Scancopyright is a tool which can be used to scan copyright info of source code,you can use it to identity source code as GPL/other license or propriertary. I wrote it for the open source of our android source code. You can submit issue for improvement or questions.
Scancopyright can be run cross platform(linux/windows...) in theory,but only linux installration is tested.
Scancopyright depend on python(2.6+)/uliweb/plugs/sqlalchemy,you should install them firstly. Example steps in ubuntu: