Can I add a license to a forked repository? Can I license only my added code?

Question

I would like to fork an existing repository which has no existing license. I would then like to add the GNU GPLv3 license to any code that I write, but it seems as though I cannot apply this license to the portions of the code I did not write.

Does GitHub support licensing only certain portions of a repository? Can I just license the entire thing, since the original repository still exists?

Answer 1

If a repository has no license, then the default copyright permissions apply. The default copyright permissions state that only the original author has the right to copy, modify or build upon the code.

The Github ToS allow you to create a fork of any repository, but that is where your rights stop unless the repository has a license.