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=-3.6 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 22B2B1FD99 for ; Wed, 10 Aug 2016 19:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933208AbcHJTdv (ORCPT ); Wed, 10 Aug 2016 15:33:51 -0400 Received: from cloud.peff.net ([104.130.231.41]:53047 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S965039AbcHJSy7 (ORCPT ); Wed, 10 Aug 2016 14:54:59 -0400 Received: (qmail 26747 invoked by uid 109); 10 Aug 2016 13:28:17 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Wed, 10 Aug 2016 13:28:17 +0000 Received: (qmail 32382 invoked by uid 111); 10 Aug 2016 13:28:16 -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, 10 Aug 2016 09:28:16 -0400 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Wed, 10 Aug 2016 09:28:15 -0400 Date: Wed, 10 Aug 2016 09:28:15 -0400 From: Jeff King To: larsxschneider@gmail.com Cc: git@vger.kernel.org, gitster@pobox.com, jnareb@gmail.com, mlbright@gmail.com, e@80x24.org, Johannes.Schindelin@gmx.de, ben@wijen.net Subject: Re: [PATCH v5 04/15] pkt-line: add packet_write_gently() Message-ID: <20160810132814.gqnipsdwyzjmuqjy@sigill.intra.peff.net> References: <20160803164225.46355-1-larsxschneider@gmail.com/> <20160810130411.12419-1-larsxschneider@gmail.com> <20160810130411.12419-5-larsxschneider@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160810130411.12419-5-larsxschneider@gmail.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Aug 10, 2016 at 03:04:00PM +0200, larsxschneider@gmail.com wrote: > From: Lars Schneider > > packet_write() has two shortcomings. First, it uses format_packet() which > lets the caller only send string data via "%s". That means it cannot be > used for arbitrary data that may contain NULs. Second, it will always > die on error. > > Add packet_write_gently() which writes arbitrary data and returns `0` for > success and `-1` for an error. So now we have packet_write() and packet_write_gently(), but they differ in more than just whether they are gentle. That seems like a weird interface. Should we either be picking a new name (e.g., packet_write_mem() or something), or migrating packet_write() to packet_write_fmt()? > diff --git a/pkt-line.c b/pkt-line.c > index e6b8410..4f25748 100644 > --- a/pkt-line.c > +++ b/pkt-line.c > @@ -3,6 +3,7 @@ > #include "run-command.h" > > char packet_buffer[LARGE_PACKET_MAX]; > +char packet_write_buffer[LARGE_PACKET_MAX]; Should this be static? I.e., are random other bits of the code allowed to write into it (I guess not because it's not declared in pkt-line.h). > +int packet_write_gently(const int fd_out, const char *buf, size_t size) > +{ > + if (size > PKTLINE_DATA_MAXLEN) > + return -1; > + packet_trace(buf, size, 1); > + memmove(packet_write_buffer + 4, buf, size); It looks like this iteration drops the idea of callers using a LARGE_PACKET_MAX buffer and only filling it at "buf+4" with PKTLINE_DATA_MAXLEN bytes (which is fine). I wonder if we still need PKTLINE_DATA_MAXLEN, or of it is just obscuring things. The magic number "4" still appears separately here, and it actually makes it harder to see that things are correct. I.e., doing: if (size > sizeof(packet_write_buffer) - 4) return -1; memmove(packet_write_buffer + 4, buf, size); is more obviously correct, because you do not have to wonder about the relationship between the size of your buffer and the macro. It might still be worth having PKTLINE_DATA_MAXLEN public, though, if callers use it to size their input to packet_write_gently(). -Peff