[Qemu-devel] JSON license is non-free - how are we affected?

[Qemu-devel] JSON license is non-free - how are we affected?

[Eric Blake]

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The QMP monitor uses JSON as its underlying base.  However, when you
read the license of JSON [1], you will note that it has a pretty severe
limitation ("The Software shall be used for Good, not Evil").  In fact,
this limitation is severe enough that the FSF has declared that the JSON
license is non-free (even if the limitation is unenforceable), and
therefore cannot be combined with GPL code:

[1] http://www.json.org/license.html
[2] https://www.gnu.org/licenses/license-list.html#JSON

How do we reconcile this?  Obviously, qemu must remain GPL, because it
has files that are licensed GPLv2, and the overall license is the
restrictive union of all source licenses.  But that implies that we
cannot include any source code or libraries provided by json.org, if
such code is under the incompatible JSON license.

Is the JSON license only applicable to code downloaded from json.org,
but not to the actual JSON language specification?  If so, does that
mean that a clean-room implementation of JSON (the language
specification) can be written with different license than JSON (the
license), and that such alternate code could then be linked into qemu?
Is this already the case?  It would be a shame to have to reinvent QMP
to use a different language specification if the entire JSON language is
deemed poisoned.

Thoughts?  Do we need to seek legal guidance from FSF, Red Hat, or any
other organization on how to proceed?

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] JSON license is non-free - how are we affected?

[Paolo Bonzini]

Il 22/05/2012 17:51, Eric Blake ha scritto:
> Is the JSON license only applicable to code downloaded from json.org,
> but not to the actual JSON language specification?

Yes, of course.  I think not even Oracle disagrees.

> If so, does that
> mean that a clean-room implementation of JSON (the language
> specification) can be written with different license than JSON (the
> license), and that such alternate code could then be linked into qemu?

That is what we did, in fact.

Paolo

Re: [Qemu-devel] JSON license is non-free - how are we affected?

[Eric Blake]

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On 05/22/2012 09:58 AM, Paolo Bonzini wrote:
> Il 22/05/2012 17:51, Eric Blake ha scritto:
>> Is the JSON license only applicable to code downloaded from json.org,
>> but not to the actual JSON language specification?
> 
> Yes, of course.  I think not even Oracle disagrees.
> 
>> If so, does that
>> mean that a clean-room implementation of JSON (the language
>> specification) can be written with different license than JSON (the
>> license), and that such alternate code could then be linked into qemu?
> 
> That is what we did, in fact.

Indeed, it looks like libvirt's choice to use YAJL (under the ISC
license) rather than code from json.org was made for the same reason.

Sorry for any false alarm scares, then :)

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] JSON license is non-free - how are we affected?

[Anthony Liguori]

On 05/22/2012 10:51 AM, Eric Blake wrote:
> The QMP monitor uses JSON as its underlying base.  However, when you
> read the license of JSON [1], you will note that it has a pretty severe
> limitation ("The Software shall be used for Good, not Evil").  In fact,
> this limitation is severe enough that the FSF has declared that the JSON
> license is non-free (even if the limitation is unenforceable), and
> therefore cannot be combined with GPL code:
>
> [1] http://www.json.org/license.html
> [2] https://www.gnu.org/licenses/license-list.html#JSON
>
> How do we reconcile this?  Obviously, qemu must remain GPL, because it
> has files that are licensed GPLv2, and the overall license is the
> restrictive union of all source licenses.  But that implies that we
> cannot include any source code or libraries provided by json.org, if
> such code is under the incompatible JSON license.
>
> Is the JSON license only applicable to code downloaded from json.org,
> but not to the actual JSON language specification?  If so, does that
> mean that a clean-room implementation of JSON (the language
> specification) can be written with different license than JSON (the
> license), and that such alternate code could then be linked into qemu?
> Is this already the case?  It would be a shame to have to reinvent QMP
> to use a different language specification if the entire JSON language is
> deemed poisoned.

Hi Eric,

When evaluating JSON implementations, I looked at the json.org license and 
immediately sought other options.  I was very aware that that clause would not 
be GPL compatible.  Ultimately, we wrote our own from scratch based on the JSON 
RFC[1].

There is no dubious claims in the RFC and I don't think there could be as it's 
simply a strict subset of the EMCA specification.

At no point have I ever looked at the json.org source but given the fact that 
the license is moronic, I expect the implementation to be equally dumb and 
wouldn't even consider it even if the license was changed at this point.

[1] http://www.ietf.org/rfc/rfc4627

Regards,

Anthony Liguori

>
> Thoughts?  Do we need to seek legal guidance from FSF, Red Hat, or any
> other organization on how to proceed?
>