Using Dovecot code in a non-LGPL package

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Using Dovecot code in a non-LGPL package

Asheesh Laroia
Hi Timo (and all!),

Venaktesh is a friend of mine working on a patch to the venerable Alpine
mail reader so it can read Maildir format mailboxes on disk.

Venkatesh wanted to know if he could use some code from Dovecot's
lib-storage (safely opening/reading Maildirs, including accounting for NFS
and ESTALE) and the UID->message mapping code.

This way, Dovecot and Alpine would agree on how to handle UIDs for a given
Maildir-format mailbox. Plus Alpine could benefit from the thought you've
put into the safety of Maildirs on IMAP (which is *not* trivial!).

But there are some possible licensing issues.

Alpine (formerly known as PINE) is now licensed under the Apache License
2.0. As far as I can tell, if he wants to contribute a patch back to
Alpine upstream, he should use use the Apache License 2.0. But Dovecot is
licensed under LGPL 2.1; if he takes Dovecot code, modifies it, and mixes
it with Alpine, that would not be allowed by the licenses together (as I
understand it).

The Apache License 2.0 is a permissive, non-copyleft license like the MIT
License, but it adds a patent retaliation clause. See
http://www.apache.org/licenses/LICENSE-2.0.html for its text and
http://www.gnu.org/philosophy/license-list.html for a short statement of
its compatibility with GPLv3;
http://en.wikipedia.org/wiki/Apache_License#GPL_compatibility has a little
more.

License-wise, there are two choices, if you're willing Timo: the modified
Dovecot code could be released under GPLv3, which *is* compatible with the
Alpine license - it would just mean Alpine+Maildir would be GPLv3 when put
together. Or you could grant a special permission to Venkatesh to
distribute the modified Dovecot code under the Apache License 2.0.

Timo (and others), what do you think? The past of least resistance is to
say that a derivative work of Dovecot can be made using GPLv3; the most
convenient would be to say that particular portions can be used under the
Apache License 2.0.

-- Asheesh.

--
Why do we have two eyes?  To watch 3-D movies with.
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Re: Using Dovecot code in a non-LGPL package

Timo Sirainen
On Tue, 2009-09-08 at 12:19 -0400, Asheesh Laroia wrote:

> Venaktesh is a friend of mine working on a patch to the venerable Alpine
> mail reader so it can read Maildir format mailboxes on disk.
>
> Venkatesh wanted to know if he could use some code from Dovecot's
> lib-storage (safely opening/reading Maildirs, including accounting for NFS
> and ESTALE) and the UID->message mapping code.
>
> This way, Dovecot and Alpine would agree on how to handle UIDs for a given
> Maildir-format mailbox. Plus Alpine could benefit from the thought you've
> put into the safety of Maildirs on IMAP (which is *not* trivial!).
Maybe I'm biased :) but I think MUAs nowadays should just use IMAP
instead of accessing mails locally directly.

Also I don't especially like Dovecot's maildir code. I guess it works
pretty good nowadays, but it could still be cleaned up somewhat.

> But there are some possible licensing issues.
..
> License-wise, there are two choices, if you're willing Timo: the modified
> Dovecot code could be released under GPLv3, which *is* compatible with the
> Alpine license - it would just mean Alpine+Maildir would be GPLv3 when put
> together. Or you could grant a special permission to Venkatesh to
> distribute the modified Dovecot code under the Apache License 2.0.

Anyway, sure, I don't really care about maildir code. And it looks like
about all of it has been written by me, so there shouldn't be a problem
for me to give it away with another license. So maybe something like:

I hereby allow Dovecot v1.2.4 release's code under
src/lib-storage/index/maildir/ directory to be redistributed under any
of the following open source licenses:

 - LGPL v2.1
 - MIT
 - Apache License 2.0


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