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[PULL 10/15] qcow2_format.py: add field-formatting class
From: |
Eric Blake |
Subject: |
[PULL 10/15] qcow2_format.py: add field-formatting class |
Date: |
Tue, 9 Jun 2020 15:52:40 -0500 |
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Allow formatter class in structure definition instead of hacking with
'mask'. This will simplify further introduction of new formatters.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200606081806.23897-10-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
tests/qemu-iotests/qcow2_format.py | 35 +++++++++++++++++++++---------
1 file changed, 25 insertions(+), 10 deletions(-)
diff --git a/tests/qemu-iotests/qcow2_format.py
b/tests/qemu-iotests/qcow2_format.py
index 898d388b8adf..74a82f9263d4 100644
--- a/tests/qemu-iotests/qcow2_format.py
+++ b/tests/qemu-iotests/qcow2_format.py
@@ -20,6 +20,25 @@ import struct
import string
+class Qcow2Field:
+
+ def __init__(self, value):
+ self.value = value
+
+ def __str__(self):
+ return str(self.value)
+
+
+class Flags64(Qcow2Field):
+
+ def __str__(self):
+ bits = []
+ for bit in range(64):
+ if self.value & (1 << bit):
+ bits.append(bit)
+ return str(bits)
+
+
class Qcow2StructMeta(type):
# Mapping from c types to python struct format
@@ -70,14 +89,10 @@ class Qcow2Struct(metaclass=Qcow2StructMeta):
def dump(self):
for f in self.fields:
value = self.__dict__[f[2]]
- if f[1] == 'mask':
- bits = []
- for bit in range(64):
- if value & (1 << bit):
- bits.append(bit)
- value_str = str(bits)
- else:
+ if isinstance(f[1], str):
value_str = f[1].format(value)
+ else:
+ value_str = str(f[1](value))
print('{:<25} {}'.format(f[2], value_str))
@@ -117,9 +132,9 @@ class QcowHeader(Qcow2Struct):
('u64', '{:#x}', 'snapshot_offset'),
# Version 3 header fields
- ('u64', 'mask', 'incompatible_features'),
- ('u64', 'mask', 'compatible_features'),
- ('u64', 'mask', 'autoclear_features'),
+ ('u64', Flags64, 'incompatible_features'),
+ ('u64', Flags64, 'compatible_features'),
+ ('u64', Flags64, 'autoclear_features'),
('u32', '{}', 'refcount_order'),
('u32', '{}', 'header_length'),
)
--
2.27.0
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