Self-modifying code

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#4309

From: JOHN RUSSELL
Date: Sat, 07 Jul 1990 19:43

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Does the shareware program PowerPacker violate the rules governing 
self-modifying code?  I would expect that its unpacking routine only 
modifies that data cache.  However I don't know if it overwrites the 
unpacking routine with any other code.

The reason I'm curious (other than a desire to avoid un-PowerPacking 
multi megs of executables if I upgrade my processor) is that PowerPacker
is perfectly content to crunch devices, libraries, handlers and fonts.  
Now I would have thought that either LoadSegging such a file would not 
result in the entry point getting called, or maybe the unpacking routine
would have displaced some magic cookies that exec looks for inside 
libraries, fonts, etc.
 
However I've got my arp.library crunched and the requester still pops 
up, likewise I can setfont to a crunched font or send stuff to SPEAK: 
and PRT: after crunching them.
 
So, is this program "processor-friendly"? 

John
---
 * Via ProDoor 3.1R

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!torsqnt!tmsoft!masnet!canremote!john.russell
From: john.russell@canremote.uucp (JOHN RUSSELL)
Newsgroups: comp.sys.amiga.tech
Subject: Self-modifying code
Message-ID: <b27040e1474d26965764@canremote.uucp>
Date: 7 Jul 90 19:43:00 GMT
Organization: Canada Remote Systems Limited, Mississauga, ON, Canada
Lines: 22