From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1Ztyr9-00033h-4n for mharc-qemu-trivial@gnu.org; Wed, 04 Nov 2015 09:16:07 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33443) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ztyr3-0002xO-1y for qemu-trivial@nongnu.org; Wed, 04 Nov 2015 09:16:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ztyqy-0001gm-I9 for qemu-trivial@nongnu.org; Wed, 04 Nov 2015 09:16:00 -0500 Received: from mail-pa0-x22c.google.com ([2607:f8b0:400e:c03::22c]:34396) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ztyqu-0001fy-3P; Wed, 04 Nov 2015 09:15:52 -0500 Received: by padhx2 with SMTP id hx2so46423722pad.1; Wed, 04 Nov 2015 06:15:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=lCobdT3b7suZaW0wFoxPstBgVaZuOJ4S1a8P1doetgc=; b=ScyG3MKkh6m//gt0uX8oQZvPGjxi2nA33pCIXqCwsQIVvMx5IkHriM7uTj5SGiHBh0 zn9PpJRb4NLP+iqkQ/ZO1gr4jx3irV6sCzck9GSg9MyNdtDO8pWat/yvCF9IHaj2Vqc4 iLWrZRJJZ30gwwdP+MivzCN5CL1Jp2p5DMYrkvcLYOHu1FzH3Pc5dpuPyIoAuVEXciEE kiDWQ4Mngdegt7UA0N2j0cjCGTe319lDrg0Ig6qPgV2d+cMGavC0awaS3X5GLCVOMgoz BZIowcu1He76YBB9+JJhdRrI4Zkfy8/O8RFPdtIALXq7MC5PjSkmP66bJ9qFJWmTjkR8 Ip/A== X-Received: by 10.66.219.39 with SMTP id pl7mr2163128pac.88.1446646551034; Wed, 04 Nov 2015 06:15:51 -0800 (PST) Received: from localhost (ec2-52-8-89-49.us-west-1.compute.amazonaws.com. [52.8.89.49]) by smtp.gmail.com with ESMTPSA id k10sm2356817pbq.78.2015.11.04.06.15.49 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Wed, 04 Nov 2015 06:15:49 -0800 (PST) Date: Wed, 4 Nov 2015 15:15:46 +0100 From: "Edgar E. Iglesias" To: Paolo Bonzini Message-ID: <20151104141546.GC20036@toto> References: <1446644927-8764-1-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1446644927-8764-1-git-send-email-pbonzini@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2607:f8b0:400e:c03::22c Cc: qemu-trivial@nongnu.org, crobinso@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH v2] qemu-sockets: do not test path with access() before unlinking X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Nov 2015 14:16:05 -0000 On Wed, Nov 04, 2015 at 02:48:47PM +0100, Paolo Bonzini wrote: > Using access() is a time-of-check/time-of-use race condition. It is > okay to use them to provide better error messages, but that is pretty > much it. > > This is not one such case; on the other hand, access() *will* skip > unlink() for a non-existent path, so ignore ENOENT return values from > the unlink() system call. > > Signed-off-by: Paolo Bonzini Reviewed-by: Edgar E. Iglesias > --- > util/qemu-sockets.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c > index 9142917..de9145a 100644 > --- a/util/qemu-sockets.c > +++ b/util/qemu-sockets.c > @@ -751,8 +751,7 @@ int unix_listen_opts(QemuOpts *opts, Error **errp) > qemu_opt_set(opts, "path", un.sun_path, &error_abort); > } > > - if ((access(un.sun_path, F_OK) == 0) && > - unlink(un.sun_path) < 0) { > + if (unlink(un.sun_path) < 0 && errno != ENOENT) { > error_setg_errno(errp, errno, > "Failed to unlink socket %s", un.sun_path); > goto err; > -- > 2.5.0 > > From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33403) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ztyqx-0002uL-MY for qemu-devel@nongnu.org; Wed, 04 Nov 2015 09:15:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ztyqu-0001g7-9R for qemu-devel@nongnu.org; Wed, 04 Nov 2015 09:15:55 -0500 Date: Wed, 4 Nov 2015 15:15:46 +0100 From: "Edgar E. Iglesias" Message-ID: <20151104141546.GC20036@toto> References: <1446644927-8764-1-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1446644927-8764-1-git-send-email-pbonzini@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2] qemu-sockets: do not test path with access() before unlinking List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-trivial@nongnu.org, crobinso@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com On Wed, Nov 04, 2015 at 02:48:47PM +0100, Paolo Bonzini wrote: > Using access() is a time-of-check/time-of-use race condition. It is > okay to use them to provide better error messages, but that is pretty > much it. > > This is not one such case; on the other hand, access() *will* skip > unlink() for a non-existent path, so ignore ENOENT return values from > the unlink() system call. > > Signed-off-by: Paolo Bonzini Reviewed-by: Edgar E. Iglesias > --- > util/qemu-sockets.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c > index 9142917..de9145a 100644 > --- a/util/qemu-sockets.c > +++ b/util/qemu-sockets.c > @@ -751,8 +751,7 @@ int unix_listen_opts(QemuOpts *opts, Error **errp) > qemu_opt_set(opts, "path", un.sun_path, &error_abort); > } > > - if ((access(un.sun_path, F_OK) == 0) && > - unlink(un.sun_path) < 0) { > + if (unlink(un.sun_path) < 0 && errno != ENOENT) { > error_setg_errno(errp, errno, > "Failed to unlink socket %s", un.sun_path); > goto err; > -- > 2.5.0 > >