Re: [PATCH v8 05/10] qcow2_format.py: Dump bitmap directory information

[Andrey Shinkevich]

On 11.07.2020 22:11, Vladimir Sementsov-Ogievskiy wrote:
> 03.07.2020 16:13, Andrey Shinkevich wrote:
> > Read and dump entries from the bitmap directory of QCOW2 image.
> > It extends the output in the test case #291.
...
> >   diff --git a/tests/qemu-iotests/qcow2_format.py 
> > b/tests/qemu-iotests/qcow2_format.py
> > index d8c058d..7c0dc9a 100644
> > --- a/tests/qemu-iotests/qcow2_format.py
> > +++ b/tests/qemu-iotests/qcow2_format.py
> > @@ -132,6 +132,50 @@ class Qcow2BitmapExt(Qcow2Struct):
> >         def __init__(self, fd):
> >           super().__init__(fd=fd)
> > +        self.read_bitmap_directory(fd)
> > +
> > +    def read_bitmap_directory(self, fd):
> > +        fd.seek(self.bitmap_directory_offset)
> > +        self.bitmap_directory = \
> > +            [Qcow2BitmapDirEntry(fd) for _ in range(self.nb_bitmaps)]
>
> sounds good. I think, we should restore fd position after reading 
> bitmap_directory, to point at the end of extension, to not break 
> further extensions loading
Yes, it is done in the constructor of QcowHeaderExtension:

if self.magic == QCOW2_EXT_MAGIC_BITMAPS:

...

position = fd.tell()

...

self.obj = Qcow2BitmapExt(fd=fd)

fd.seek(position)


Andrey