Re: libgit2 - a true git library

From: Pierre Habouzit <madcoder@debian.org>
Date: Nov 1, 2008, 01:08 UTC
Message-ID: <20081101010824.GE29036@artemis.corp>
In-Reply-To: <alpine.DEB.1.10.0810311802360.5851@asgard.lang.hm>

On Sat, Nov 01, 2008 at 01:04:50AM +0000, david@lang.hm wrote:

Show 35 quoted lines

> On Fri, 31 Oct 2008, Shawn O. Pearce wrote:
> 
> >david@lang.hm wrote:
> >>On Fri, 31 Oct 2008, Shawn O. Pearce wrote:
> >>>Junio C Hamano <gitster@pobox.com> wrote:
> >>>>
> >>>>I.e. use the supplied custom function to do proprietary magic, such 
> >>>>as
> >>>>reading the object lazily from elsewhere over the network.  And we 
> >>>>will
> >>>>never get that magic bit back.
> >>>
> >>>Maybe I just think too highly of the other guy, but I'd hope that
> >>>anyone patching libgit2 like above would try to avoid it, because
> >>>they'd face merge issues in the future.
> >>
> >>the issue that I see is that libgit2 will be (on most systems) a shared
> >>library.
> >>
> >>what's to stop someone from taking the libgit2 code, adding the magic
> >>proprietary piece, and selling a new libgit2 library binary 'just 
> >>replace
> >>your existing shared library with this new one and all your git related
> >>programs gain this feature'
> >
> >True.  The only thing that prevents that is the normal GPL. The
> >LGPL and GPL+"gcc exception" allow this sort of mean behavior.
> >I doubt there's enough of a market for that; replacing a library
> >is something of a pain and if the feature really is interesting or
> >useful someone will write a clean-room re-implementation and submit
> >patches to do the same thing.
> 
> how would the LGPL of GPL+gcc extention allow this? if they modify the 
> code in the library and then distribute the modified library wouldn't 
> they be required to distribute the changes to that library?

See junio's example. It's rather easy to add hooks into the library to implement a feature outside of it. It's even possible to do it while preserving the ABI fully IMHO (by being a strict superset of it).

The patch would be so trivial, that I see no reason why they wouldn't provide it. Though the real implementation of the feature that would be delegated through it would be in their closed source stuff.

-- 
·O·  Pierre Habouzit
··O                                                madcoder@debian.org
OOO                                                http://www.madism.org