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From: arneme@nic.uit.no (Arne Munch-Ellingsen)
Newsgroups: comp.sys.mac.programmer
Subject: ThinkC's handling of CODE resources.
Keywords: ThinkC
Message-ID: <1990Jul10.150057.24765@hod.uit.no>
Date: 10 Jul 90 15:00:57 GMT
Sender: news@hod.uit.no (USENET News System)
Reply-To: arneme@sfd.uit.no
Followup-To: arneme@nic.uit.no
Organization: FORUT/University of Tromsoe, Norway.
Lines: 29

I am working on a fairly large thinkC project that divides the code
into 8 code segments. Trying to debug the project I single steps the
program using the "step" and "in" commands up to the following
statement:

	button_name = (char *)malloc( maximum_name_length + 1 );

Using the Data window gives this value for maximum_name_length:

	maximum_name_length = 27

The call to malloc never returns, the mac hangs on me.

This makes me wonder about how thinkC handles it's CODE segments. It
seems to me that the CODE segment from where malloc is called is
relocated while the malloc is executing. On return from malloc the
return address is taken from the stack, and oops, the CODE segment is
not there anymore. I had another problem of this sort, running code in
CODE segment 1, calling a routine in another segment resulted in a
jump to an address where the code for the called routine was not
located. Moving the file in question to CODE segment 1 resulted in
that the routine was found and executed without problems.

I am not doing any UnloadSeg or GetResource calls in my program source.

Has anyone experienced similar behavior when using thinkC, or is it
probable that my guess on what is happening is far out?

Arne.