Re: [PATCH v8 07/10] qcow2_format.py: Dump bitmap table serialized entries

[Andrey Shinkevich]

On 03.07.2020 16:13, Andrey Shinkevich wrote:
> Add bitmap table information to the QCOW2 metadata dump.
...
> --- a/tests/qemu-iotests/qcow2_format.py
> +++ b/tests/qemu-iotests/qcow2_format.py
> @@ -171,14 +171,56 @@ class Qcow2BitmapDirEntry(Qcow2Struct):
>           entry_raw_size = self.bitmap_dir_entry_raw_size()
>           padding = ((entry_raw_size + 7) & ~7) - entry_raw_size
>           fd.seek(padding, 1)
> +        position = fd.tell()
> +        self.read_bitmap_table(fd)
> +        fd.seek(position)
>   
>       def bitmap_dir_entry_raw_size(self):
>           return struct.calcsize(self.fmt) + self.name_size + \
>               self.extra_data_size
>   
> +    def read_bitmap_table(self, fd):
> +        fd.seek(self.bitmap_table_offset)
> +        table_size = self.bitmap_table_size * 8 * 8
> +        table = [e[0] for e in struct.iter_unpack('>Q', fd.read(table_size))]
> +        self.bitmap_table = Qcow2BitmapTable(raw_table=table,
> +                                             cluster_size=self.cluster_size)

As an option, one make the class Qcow2BitmapTableEntry derived from 
Qcow2Struct

with the member:

fields = (

('u64', '{:#x}', 'table_entry')

)

and read entry by entry bitmap_table_size times from the disk in a loop.


Andrey

> +
>       def dump(self):
>           print(f'{"Bitmap name":<25} {self.name}')
>           super(Qcow2BitmapDirEntry, self).dump()
> +        self.bitmap_table.dump()
> +
> +
> +class Qcow2BitmapTableEntry:
> +
> +    BME_TABLE_ENTRY_OFFSET_MASK = 0x00fffffffffffe00
> +    BME_TABLE_ENTRY_FLAG_ALL_ONES = 1
> +
> +    def __init__(self, entry):
> +        self.offset = entry & self.BME_TABLE_ENTRY_OFFSET_MASK
> +        if self.offset:
> +            self.type = 'serialized'
> +        elif entry & self.BME_TABLE_ENTRY_FLAG_ALL_ONES:
> +            self.type = 'all-ones'
> +        else:
> +            self.type = 'all-zeroes'
> +
> +
> +class Qcow2BitmapTable:
> +
> +    def __init__(self, raw_table, cluster_size):
> +        self.entries = []
> +        self.cluster_size = cluster_size
> +        for entry in raw_table:
> +            self.entries.append(Qcow2BitmapTableEntry(entry))
> +
> +    def dump(self):
> +        size = self.cluster_size
> +        bitmap_table = enumerate(self.entries)
> +        print(f'{"Bitmap table":<14} {"type":<15} {"offset":<24} {"size"}')
> +        for i, entry in bitmap_table:
> +            print(f'{i:<14} {entry.type:<15} {entry.offset:<24} {size}')
>   
>   
>   QCOW2_EXT_MAGIC_BITMAPS = 0x23852875