From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54427) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WkwY4-0003Lo-0U for qemu-devel@nongnu.org; Thu, 15 May 2014 10:22:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WkwXw-0003VM-BP for qemu-devel@nongnu.org; Thu, 15 May 2014 10:22:15 -0400 From: Kevin Wolf Date: Thu, 15 May 2014 16:21:53 +0200 Message-Id: <1400163717-1898-2-git-send-email-kwolf@redhat.com> In-Reply-To: <1400163717-1898-1-git-send-email-kwolf@redhat.com> References: <1400163717-1898-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH v2 1/5] qcow1: Make padding in the header explicit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, benoit.canet@irqsave.net, qemu-stable@nongnu.org, stefanha@redhat.com, ppandit@redhat.com We were relying on all compilers inserting the same padding in the header struct that is used for the on-disk format. Let's not do that. Mark the struct as packed and insert an explicit padding field for compatibility. Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf Reviewed-by: Benoit Canet --- block/qcow.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/qcow.c b/block/qcow.c index 937dd6d..3684794 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -48,9 +48,10 @@ typedef struct QCowHeader { uint64_t size; /* in bytes */ uint8_t cluster_bits; uint8_t l2_bits; + uint16_t padding; uint32_t crypt_method; uint64_t l1_table_offset; -} QCowHeader; +} QEMU_PACKED QCowHeader; #define L2_CACHE_SIZE 16 -- 1.8.3.1