There are two ways to initialize a class derived from Qcow2Struct:
1. Pass a block of binary data to the constructor.
2. Pass the file descriptor to allow reading the file from constructor.
Let's change the Qcow2BitmapExt initialization method from 1 to 2 to
support a scattered reading in the initialization chain.
The implementation comes with the patch that follows.
Suggested-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com>
---
tests/qemu-iotests/qcow2_format.py | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)
diff --git a/tests/qemu-iotests/qcow2_format.py
b/tests/qemu-iotests/qcow2_format.py
index 2f3681b..cbaffc4 100644
--- a/tests/qemu-iotests/qcow2_format.py
+++ b/tests/qemu-iotests/qcow2_format.py
@@ -113,6 +113,11 @@ class Qcow2BitmapExt(Qcow2Struct):
('u64', '{:#x}', 'bitmap_directory_offset')
)
+ def __init__(self, fd):
+ super().__init__(fd=fd)
+ pad = (struct.calcsize(self.fmt) + 7) & ~7
+ if pad:
+ fd.seek(pad, 1)
QCOW2_EXT_MAGIC_BITMAPS = 0x23852875
@@ -161,21 +166,21 @@ class QcowHeaderExtension(Qcow2Struct):
else:
assert all(v is None for v in (magic, length, data))
super().__init__(fd=fd)
- padded = (self.length + 7) & ~7
- self.data = fd.read(padded)
- assert self.data is not None
-
- data_str = self.data[:self.length]
- if all(c in string.printable.encode('ascii') for c in data_str):
- data_str = f"'{ data_str.decode('ascii') }'"
- else:
- data_str = '<binary>'
- self.data_str = data_str
+ if self.magic == QCOW2_EXT_MAGIC_BITMAPS:
+ self.obj = Qcow2BitmapExt(fd=fd)
+ else:
+ padded = (self.length + 7) & ~7
+ self.data = fd.read(padded)
+ assert self.data is not None
+ self.obj = None
+ data_str = self.data[:self.length]
+ if all(c in string.printable.encode(
+ 'ascii') for c in data_str):
+ data_str = f"'{ data_str.decode('ascii') }'"
+ else:
+ data_str = '<binary>'
+ self.data_str = data_str
- if self.magic == QCOW2_EXT_MAGIC_BITMAPS:
- self.obj = Qcow2BitmapExt(data=self.data)
- else:
- self.obj = None
def dump(self):
super().dump()
--
1.8.3.1
