Hi Max,
You're wrong there, except for the fact that linking to closed source
SYSTEM LIBRARIES and distributing the result is allowed according to
GPLv2 and GPLv3. Without this clause in the GPL it would never be
possible to distribute lots of GPL application to the Windows platform,
because the usage of Windows or OSX libraries which are obviously are
closed source.
I am not trying to get in a discussion, but for system libraries there
is an exception in place, as it should be.
More information in GPL license regarding system libraries here:
http://www.gnu.org/licenses/gpl-faq.html#GPLIncompatibleLibs
In *Section 1* it clearly states:
The "System Libraries" of an executable work include anything, other
than the work as a whole, that (a) is included in the normal form of
packaging a Major Component, but which is not part of that Major
Component, and (b) serves only to enable use of the work with that Major
Component, or to implement a Standard Interface for which an
implementation is available to the public in source code form. A "Major
Component", in this context, means a major essential component (kernel,
window system, and so on) of the specific operating system (if any) on
which the executable work runs, or a compiler used to produce the work,
or an object code interpreter used to run it.
The "Corresponding Source" for a work in object code form means all the
source code needed to generate, install, and (for an executable work)
run the object code and to modify the work, including scripts to control
those activities. However, it does not include the work's System
Libraries, or general-purpose tools or generally available free programs
which are used unmodified in performing those activities but which are
not part of the work. For example, Corresponding Source includes
interface definition files associated with source files for the work,
and the source code for shared libraries and dynamically linked
subprograms that the work is specifically designed to require, such as
by intimate data communication or control flow between those subprograms
and other parts of the work.
*And even more clear in the FAQ*
Both versions of the GPL have an exception to their copyleft, commonly
called the system library exception. If the GPL-incompatible libraries
you want to use meet the criteria for a system library, then you don't
have to do anything special to use them; the requirement to distribute
source code for the whole program does not include those libraries, even
if you distribute a linked executable containing them.
The criteria for what counts as a "system library" vary between
different versions of the GPL. GPLv3 explicitly defines "System
Libraries" in section 1, to exclude it from the definition of
"Corresponding Source." GPLv2 says the following, near the end of section 3:
However, as a special exception, the source code distributed need not
include anything that is normally distributed (in either source or
binary form) with the major components (compiler, kernel, and so on) of
the operating system on which the executable runs, unless that component
itself accompanies the executable
MPD is not exception in this, in theory anyone is able to compile it to
a closed source *system library* (like file I/O of windows, sound for
NMT etc) and distribute it without breaking the GPL license.
It's not interpretation, just a matter of reading the GPL license. It is
there.
Best regards,
Ger
Max Kellermann wrote:
On 2009/06/30 19:59, Ger Teunis <g.teu...@gmail.com> wrote:
Hi Max,
First of all I have to congratulate you with the excellent MPD application.
I created the repository and installer for the Network Media Tank and
was still publishing MPD for Network Media Tank users.
Today I was contacted by an user of the forum mentioning that I was
publishing a application which as breaking the GPL license.
After some discussion and GPL study it seems it is not breaking any
license it is just linked to a closed source system library.
I know this is not preferable in open source word, but almost all GPL
Windows programs are linked in a similar matter.
I've hear that you really do not like the idea, in contrary to your MPD
is stating.
Because it is not really breaking the GPL license and users really like
the product. Would you allow me to enable the download again so the
users can enjoy using your program again. I would really like the users
to install the product again.
The previous developer got scared and is planning to bypass the system
library all together, but it will take a while. It would be sad if your
users could not use the MPD application until he is finished.
So in short: we are not closing the source, respecting the GPL license
but only are linking (legally) to a system library.
Hope you also would like the users to use MPD on NMT again.
I've disabled the download for now, just to respect your opinion.
Hi Ger,
you do not have to ask for any permission, because I cannot give you
any. There are nearly 100 copyright holders of the MPD code base, and
even if I allowed you to do something with my part of the code, there
would be 99 other people left who can sue you.
Copyright law allows you to download the source code, to compile and
use it, you are even allowed to link MPD with proprietary libraries!
Copyright law isn't about that, it is all about distributing copies.
The terms of the GPL strike when you distribute MPD, either as source
code or as binary.
You MUST NOT distribute MPD linked with proprietary code. The GPL
does not allow that.
Linking MPD with a non-free library obviously creates a "derivative
work" of both. GPL paragraph 6 states: "You may not impose any
further restrictions on the recipients' exercise of the rights granted
herein." Problem is: your derived work has added restrictions,
because the non-free part limits the rights granted by the GPL.
You may have a different interpretation of the GPL or copyright law,
but keep in mind: the GPL has been proven in court in many countries
in similar cases, and any of the MPD contributors may sue you for
violating it.
Let's concentrate on promoting free code and open hardware, instead of
doing this discussion over and over.
Max
------------------------------------------------------------------------------
_______________________________________________
Musicpd-dev-team mailing list
Musicpd-dev-team@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/musicpd-dev-team
