From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF313C6FD1F for ; Thu, 16 Mar 2023 11:25:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229480AbjCPLZE (ORCPT ); Thu, 16 Mar 2023 07:25:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229787AbjCPLYw (ORCPT ); Thu, 16 Mar 2023 07:24:52 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82AFAEB4C for ; Thu, 16 Mar 2023 04:24:51 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1pcliz-0006Tu-Nm; Thu, 16 Mar 2023 12:24:49 +0100 Date: Thu, 16 Mar 2023 12:24:49 +0100 From: Florian Westphal To: Jeremy Sowden Cc: Netfilter Devel Subject: Re: [PATCH ulogd2 v3 1/2] pcap: simplify opening of output file Message-ID: <20230316112449.GI4072@breakpoint.cc> References: <20230316110754.260967-1-jeremy@azazel.net> <20230316110754.260967-2-jeremy@azazel.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230316110754.260967-2-jeremy@azazel.net> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Jeremy Sowden wrote: > Instead of statting the file, and choosing the mode with which to open > it and whether to write the PCAP header based on the result, always open > it with mode "a" and _then_ stat it. This simplifies the flow-control > and avoids a race between statting and opening. > > Signed-off-by: Jeremy Sowden > --- > output/pcap/ulogd_output_PCAP.c | 42 ++++++++++++--------------------- > 1 file changed, 15 insertions(+), 27 deletions(-) > > diff --git a/output/pcap/ulogd_output_PCAP.c b/output/pcap/ulogd_output_PCAP.c > index e7798f20c8fc..220fc6dec5fe 100644 > --- a/output/pcap/ulogd_output_PCAP.c > +++ b/output/pcap/ulogd_output_PCAP.c > @@ -220,33 +220,21 @@ static int append_create_outfile(struct ulogd_pluginstance *upi) > { > + struct stat st_of; > + > + pi->of = fopen(filename, "a"); > + if (!pi->of) { > + ulogd_log(ULOGD_ERROR, "can't open pcap file %s: %s\n", > + filename, > + strerror(errno)); > + return -EPERM; > + } > + if (fstat(fileno(pi->of), &st_of) == 0 && st_of.st_size == 0) { > + if (!write_pcap_header(pi)) { > + ulogd_log(ULOGD_ERROR, "can't write pcap header: %s\n", > + strerror(errno)); > + return -ENOSPC; LGTM, but should that fclose() before -ENOSPC?