Mailing-List: contact cygwin-help AT sourceware DOT cygnus DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT sources DOT redhat DOT com>
List-Archive: <http://sources.redhat.com/ml/cygwin/>
List-Post: <mailto:cygwin AT sources DOT redhat DOT com>
List-Help: <mailto:cygwin-help AT sources DOT redhat DOT com>, <http://sources.redhat.com/ml/#faqs>
Sender: cygwin-owner AT sources DOT redhat DOT com
Delivered-To: mailing list cygwin AT sources DOT redhat DOT com
Date: Sat, 3 Feb 2001 13:21:38 -0500
From: Christopher Faylor <cgf AT redhat DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: lseek()/read() to physical drive returning wrong data.
Message-ID: <20010203132138.A6334@redhat.com>
Reply-To: cygwin AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
References: <3A7C4445 DOT B5F8FAB0 AT compaq DOT com> <20010203191915 DOT Z19867 AT cygbert DOT vinschen DOT de>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.3.11i
In-Reply-To: <20010203191915.Z19867@cygbert.vinschen.de>; from cygwin@cygwin.com on Sat, Feb 03, 2001 at 07:19:15PM +0100

On Sat, Feb 03, 2001 at 07:19:15PM +0100, Corinna Vinschen wrote:
>On Sat, Feb 03, 2001 at 12:47:49PM -0500, Robin T. Miller wrote:
>> Hi All,
>> 	I have a Unix test program named 'dt' which runs with Cygwin.
>> This program tests a variety of devices as well as file systems.  The
>> tests which use lseek() to raw mounted disks, are failing with data
>> compare errors.  It appears either lseek() is positioning incorrectly
>> or read() is returning the wrong data after lseek'ing.
>> 
>> 	This random I/O sequence seems to work correctly to a regular
>> file, so maybe the raw device buffering is messing up?  I'm not sure.
>
>Lseek on raw devices isn't yet fully implemented. The underlying
>*cough* operating system *cough* isn't able to do a bytewise access
>to the raw device but only in steps of 512 bytes. A full lseek
>implementation would need to do it's own buffering to simulate
>bytewise buffering. This is still missing.
>
>> 	The only other program restrictions is 32-bit file offsets.
>> 
>> 	BTW: Are there any plans to release 64-bit file support?
>
>Not in the near future.

Not in the non-near future, either.  :-)

cgf

--
Want to unsubscribe from this list?
Check out: http://cygwin.com/ml/#unsubscribe-simple