Path: utzoo!attcan!uunet!lll-winken!elroy.jpl.nasa.gov!peregrine!ccicpg!felix!dhw68k!thecloud
From: thecloud@dhw68k.cts.com (Ken McLeod)
Newsgroups: comp.sys.mac.programmer
Subject: Re: detecting macsbug
Message-ID: <1990Sep30.124813.4364@dhw68k.cts.com>
Date: 30 Sep 90 12:48:13 GMT
References: <109400@tiger.oxy.edu> <20759@well.sf.ca.us>
Reply-To: thecloud@dhw68k.cts.com (Ken McLeod)
Organization: Wolfskill & Dowling residence; Anaheim, CA (USA)
Lines: 33

In article <20759@well.sf.ca.us> smoke@well.sf.ca.us (Nicholas Jackiw) writes:
>In article <109400@tiger.oxy.edu> sonenbli@oxy.edu (Andrew D. Sonenblick) writes:
>>is there a cool way of detecting whether macsbug is installed?
>
>Can you just check if GetTrapAddress($A9FF)<>GetTrapAddress(UnImplTrapNum)?
>This will, of course, only tell you if -somebody- has installed a debugger,
>not necessarily whether -macsbug- has.  ($A9FF is the _Debug trap.)  Check out

 Checking to see if the _Debugger and/or _DebugStr traps are implemented is
the obvious thing to do... unfortunately, they appear to be implemented all
the time now in current systems, whether a debugger is installed or not.
Another method, also fraught with peril, is to test the low-memory vector
MacJmp ($120) for a valid (positive, even, non-zero address) pointer to
Macsbug's code. This is the method MacEnvy uses, as of 2.1; however, it
hasn't proved to be a 100% infallible test. :(  If MacJmp contains an
*invalid* pointer, you can be reasonably sure that Macsbug is NOT installed.
A third method would be to read the name of the debugger from the boot
blocks, then try to OpenRFPerm() that file in the System Folder and see
whether ResError() returns noErr or resFNotFound. Obviously, this wouldn't
work if someone placed the Macsbug file in their System Folder after boot
time (or removed it after boot time) before your program had a chance to
check for it.

 Maybe there will eventually be a Gestalt selector for this. Or not.

-ken

 
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