Article View: comp.sys.amiga.tech
Article #7210UnLocking locks returned by CurrentDir()
From: Bob Laughlin
Date: Wed, 05 Dec 1990 10:47
Date: Wed, 05 Dec 1990 10:47
48 lines
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2091 bytes
I've been using the following code to move around directories
from within a program and restore the original current directory
on termination. It seems to work and I originally got the code
from an example posted here a few years ago.
// at program startup store a lock on the current directory
if ((startdir = Lock ("", ACCESS_READ)) == NULL)
error ...
........
// during the program move around the directories with ...
if ((newlock = Lock (newdir, ACCESS_READ) != NULL) {
oldlock = CurrentDir (newlock) ; // oldlock == NULL is a valid lock!
UnLock (oldlock) ;
}
........
// at program termination restore the original directory
oldlock = CurrentDir (startdir) ;
UnLock (oldlock) ;
However, reading Rob Peck's Programmer's Guide to the Amiga
lately I notice that on page 30 it states that you should NOT
call UnLock() on locks obtained from a call to CurrentDir().
Also, the 1.3 AutoDocs only mention using UnLock() on a lock obtained
from Lock(), DupLock(), or CreateDir(). If this is correct then how do
you move around directories without leaving any locks around when the
program exits?
My guess is that you something like the following:
// at program startup store a lock on the current directory
startdir = Lock ("", ACCESS_READ) ;
........
// during the program move around the directories with ...
if ((newlock = Lock (newdir, ACCESS_READ) != NULL)
CurrentDir (newlock) ;
...... use newlock
UnLock (newlock) ;
}
........
// at program termination restore the original directory
CurrentDir (startdir) ;
UnLock (startdir) ;
Is this correct?
--
Bob Laughlin laughlin@cs.sfu.ca
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!van-bc!ubc-cs!fornax!laughlin From: laughlin@fornax.UUCP (Bob Laughlin) Newsgroups: comp.sys.amiga.tech Subject: UnLocking locks returned by CurrentDir() Message-ID: <1733@fornax.UUCP> Date: 5 Dec 90 10:47:06 GMT Organization: School of Computing Science, Simon Fraser University Lines: 48