Path: utzoo!attcan!uunet!lll-winken!ames!killer!pollux!ti-csl!m2!holland
From: holland@m2.csc.ti.com (Fred Hollander)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Open Resource File List
Message-ID: <67107@ti-csl.CSNET>
Date: 13 Jan 89 03:37:45 GMT
References: <67009@ti-csl.CSNET> <6265@hoptoad.uucp>
Sender: news@ti-csl.CSNET
Reply-To: holland@m2.UUCP (Fred Hollander)
Organization: TI Computer Science Center, Dallas
Lines: 39

In article <6265@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes:
>In article <67009@ti-csl.CSNET> holland@mips.csc.ti.com (Fred Hollander) write
>
>>Another resource problem.  I need to temporarily change the permission of a
>>resource file.  Right now I CloseResFile and OpenRFPerm, but I'm worried
>>about the path number changing
>
>I would strongly recommend against trying to do this.  Why do you want
>to change the permission?  The Mac has no way in the file system of
>changing the access permission on an open file.  If you close and
>re-open the file, then you may very well wind up with a different
>reference number.  Reference numbers are offsets into the file control

My concern exactly.  I was also alerted to the fact that handles to open
resources would be invalidated.  I didn't intend to use this method, it was
a temporary hack to test the effect of write-protecting a file.  I was hoping
someone could tell me the proper way to change the file protection.

>block table; when you open a file, the offset to the lowest unused FCB
>is used.  So, if another file has closed since the resource file was
>opened, you will change the reference number and the application will
>become confused.  Not only that, but if another resource file has
>opened since your resource file was opened, you are changing the search
>path order.  In my immodest opinion, a patch that does this is a broken
>patch.  Don't.

Ok, I won't.  Thanks for telling me that the Mac file system cannot change the
permission of an open file.  At least I can stop looking.  Anyway, I think I
I have another approach that's a little cleaner.

>--
>Tim Maroney, Consultant, Eclectic Software, sun!hoptoad!tim

Fred Hollander
Computer Science Center
Texas Instruments, Inc.
holland%ti-csl@csnet-rela

The above statements are my own and not representative of Texas Instruments.