LGPL relicense port of rsync

Martin Pool mbp at sourcefrog.net
Sun Jan 24 17:53:42 UTC 2016

> >
> > > I guess I could write an initial protocol specification - but it would
> > > not be complete and I wouldn't be able to relicense my library to
> > > LGPL anyway.
> > >
> > > So I guess I have convinced myself that it is not worth the effort
> > > trying. Time is probably better spent coding ;) And that's OK too, it
> is not
> > > that big of a deal anyway.
> >
> > Or think about following. You insist that your Java library is
> > derivative work from the C program. OK. However, I believe a
> > "translation into other languages" doesn't mean you make changes into
> > the workflow by code restructuring, introducing another data
> > structures, classes and so on. More such changes you made, less it just
> > a "translation" and more an inspiration. Often I read in code not
> > "based on" but "inspired by".
> >
> > Anyway, you have written every line in Java. This means you're a
> > copyright holder on this. Thus you're allowed to license your work as
> > you wish. In case you still insist it is a derivative work, you're
> > required to allow the usage of your code under GPL. But! As a copyright
> > holder you're allowed to give an arbitrary license additionally and
> > even on a per case basis.
> >
> > This was my opinion. Additional references to approve or disapprove are
> > welcome :)
> You might be right but I am a bit hesitant.
> http://programmers.stackexchange.com/questions/58338/when-porting-code-must-i-follow-the-original-license
> http://programmers.stackexchange.com/questions/90232/original-author-rights-in-a-licensed-software-project?rq=1
> http://programmers.stackexchange.com/questions/86754/is-it-possible-to-rewrite-every-line-of-an-open-source-project-in-a-slightly-dif

These are talking about different situations:

 - 'porting' in the sense of making code run on a different platform while
still having some code in common
 - line-by-line rewrite or translation
 - writing a new program using the rsync source as documentation of the
protocol, as you are doing

In my (not a lawyer) opinion, the last of them does not create a copyright
derivative, and (separately) I don't object to you doing that on GPL'd work
that I wrote. I would consider the first two to be a violation.

I think you have a couple of cheap options to get some clarity:

 - mail the other key authors listed above explaining what you're doing and
ask if they object
 - mail the FSF or SFLC as custodians of the L/GPL

> I think that the best thing would be if rsync would be split into a
> library part (LGPL) and application part (GPL). This could make the
> rsync protocol even more used.
> But again, it could be quite some substantial work, both coding (?)
> but also getting permissions from previous contributors to relicense
> the library part.
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