Message-Id: <200007210759.KAA15139@mailgw1.netvision.net.il>
Date: Fri, 21 Jul 2000 10:59:44 +0200
To: "Thorsten Erdmann" <thorsten DOT erdmann AT gmx DOT de>
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From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
CC: djgpp AT delorie DOT com
In-reply-to: <8l7gic$2ku$1@riker.addcom.de> (thorsten.erdmann@gmx.de)
Subject: Re: How to flush CDROMs and MSCDEX buffers
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> From: "Thorsten Erdmann" <thorsten DOT erdmann AT gmx DOT de>
> Newsgroups: comp.os.msdos.djgpp
> Date: Thu, 20 Jul 2000 20:28:47 +0200
> 
> I have some problems with my Joliet driver. For reading from CD I use
> MSCDEX. It's Readblock and DiskInfo functions return the same sectors even
> if I change the CD. So I read the directory of the first CD, all works fine.
> When I insert another CD and read the directory again I get that one from
> the old CD. So someone seems to buffer some CD sectors, maybe the CD drive
> itself or  MSCDEX.

It's MSCDEX and/or the disk cache (if you have one installed).

> How can I flush that buffer to read the actual info?

Try looking at files statfs.c and mntent.c in the DJGPP library
sources (v2/djlsr203.zip from the usual DJGPP sites).  They use a few
subfunctions of function 15h of interrupt 2Fh to read information from
the CD drive, and they do it in a manner that avoids getting stale
info when the disk changes.  They might give you a few ideas.