Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!gatech!dcatla!holos0!lbr
From: lbr@holos0.UUCP (Len Reed)
Newsgroups: comp.sys.ibm.pc
Subject: Disk I/O in Resident MS-DOS Program
Message-ID: <1872@holos0.UUCP>
Date: 16 Feb 89 16:40:45 GMT
Reply-To: lbr@holos0.UUCP (Len Reed)
Distribution: usa
Organization: Holos Software, Atlanta
Lines: 30

I have an MS-DOS terminate-and-stay resident program that must be able
to open/close/read/write hard disk files.  It appears that the "file
handles" move on me.  That is, if this routine opens a file, as the
foreground processes spawn and die, I lose my handles since they
really belong to the foreground processes.

FCB I/O appears to work better, but I'm not crazy about using it since
it is primitive.  My opens and closes have to be in the current directory,
which means I have to perform the following to do an open or close:
	1. Lock the foreground out of DOS.  (I have a mechanism in place to
	   stall DOS calls.)
	2. Save the current directory.  (MS-DOS has one directory per disk,
	   not--as in UNIX--one per process.)
	3. Go to the proper directory.
	4. Perform the open/close.
	5. Go back to the original directory.
	6. Unlock DOS.

This scenerio seems unnecessary for read/writes.  I can do them regardless
of my current directory.

Is there a better way to do this?  What I'm doing seems to work; am I
missing something that will cause it not to work?

BTW--the application is a communications package that sits in the background
and steals time to transfer/receive files to/from a mainframe.

Thanks for any help.
-- 
    -    Len Reed