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=-3.4 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,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 1E3A41F8C5 for ; Thu, 17 Mar 2022 03:17:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242003AbiCQDS0 (ORCPT ); Wed, 16 Mar 2022 23:18:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39030 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244548AbiCQDSJ (ORCPT ); Wed, 16 Mar 2022 23:18:09 -0400 Received: from mail-wm1-x32c.google.com (mail-wm1-x32c.google.com [IPv6:2a00:1450:4864:20::32c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 11EB421246 for ; Wed, 16 Mar 2022 20:16:46 -0700 (PDT) Received: by mail-wm1-x32c.google.com with SMTP id q7-20020a7bce87000000b00382255f4ca9so4256540wmj.2 for ; Wed, 16 Mar 2022 20:16:45 -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=Q7v2mLorAec+4joH9KxenWTWCzFmP6q0r+BgYKi/NWc=; b=KBLqgzjsk/cD1/mJmnzSGGi8EHm7lBpi8pMtYt0khdYalHpwY/MTyUM0It/8BgXXI5 eCKm+LvhAli2zmuygaHwUXUlXmUzfyWSMgad3Jb8DbWvxjP44nuULSM/Cd99cK/FPu3b /ljrxHxuzCaIpCc2SZIVSbGRv/SaLBmcf8pwSvECPPdD2+gCd8wTY0c8yXc+8vzXkwlE JUqZuIDqN8NiJ8GoHzOWf4uJS1RGhiUOsx698I6jv9arnKoqXLnwukBSX0nC0L94hLVA sngfMQ/IZW6KWChmZ6guThOx9Y0hTX3XQ4Gz127k+FSsH1+P5ws+vl2Ti27fIk3CvzjS pSMg== 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=Q7v2mLorAec+4joH9KxenWTWCzFmP6q0r+BgYKi/NWc=; b=DZ51b5b5Y5/bSrqpVZWzSi7UxlSOUDZMIx4GYI7UibMDpj+xNI4T9/ZlwWOgtrwN4g dICdnGB2/fMb/91OJ6dL/Ts0Ffhm3KcihUxWldCMkptQJwf8DNamx6J/SnGzN+60mpO9 7GJX3nMKG/3rgubTOrXDtLc4GLUGCZjTZXTLZByLbEV+1KUjUN+RLlznf5qb5bhsf78E rRdH4RVl4ynIRWdpZH+8RpBV+ZznAsL81jtpBnsIajAQPZFdS+vuumAbBAVTiaeFmT6d aMrjE9k+PjT+l+pFEp1rZRpTNe0NgoiAljOhu8amM/f8D1oXQeWbV8txKj7HBuLZ4qqn PGdw== X-Gm-Message-State: AOAM533dawl9Sa/m/+X6JSKb3+44BhhR1ugcDiszsdaEeiDbrMjZeLBC Y3QnQcEQUldiQU8cmnJDO6sCm9SnzyQ= X-Google-Smtp-Source: ABdhPJxnD857xOo19/pSMahlo4jErVH3dBNwI9zH5Om0wHRlL6MszhLkdGO72EFDdV3W0WBLlWlt9A== X-Received: by 2002:a05:600c:3c9c:b0:389:cc3b:9462 with SMTP id bg28-20020a05600c3c9c00b00389cc3b9462mr9766194wmb.105.1647487004413; Wed, 16 Mar 2022 20:16:44 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id p125-20020a1c2983000000b00389cc36a3bfsm6573856wmp.6.2022.03.16.20.16.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Mar 2022 20:16:43 -0700 (PDT) Message-Id: In-Reply-To: References: From: "John Cai via GitGitGadget" Date: Thu, 17 Mar 2022 03:16:41 +0000 Subject: [PATCH v3 2/2] 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 , 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 a sha, 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(). update_refs() checks ropts.branch to decide whether or not to switch brancheds. 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 $(git rev-parse topic) without dereferencing it. Fix this bug by adding the RESET_HEAD_DETACH flag in checkout_up_to_date if is not a valid branch. so that once reset_head() calls update_refs(), it calls update_ref() with REF_NO_DEREF which updates HEAD directly intead of deferencing it and updating the branch that HEAD points to. Also add a test to ensure this behavior. 1. https://lore.kernel.org/git/xmqqsfrpbepd.fsf@gitster.g/ Reported-by: Michael McClimon Signed-off-by: John Cai --- builtin/rebase.c | 5 ++++- t/t3400-rebase.sh | 9 +++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/builtin/rebase.c b/builtin/rebase.c index b29ad2b65e7..5ae7fa2a169 100644 --- a/builtin/rebase.c +++ b/builtin/rebase.c @@ -827,8 +827,11 @@ static int checkout_up_to_date(struct rebase_options *options) getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options->switch_to); ropts.oid = &options->orig_head; - ropts.branch = options->head_name; ropts.flags = RESET_HEAD_RUN_POST_CHECKOUT_HOOK; + if (options->head_name) + ropts.branch = options->head_name; + else + ropts.flags |= RESET_HEAD_DETACH; ropts.head_msg = buf.buf; if (reset_head(the_repository, &ropts) < 0) ret = error(_("could not switch to %s"), options->switch_to); diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh index 0643d015255..d5a8ee39fc4 100755 --- a/t/t3400-rebase.sh +++ b/t/t3400-rebase.sh @@ -394,6 +394,15 @@ test_expect_success 'switch to branch not checked out' ' git rebase main other ' +test_expect_success 'switch to non-branch detaches HEAD' ' + git checkout main && + old_main=$(git rev-parse HEAD) && + git rebase First Second^0 && + test_cmp_rev HEAD 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' ' git checkout main && git worktree add wt && -- gitgitgadget