Path: utzoo!mnetor!uunet!husc6!hao!ames!ucbcad!ucbvax!hplabs!pyramid!prls!gardner
From: gardner@prls.UUCP (Robert Gardner)
Newsgroups: comp.sys.mac
Subject: Another SFGetFile question
Message-ID: <8152@prls.UUCP>
Date: 21 Dec 87 20:22:33 GMT
References: <2260@chalmers.UUCP>
Reply-To: gardner@prls.UUCP (Robert Gardner)
Organization: Philips Research Labs, Sunnyvale, California
Lines: 20

And now yet another SFGetFile() question! The help I've gotten from
the net on all my various and sundry questions has sure been appreciated.

I want to filter out all opened files during SFGetFile calls. What seemed
easiest was to just check the ioRefNum field of the parameter block
against 0, since ioRefNum is supposed to contain a file's reference 
number if the file is open (interesting, Inside Mac doesn't say what it
contains if the file is NOT open...). This works just fine on my Mac+.
However, when I try the same procedure on a 64K ROM Mac EVERY file looks
open -- i.e. it's ioRefNum field is non-zero. I haven't yet figured
out what the field is... haven't had time to configure TMON for that Mac.

Well, we haven't yet given up on 64K ROM machines, but worse, if this
method fails on 64K ROM machines, will it fail on SE's, Mac II's, or
future machines? So, I guess the real question is, is there a foolproof
way to tell from within SFGetFile() filters whether or not a given file
is already open?

Thank you,
Robert Gardner