From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11785C64E7A for ; Tue, 1 Dec 2020 11:11:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A11A520809 for ; Tue, 1 Dec 2020 11:11:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="c9c8FDAP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727473AbgLALLM (ORCPT ); Tue, 1 Dec 2020 06:11:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726344AbgLALLM (ORCPT ); Tue, 1 Dec 2020 06:11:12 -0500 Received: from mail-vk1-xa44.google.com (mail-vk1-xa44.google.com [IPv6:2607:f8b0:4864:20::a44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41C32C0613D2 for ; Tue, 1 Dec 2020 03:10:26 -0800 (PST) Received: by mail-vk1-xa44.google.com with SMTP id u16so337617vkb.1 for ; Tue, 01 Dec 2020 03:10:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Aqtwzq5BemVUGNUP5RyBwytY0JIZkCss0EBQtIgx2NQ=; b=c9c8FDAP6H92oevgIsqjVoa11gSH4KtBuJDwyHUeNrqoFwv+LJzDxRGmUrX3diY+Xp qswNDOPjtIhVqcXIfefK5dMV1ygpWPKBYfZn2hd0+oEvw8kKNtfB7QDMf0MMH8e5+/tI 8I+lUI+6VTa6EmiliujziA0IvmhS6B4db2bKIEaPhTcdEZSZ2f/4XgWRWnB4hSoHFGLH U4hgTkwKdx0B+jR76vSovLS8V3OBVsmT3L/eEpJeFSvOqUSlg8Yb0yLgAuLNjS2OMCA3 UcqdVmiKMM0GpRjyyzw2rmqUeYORlCYS3HzqAx5XdyauwA5Ogc77mkhw0SfBxs6G0/SJ 1Wrw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Aqtwzq5BemVUGNUP5RyBwytY0JIZkCss0EBQtIgx2NQ=; b=oQK91FomCc/kftYooue+OF8eKV1DIG3JMhP2qImNADquyBXwJxhX80XD5TMP36WP+A oieByYniCiXxCY21i8nuOOGV113wnM+pCZi+Cf8ynblPHDlFdIXItiOGKPJeKiUF8dga GlnovFXIBJ/UgLwRKKTqfGrhVibL4kOrCkJersG00BHGgqHZfA+9piyXyxMXZAY8RtUa gMk1VIP+8kPVf2Wpvd1uQQyCdxXwdKOTZr+R/eWLN8hdTUnWzcO1j+T6IEK8joV3SQiG zCgbvS7id0IEjLInHLmDjhjwa/r76hvF0T8h0qWQj7JJRpHFSEt9/FyxRX6ZBvzErZIe wl9g== X-Gm-Message-State: AOAM531AyHZGDdTBb/MzS+InfZoQjenE379deVxHrlUmHbZ+Rx28VTP1 Ioum7RhXJDzSN2ajgbaEgsJYXbz3cKitlwBuPYGCjQ== X-Google-Smtp-Source: ABdhPJxf+muedVxxhA5DcTRDJuI68+kPjR+FfUK9AtNP3emfmnjgFOGKtKevwl3qfJ8+7WerIndzL9SGauBsxO2SbUs= X-Received: by 2002:ac5:c55c:: with SMTP id d28mr1600394vkl.19.1606821025257; Tue, 01 Dec 2020 03:10:25 -0800 (PST) MIME-Version: 1.0 References: <58f2b0394546e8da2922adcbc38bdb6b53f2b313.1606545878.git.gitgitgadget@gmail.com> In-Reply-To: From: Han-Wen Nienhuys Date: Tue, 1 Dec 2020 12:10:14 +0100 Message-ID: Subject: Re: [PATCH 3/6] fixup! reftable: rest of library To: Jeff King Cc: Johannes Schindelin via GitGitGadget , git , Han-Wen Nienhuys , Johannes Schindelin Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Tue, Dec 1, 2020 at 11:26 AM Jeff King wrote: > > On Sat, Nov 28, 2020 at 06:44:35AM +0000, Johannes Schindelin via GitGitG= adget wrote: > > > From: Johannes Schindelin > > > > 0-sized arrays are actually not portable. > > Definitely. > > > static void test_sizes_to_segments_empty(void) > > { > > - uint64_t sizes[0]; > > + uint64_t sizes[1]; > > > > int seglen =3D 0; > > struct segment *segs =3D > > - sizes_to_segments(&seglen, sizes, ARRAY_SIZE(sizes)); > > + sizes_to_segments(&seglen, sizes, 0); > > EXPECT(seglen =3D=3D 0); > > reftable_free(segs); > > I think passing: > > sizes_to_segments(&seglen, NULL, 0); > > may make the code more obvious. Unlike system functions like memcpy(), > we can be assured of whether our functions avoid looking at a > zero-length array (and size_to_segments does follow that rule). > > This function, of course, is nonsense that real code would not do, and This test was added because 'real' code did this. In particular, if you initialize a stack of reftables, the stack has zero elements. The test was for the following bugfix https://github.com/google/reftable/commit/b2e42ecb54e413e494c1fcc13c21e2442= 2645007 Changing the array size to 1 here also prevents Valgrind to mark a regression as a OOB write. --=20 Han-Wen Nienhuys - Google Munich I work 80%. Don't expect answers from me on Fridays. -- Google Germany GmbH, Erika-Mann-Strasse 33, 80636 Munich Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado