On Fri, 9 Oct 1998, Geoffrey L. Brimhall wrote: > > The big problem is that KDE includes GPLed code without asking and > > links it against qt. That is a not legal. I wonder what RMS would do > > if they provide an kemacs. :-) > > I guess this is the part which I'm needing a bit more understanding > with (because I've not been the best at interpreting the legalese of > the gpl). > > My understanding is that you *don't* have to ask the original author > of gpl code for permission to use it or modify it, so long as the > modifications are themselves fully published under the GPL.
this is mostly correct. the only nit to pick here is that you don't have to publish if you don't want to...but if you do publish, then it MUST be under the terms of the GPL. > Based on the above, if you did publish the modifications in the GPL, > but the modifications required linking to a proprietary library, then > this would be a violation unless the original authors were contacted > and OK'd the publication. Correct ? no, the modifications to the source are fine. the GPL does not in any way restrict the kinds of modifications you can make to GPL-ed source code. You have the source, you can do what you want with it. This is one of the freedoms guarranteed to you by the GPL. the problem arises when you compile and link with a non-free library (e.g. Qt or Xforms). doing that creates a combined work (the binary) which is a derivative of both GPL-ed code and non-free code. if you don't wish to distribute this derived work then there is still no problem. If you do, however, wish to distribute the work then you have a complication. The GPL says that if you can not distribute the entire source for all parts of the derived or combined work under the terms of the GPL then you may not distribute it at all. this is the key point. the act of compiling and linking creates a derived work. the derived work may ONLY be distributed if ALL parts of it can be distributed under the terms of the GPL. of course, this doesn't affect the author's right to distribute - they are the copyright holder and aren't limited by their own license - but it does affect what third parties can do. unless additional permission is granted (e.g. "this program is licensed under the GPL with the additional permission that you may link with libfoo"), a binary may not be distributed by anyone but the author. (as a side note, this is complicated in the case of KDE because KDE has re-used some existing GPL code and linked it to Qt. While they have every right under the GPL to modify the source to do that, the GPL prohibits them from legally distributing binaries until they receive permission from the original author(s)) BTW, this is not a bug in the GPL. it is a feature. it was deliberately designed this way in order to prevent Free Software from being stolen and made proprietary. this is one of the things which makes the GPL so valuable as a Free Software license. it guarantees that once free, always free. It can complicate things sometimes for free/non-free hybrids but it is a Good Thing. it is there to protect the interests of Free Software programmers and users. > I find this interesting because there is quite a bit of various > efforts to port GPL'd code and programs to the MS Windows > environments. Legally, this would imply stepping very carefully > because who knows what proprietary libraries might be linked to get > the port to work. Am I correct in this statement ? i doubt if this would affect windows ports at all. for one thing, there is a special exemption in the GPL which allows linking with libraries which come with the operating system. this was there so that GNU programs could be linked with Motif (which came with Solaris)...it applies equally to the libraries (DLLs) which come with windows. in any case, why would anyone *want* to port stuff to a dying, moribund toy operating system? sounds a bit far-fetched to me. :-) craig -- craig sanders
