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: AS3215 2.6.0.0/16 X-Spam-Status: No, score=-3.5 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by dcvr.yhbt.net (Postfix) with ESMTP id EE2AE1F8C5 for ; Thu, 17 Mar 2022 19:54:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229777AbiCQTzS (ORCPT ); Thu, 17 Mar 2022 15:55:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229630AbiCQTzO (ORCPT ); Thu, 17 Mar 2022 15:55:14 -0400 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C49B21593E for ; Thu, 17 Mar 2022 12:53:53 -0700 (PDT) Received: by mail-wm1-x336.google.com with SMTP id bi13-20020a05600c3d8d00b0038c2c33d8f3so2896636wmb.4 for ; Thu, 17 Mar 2022 12:53:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=ziQ91RNazjwTIQyvEbsgGE6LoYOwbXNj2YyU1ILBdSI=; b=hoq+71LSDiJUUsl4bzxCzNUUNQGn76CffkGjFOYO6jtRY72y7nnImMsZx7MZBGy8sH RV5zJtwWJpwt7BQ9bsZ1MDdI+cbs3PbC9ppWu5NNq7rEk6ZhzdtPveY/qMgCM2eakZXS xg7vQJrZrJtwWHzRhGOHODDawOISE0b9cChEwPzUC05phTjPiM1G5M4fc0tzmKM3gezO q67NwCk8BRL25NdeCp0fwlq/XXZGWx6f8N3dWVTCRfvn8yBzJfKEg2Z2fSajxdQDm1rZ 8yIGleZuoN6ipcXPhJIHc55HU6enECyagzkp3MB9ok6ECt+Xc/J8ysdEV1Y3nuv8rmRL 1dxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=ziQ91RNazjwTIQyvEbsgGE6LoYOwbXNj2YyU1ILBdSI=; b=Vgpmv9gpzf3tmG2neayBJxtBy0uxCIRa2c8UlrXi9Al/GkDwjvxKjYPAo40SbAIIds QF/I33zwyc6UGFvY8aPD4g5UWC+txf6cxwaJcmfUR7X5hi1+eXF9ShVYIRzauHYngjz4 VzWRUzs89tuTwPv4bsY2d+BdMGFFrcq0g42j2p57FFn23UmZ4nhiFrOxBaJ990Ku3rQk m8qeIDH5OXREopyQIVA0u9KLpMuo2M0S2/8JMimn0FRGNlR14gAl4V518fEMJX1SDmQd n9DqxyMIZzjAOPpt6avcXhhMKS70yrf8G574KS3RJmE9qGDG05Te0NL+bxIC97eEF/e8 3khA== X-Gm-Message-State: AOAM531/y2I6npXeYMWC1f1eBYSbo7xVhRdysThDSW2siu0dGz6z7Rn+ Vk3mrAKnrYIWFOox22x1O5qo2AuOOGY= X-Google-Smtp-Source: ABdhPJxi0MJwS3/e5V26uVQtozD9W8/hYMahJImiG6QXXfea6lh+XQSCsOBtHdgvTx52YAkNga1b9Q== X-Received: by 2002:a05:600c:3b26:b0:38c:8358:4b84 with SMTP id m38-20020a05600c3b2600b0038c83584b84mr2271059wms.185.1647546831623; Thu, 17 Mar 2022 12:53:51 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id k2-20020a1ca102000000b0038c78fdd59asm2240487wme.39.2022.03.17.12.53.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Mar 2022 12:53:51 -0700 (PDT) Message-Id: <13c5955c317713bbc6a91b9f44081395880abb67.1647546828.git.gitgitgadget@gmail.com> In-Reply-To: References: From: "John Cai via GitGitGadget" Date: Thu, 17 Mar 2022 19:53:48 +0000 Subject: [PATCH v4 3/3] rebase: set REF_HEAD_DETACH in checkout_up_to_date() Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit MIME-Version: 1.0 To: git@vger.kernel.org Cc: Phillip Wood , Junio C Hamano , =?UTF-8?Q?=C3=86var_Arnfj=C3=B6r=C3=B0?= Bjarmason , John Cai , John Cai Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: John Cai Fixes a bug whereby rebase updates the deferenced reference HEAD points to instead of HEAD directly. If HEAD is on main and if the following is a fast-forward operation, git rebase $(git rev-parse main) $(git rev-parse topic) Instead of HEAD being set to $(git rev-parse topic), rebase erroneously dereferences HEAD and sets main to $(git rev-parse topic). See [1] for the original bug report. The callstack from checkout_up_to_date() is the following: cmd_rebase() -> checkout_up_to_date() -> reset_head() -> update_refs() -> update_ref() When is not a valid branch but an oid, rebase sets the head_name of rebase_options to NULL. This value gets passed down this call chain through the branch member of reset_head_opts also getting set to NULL all the way to update_refs(). Then update_refs() checks ropts.branch to decide whether or not to switch branches. If ropts.branch is NULL, it calls update_ref() to update HEAD. At this point however, from rebase's point of view, we want a detached HEAD. But, since checkout_up_to_date() does not set the RESET_HEAD_DETACH flag, the update_ref() call will deference HEAD and update the branch its pointing to, which in the above example is main. The correct behavior is that git rebase should update HEAD to $(git rev-parse topic) without dereferencing it. Fix this bug by adding the RESET_HEAD_DETACH flag in checkout_up_to_date if is not a valid branch. so that once reset_head() calls update_refs(), it calls update_ref() with REF_NO_DEREF which updates HEAD directly intead of deferencing it and updating the branch that HEAD points to. Also add a test to ensure the correct behavior. 1. https://lore.kernel.org/git/xmqqsfrpbepd.fsf@gitster.g/ Signed-off-by: John Cai --- builtin/rebase.c | 2 ++ t/t3400-rebase.sh | 8 ++++---- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/builtin/rebase.c b/builtin/rebase.c index b29ad2b65e7..27fde7bf281 100644 --- a/builtin/rebase.c +++ b/builtin/rebase.c @@ -829,6 +829,8 @@ static int checkout_up_to_date(struct rebase_options *options) ropts.oid = &options->orig_head; ropts.branch = options->head_name; ropts.flags = RESET_HEAD_RUN_POST_CHECKOUT_HOOK; + if (!ropts.branch) + ropts.flags |= RESET_HEAD_DETACH; ropts.head_msg = buf.buf; if (reset_head(the_repository, &ropts) < 0) ret = error(_("could not switch to %s"), options->switch_to); diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh index 2fb3fabe60e..cf55b017ffc 100755 --- a/t/t3400-rebase.sh +++ b/t/t3400-rebase.sh @@ -389,13 +389,13 @@ test_expect_success 'switch to branch not checked out' ' git rebase main other ' -test_expect_success 'switch to non-branch changes branch HEAD points to' ' +test_expect_success 'switch to non-branch detaches HEAD' ' git checkout main && old_main=$(git rev-parse HEAD) && git rebase First Second^0 && - test_cmp_rev HEAD main && - test_cmp_rev main $(git rev-parse Second) && - git symbolic-ref HEAD + test_cmp_rev HEAD Second && + test_cmp_rev main $old_main && + test_must_fail git symbolic-ref HEAD ' test_expect_success 'refuse to switch to branch checked out elsewhere' ' -- gitgitgadget