From owner-freebsd-hackers@FreeBSD.ORG  Thu Dec 30 14:23:57 2004
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 4D36616A4CE
	for <freebsd-hackers@FreeBSD.ORG>;
	Thu, 30 Dec 2004 14:23:57 +0000 (GMT)
Received: from episec.com (episec.com [69.55.237.141])
	by mx1.FreeBSD.org (Postfix) with SMTP id F2E6B43D2D
	for <freebsd-hackers@FreeBSD.ORG>;
	Thu, 30 Dec 2004 14:23:56 +0000 (GMT)
	(envelope-from edelkind-freebsd-hackers@episec.com)
Received: (qmail 81961 invoked by uid 1024); 30 Dec 2004 14:23:56 -0000
Date: Thu, 30 Dec 2004 09:23:56 -0500
From: ari edelkind <edelkind-freebsd-hackers@episec.com>
To: freebsd-hackers@FreeBSD.ORG
Message-ID: <20041230142356.GQ3608@episec.com>
Mail-Followup-To: ari edelkind <edelkind-freebsd-hackers@episec.com>,
	freebsd-hackers@FreeBSD.ORG
References: <1104358540.2895.10.camel@kaiser.sig11.org>
	<20041230103433.GB830@straylight.m.ringlet.net>
	<1104409708.6657.1.camel@kaiser.sig11.org>
	<20041230123116.GE830@straylight.m.ringlet.net>
	<41D4036B.1060600@portaone.com>
	<20041230140007.GH830@straylight.m.ringlet.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20041230140007.GH830@straylight.m.ringlet.net>
Subject: Re: Creating Compressed Loop FS from stdin
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 30 Dec 2004 14:23:57 -0000

roam@ringlet.net wrote:

> > It will not help, since AFAIK you can't seek stdin anyway, or even if I 
> > am wrong and you can seek it to the end you will be unable to seek it 
> > backward.
> 
> I tested the patch before posting it, fully expecting to find that stdin
> really cannot be seeked (sought? :), and surprisingly it worked, at least
> on RELENG_5 as of today!

You can always seek stdin, if stdin happens to be associated with a
seekable descriptor.  It isn't given any special treatment simply
because it has a vector of 0.  That is, if you use something along the
lines of:

    % ./seekme </etc/services

then /etc/services is associated with descriptor 0, and you can seek all
you like.  If you use

    % cat /etc/services |./seekme

... then the descriptor isn't associated with a file, and you'll run
into problems.

ari