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"""
@copyright: 2009 Bastian Blank <waldi@debian.org>
@license: GNU GPL-3
"""
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import struct
from .general import DescriptorTag, ExtentAD
class AnchorVolumeDescriptorPointer:
_struct = struct.Struct('<16x20s20s')
def __init__(self, tag, buf):
self.tag = tag
if tag.identifier != 2:
raise RuntimeError('Anchor Volume Descriptor Pointer illegal')
data = self._struct.unpack(buf[:56])
self.main_descriptor_extent = ExtentAD(data[0])
self.reserve_descriptor_extent = ExtentAD(data[1])
def _DescriptorSequence(media, location, length):
buf = media.read_sector(location, length)
cur = 0
while cur < length:
tag = DescriptorTag(buf[cur:cur + 16])
if tag.identifier == 8:
break
yield tag, buf[cur:cur + 2048]
cur += 2048
class Volume:
_lazy = 'partitions',
def __init__(self, media):
self._media = media
buf = media.read_sector(256)
tag = DescriptorTag(buf)
self.anchor = AnchorVolumeDescriptorPointer(tag, buf)
def __getattr__(self, key):
if key in self._lazy:
self._populate()
return super().__getattribute__(key)
def _read_descriptors(self, extent):
seq = _DescriptorSequence(self._media, extent.location, extent.length)
partitions = {}
for tag, buf in seq:
if tag.identifier == 5:
p = Partition(self._media, self, tag, buf)
partitions[p.number] = p
elif tag.identifier == 6:
# TODO
pass
if partitions:
return partitions
raise RuntimeError
def _populate(self):
try:
data = self._read_descriptors(self.anchor.main_descriptor_extent)
except RuntimeError:
data = self._read_descriptors(self.anchor.reserve_descriptor_extent)
self.partitions = data
class Partition:
_lazy = 'fileset'
_struct = struct.Struct('<16x4xHH164xII316x')
def __init__(self, media, volume, tag, buf):
self._media = media
self._volume = volume
self.tag = tag
if tag.identifier != 5:
raise RuntimeError('Partition Descriptor illegal')
data = self._struct.unpack(buf[:512])
self.flags, self.number, self.location, self.length = data
def __getattr__(self, key):
if key in self._lazy:
self._populate()
return super().__getattribute__(key)
def _populate(self):
from .filesystem import FileSet
seq = _DescriptorSequence(self._media, self.location, self.length)
for tag, buf in seq:
if tag.identifier == 256:
self.fileset = FileSet(self._media, self._volume, self.number, tag, buf)
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