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From: resnick@lees.cogsci.uiuc.edu (Pete Resnick)
Newsgroups: comp.sys.mac.programmer
Subject: Files and Drivers
Message-ID: <1990Jul23.201524.13849@ux1.cso.uiuc.edu>
Date: 23 Jul 90 20:15:24 GMT
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Organization: University of Illinois at Urbana
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Hopefully an easy question.....

I am writing a driver that will be called with the dNeedTime mechanism
(accRun control call) by the system every so often. This driver gets
input from a text file that I open in my control routine if certain
conditions are satisfied. The problem is that I may not be able to
read all of the information during one call of the routine, so (as
it is written now) I leave the file open and hang on to its RefNum for
the next call.

1. Is this a problem as is? Will my file stay open between calls with
the file mark in the right place? I would prefer not to close it if
I don't have to (if nothing else to save the time of closing, re-opening
and setting the file mark each time).

2. I have the file open as fsRdPerm (read-only). If someone goes and
changes the file while I am in it and the file gets shorter, am I
in big trouble (i.e. will this crash the Mac), will the file just get
eof immediately, or will the buffer that I am working on remain the
same?

pr
--
Pete Resnick             (...so what is a mojo, and why would one be rising?)
Graduate assistant - Philosophy Department, Gregory Hall, UIUC
System manager - Cognitive Science Group, Beckman Institute, UIUC
Internet/ARPAnet/EDUnet  : resnick@kant.cogsci.uiuc.edu
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