Re: cygwin and GPL (again)

[Christopher Faylor <cgf at redhat dot com>]

On Wed, Feb 14, 2001 at 10:11:58PM -0500, Dennis McCunney wrote:
>> -----Original Message-----
>> From: cygwin-owner@sources.redhat.com
>> [mailto:cygwin-owner@sources.redhat.com]On Behalf Of David Case
>> Sent: 2001. February 14. 21:23
>> To: cygwin@cygwin.com
>> Subject: Re: cygwin and GPL (again)
>>
>> On Wed, Feb 14, 2001, Christopher Faylor wrote:
>> >
>> > Btw, if you use Cygwin in an application, the application
>> > automatically becomes free software.  Just so you know.
>>
>> Just so *I* know, isn't the above oversimplified?
>
>Not exactly.
>
>> If I *distribute* an application linked to cygwin to others,
>> I am obliged to follow GPL-like rules for the whole application.\
>> But simply *using* cygwin (e.g. to compile some code that expects
>> a Unix environment) for my own use should not taint the code.
>> Is this not correct?
>
>AFAIK and IANAL:
>Depends.  If your code links to the Cygwin1.dll, which is GPLed, your code
>becomes GPLed too.  If your code uses the MS run-time, it does not become
>GPLed.  And the whole question is moot if you don't distribute your software
>to others, but just build for your own use.
>
>I believe "if you use Cygwin in an application" above, should be read as "if
>your application uses the Cygwin1.dll".  There is nothing I am aware of in
>the GPL that says you can't use GNU tools to build non-GNU software.  There
>_is_ such a restriction on the use of GPLed _code_.  If you are simply using
>the GNU compiler to compile code you have written, linked against non-GPLed
>libraries, I see no issue.
>
>> As a somewhat more realistic example, if I distribute source
>> code under conditions other than the GPL, and suggest to users
>> that they could use the cygwin package to compile my code on
>> their Windows machine, would such a suggestion somehow make the
>> source code free software?
>
>The essense of free software is that the folks who use it _can_ get the
>source code.  The essense of the GPL is that you will provide the source
>code, and that you will _tell_ the people who use your application that you
>will do so.  Most of the questions about the GPL here have taken the form of
>"Do I have to distribute my source _with_ my application, or can I provide
>it seperately?"  My understanding of the GPL is that you _can_ provide it
>seperately, as long as you make clear to the users you _will_ do so, and
>that you do so in a fashion convenient to the users.  Many folks don't
>want/can't use the source, but those that do should be able to get it on
>demand.
>
>> ...thanks for any clarification....dac
>
>I believe the above is accurate.  If not, I _know_ I will hear about it.

I'm still waiting for DJ (our resident GPL expert) to weigh in here, but
I believe that your interpretation is pretty much spot on.  You
accurately interpreted what I was saying and reworded what I said to
make it clearer.  Thanks.

I try to mention the Cygwin and the GPL fairly frequently because people
have professed surprise about it in the past.  Usually in this context,
I also point out that Red Hat does retain the copyright on Cygwin and we
do occasionally sell proprietary-use versions of it to people who are
scared of the GPL.  These licenses are part of what keeps the project
going, paradoxically enough.

Btw, I did oversimplify things slightly with respect to the Cygwin DLL
licensing terms.  I'm not going to go into details here but interested
parties can check out the "Licensing Terms" link at http://cygwin.com/ .

cgf

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