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=-4.2 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 61B6D201B0 for ; Wed, 22 Feb 2017 19:16:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755161AbdBVTQr (ORCPT ); Wed, 22 Feb 2017 14:16:47 -0500 Received: from cloud.peff.net ([104.130.231.41]:60117 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755154AbdBVTQp (ORCPT ); Wed, 22 Feb 2017 14:16:45 -0500 Received: (qmail 17710 invoked by uid 109); 22 Feb 2017 19:16:44 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Wed, 22 Feb 2017 19:16:44 +0000 Received: (qmail 26473 invoked by uid 111); 22 Feb 2017 19:16:47 -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, 22 Feb 2017 14:16:47 -0500 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Wed, 22 Feb 2017 14:16:42 -0500 Date: Wed, 22 Feb 2017 14:16:42 -0500 From: Jeff King To: Junio C Hamano Cc: "brian m. carlson" , git@vger.kernel.org, Michael Haggerty , Ramsay Jones Subject: Re: [PATCH v5 03/19] builtin/diff-tree: convert to struct object_id Message-ID: <20170222191641.o2rtt2ymtb4h2yqe@sigill.intra.peff.net> References: <20170221234737.894681-1-sandals@crustytoothpaste.net> <20170221234737.894681-4-sandals@crustytoothpaste.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Feb 22, 2017 at 10:50:21AM -0800, Junio C Hamano wrote: > "brian m. carlson" writes: > > > Convert most leaf functions to struct object_id. Change several > > hardcoded numbers to uses of parse_oid_hex. In doing so, verify that we > > when we want two trees, we have exactly two trees. > > > > Finally, in stdin_diff_commit, avoid accessing the byte after the NUL. > > This will be a NUL as well, since the first NUL was a newline we > > overwrote. However, with parse_oid_hex, we no longer need to increment > > the pointer directly, and can simply increment it as part of our check > > for the space character. > > After reading the pre- and post-image twice, I think I convinced > myself that this is a faithful conersion and they do the same thing. I think this is correct, too (but then, I think it largely comes from the patch I wrote the other night. So I did look at it carefully, but it's not exactly an independent review). > What the function does appears somewhat iffy in the modern world. > We are relying on the fact that while Git is operating in this mode > of reading a tuple of commits per line and doing log-tree, that Git > itself will not do the history traversal (instead, another instance > of Git that feeds us via our standard input is walking the history) > for this piece of code to work correctly. > > Of course, the "diff-tree --stdin" command was meant to sit on the > downstream of "rev-list --parents", so the assumption the code makes > (i.e. the parents field of the in-core commit objects do not have to > be usable for history traversal) may be reasonable, but still... I'm not sure it's that weird. "diff-tree" is about diffing, not traversal. The only reason it touches commit->parents at all (and doesn't just kick off a diff between the arguments it gets) is that it's been stuck with pretty-printing the commits, which might ask to show the parents. -Peff