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Date: Fri, 20 Jun 2003 12:44:31 -0400
From: Christopher Faylor <cgf AT redhat DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: cygwin license with windows apps?
Message-ID: <20030620164431.GA2447@redhat.com>
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On Fri, Jun 20, 2003 at 12:18:41PM -0400, Cary Lewis wrote:
>Some more questions:
>
>Why is it that linking to the cygwin.dll makes a program covered by GPL?

Because that's how the GPL works.  From the GNU GPL FAQ:

"Linking FOO statically or dynamically with other modules is making a
combined work based on FOO.  Thus, the terms and conditions of the GNU
General Public License cover the whole combination."

The cygwin DLL == FOO.

>On Linux systems, does linking to the open source 'C' libraries, etc. cause
>a program to be covered by the GPL?

No, it doesn't because the C library on linux is not covered by the GPL.
It is covered by the LGPL.

>For what it's worth, I would like to very much like to continue using
>Cygwin, I think that there is a lot of power in it. I simply want to do the
>right thing in terms of the licensing and additionally respect the
>constraints that I have in terms of other stake holders and whether I can
>publish my source.

I don't know what this means but you have two alternatives.  They've already
been discussed.  There is no need to beat them to death.  The fact that
you like cygwin is nice, just adhere to the rules and you should be fine.

>I have trouble believing that there are systems out there that use cygwin in
>a commercial fashion that have not purchased the breakout license.

Did you mean to put the "not" there?  The fact that there may be a company
illegally selling programs using cygwin without including source code is
sort of irrelevant if you want to be above board in your use of the cygwin
DLL.  If there is such a company out there, I'm sure Red Hat's legal staff
would love to know about them.

>Thanks for all of your advice and for your patience.

If you are looking for advice on how to distribute your program without
including source code, I think you've gotten all of the advice you are
going to get.  You have two options:

1) Use -mno-cygwin and do not include any cygwin libraries on the link line.
   (Verify with cygcheck that cygwin1.dll is not being included in your
   program)

2) Purchase a license from Red Hat allowing you to distribute your program
   without distributing the source.

Those are your options.
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