As a follow up from GPL V3 with OpenSSL Exception, I'm curious about linking an LGPLv3 project with a GPLv3 project that has a special exception for OpenSSL. In the answer to the aforementioned question, it was stated:

Note, however, that you can only add exceptions to work for which you have copyright control. If you want to include a third-party GPL-licensed library in your project, you cannot make that library adopt the exceptions present in your project.

This makes sense, obviously I can't and shouldn't modify the License for another person's copyright. That being said, I'm curious if I could link a LGPLv3 license with a GPLv3 license that is modified with exceptions? I suppose a simple way to answer this would be to check for compatibility between OpenSSL and LGPLv3. Thus far I've found nothing, so I've posted here. Will update with any new information.

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    Excellent question. From the perspective of "what grounds would there be to sue me?" it looks like there's probably none. With a GPL library, the author would say, "Hey, if you want to allow linking to OpenSSL, that's your business for your own code, but I never gave permission do that for my GPL library." However, in the case of an LGPL library, that's exactly a permission the author gave. To be sure, though, I'd ask the FSF Licensing Team (licensing@fsf.org). (On a personal note, I like to drop a few bucks in their donation jar whenever I do.) – apsillers Jan 4 '16 at 13:58
  • @apsillers Thanks for the suggestion(s). :) – user3570 Jan 4 '16 at 14:04
  • @TechnikEmpire if you get an answer, please share it here. – vonbrand Jan 4 '16 at 22:04
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    @vonbrand I've emailed them asking. I'm not sure if this is an issue at all, being that its LGPL and I'm just linking against it, not merging sources in. I'll post any other information I get. – user3570 Jan 4 '16 at 22:17
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    @vonbrand I meant to communicate that I think they'd lose their suit if they tried to bring the same complaint for use of their LGPL library as the (probably successful) quoted complaint I suggested for a GPL library. I probably could have made that clearer (and maybe there's a formulation of a complaint that would be valid for an LGPL library that I haven't thought of.) – apsillers Jan 23 '16 at 12:11

I realized after posting this question that, due to how permissive the LGPLv3 is, this was probably a non-issue. However, I still asked the FSF for official comment, and I received the following response:

Once you've added the exception, you cannot link to other GPLv3 software which do not carry such an exception. If this wasn't the case it would be trivial to circumvent the terms of the GPL for providing the complete corresponding source code for a work by just writing a trivial piece of bridge/wrapper/shim code, add an exception to that, and then link to anything you wanted through it.

However, LGPLv3 licensed code already has a broad exception to its terms and shouldn't be an issue as long as you abide by the terms of the license.

I hope this is of help.

P.S. I don't know if it's relevant in your case, but the FSF recommends using GNUTLS instead of OpenSSL in software you write.


Donald R. Robertson, III,
J.D. Copyright & Licensing Associate Free Software Foundation
51 Franklin Street, Fifth Floor
Boston, MA 02110, USA

So there you have it, there's no concern with GPLv3 exceptions conflicting with the LGPLv3.

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