From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: copyfile semantics. Date: Wed, 6 May 2009 07:57:12 +0200 Message-ID: <20090506055712.GA7562@logfs.org> References: <1241331303-23753-1-git-send-email-joel.becker@oracle.com> <1241331303-23753-2-git-send-email-joel.becker@oracle.com> <20090505010703.GA12731@shareable.org> <20090505071608.GB10258@mail.oracle.com> <20090505130114.GD17486@mit.edu> <20090505131907.GF25328@shareable.org> <1241530798.7244.65.camel@think.oraclecorp.com> <20090505153629.GB31100@shareable.org> <20090505164619.GA32180@logfs.org> <20090505214454.GP3209@webber.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jamie Lokier , Chris Mason , Theodore Tso , linux-fsdevel@vger.kernel.org, jmorris@namei.org, ocfs2-devel@oss.oracle.com, viro@zeniv.linux.org.uk To: Andreas Dilger Return-path: Received: from lazybastard.de ([212.112.238.170]:38527 "EHLO longford.logfs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750702AbZEFF52 (ORCPT ); Wed, 6 May 2009 01:57:28 -0400 Content-Disposition: inline In-Reply-To: <20090505214454.GP3209@webber.adilger.int> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, 5 May 2009 15:44:54 -0600, Andreas Dilger wrote: >=20 > > or copyfile() will also have to create a tempfile, rename the > > tempfile when the copy is done and deal with all possible errors. = And > > if the system crashes, who will remove the tempfile on reboot? Wil= l the > > tempfile have a well-known name, allowing for easy DoS? Or will it= be > > random, causing much fun locating it after reboot. >=20 > Maybe I'm missing something, but why do we need a tempfile at all? > I can't imagine that people expect atomic semantics for copyfile(), > any more than they expect atomic sematics for "cp" in the face of a > crash. In the case of cowlink() a tempfile is required when breaking the link. Otherwise open() can result in the file disappearing or being truncated= =2E Rather unexpected. If copyfile() doesn't try to be smart and does the actual copy when being called, I could certainly live with half-written files. J=C3=B6rn --=20 "Security vulnerabilities are here to stay." -- Scott Culp, Manager of the Microsoft Security Response Center, 2001 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html