Re: When linking to a C library, do I need to use its license?

Thanks for all the great feedback all!

Because I opt to put all of my CPAN modules under the standard Perl license (and always have), I'm going to try to keep it that way.

If a library is released under the GPL (not the LGPL), does that mean that any software which uses it has to be under the GPL or a GPL-compatible license?

Yes, because the software as it is actually run includes the library.

Because my code is not compiled before it is actually installed, my distribution will not contain any code of the included library. It's only during the make process that the libs are sucked in. This leads me to believe that this is a copyright issue (like anonymonk said in Re: When linking to a C library, do I need to use its license?), as I am directly using API calls into the library, but only after a user links the two.

I think what I'll do here is contact the author, state what I'm doing, and see if I can get a blanket exemption (license and copyright) in writing, so long as I never include any code.

If that fails, I'll give my lawyer a couple hours worth of work, and if it can't be sorted within that time, I'll just GPL the code and remove the Artistic license.

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Re^2: When linking to a C library, do I need to use its license? by haukex (Archbishop) on Aug 10, 2016 at 16:18 UTC
Hi stevieb, Disclaimer: I'm not a GNU/GPL advocate, expert, or lawyer, I've just spent some time researching and thinking about the issue, from both sides - I've released GPLed code, and I've been in the situation of wanting to link open source code into proprietary code often enough. ... my distribution will not contain any code of the included library ... Your argument is one of the common counterarguments to the "any code that touches GPLed code must be GPL as well" stance. If I don't modify the GPLed code, only link to it dynamically, and even distribute the GPLed code, why should that force my code to become GPLed as well? There was - and still is, albeit smaller - a gray area as to what this "linking" thing is. However, I think the GPL has become more clear on this topic, and it sounds to me like your use of the GPLed code falls under the definition of "linking". I'll just GPL the code and remove the Artistic license The way I understand the GNU website is that if you place your code under the Perl license (dual license), that's GPL-compatible. But if you want to play it safe of course you can just remove the Artistic License, since under the Perl license your code is GPLed already anyway. I get the feeling that, unfortunately, many people simply slap the GPL on their code without thinking about whether the LGPL might be more appropriate to their code, and I often think it would help them reach a wider audience. If you do contact the author, perhaps you can get him/her to consider licensing the library under the LGPL instead. Hope this helps, -- Hauke D	[reply]

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Re^2: When linking to a C library, do I need to use its license?
by haukex (Archbishop) on Aug 10, 2016 at 16:18 UTC

Hi stevieb,

Disclaimer: I'm not a GNU/GPL advocate, expert, or lawyer, I've just spent some time researching and thinking about the issue, from both sides - I've released GPLed code, and I've been in the situation of wanting to link open source code into proprietary code often enough.

... my distribution will not contain any code of the included library ...

Your argument is one of the common counterarguments to the "any code that touches GPLed code must be GPL as well" stance. If I don't modify the GPLed code, only link to it dynamically, and even distribute the GPLed code, why should that force my code to become GPLed as well? There was - and still is, albeit smaller - a gray area as to what this "linking" thing is. However, I think the GPL has become more clear on this topic, and it sounds to me like your use of the GPLed code falls under the definition of "linking".

I'll just GPL the code and remove the Artistic license

The way I understand the GNU website is that if you place your code under the Perl license (dual license), that's GPL-compatible. But if you want to play it safe of course you can just remove the Artistic License, since under the Perl license your code is GPLed already anyway.

I get the feeling that, unfortunately, many people simply slap the GPL on their code without thinking about whether the LGPL might be more appropriate to their code, and I often think it would help them reach a wider audience. If you do contact the author, perhaps you can get him/her to consider licensing the library under the LGPL instead.

Hope this helps,
-- Hauke D

[reply]