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Mail Archives: opendos/1997/04/15/10:39:01

Date: Tue, 15 Apr 1997 16:33:08 +0100
From: Matthias Paul <PAUL-MA AT reze-1 DOT rz DOT rwth-aachen DOT de>
Subject: Re: Usage of directory entries
To: opendos-developer AT delorie DOT com
Reply-to: Matthias DOT Paul AT post DOT rwth-aachen DOT de
Message-id: <7BDBB14DFE@reze-1.rz.rwth-aachen.de>
Organization: Rechenzentrum RWTH Aachen
MIME-version: 1.0

On Tue, 15 Apr 1997, Mark Habersack wrote:

> > Using some more 'intelligent' algorithms 
> > also decoding the context of an entry, it should be possible to 
> It is possible to tell the LFN from SFN entry by just looking at 
> the starting cluster field which in LFN is always zero. To 
> confirm we're dealing with LFN it is also possible to check the 
> attributes of an entry: 0xFF for LFN. 

Looking at a cluster of zero is a rather nice idea, but probably won't 
work any more with FAT32 partitions, where the start-cluster word is 
only the low-word of the actual start cluster.  We'd need at least 
some more plausibility checks.  Unfortunately, a set volume attribut 
is also used by DELWATCH...  If we cannot develop some nice fitting 
decoding algorithms for the several combinations of usage, we might 
need to modify DELWATCH, rather than 'standard' LFNs.  Changing 
DELWATCH might also break UNDELETE, DELPURGE, CHKDSK, and the file-io 
in the kernel.  For future OpenDOS issues, we should at least 
introduce a flag/type byte in the directory entry, describing the 
future usage of a directory entry under OpenDOS, and the kernel and 
all affected utilities would need several case decisions for 'old' 
and 'new' variants of usage.  Doing so, we'd need to 'guess' the 
actual usage of an entry only for old entries not using this type 
byte...

> > decide LFN-entries from normal directory entries, while still 
> > maintaining compatibility with "DR DOS"-features, which use the 
> > same entries, but in a different context.  However, for full 
> > LFN-support we should better slightly modify the usage of these 
> > structures...
> I've just started to write a TSR to provide LFN support. As soon as 
> it has some shape, I will make it available for all to review and 
> improve. 

Hey, now that's good news!!! ;-)
Are you utilizing DPMS?

> >    More detailed info on the usage of these structures can be found in
> >    NWDOSTIP.TXT (from my MPDOSTIP.ZIP) and in Ralf Brown's interrupt
> >    list INTER53+.
> Great info! Thanx!

:-)

Well, INTER53 still does not cover LFN in full details, but INTER54 
or INTER55 should become much better...  ;-)  Also, I'm just writing 
new LFN infos down for Ralf, you'll get a CC: if ready for release.

> P.S. Could you send me MPDOSTIP.ZIP by email? I was unable to 
> ftpsearch it anywhere??
Opps, it is located on several FTP servers in Germany, namely 
the three sites directly supported by me are:

 ftp://ftp.rhrz.uni-bonn.de/     
 ftp://ftp.uni-stuttgart.de/
 ftp://ftp.leo.org/    also via http://www.leo.org/

Most of the time, the last one (leo) is several weeks in back with 
its updates, since they have to create some extra info files for each 
release.

I would recommend you looking at my web-page - see the URL in my 
signature (I thought, I had mentioned this serveral times in the 
past).  There you can find MPDOSTIP.ZIP and several other tools, 
some of them especially written for DR DOS, Novell DOS, and 
OpenDOS.  Also included are links to other OpenDOS info providers 
and related programs.

Of course, if you cannot get the file from there (for what reasons 
ever), I could also send it to you by email, but does your in-box 
allow for mega-bytes of mails?  (The current version of MPDOSTIP.ZIP 
as of 1997-04-14 is ca. 525KB zipped...)  However, if you run into 
any problems when downloading my files, please email me again, and 
I will sure help you.

Bye,

 Matthias
 
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