[PULL 09/14] qcow2_format.py: collect fields to dump in JSON format

[Eric Blake]

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

As __dict__ is being extended with class members we do not want to
print, add the to_json() method to classes that returns a json-dumpable
object with desired fields and their values. Extend it in subclass when
necessary to print the final dictionary in the JSON output which
follows.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: 
<1596742557-320265-10-git-send-email-andrey.shinkevich@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/qcow2_format.py | 36 ++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/tests/qemu-iotests/qcow2_format.py 
b/tests/qemu-iotests/qcow2_format.py
index de0adcbf9db0..5a298b2f1357 100644
--- a/tests/qemu-iotests/qcow2_format.py
+++ b/tests/qemu-iotests/qcow2_format.py
@@ -119,6 +119,9 @@ class Qcow2Struct(metaclass=Qcow2StructMeta):

             print('{:<25} {}'.format(f[2], value_str))

+    def to_json(self):
+        return dict((f[2], self.__dict__[f[2]]) for f in self.fields)
+

 class Qcow2BitmapExt(Qcow2Struct):

@@ -151,6 +154,11 @@ class Qcow2BitmapExt(Qcow2Struct):
             print()
             entry.dump()

+    def to_json(self):
+        fields_dict = super().to_json()
+        fields_dict['bitmap_directory'] = self.bitmap_directory
+        return fields_dict
+

 class Qcow2BitmapDirEntry(Qcow2Struct):

@@ -189,6 +197,14 @@ class Qcow2BitmapDirEntry(Qcow2Struct):
         super(Qcow2BitmapDirEntry, self).dump()
         self.bitmap_table.dump()

+    def to_json(self):
+        # Put the name ahead of the dict
+        return {
+            'name': self.name,
+            **super().to_json(),
+            'bitmap_table': self.bitmap_table
+        }
+

 class Qcow2BitmapTableEntry(Qcow2Struct):

@@ -214,6 +230,10 @@ class Qcow2BitmapTableEntry(Qcow2Struct):
         else:
             self.type = 'all-zeroes'

+    def to_json(self):
+        return {'type': self.type, 'offset': self.offset,
+                'reserved': self.reserved}
+

 class Qcow2BitmapTable:

@@ -234,6 +254,9 @@ class Qcow2BitmapTable:
                 size = 0
             print(f'{i:<14} {entry.type:<15} {size:<12} {entry.offset}')

+    def to_json(self):
+        return self.entries
+

 QCOW2_EXT_MAGIC_BITMAPS = 0x23852875

@@ -249,6 +272,9 @@ class QcowHeaderExtension(Qcow2Struct):
             0x44415441: 'Data file'
         }

+        def to_json(self):
+            return self.mapping.get(self.value, "<unknown>")
+
     fields = (
         ('u32', Magic, 'magic'),
         ('u32', '{}', 'length')
@@ -311,6 +337,16 @@ class QcowHeaderExtension(Qcow2Struct):
         else:
             self.obj.dump()

+    def to_json(self):
+        # Put the name ahead of the dict
+        res = {'name': self.Magic(self.magic), **super().to_json()}
+        if self.obj is not None:
+            res['data'] = self.obj
+        else:
+            res['data_str'] = self.data_str
+
+        return res
+
     @classmethod
     def create(cls, magic, data):
         return QcowHeaderExtension(magic, len(data), data)
-- 
2.28.0