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From: rs4u+@ANDREW.CMU.EDU (Richard Siegel)
Newsgroups: comp.sys.mac
Subject: Locking Files under AppleShare
Message-ID: <wV3SGxy00V4Iz3407n@andrew.cmu.edu>
Date: Wed, 29-Jul-87 08:04:13 EDT
Article-I.D.: andrew.wV3SGxy00V4Iz3407n
Posted: Wed Jul 29 08:04:13 1987
Date-Received: Fri, 31-Jul-87 02:32:49 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 23


I'm working on an application that handles multiple data and
resource files, as documents. In order for my Revert
function to work safely, I have to somehow lock the files
while they're open so that they can't get moved; if
a file gets moved between the time that it's opened and the time
that Revert is called, havoc can result.

As it is now, I open the file (with FSOpen and OpenResFile), read
whatever information I need (with FSRead and GetResource), and then
close the file (with FSClose and CloseResFile). 

I need also to prevent a file from being opened twice, is there a way to
do this? Simply leaving it open doesn't seem to work, and I definitely don't
want to try to close the same access path twice -- doing so can have
horrible consequences...

Notice that the same considerations apply to an application that's 
runnning under Juggler...

Any help would be appreciated.

		--Rich