From patchwork Mon Feb 27 16:27:25 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 143222 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 54C7DB6FBD for ; Tue, 28 Feb 2012 03:24:12 +1100 (EST) Received: from localhost ([::1]:54935 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S23Mw-0001l5-AW for incoming@patchwork.ozlabs.org; Mon, 27 Feb 2012 11:24:10 -0500 Received: from eggs.gnu.org ([208.118.235.92]:41862) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S23Ml-0001kk-1O for qemu-devel@nongnu.org; Mon, 27 Feb 2012 11:24:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S23Mj-0000zF-OY for qemu-devel@nongnu.org; Mon, 27 Feb 2012 11:23:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58291) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S23Mj-0000z9-GS for qemu-devel@nongnu.org; Mon, 27 Feb 2012 11:23:57 -0500 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q1RGNupF030001 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 27 Feb 2012 11:23:56 -0500 Received: from dhcp-5-188.str.redhat.com (vpn1-6-95.ams2.redhat.com [10.36.6.95]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q1RGNtYd003531; Mon, 27 Feb 2012 11:23:55 -0500 From: Kevin Wolf To: qemu-devel@nongnu.org Date: Mon, 27 Feb 2012 17:27:25 +0100 Message-Id: <1330360045-27198-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com Subject: [Qemu-devel] [PATCH] qcow2: Fix offset in qcow2_read_extensions X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org The spec says that the length of extensions is padded to 8 bytes, not the offset. Currently this is the same because the header size is a multiple of 8, so this is only about compatibility with future changes to the header size. While touching it, move the calculation to a common place instead of duplicating it for each header extension type. Signed-off-by: Kevin Wolf Reviewed-by: Stefan Hajnoczi --- block/qcow2.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index dea12c1..f68f0e1 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -126,7 +126,6 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset, #ifdef DEBUG_EXT printf("Qcow2: Got format extension %s\n", bs->backing_format); #endif - offset = ((offset + ext.len + 7) & ~7); break; default: @@ -143,11 +142,11 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset, if (ret < 0) { return ret; } - - offset = ((offset + ext.len + 7) & ~7); } break; } + + offset += ((ext.len + 7) & ~7); } return 0;