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From: lsr@Apple.COM (Larry Rosenstein)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Writing resources to a file
Message-ID: <11022@apple.Apple.Com>
Date: 25 May 88 22:31:32 GMT
References: <51379@sun.uucp> <600@kinetics.UUCP> <23980@ucbvax.BERKELEY.EDU>
Reply-To: lsr@apple.UUCP (Larry Rosenstein)
Distribution: na
Organization: Advanced Technology Group, Apple Computer
Lines: 23

In article <23980@ucbvax.BERKELEY.EDU> oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster) writes:
>In article <600@kinetics.UUCP> markw@kinetics.UUCP (Mark Wittenberg) writes:
>>1.  How do you tell if a resource file is already open?
>Well, one easy way to do it is, before opening the file with
>OpenResFile(), try opening it with PBOpenRF(). If it is already open,
>since you are opening it for read/write you get back the vRef of the
>existing access path and an "already open" error code. Close the file in

Tech Note 185 mentions a problem with this under MultiFinder.  The the file
is opened by another process and you ask for read/write permission (or use
OpenResFile) then you will get back -1 as the refnum and ResError will be
-49.  You need to check for this case as well.

I think you can also do a PBGetFInfo, since that returns the refnum of an
access path if the file is open.  (I don't think it distinguishes the data
and resource forks.)  Also, on 64K ROMs, I think you have to zero the refnum
field before the call.

-- 
		 Larry Rosenstein,  Object Specialist
 Apple Computer, Inc.  20525 Mariani Ave, MS 27-AJ  Cupertino, CA 95014
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