Revised Cygwin32 licensing terms

Gordon Irlam gordoni@cygnus.com
Wed Jul 9 15:47:00 GMT 1997


> It looks like "cygwin.dll" can no longer be used in GPL'ed
> applications.  The added restrictions against competitors conflict
> with the GPL's prohibition against adding further restrictions.

This is wrong for several reasons:

a) At a technical level, the US copyright act does not impose any
   restrictions on use.  Copyright only restricts reproduction,
   preparation of derivative works, and distribution.  GPL'ed and
   non-GPL'ed applications are both free to make use cygwin.dll.

b) A GPL'ed application and cygwin.dll are, for copyright purposes,
   considered separate works.  The GPL only comes into play if a
   GPL'ed worked is combined with another work to create a derivative
   work.  cygwin.dll is a dynamic library, and it is not combined
   with other works (in a copyright sense) to create a derivative work.
   Other works only perform calls to the cygwin.dll.  So distributing
   a GPL'ed work and cygwin.dll separately, even on the same media, does
   not cause any conflicts with the GPL.

c) The creation of RAM resident images derived from multiple works
   does not constitute the creation a derivative work.  This was argued
   at the recent WIPO diplomatic conference, and fortunately the US
   position, that temporary copies should be considered derivative works,
   was defeated.  (Incidentally, if such laws ever passed, it would
   be very bad for the s/w industry as a whole.  Microsoft could use
   them to control who was allowed to develop applications for the
   Windows platform, and on the web people could use them to prevent
   the cacheing of web pages).

d) In addition, cygwin.dll essentially provides a Unix operating system
   emulation layer, and so it's use by a GPL'ed application is essentially
   no different than the use of any other operating system layer.  The
   fact that an O/S is not under the GPL does not prevent the O/S from
   being used by GPL'ed applications.

e) We were concerned about ensuring Cygwin32 could continue to be used
   by GPL'ed applications.  If you read the license carefully you will
   notice we removed all restrictions on the use of libcygwin.a.  Our
   reason for doing this was because unlike cygwin.dll, libcygwin.a
   is linked into GPL'ed applications, and the result thus constitutes
   a derivative work.  Because of this, and our desire to ensure Cygwin32
   could be used in conjunction with GPL'ed applications, we decided to
   remove all restrictions from the use of libcygwin.a.

                                               Gordon Irlam
                                               Cygnus Solutions
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