Message-Id: <5.0.1.4.0.20001201005653.025bd770@pop5.banet.net>
X-Sender: usbanet DOT farley3 AT pop5 DOT banet DOT net
X-Mailer: QUALCOMM Windows Eudora Version 5.0.1
Date: Fri, 01 Dec 2000 01:01:47 -0500
To: "Mark E." <snowball3 AT bigfoot DOT com>
From: "Peter J. Farley III" <pjfarley AT banet DOT net>
Subject: Re: Locking fcntl() and flock() patches
Cc: djgpp-workers AT delorie DOT com
In-Reply-To: <3A26CFC0.4125.70F7C@localhost>
References: <5 DOT 0 DOT 1 DOT 4 DOT 0 DOT 20001130214616 DOT 025cb150 AT pop5 DOT banet DOT net>
 <3A261D6D DOT 4791 DOT 3157C2 AT localhost>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Reply-To: djgpp-workers AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: djgpp-workers AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

At 10:08 PM 11/30/00 -0500, Mark E. wrote:
>> At 09:27 AM 11/30/00 -0500, Mark E. wrote:
>>  >> Does the IOCTL subfunction or poking the SFT allow to set the
>>  >> SH_DENY* bits for files that are already open?
>> 
>>  >You can fiddle with those flags in the SFT, but I haven't 
>> experimented >with them.
>> 
>> OK, you folk are beyond my level of knowledge here.  Are you saying 
>> there is an alternate way to set up read locks?  Assuming that these 
>> bits can be set on an open file, how would it work?
>
>A file handle's SH_DENY* flags are stored in the JFT like a lot of other 
>flags passed to open(). If you manipulate them using undocumented 
>methods, you just might be able to have a read lock for the whole file 
>that can then be unlocked by fiddling with the handle's open flagst. 
>However, I haven't tried this and I doubt it's worth the effort to work 
>on this just to get one special case of read locks working.

OK, then we stay with the current F_RDLCK workaround, and allow whole-file 
read locks as previously discussed?

BTW, I was looking through RBIL, and I didn't see anything that suggested
SH_DENY* equivalents in the SFT, but maybe I'm not reading the right 
section.

And I also don't see anything in a JFT except the SFT number.  Am I missing something there?  It's only one byte per file in the JFT, right?



---------------------------------------------------------
Peter J. Farley III (pjfarley AT dorsai DOT org OR
                     pjfarley AT banet DOT net)