[gentoo-embedded] Licence compliance - capturing all source files used to make a build?

[Ed W]

Hi, how do others handle open source licence compliance when building 
some base system using gentoo?

In particular I guess simply capturing the ebuilds is not sufficient and 
it's necessary to capture and distribute all the source and patch files 
used to create a build.  The emerge tool doesn't obviously give a way to 
capture this stuff.  I looked in the eclasses, particularly the epatch 
file and I'm not clear that I can easily hook into that.

At the moment I'm using a bashrc file to grab everything from the build 
directory.  This seems reasonably robust for source files.  However, for 
patches I have considered creating a fake patch utility which would 
record all the files it operates on.  Any other suggestions?  Perhaps 
catalyst already has done something like that - not familiar with it though?

Whilst the above is largely targeting GPL type licences, are there other 
things I should consider for other licences? Other things I need to 
ensure I distribute for GPL? Any pointers to (simple) documentation on 
how one can be a compliant open source citizen..?

Thanks

Ed W