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Message-ID: <437AE5F0.5050509@latnet.lv>
Date: Wed, 16 Nov 2005 09:55:28 +0200
From: Andris Pavenis <pavenis AT latnet DOT lv>
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To: "Schumacher, Gordon" <gordon_schumacher AT maxtor DOT com>
Cc: "DJGPP List (E-mail)" <djgpp AT delorie DOT com>
Subject: Re: Executable corruption with UPX v1.24 and v1.25
References: <71078E41DDE3E541B024832F34BC3D0DA30816 AT cowexc03 DOT corp DOT mxtr DOT net>
In-Reply-To: <71078E41DDE3E541B024832F34BC3D0DA30816@cowexc03.corp.mxtr.net>
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Reply-To: djgpp AT delorie DOT com

Schumacher, Gordon wrote:
> Just a heads-up to those out there using UPX to compress their
> executables...
>
> With the v1.25 release of UPX, if I build a particular executable (linked
> with -s to strip debug symbols), and then compress and decompress
> the generated executable, the finished product is 4KB smaller than the
> original compiled program - and crashes in a way that the original does
> not.
>
> If I use version 1.93 beta of UPX, the file compares properly after
> compression and decompression.
>
> I've e-mailed the authors of UPX, and Markus Oberhumer has replied that
> he recalls that v1.93 adds a workaround for a DJGPP linker bug.  I don't
> have any more information than that - but I thought I'd give everyone out
> there a warning so you're not tearing at your hair if your executable is
> crashing inexplicably (especially if it's only the "release" build!)
>   
Known problem. Long time ago I used UPX (perhaps version 1.23) to 
compress release
binaries of GCC which I uploaded for DJGPP distribution. No one 
complained, but after some time I found that unpacked gcc.exe crashes. A 
safeguards were added beginning with UPX-1.24 to prevent compression of 
binaries generated by incompatible binutils versions
(or GCC versions). So it seems strange that You succeeded to compress 
executables with
UPX-1.24 and 1.25 at all.

Andris