Re: Automake: use of modified Perl modules & GPL

[Russ Allbery]

Richard Stallman <address@hidden> writes:

>     "Yes. With rare exception, the Perl distribution is covered by both
>     the Artistic License or the GPL, whichever is more appropriate for
>     your needs and it doesn't sound like you would be in conflict with
>     either of them."

> These are the words that were not clear--they say that exceptions are
> rare, but they don't say how to recognize when the rare exceptions
> occur.

> I was sent a bunch of previous messages, which did not make it very
> clear who was saying what and why.  I thought perhaps those words were
> the statement used on CPAN itself to say what the licenses are.  If that
> is the case, then they ought to be clarified--they should give a
> reliable recipe to tell what the license of any package is.

I'm fairly certain that, unfortunately, what you're looking specifically
for doesn't exist.

The above statement is an informal statement about the licensing status of
the code that ships with the main Perl distribution, as I understand it.
It is, in my opinion, reasonable to assume that anything in the main Perl
distribution that does not have an explicit separate license is licensed
under the general terms of the Perl core distribution (GPL and Artistic
dual license).  Whether it's sufficiently clear for legal purposes, I
don't know.  Since Perl doesn't require copyright assignments, there's an
inherent limit to how *sure* anyone can be about the full status of the
licensing; Perl, like a lot of free software projects and probably most
open source projects (skipping the question of which Perl is), took the
route of making it easier for people to contribute instead of being sure
of the licensing status.

The CPAN archive is a completely separate matter from the Perl core
distribution, and is more comparable to a mirrored ftp server containing a
wide variety of software.  The software on CPAN is all released
independently, and while I believe there are some basic limits on what
licenses are accepted, within that there is a huge variation.  I know of
modules on CPAN that are under the GPL solely, under the Artistic License
solely, under a BSD-style or MIT-style license, and under a few home-grown
licenses.  Probably the majority of packages are distributed "under the
same terms as Perl itself," but there's a lot of variation among the rest.

> The important thing is that it should be stated clearly in CPAN what the
> license terms of each module on CPAN are.

I agree that that would be desirable.  CPAN is fairly loosely structured,
though, and there aren't a lot of pre-requisites that have to be met for
getting a module onto CPAN.  I'm not sure if such a requirement would be
workable within the current way that CPAN is structured.  I think that
authors should definitely be encouraged to make some explicit statement
about licensing, whatever scheme they may choose.

In any event, the specific module in question at the start of this thread
was apparently contributed directly to Perl core, so provided that one can
assume that someone contributing to a package under a specific license is
implicitly licensing their code under that same license unless they say
otherwise, that module is under the same terms as Perl itself.  I don't
know what the GNU Project policy is on whether or not that assumption can
be safely made in a case like this.

-- 
Russ Allbery (address@hidden)             <http://www.eyrie.org/~eagle/>