From patchwork Wed Jan 18 20:55:55 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 716839 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3v3fbR5q2Zz9t23 for ; Thu, 19 Jan 2017 08:04:03 +1100 (AEDT) Received: from localhost ([::1]:44305 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cTxOj-0001FW-DT for incoming@patchwork.ozlabs.org; Wed, 18 Jan 2017 16:04:01 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41550) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cTxH0-0003tU-CG for qemu-devel@nongnu.org; Wed, 18 Jan 2017 15:56:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cTxGz-00010U-1P for qemu-devel@nongnu.org; Wed, 18 Jan 2017 15:56:02 -0500 Received: from mail.kernel.org ([198.145.29.136]:56652) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cTxGy-0000zb-RG for qemu-devel@nongnu.org; Wed, 18 Jan 2017 15:56:00 -0500 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 82557203E3; Wed, 18 Jan 2017 20:55:58 +0000 (UTC) Received: from redhat.com (unknown [66.187.232.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E336E203DC; Wed, 18 Jan 2017 20:55:56 +0000 (UTC) Date: Wed, 18 Jan 2017 22:55:55 +0200 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Message-ID: <1484772931-16272-5-git-send-email-mst@redhat.com> References: <1484772931-16272-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1484772931-16272-1-git-send-email-mst@redhat.com> X-Mailer: git-send-email 2.8.0.287.g0deeb61 X-Mutt-Fcc: =sent X-Virus-Scanned: ClamAV using ClamSMTP X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 198.145.29.136 Subject: [Qemu-devel] [PATCH v2 4/4] ARRAY_SIZE: check that argument is an array X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, Sergey Fedorov , Markus Armbruster , Peter Maydell Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" It's a familiar pattern: some code uses ARRAY_SIZE, then refactoring changes the argument from an array to a pointer to a dynamically allocated buffer. Code keeps compiling but any ARRAY_SIZE calls now return the size of the pointer divided by element size. Let's add build time checks to ARRAY_SIZE before we allow more of these in the code-base. Signed-off-by: Michael S. Tsirkin Reviewed-by: Markus Armbruster --- include/qemu/osdep.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 689f253..24bfda0 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -199,7 +199,13 @@ extern int daemon(int, int); #endif #ifndef ARRAY_SIZE -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +/* + * &(x)[0] is always a pointer - if it's same type as x then the argument is a + * pointer, not an array as expected. + */ +#define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + QEMU_BUILD_BUG_ON_ZERO( \ + __builtin_types_compatible_p(typeof(x), \ + typeof(&(x)[0])))) #endif int qemu_daemon(int nochdir, int noclose);