From 709786ed4fa98cd281beaac3c6770292bd045a30 Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Wed, 7 May 2014 16:56:10 +0200

Subject: [PATCH] qcow1: Make padding in the header explicit

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 <kwolf@redhat.com>

Reviewed-by: Benoit Canet <benoit@irqsave.net>

(cherry picked from commit ea54feff58efedc809641474b25a3130309678e7)

---

 block/qcow.c | 3 ++-

 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/qcow.c b/block/qcow.c

index d5a7d5f..9018f44 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