qcow2.py: Add required padding for header extensions

The qcow2 specification requires that the header extension data be
padded to round up the extension size to the next multiple of 8 bytes.

Signed-off-by: Kevin Wolf <[email protected]>
Reviewed-by: Max Reitz <[email protected]>
Message-id: [email protected]
Signed-off-by: Stefan Hajnoczi <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
(cherry picked from commit 8884dd1)
Signed-off-by: Michael Roth <[email protected]>
(cherry picked from commit a163ac3f57b5baa117158f7c0488d276ba3377e2)
Signed-off-by: Michael Roth <[email protected]>

Author: kevmw

tests/qemu-iotests/qcow2.py

@@ -7,6 +7,10 @@
 class QcowHeaderExtension:
 
     def __init__(self, magic, length, data):
+        if length % 8 != 0:
+            padding = 8 - (length % 8)
+            data += "\0" * padding
+
         self.magic  = magic
         self.length = length
         self.data   = data