From patchwork Wed Sep 21 15:30:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Schindelin X-Patchwork-Id: 12983890 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 335F3ECAAD8 for ; Wed, 21 Sep 2022 15:35:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230342AbiIUPf3 (ORCPT ); Wed, 21 Sep 2022 11:35:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232024AbiIUPeh (ORCPT ); Wed, 21 Sep 2022 11:34:37 -0400 Received: from mail-wm1-x333.google.com (mail-wm1-x333.google.com [IPv6:2a00:1450:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5EC759C222 for ; Wed, 21 Sep 2022 08:31:59 -0700 (PDT) Received: by mail-wm1-x333.google.com with SMTP id n40-20020a05600c3ba800b003b49aefc35fso3987731wms.5 for ; Wed, 21 Sep 2022 08:31:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :message-id:from:to:cc:subject:date; bh=MabCfAzJk6F4sT/W3jKTzGUQFzPyLFyB/Yzr4hMqRlE=; b=YeiamJNTBF45njL/0u4Sfh8wcINfblydN6CBBoDmKEgJ2vev1W8sfRDrgBpfLPcnir USEaiB8d7DG1Cy5LqWbqZ1KTn2bIygKmVIBcMcZ2EHXNYL12XJiPOF1D19UkCORN23gN RCv3+S6G/ffJASK9H48EWuoaPRj2HxNPH3HlIEkjQ2XBqGTlggKUeF69VSzi+7/xcf1x jMAZVIzSB/u5KpVMCF/kLDjg7TyYOxHr9/TOIXoONMp44Cz9S3Slr+dbWwPf5C2YYvPD eAW+iv+sOT/UpS0bJE/sg1Ofa1ct+Is42A89JSYWuNh+uugr0dERuet+/ZAZF2/l7F4Q Lnpw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :message-id:x-gm-message-state:from:to:cc:subject:date; bh=MabCfAzJk6F4sT/W3jKTzGUQFzPyLFyB/Yzr4hMqRlE=; b=XZkzzADS80rho03BYUdm/EU4+AoazBcnZnC7rI28HiDAQvAuUyK7SUdLasZvtVyviC bLQlp0YJDqb4kkMq+kLRZH0vv+9KKUZqIPsSA4ZZeQ1VmmBmfqX46zXeKbO/acnVP7i9 T56b5vLKoFkqoYLgsE2wsesg04CyfmXpiqb5FnCss++a9qICPm/ZGNGI9U1EcbefJcHn sClMaSUngKxCMOE7ADlE4anuU9RK4cMQe4X1t6aCo68jKBMwBJueRUcUQaeE7oFWouzk 4lv3dkoN9B+EOViiRCvFr7Gdma3VjnbTW2THdL70Y9rcixd9Ecmft9u8FCHC+EriDuoM hDdg== X-Gm-Message-State: ACrzQf3fEpui/HKs1CiRGE8Vsce4IX5ctNwxNvlkiaSWGVUmah9cFS3u srs3bNSwz2Q7jl25r/Eg/VpH8Z+spNY= X-Google-Smtp-Source: AMsMyM5wtHMgrXlYNyLutpgd2KKSygPbL8lgx7y5KW1/AHOYKmAKp3gRl9Zn+YW+BY9A/Etf5nX/cw== X-Received: by 2002:a05:600c:1f0d:b0:3b4:ba4d:272a with SMTP id bd13-20020a05600c1f0d00b003b4ba4d272amr6490309wmb.105.1663774249741; Wed, 21 Sep 2022 08:30:49 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id l30-20020a05600c1d1e00b003a601a1c2f7sm3655540wms.19.2022.09.21.08.30.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Sep 2022 08:30:49 -0700 (PDT) Message-Id: Date: Wed, 21 Sep 2022 15:30:48 +0000 Subject: [PATCH] merge-tree: fix segmentation fault in read-only repositories Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Elijah Newren , Johannes Schindelin , Johannes Schindelin Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Johannes Schindelin From: Johannes Schindelin Independent of the question whether we want `git merge-tree` to report a tree name even when it failed to write the tree objects in a read-only repository, there is no question that we should avoid a segmentation fault. Signed-off-by: Johannes Schindelin --- merge-tree: fix segmentation fault in read-only repositories Turns out that the segmentation fault reported by Taylor [https://lore.kernel.org/git/YyopQD+LvPucnz3w@nand.local/] happened while testing merge-ort in a read-only repository, and that the upstream version of git merge-tree is as affected as GitHub's internal version. Note: I briefly considered using the OID of the_hash_algo->empty_tree instead of null_oid() when no tree object could be constructed. However, I have come to the conclusion that this could potentially cause its own set of problems because it would relate to a valid tree object even if we do not have any valid tree object to play with. Also note: The question I hinted at in the commit message, namely whether or not to try harder to construct a tree object even if we cannot write it out, maybe merits a longer discussion, one that I think we should have after v2.38.0 is released, so as not to distract from focusing on v2.38.0. Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1362%2Fdscho%2Fmerge-tree-in-read-only-repos-v1 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1362/dscho/merge-tree-in-read-only-repos-v1 Pull-Request: https://github.com/gitgitgadget/git/pull/1362 builtin/merge-tree.c | 4 +++- t/t4301-merge-tree-write-tree.sh | 8 ++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) base-commit: dda7228a83e2e9ff584bf6adbf55910565b41e14 diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c index ae5782917b9..25c7142a882 100644 --- a/builtin/merge-tree.c +++ b/builtin/merge-tree.c @@ -412,6 +412,7 @@ static int real_merge(struct merge_tree_options *o, struct commit_list *merge_bases = NULL; struct merge_options opt; struct merge_result result = { 0 }; + const struct object_id *tree_oid; parent1 = get_merge_parent(branch1); if (!parent1) @@ -446,7 +447,8 @@ static int real_merge(struct merge_tree_options *o, if (o->show_messages == -1) o->show_messages = !result.clean; - printf("%s%c", oid_to_hex(&result.tree->object.oid), line_termination); + tree_oid = result.tree ? &result.tree->object.oid : null_oid(); + printf("%s%c", oid_to_hex(tree_oid), line_termination); if (!result.clean) { struct string_list conflicted_files = STRING_LIST_INIT_NODUP; const char *last = NULL; diff --git a/t/t4301-merge-tree-write-tree.sh b/t/t4301-merge-tree-write-tree.sh index 28ca5c38bb5..e56b1ba6e50 100755 --- a/t/t4301-merge-tree-write-tree.sh +++ b/t/t4301-merge-tree-write-tree.sh @@ -810,4 +810,12 @@ test_expect_success 'can override merge of unrelated histories' ' test_cmp expect actual ' +test_expect_success 'merge-ort fails gracefully in a read-only repository' ' + git init --bare read-only && + git push read-only side1 side2 && + test_when_finished "chmod -R u+w read-only" && + chmod -R a-w read-only && + test_must_fail git -C read-only merge-tree side1 side2 +' + test_done