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[116/156] qcow1: Make padding in the header explicit

Message ID 1404839947-1086-117-git-send-email-mdroth@linux.vnet.ibm.com
State New
Headers show

Commit Message

Michael Roth July 8, 2014, 5:18 p.m. UTC 
From: Kevin Wolf <kwolf@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 <kwolf@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
(cherry picked from commit ea54feff58efedc809641474b25a3130309678e7)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 block/qcow.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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Patch

diff --git a/block/qcow.c b/block/qcow.c
index c470e05..1ca04e6 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