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123 lines
5.5 KiB
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123 lines
5.5 KiB
Plaintext
GPL vs LGPL, in the context of adns
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-----------------------------------
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Several people have asked me to release GNU adns under the GNU Lesser
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General Public Licence (LGPL, formerly the Library GPL) instead of the
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`stronger' GPL. This file is intended to answer most of these
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questions. If you still have questions or comments, please mail me at
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<adns-maint@chiark.greenend.org.uk>.
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Typically there are two or three kinds of situation where people make
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this request: the first is where someone is developing a proprietary
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program and wishes to make use of adns but doesn't wish to make their
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program free software. The second case is where a free software
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project is currently using an MIT-like licence or the LGPL and fear
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`GPL infection'. The third case, which often overlaps with the
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second, is where another free software project currently using a
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GPL-incompatible licence, wishes to use adns.
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1. Proprietary applications of adns
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-----------------------------------
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So, let me get this straight. You're writing a proprietary
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program, by which I mean that you will not be distributing source code
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and not allowing users to modify and share your software; most likely
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you are doing this for your own (personal or corporate) financial
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gain.
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However, you want to take advantage of adns, software which I have
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spent my time and effort on, and which I release as free software so
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that everyone can improve, share and use it.
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Don't you think that is a little hypocritical ? I'm sorry, but I
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don't want you to just take my nice convenient software, without
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giving something back to the free software community or giving the
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same rights to your users as I do to you.
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If you really aren't the nasty kind of person I've described here, for
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example if you have a good reason other than your own selfishness for
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wanting to restrict distribution of your program, then perhaps you
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should contact me to discuss it.
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2. GPL-avoiding projects (MIT licence, et al)
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---------------------------------------------
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Some free software projects prefer to avoid the GPL and other licences
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which force the software always to be free. Instead they use
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something like the MIT X licence, which allows proprietary versions of
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their software, or the in the case of some free libraries, the LGPL,
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which allows proprietary applications. I have to say that I think
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these people are misguided, but that doesn't mean that they don't have
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a perfect right to do that.
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Some of these people think that merely writing to an interface
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provided by GPL'd software will cause their program to become GPL'd
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too, even if they don't distribute the GPL'd software. I don't think
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this is the case. I'm perfectly happy for non-GPL'd but
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GPL-compatible software to refer to adns in its source code. However,
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I think that exectuables (or compiled libraries) which contain or are
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dynamically linked against adns must be GPL'd; likewise executable
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programs (whether compiled or in an interpreted language) which
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require utilities from adns to function properly must be GPL'd.
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So, you can distribute your non-GPL'd program source which needs adns
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to compile (provided it's under a GPL-compatible licence), but people
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who wish to distribute binaries must do so under the terms of the GNU
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GPL. This may make sense for some GPL-avoiding free software
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projects; people can still make proprietary programs from your code,
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provided that they make some provision to replace adns with something
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whose copyright allows proprietary versions.
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However, this doesn't make much sense for the authors of LGPL'd
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libraries. All I can say to them is to ask which is more important:
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that their library be well-constructed and use all the best technology
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available as free software, or whether it is worth degrading quality
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of their library in order to allow proprietary programs to use it !
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To help the case of LGPL'd libraries for which adns is not a vital
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component - for example, a library which provides access to other
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libraries so that programs which use it need only use certain parts,
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I have released adns.h (just the public header file) under the LGPL as
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well as the GPL. See the copyright notice in adns.h for details.
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Note that this will not help you if it adns is essential to the
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functioning of your library, because all programs using your library
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must link against both your library and adns and so must be GPL'd.
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For some information and views from the Free Software Foundation on
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free software licensing, visit:
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Various licenses and comments about them
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at http://www.fsf.org/philosophy/license-list.html
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Why you shouldn't use the Library GPL for your next library
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at http://www.fsf.org/philosophy/why-not-lgpl.html
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3. GPL-incompatible free software licences
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------------------------------------------
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Regrettably, there are a number of free software licences (and
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semi-free licences) in existence which are not compatible with the
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GPL. That is, they impose restrictions which are not present in the
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GPL, and therefore distributing a whole work which contains both such
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a program and a GPL'd program is not possible: either the combination
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would have to be distributed under the GPL (violating the restrictions
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made by the original author), or under the GPL-incompatible licence
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(violating the GPL).
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I may be prepared to make exceptions for such a licence. Please
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contact me at <adns-maint@chiark.greenend.org.uk> with the full text
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of the GPL-incompatible licence. However, I would usually prefer it
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if you could use a GPL-compatible licence for your project instead.
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-- Ian Jackson 17.9.2000
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Local variables:
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mode: text
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End:
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