The term _linking_ in the licence

The term _linking_ in the licence

[David E. Meier]

Hi list,

I am confused about the GPL licence. Both suggested sites for reading
before posting to this list about licencing only mention 'linking' with
other programs.

I face the following siuation:

I have written a program in C# that makes use of tools like ssh, rsync and
some bash shell built-ins. The C# program is the main .exe and does not
link to any of the GPL-programs while building and therefore the C# binary
does not contain any cygwin code. The GPL-exe's are called as system calls
at runtime via the cmd.exe.

Does the C# program need to be redistributed under the GPL as well?

Dave

Re: The term _linking_ in the licence

[Igor Pechtchanski]

On Thu, 16 Jun 2005, David E. Meier wrote:

> I am confused about the GPL licence. Both suggested sites for reading
> before posting to this list about licencing only mention 'linking' with
> other programs.
>
> I face the following siuation:
>
> I have written a program in C# that makes use of tools like ssh, rsync and
> some bash shell built-ins. The C# program is the main .exe and does not
> link to any of the GPL-programs while building and therefore the C# binary
> does not contain any cygwin code. The GPL-exe's are called as system calls
> at runtime via the cmd.exe.
>
> Does the C# program need to be redistributed under the GPL as well?

AIUI -- no.  Linking usually involves the linked parts running in the same
memory space, while fork/exec (used by system()) loads the program in a
separate memory space.  But IANAL, and you can always say YANALATEYHSMBSI.

There's also the GPL FAQ which contains an answer to this exact question,
IIRC.
	Igor
-- 
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RE: The term _linking_ in the licence

[Dave Korn]

----Original Message----
>From: David E. Meier
>Sent: 16 June 2005 16:13

> Hi list,
> 
> I am confused about the GPL licence. Both suggested sites for reading
> before posting to this list about licencing only mention 'linking' with
> other programs.
> 
> I face the following siuation:
> 
> I have written a program in C# that makes use of tools like ssh, rsync and
> some bash shell built-ins. The C# program is the main .exe and does not
> link to any of the GPL-programs while building and therefore the C# binary
> does not contain any cygwin code. 

  Bear in mind there's also such a thing as runtime linking... If you
LoadLibrary ("cygwin1.dll") and GetProcAddress a function and call it, that
counts as linking and your app must be GPL'd.

>The GPL-exe's are called as system calls at runtime via the cmd.exe.
> 
> Does the C# program need to be redistributed under the GPL as well?

  However, as Igor said, as long as the executables and process spaces are
completely separate, you will have no problem.  The GPL spreads out within a
single process space, but it is not conveyed across IPC mechanisms!

  And also, bear in mind that if you're distributing the ssh/rsync/bash
binaries along with your app, you need to provide (or offer to provide) the
sources for them.

    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....

RE: The term _linking_ in the licence

[David E. Meier]

Hi Dave and Igor,

thanks for answering my question. That cleared it up.

Dave

>> I have written a program in C# that makes use of tools like ssh, rsync
>> and
>> some bash shell built-ins. The C# program is the main .exe and does not
>> link to any of the GPL-programs while building and therefore the C#
>> binary does not contain any cygwin code.
>
>   Bear in mind there's also such a thing as runtime linking... If you
> LoadLibrary ("cygwin1.dll") and GetProcAddress a function and call it,
> that counts as linking and your app must be GPL'd.
>
>>The GPL-exe's are called as system calls at runtime via the cmd.exe.
>>
>> Does the C# program need to be redistributed under the GPL as well?
>
>   However, as Igor said, as long as the executables and process spaces are
> completely separate, you will have no problem.  The GPL spreads out within
> a single process space, but it is not conveyed across IPC mechanisms!
>
>   And also, bear in mind that if you're distributing the ssh/rsync/bash
> binaries along with your app, you need to provide (or offer to provide)
> the sources for them.
>
>     cheers,
>       DaveK
> --
> Can't think of a witty .sigline today....
>
>
>