From owner-cvs-src@FreeBSD.ORG  Thu Dec 27 21:54:15 2007
Return-Path: <owner-cvs-src@FreeBSD.ORG>
Delivered-To: cvs-src@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id CABDE16A418;
	Thu, 27 Dec 2007 21:54:15 +0000 (UTC)
	(envelope-from brde@optusnet.com.au)
Received: from mail14.syd.optusnet.com.au (mail14.syd.optusnet.com.au
	[211.29.132.195])
	by mx1.freebsd.org (Postfix) with ESMTP id 5726413C442;
	Thu, 27 Dec 2007 21:54:15 +0000 (UTC)
	(envelope-from brde@optusnet.com.au)
Received: from c211-30-219-213.carlnfd3.nsw.optusnet.com.au
	(c211-30-219-213.carlnfd3.nsw.optusnet.com.au [211.30.219.213])
	by mail14.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id
	lBRLsAfc002713
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO);
	Fri, 28 Dec 2007 08:54:13 +1100
Date: Fri, 28 Dec 2007 08:54:10 +1100 (EST)
From: Bruce Evans <brde@optusnet.com.au>
X-X-Sender: bde@delplex.bde.org
To: Diomidis Spinellis <dds@FreeBSD.org>
In-Reply-To: <200712271133.lBRBXhjY038891@repoman.freebsd.org>
Message-ID: <20071228083650.L17488@delplex.bde.org>
References: <200712271133.lBRBXhjY038891@repoman.freebsd.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/bin/mv mv.c
X-BeenThere: cvs-src@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: CVS commit messages for the src tree <cvs-src.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-src>
List-Post: <mailto:cvs-src@freebsd.org>
List-Help: <mailto:cvs-src-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 27 Dec 2007 21:54:15 -0000

On Thu, 27 Dec 2007, Diomidis Spinellis wrote:

> dds         2007-12-27 11:33:42 UTC
>
>  FreeBSD src repository
>
>  Modified files:
>    bin/mv               mv.c
>  Log:
>  - Roll-back attempts to mimic rename(2) atomicity introduced in 1.47,
>    and follow the letter of the POSIX specification.
>
>  - Moving a directory to an existing non-empty directory will now fail,
>    as required.

It should be noted that the previous behaviour was very dangerous.  It
could destroy target directory trees of any size in order to replace
them with a typo, but of course a local rename() can only destroy the
target directory tree if that tree consists of an empty target directory.
The destroyed target directory tree cannot quite be /, but it can be
almost as important:

 	mkdir /tmp/usr
 	cd /tmp
 	mv usr /		# when /tmp and /usr are on different fs's.
 				# this replaced /usr by the empty usr,
 				# using esentially the following:
 	mv /usr /usr.backup
 	cp -pRp usr /
 	rm -rf /usr.backup
 	rm -rf usr

Bruce