From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.8 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 682221F40E for ; Wed, 3 Aug 2016 21:54:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752786AbcHCVyQ (ORCPT ); Wed, 3 Aug 2016 17:54:16 -0400 Received: from cloud.peff.net ([50.56.180.127]:54274 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754597AbcHCVyP (ORCPT ); Wed, 3 Aug 2016 17:54:15 -0400 Received: (qmail 18671 invoked by uid 102); 3 Aug 2016 21:27:22 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Wed, 03 Aug 2016 17:27:22 -0400 Received: (qmail 6076 invoked by uid 107); 3 Aug 2016 21:27:49 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.84) with SMTP; Wed, 03 Aug 2016 17:27:49 -0400 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Wed, 03 Aug 2016 17:27:18 -0400 Date: Wed, 3 Aug 2016 17:27:18 -0400 From: Jeff King To: Junio C Hamano Cc: larsxschneider@gmail.com, git@vger.kernel.org, jnareb@gmail.com, tboegi@web.de, mlbright@gmail.com, e@80x24.org Subject: Re: [PATCH v4 01/12] pkt-line: extract set_packet_header() Message-ID: <20160803212718.cdqhd2zfzce7mqfa@sigill.intra.peff.net> References: <20160729233801.82844-1-larsxschneider@gmail.com> <20160803164225.46355-1-larsxschneider@gmail.com> <20160803164225.46355-2-larsxschneider@gmail.com> <20160803211221.t2zdhvwjum2baeqs@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160803211221.t2zdhvwjum2baeqs@sigill.intra.peff.net> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Aug 03, 2016 at 05:12:21PM -0400, Jeff King wrote: > The alternative is to hand-code it, which is what send_sideband() does > (it uses xsnprintf("%04x") to do the hex formatting, though). After seeing that, I wondered why we need set_packet_header() at all. But we do for the case when we are filling in the size at the start of a buffer, because xsnprintf() will write an extra NUL that we do not care about. send_sideband() is happy to then overwrite it with data, but code (like format_packet) that computes the buffer, then fills in the size, must avoid overwriting the first byte of the buffer. -Peff