UPX is an exe file compressor. It works by injecting
our decompressor stub code (which is under the GPL) into
every compressed executable.
As this injection is in fact some special form of linking,
any compressed program will automaticlly fall under
the GNU GPL (as it will be linked against our GPL code).
To accomodate for the needs of commercial users we
grant some special excecptions *beyond* the GPL.
But the need for requiring the use of an unmodified UPX version
for any proprietary programs is quite obvious - it gives
*the authors* some legal background against all those unfortunate
people who misuse modified UPX versions for virii, trojans, etc.
(yes, this has happened quite a few times...).
Please re-read the LICENSE carefully. Also note that even if
we removed our exceptional grants (thereby making UPX a pure GPL
package) the term below would still apply - even worse, you simply
could not use UPX at all for non-GPL compatible executables
(because of the implicit linking of GPL code).
/author of UPX and UCL
> The copyright file is very incomplete; it claims upx-ucl is under the
> GPL whereas the LICENSE file adds lots of additional conditions,
> e.g. from LICENSE:
> | - You can use a modified UPX version or modified UPX stub only for
> | programs that are compatible with the GNU General Public License.
> This fails the discrimination clause of the DFSG.
> If you disagree with this analysis, feel free to bring it up on
---- Markus F.X.J. Oberhumer @ http://oberhumer.tsx.org ----
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ceterum censeo Carthaginem esse delendam