101     def __init__(self, fd=None, offset=None, data=None):  argument
104             1. Specify data. fd and offset must be None.
105             2. Specify fd and offset, data must be None. offset may be omitted
106                in this case, than current position of fd is used.
109             assert fd is not None
112                 fd.seek(offset)
113             data = fd.read(buf_size)
115             assert fd is None and offset is None
148     def __init__(self, fd, cluster_size):  argument
149         super().__init__(fd=fd)
152             fd.seek(8 - tail, 1)
153         position = fd.tell()
155         self.read_bitmap_directory(fd)
156         fd.seek(position)
158     def read_bitmap_directory(self, fd):  argument
159         fd.seek(self.bitmap_directory_offset)
161             [Qcow2BitmapDirEntry(fd, cluster_size=self.cluster_size)
188     def __init__(self, fd, cluster_size):  argument
189         super().__init__(fd=fd)
192         fd.seek(self.extra_data_size, 1)
193         bitmap_name = fd.read(self.name_size)
198         fd.seek(padding, 1)
199         self.bitmap_table = Qcow2BitmapTable(fd=fd,
232     def __init__(self, fd):  argument
233         super().__init__(fd=fd)
253     def __init__(self, fd, offset, nb_entries, cluster_size):  argument
255         position = fd.tell()
256         fd.seek(offset)
257         self.entries = [Qcow2BitmapTableEntry(fd) for _ in range(nb_entries)]
258         fd.seek(position)
298     def __init__(self, magic=None, length=None, data=None, fd=None,  argument
301         Support both loading from fd and creation from user data.
302         For fd-based creation current position in a file will be used to read
315         if fd is None:
325             super().__init__(fd=fd)
327                 self.obj = Qcow2BitmapExt(fd=fd, cluster_size=cluster_size)
331                 self.data = fd.read(padded)
394     def __init__(self, fd):  argument
395         super().__init__(fd=fd, offset=0)
400         fd.seek(self.header_length)
401         self.load_extensions(fd)
404             fd.seek(self.backing_file_offset)
405             self.backing_file = fd.read(self.backing_file_size)
417     def load_extensions(self, fd):  argument
425         while fd.tell() < end:
426             ext = QcowHeaderExtension(fd=fd, cluster_size=self.cluster_size)
432     def update_extensions(self, fd):  argument
434         fd.seek(self.header_length)
439             fd.write(buf)
440             fd.write(ex.data)
443             self.backing_file_offset = fd.tell()
444             fd.write(self.backing_file)
446         if fd.tell() > self.cluster_size:
449     def update(self, fd):  argument
452         self.update_extensions(fd)
454         fd.seek(0)
458         fd.write(buf)