd file is the "source code."

In general you cannot change the terms of a license for derivative works. The deal with PocketCAS is the author is bundling the GPL apps together, sort of like how running a program on Windows doesn't make your program licensed under the same terms as Windows. In other words, it's not really a derivative work. He can download straight from upstream, not apply any patches, and compile directly for his platform.

There's also a lot to be said for following the spirit of the GPL by offering his own work free for non-commercial use. That probably gives him a pass on some gray areas because it is a show of good faith that if a court ordered it, he wouldn't lose much by opening all the code. If you intend to be more restrictive than that, you should really consult a lawyer.