Re: Licenses not in /usr/share/common-licenses

[Russ Allbery <rra@debian.org>]

"Thomas Preud'homme" <robotux@celest.fr> writes:

> Back to the redistribution. In the section 4 (Conveying Verbatim
> Copies), what is discussed is the redistribution of the Program as
> source code form. Every word is part of the same sentence, whose
> structure is: You may convey verbatim copies (…) provided that <item1> ;
> <item2> ; <item3> ; <item4>.

> I agree that the fact section 6 refers to section 4 is very (at least to
> me) ambiguous. I think the sentence must be read this way:

> You may convey, in object code, a covered work which is under the terms
> of sections 4 and 5, provided that …

That reading seems strained to me.

What I think is the intended structure of the GPL v3 goes like this: If
you want to convey X, you have to do A and B.  If you want to do Y, you
have to do everything you'd have to do for X plus C.  If you want to do Z,
you have to do everything you'd have to do for Y plus D.  This means that,
if you want to do Z, you have to do A, B, C, and D.  All the terms are
cumulative; each action listed in the GPL requires doing everything listed
for the previous actions plus some additional things.

In this case, section 4 says:

    You may convey verbatim copies of the Program's source code as you
    receive it, in any medium, provided that you [...] give all recipients
    a copy of this License along with the Program.

and section 6 says:

    You may convey a covered work in object code form under the terms of
    sections 4 and 5, provided that you also [...]

So you have to comply with the terms of section 4 and 5, including the
added provisions, which means that you have to give all recipients a copy
of the license.

> That is, "under the terms of sections 4 and 5" applies to "covered
> work", not "covered work in object code".

But it doesn't say that.  It says "convey a covered work in object code
under the terms of sections 4 and 5."  The corresonding wording in the GPL
v2 was more of a mess; this is much clearer.

> Also, since the license always requires the source to be distributed, it
> doesn't seem very important to have the license in both binary code and
> source code.

But it *doesn't* always require the source to be distributed:

    b) Convey the object code in, or embodied in, a physical product
    (including a physical distribution medium), accompanied by a written
    offer, valid for at least three years and valid for as long as you
    offer spare parts or customer support for that product model, to give
    anyone who possesses the object code either (1) a copy of the
    Corresponding Source for all the software in the product that is
    covered by this License, on a durable physical medium customarily used
    for software interchange, for a price no more than your reasonable
    cost of physically performing this conveying of source, or (2) access
    to copy the Corresponding Source from a network server at no charge.

Also 6c, 6d, and 6e, all of which specify circumstances in which you don't
have to distribute the source.  So without the requirements in section 4,
it's quite possible for someone to end up with a covered work without a
copy of the license.

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