Viral permissiveness

Matthew Flaschen matthew.flaschen at
Tue Jan 20 18:49:53 UTC 2009

Steve Thomas wrote:
> Moreover, I note the following comment [3] by OpenBSD founder, Theo de Raadt:

I'm not going to address this, as it's deliberately inflammatory, and
not really relevant to the "technical" issue of how to craft a license
that does what you want (if it's possible to do so).

> Consider the following scenario:
>   (1) I make my code available under some open source license.
>   (2) After a chain of 1+ verbatim copies and/or derivations, the code
> (or derivative work thereof) ends up in the possession of a certain Mr
> Takesallsorts.
>   (3) Mr Takesallsorts creates a derivative work from the code he obtained.
>   (4) Mr Takesallsorts licenses copies of his derivative work
> exclusively under GPL.
>   After (4), companies can :
>   (5) Create a derivative work of Mr Takesallsorts's code
>   but cannot then :
>   (6) Sell binaries of this derivative work without making the source available.
> Does a license already exist that, for any such chain as in (2), would
> preclude step (4) whilst allowing (5) and (6) in the event that Mr
> Takesallsorts chooses to distribute his derivative work ?

If I understand correctly (please, tell me if not), you /don't/ want
Takesallsorts to be able to license the "work as a whole" (in GPL
jargon) under GPL, unless he /also/ dual-licenses his changes under your
permissive license.

You /do/ want derivative works of Takesallsorts' work a whole to be
allowed.  And you don't want recipients of those derivative works to be
guaranteed the ability to request source.

I don't know any such license, nor am I confident one is possible.  The
tricky parts are:

a. You want to allow GPL derivative works, but only if the changes are
b. You don't want recipients of GPL derivative works to be able to
request source.

> Is it possible for any such license to be GPL-compatible ?

I doubt that.

Matt Flaschen

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