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Old 06-30-2005, 09:45 PM   #1
Rotwang
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GPL license questions


I know you're not lawyers but some of you probably know more about GPL than me, so here's my questions. Please don't answer at all unless you're really pretty sure:

Can I make a new open source GPL app that uses chunks of code from other GPL apps?

In other words, is all GPLed code- functions, libraries, etc., fair game for other GPL apps to freely copy and use?

also:

Is it ok to write GPL plug-ins for proprietary apps? Like could I write a GPLed filter plug-in for Photoshop? So, the plug-in would be open source but the app it plugs into isn't. (Let's pretend that Adobe was ok with that- would GPL allow that?)

thanks

Last edited by Rotwang; 06-30-2005 at 09:46 PM.
 
Old 06-30-2005, 10:21 PM   #2
win32sux
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Re: GPL license questions

Quote:
Originally posted by Rotwang
Can I make a new open source GPL app that uses chunks of code from other GPL apps?

In other words, is all GPLed code- functions, libraries, etc., fair game for other GPL apps to freely copy and use?
YES... as long as they comply with the terms of the license...
 
Old 07-01-2005, 01:40 AM   #3
jlliagre
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Quote:
Is it ok to write GPL plug-ins for proprietary apps? Like could I write a GPLed filter plug-in for Photoshop? So, the plug-in would be open source but the app it plugs into isn't. (Let's pretend that Adobe was ok with that- would GPL allow that?)
I'm not a lawyer, but here is my understanding:

Adobe is probably OK with you writing an open source free plugin, but GPL would at least prevent them to bundle or even distribute your plugin without opensourcing and GPL'ing photoshop code itself, which they certainly strongly object ...

GPL forbid to distribute GPL code linked with non GPL code, even open source, this is sometime called the GPL "viral effect". This is what is preventing GPL'd Linux drivers to be incorporated in *BSD or Solaris kernels.
GPL v3 is even going further, as code need to comply with "future" versions of the GPL, whatever they are !

For this kind of plugin development, there are many OSI license that seem more suitable:

BSD, mozilla, apache, MIT, Sun CDDL, IBM's CPL or LGPL ...

That said, it looks like there are many photoshop plugins available on the web that are distributed under the GPL license, but as they are not distributing photoshop, this is perhaps allowed by the license ... better ask your lawyer if you want to do it yourself !
 
Old 07-01-2005, 11:14 AM   #4
Rotwang
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Thanks. So it looks like nothing prevents adobe from distributing the GPLed plugins, as long as they don't bundle them on the photoshop disc that they're charging money for. They would have to seperately make the GPLed plugins available, on the adobe web site, for free (along with the source). And then I think everyone's legally happy.

So like, the adobe web site could say:

Here is Photoshop, download it for $299 click here. photoshop.zip

And here are some GPL plugin filters (which aren't in the $299 zip file), you can download these for free. And here's the source too. gplfilters.zip
 
Old 07-01-2005, 12:22 PM   #5
jlliagre
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I wouldn't bet the GPL really allow the non GPL code owner to distribute GPL code, even unbundled ...

In fact, the opposite already happen, Donald Becker, a famous linux network driver developer, once challenged Sun for distributing code allowing to reuse his GPL'd drivers on Solaris (Driver Porting Kit), this code was pulled out by Sun.

Perhaps Becker's interpretation of the GPL was too restrictive, but Adobe is probably safer in distributing no GPL code at all.

As I wrote before, LGPL and other are likely OK.

Again, I'm not a lawyer, don't trust me or anyone else on a forum for legal issues ...
 
Old 07-01-2005, 12:35 PM   #6
irfanhab
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There;s currently a Slashdot post running on this topic

http://linux.slashdot.org/linux/05/0...&tid=8&tid=106
 
Old 07-01-2005, 12:52 PM   #7
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Quote:
Originally posted by jlliagre
I wouldn't bet the GPL really allow the non GPL code owner to distribute GPL code, even unbundled ...
Er, ok, the GPL does allow the non GPL code owner to distribute GPL code, that I know.

http://www.gnu.org/copyleft/gpl.html

First thing in the terms:
Quote:
1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.
 
Old 07-01-2005, 02:11 PM   #8
jlliagre
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Sure I agree with you, this article say it is allowed, but you have to read the whole thing.

My point here is concerning the case where the GPL code is not standalone, but can only run when linked with the non GPL code, and this is definitely applying to plug-ins.

2.b is telling
Quote:
You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
If there was no problem, then the LGPL wouldn't have been created.
 
Old 07-02-2005, 03:20 AM   #9
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No, I don't get it- so you're saying that a plug-in for a commercial app can't be GPL?

So those photoshop filters that are GPL (not LGPL) are incorrectly GPL and need to change their license?

The commercal app (photoshop) itself, is *not* "derived" from any plug-in, "in whole or part". Photoshop can run without the plugin.
 
Old 07-02-2005, 04:22 AM   #10
jlliagre
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Quote:
No, I don't get it- so you're saying that a plug-in for a commercial app can't be GPL?
I didn't wrote that.
I just think Adobe cannot distribute a GPL'd plug-in.
Quote:
So those photoshop filters that are GPL (not LGPL) are incorrectly GPL and need to change their license?
That would be a good idea, interpretations of the GPL may also forbid such distribution.
Quote:
The commercal app (photoshop) itself, is *not* "derived" from any plug-in, "in whole or part". Photoshop can run without the plugin.
The problem here is the plug-in can't run without Photoshop.

From the LGPL license:

When a program is linked with a library, whether statically or using a shared library, the combination of the two is legally speaking a combined work, a derivative of the original library. The ordinary General Public License therefore permits such linking only if the entire combination fits its criteria of freedom. The Lesser General Public License permits more lax criteria for linking other code with the library.
 
Old 07-02-2005, 06:34 PM   #11
Rotwang
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I appreciate your responses but I completely don't understand you!

1. Yes or no: Can someone write a GPLed (not LGPL) photoshop filter without violating GPL?

2. Why can't adobe distribute a GPLed filter, if they distribute it for free, seperate from adobe photshop- not on the photshop CD, not for a fee, but for free? The GPL doesn't make any exemptions about who can distribute GPL code, it only says that you can't distribute GPL code *along with* a commercial application. If adobe distributes GPL plugins seperately, for free, then how have they violated GPL?
 
Old 07-03-2005, 02:35 AM   #12
jlliagre
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Quote:
I appreciate your responses but I completely don't understand you!
What you and most of the rest of us do not completely understand, it is the GPL and LGPL ...
I suspect all these texts written by lawyers to be ambiguous on purpose ...
Quote:
1. Yes or no: Can someone write a GPLed (not LGPL) photoshop filter without violating GPL?
I think no. he/she'd rather use a non viral license.
Quote:
2. Why can't adobe distribute a GPLed filter, if they distribute it for free, seperate from adobe photshop- not on the photshop CD, not for a fee, but for free? The GPL doesn't make any exemptions about who can distribute GPL code, it only says that you can't distribute GPL code *along with* a commercial application. If adobe distributes GPL plugins seperately, for free, then how have they violated GPL?
They have probably violated the GPL, as the result would be a mixture of GPL and non GPL code, which is illegal as the LGPL excerpt I posted previously is telling.
 
Old 07-05-2005, 08:09 PM   #13
jlliagre
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Quote:
1. Yes or no: Can someone write a GPLed (not LGPL) photoshop filter without violating GPL?
After a deeper reading of the GPL, and specially its last words, the answer is clearly no, you cannot distribute a GPL photoshop plugin without violating this license.

This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License.
 
  


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