[PULL 06/14] qcow2_format.py: pass cluster size to substructures

[Eric Blake <eblake@redhat.com>]

From: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>

The cluster size of an image is the QcowHeader class member and may be
obtained by dependent extension structures such as Qcow2BitmapExt for
further bitmap table details print.

Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <1596742557-320265-7-git-send-email-andrey.shinkevich@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/qcow2_format.py | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/qcow2_format.py b/tests/qemu-iotests/qcow2_format.py
index 05a8aa98f72c..ca0d3501e0a2 100644
--- a/tests/qemu-iotests/qcow2_format.py
+++ b/tests/qemu-iotests/qcow2_format.py
@@ -129,19 +129,21 @@ class Qcow2BitmapExt(Qcow2Struct):
         ('u64', '{:#x}', 'bitmap_directory_offset')
     )

-    def __init__(self, fd):
+    def __init__(self, fd, cluster_size):
         super().__init__(fd=fd)
         tail = struct.calcsize(self.fmt) % 8
         if tail:
             fd.seek(8 - tail, 1)
         position = fd.tell()
+        self.cluster_size = cluster_size
         self.read_bitmap_directory(fd)
         fd.seek(position)

     def read_bitmap_directory(self, fd):
         fd.seek(self.bitmap_directory_offset)
         self.bitmap_directory = \
-            [Qcow2BitmapDirEntry(fd) for _ in range(self.nb_bitmaps)]
+            [Qcow2BitmapDirEntry(fd, cluster_size=self.cluster_size)
+             for _ in range(self.nb_bitmaps)]

     def dump(self):
         super().dump()
@@ -162,8 +164,9 @@ class Qcow2BitmapDirEntry(Qcow2Struct):
         ('u32', '{}', 'extra_data_size')
     )

-    def __init__(self, fd):
+    def __init__(self, fd, cluster_size):
         super().__init__(fd=fd)
+        self.cluster_size = cluster_size
         # Seek relative to the current position in the file
         fd.seek(self.extra_data_size, 1)
         bitmap_name = fd.read(self.name_size)
@@ -203,11 +206,13 @@ class QcowHeaderExtension(Qcow2Struct):
         # then padding to next multiply of 8
     )

-    def __init__(self, magic=None, length=None, data=None, fd=None):
+    def __init__(self, magic=None, length=None, data=None, fd=None,
+                 cluster_size=None):
         """
         Support both loading from fd and creation from user data.
         For fd-based creation current position in a file will be used to read
         the data.
+        The cluster_size value may be obtained by dependent structures.

         This should be somehow refactored and functionality should be moved to
         superclass (to allow creation of any qcow2 struct), but then, fields
@@ -230,7 +235,7 @@ class QcowHeaderExtension(Qcow2Struct):
             assert all(v is None for v in (magic, length, data))
             super().__init__(fd=fd)
             if self.magic == QCOW2_EXT_MAGIC_BITMAPS:
-                self.obj = Qcow2BitmapExt(fd=fd)
+                self.obj = Qcow2BitmapExt(fd=fd, cluster_size=cluster_size)
                 self.data = None
             else:
                 padded = (self.length + 7) & ~7
@@ -319,7 +324,7 @@ class QcowHeader(Qcow2Struct):
             end = self.cluster_size

         while fd.tell() < end:
-            ext = QcowHeaderExtension(fd=fd)
+            ext = QcowHeaderExtension(fd=fd, cluster_size=self.cluster_size)
             if ext.magic == 0:
                 break
             else:
-- 
2.28.0