From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58556) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cTwsX-0007NJ-0O for qemu-devel@nongnu.org; Wed, 18 Jan 2017 15:30:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cTwsW-0001en-CS for qemu-devel@nongnu.org; Wed, 18 Jan 2017 15:30:45 -0500 Received: from mail.kernel.org ([198.145.29.136]:49666) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cTwsW-0001dc-53 for qemu-devel@nongnu.org; Wed, 18 Jan 2017 15:30:44 -0500 Date: Wed, 18 Jan 2017 22:30:38 +0200 From: "Michael S. Tsirkin" Message-ID: <1484771412-28024-5-git-send-email-mst@redhat.com> References: <1484771412-28024-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1484771412-28024-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PATCH 4/4] ARRAY_SIZE: check that argument is an array List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com, Eric Blake , Peter Maydell , Markus Armbruster , Sergey Fedorov 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 --- 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); -- MST