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Re (tilly) 1: GPL and LGPL linkage to Perl

by tilly (Archbishop)
on Feb 28, 2002 at 18:22 UTC ( #148324=note: print w/replies, xml ) Need Help??


in reply to GPL and LGPL linkage to Perl

First of all none of us are lawyers, so take anything we say with appropriate amounts of salt. Furthermore note that without case law, there are huge grey areas which might resolve in any way at all.

Since the GPL is entirely a copyright license, the legal question is at what point you have a derivative work under copyright. When you compile something with gcc, it is fairly clear. The output files don't contain copyrighted material from gcc, so it isn't a derivative work (under copyright law). When you use a templating system it is also clear. The output includes copyrighted material from the templates, so you have a derivative work. (There may be no derivation from the implementation of the templating system.) Where it is grey is when you have a program that interoperates with other code. At what point are they separate, and at what point do you have a copyrightable whole? This is unresolved, though historically people said, "If you link, it is a whole, if they merely talk through IPC, it isn't."

Whatever the answer there, there is a parallel non-trivial complication in the case of Perl. Perl is distributed with your choice of the GPL or Artistic license. Should you link Perl with GPLed code, your copy would then have to be GPLed. You can link in LGPLed code and there is no problem. Now suppose that you write a Perl program, and you have a GPLed copy of Perl, and have linked in (and loaded) lots of GPLed stuff. Does your script need to be GPLed? I know of no definitive answer, but at least one opinion saying "No" and another saying "Yes".

If you want more detailed discussion of this question, I would suggest looking up the free software license discussion mailing list. (They might send you to a more appropriate list still. If so, then I don't know which one.)

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Re: Re (tilly) 1: GPL and LGPL linkage to Perl
by mdupont (Scribe) on Feb 28, 2002 at 23:17 UTC
    I quote joe buck from the gcc mailling list :

    http://gcc.gnu.org/ml/gcc/2002-02/msg01823.html

    I wrote to him :

    Also with Perl, you can just link to perl and you have gone around the GPL.

    He said :
    In this case I think you're wrong. Perl is dual-licensed, but if you link Perl to GPL (only) code, the program as a whole can only be distributed under GPL terms.

    So does that mean that all the GPL xs routines are going to have to be reviewed?

    In the other section on the gnu faq that you pointed out it is answered very clearly :

    A concequence is that if you choose to use GPL'd Perl modules or Java classes in your program, you must release the program In a GPL-compatible way, regardless of the license used in the Perl or Java Interpreter that the combined Perl or Java program will run on.

    Why would it allowed to link to a gzip routine, but not to the compiler itself?

    It really comes down to asking permission and getting

    it, as provided in the GPL.

    I wrote to this topic to Richard Stallman.

    Richard Stallman said to me in the question if the

    data exchange over the network is not linking and

    therefore not covered by the GPL

    "We have a different interpretation of the situation. Connecting modules through sockets or pipes does not necessarily mean they are separate programs. In simple cases they are separate, but not when they exchange complex data structures."

    That would support the idea that all these are derived

    works and fall under the GPL.

    I wrote to Linus Torvalds who said :

    Feel free to consider this email (in its

    entirety, not snipped into pieces) as being

    public, so if you think you want to post it, go

    ahead.

    The GPL notion of "linking" is really nothing but

    a specific technical way of trying to define

    "derived work".

    From a legal standpoint, technical issues have

    some validity, but in the end the _only_ thing

    that matters is whether it is derived or not.

    Linking is only one (strong) indicator that it is

    indeed derived. There are others. There are

    >counter-indicators as well, of course, one of

    them being "previous work" (thus my willingness,

    for example, to have binary modules that were

    basically derived from SCO device drivers that

    existed prior to Linux - one of the original

    impetuses for the module interface).

    And intent matters.

    Linus

    So from that standpoint,

    I would say, All of these tools the use the GPL code are derived works and are GPLED.

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