From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_NONE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 5BCE01F731 for ; Thu, 1 Aug 2019 17:24:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728916AbfHARYU (ORCPT ); Thu, 1 Aug 2019 13:24:20 -0400 Received: from siwi.pair.com ([209.68.5.199]:64810 "EHLO siwi.pair.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726017AbfHARYU (ORCPT ); Thu, 1 Aug 2019 13:24:20 -0400 Received: from siwi.pair.com (localhost [127.0.0.1]) by siwi.pair.com (Postfix) with ESMTP id 467893F40DA; Thu, 1 Aug 2019 13:24:19 -0400 (EDT) Received: from [IPv6:2001:4898:6808:13e:9bc:1dec:170a:44ce] (unknown [IPv6:2001:4898:a800:1010:baf1:1dec:170a:44ce]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by siwi.pair.com (Postfix) with ESMTPSA id E598B3F40D9; Thu, 1 Aug 2019 13:24:18 -0400 (EDT) Subject: Re: [PATCH v2 1/1] config: work around bug with includeif:onbranch and early config To: Jeff King , Johannes Schindelin Cc: Johannes Schindelin via GitGitGadget , git@vger.kernel.org, Junio C Hamano References: <20190731220204.GA1933@sigill.intra.peff.net> <20190731231257.GB1933@sigill.intra.peff.net> <20190801004928.GA6351@sigill.intra.peff.net> From: Jeff Hostetler Message-ID: <7f4257d3-5ae0-3a83-84f1-bee83682fa36@jeffhostetler.com> Date: Thu, 1 Aug 2019 13:24:17 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190801004928.GA6351@sigill.intra.peff.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On 7/31/2019 8:49 PM, Jeff King wrote: > On Wed, Jul 31, 2019 at 07:12:57PM -0400, Jeff King wrote: > >> Hrm. But common-main calls initialize_the_repository(), which points it >> at &the_repo. And I can't find any other assignments. So how does it >> become NULL? And is every caller of have_git_dir() at risk of >> segfaulting? >> >> Ah, I see. I think it is that trace2 reads the configuration very early. >> I think we ought to do this: >> >> diff --git a/common-main.c b/common-main.c >> index 582a7b1886..89fd415e55 100644 >> --- a/common-main.c >> +++ b/common-main.c >> @@ -39,14 +39,14 @@ int main(int argc, const char **argv) >> >> git_resolve_executable_dir(argv[0]); >> >> + initialize_the_repository(); >> + >> trace2_initialize(); >> trace2_cmd_start(argv); >> trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP); >> >> git_setup_gettext(); >> >> - initialize_the_repository(); >> - >> attr_start(); >> >> result = cmd_main(argc, argv); > > By the way, I wondered why trace2's existing config reading did not > cause us to segfault because of this. It is because it invented the > "very early config" function which always ignores some config sources > (working around this problem, but also making it weirdly unlike most > other config). Yes, I added the "very early config" to try to work around some of the chicken-n-egg problems. I can't say that I was completely happy with having to do that. I haven't had time to play with your patch suggestion here, but I think it would be fine to do if it will help with the original problem. In [1] I added code to just start the clock in isolation (rather than being part of the trace2_initialize() -- which does all the config loading and subsystem initialization). So it is OK to let the trace2_initialize() run a little later. (Part of the reason for that split was to allow git_resolve_executable_dir() to run first, since that data was needed to find the location of the system config relative to the exe path (sigh).) [1] a089724958a trace2: refactor setting process starting time So, as you suggested in your previous response, something like this would/should be fine. $ git diff diff --git a/common-main.c b/common-main.c index 582a7b1886..71e21dd20a 100644 --- a/common-main.c +++ b/common-main.c @@ -39,16 +39,16 @@ int main(int argc, const char **argv) git_resolve_executable_dir(argv[0]); - trace2_initialize(); - trace2_cmd_start(argv); - trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP); - git_setup_gettext(); initialize_the_repository(); attr_start(); + trace2_initialize(); + trace2_cmd_start(argv); + trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP); + result = cmd_main(argc, argv); trace2_cmd_exit(result);