From owner-freebsd-current@FreeBSD.ORG  Tue Jul 20 18:00:59 2004
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 8F4FE16A4CE
	for <current@freebsd.org>; Tue, 20 Jul 2004 18:00:59 +0000 (GMT)
Received: from moghedien.mukappabeta.net (moghedien.mukappabeta.net
	[194.145.150.66])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 4159F43D31
	for <current@freebsd.org>; Tue, 20 Jul 2004 18:00:59 +0000 (GMT)
	(envelope-from mkb@moghedien.mukappabeta.net)
Received: by moghedien.mukappabeta.net (Postfix, from userid 1000)
	id 7A7C92D87; Tue, 20 Jul 2004 19:57:40 +0200 (CEST)
From: Matthias Buelow <mkb@mukappabeta.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Message-ID: <16637.23827.578767.763759@moghedien.mukappabeta.net>
Date: Tue, 20 Jul 2004 19:57:39 +0200
To: Peter Jeremy <PeterJeremy@optushome.com.au>
In-Reply-To: <20040720081051.GB3001@cirb503493.alcatel.com.au>
References: <40F963D8.6010201@freebsd.org>
	<20040719060730.GA87697@nagual.pp.ru>
	<40FC9FC2.8050400@kientzle.com>
	<20040720081051.GB3001@cirb503493.alcatel.com.au>
X-Mailer: VM 7.18 under Emacs 21.3.1
cc: current@freebsd.org
Subject: Re: NEW TAR
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 20 Jul 2004 18:00:59 -0000

Peter Jeremy writes:

>Actually, it's not possible to accurately determine the holes in a
>file by reading it - you can't differentiate between a hole and a
>allocated block of zeroes.  What you need is a (new) syscall that

but that's the point, isn't it.  if you get a larger block of zeroes,
you seek forward that number in the output file, and let the
filesystem create (any) holes.

>invokes a new VOP_... and returns a bitmap of allocated blocks.  This
>would be non-trival unfortunately.

this is completely unnecessary and wouldn't work across filesystems
anyways.

-- 
  Matthias Buelow; mkb@{mukappabeta,informatik.uni-wuerzburg}.de