# -*- coding: utf-8 -*-
"""The Core Storage (CS) file system implementation."""
import pyfvde
from dfvfs.lib import cs_helper
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import cs_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import cs_file_entry
from dfvfs.vfs import file_system
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class CSFileSystem(file_system.FileSystem):
"""File system that uses pyfvde."""
TYPE_INDICATOR = definitions.TYPE_INDICATOR_CS
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def __init__(self, resolver_context, path_spec):
"""Initializes a file system.
Args:
resolver_context (Context): resolver context.
path_spec (PathSpec): a path specification.
"""
super(CSFileSystem, self).__init__(resolver_context, path_spec)
self._fvde_volume = None
self._fvde_volume_group = None
self._file_object = None
def _Close(self):
"""Closes the file system.
Raises:
IOError: if the close failed.
"""
self._fvde_volume_group = None
self._fvde_volume.close()
self._fvde_volume = None
self._file_object = None
def _Open(self, mode='rb'):
"""Opens the file system defined by path specification.
Args:
mode (Optional[str]): file access mode. The default is 'rb'
read-only binary.
Raises:
AccessError: if the access to open the file was denied.
IOError: if the file system could not be opened.
PathSpecError: if the path specification is incorrect.
ValueError: if the path specification is invalid.
"""
if not self._path_spec.HasParent():
raise errors.PathSpecError(
'Unsupported path specification without parent.')
resolver.Resolver.key_chain.ExtractCredentialsFromPathSpec(self._path_spec)
file_object = resolver.Resolver.OpenFileObject(
self._path_spec.parent, resolver_context=self._resolver_context)
fvde_volume = pyfvde.volume()
encrypted_root_plist = resolver.Resolver.key_chain.GetCredential(
self._path_spec, 'encrypted_root_plist')
if encrypted_root_plist:
fvde_volume.read_encrypted_root_plist(encrypted_root_plist)
fvde_volume.open_file_object(file_object)
# TODO: implement multi physical volume support.
fvde_volume.open_physical_volume_files_as_file_objects([file_object])
fvde_volume_group = fvde_volume.get_volume_group()
self._file_object = file_object
self._fvde_volume = fvde_volume
self._fvde_volume_group = fvde_volume_group
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def FileEntryExistsByPathSpec(self, path_spec):
"""Determines if a file entry for a path specification exists.
Args:
path_spec (PathSpec): path specification.
Returns:
bool: True if the file entry exists.
"""
volume_index = cs_helper.CSPathSpecGetVolumeIndex(path_spec)
# The virtual root file has no corresponding volume index but
# should have a location.
if volume_index is None:
location = getattr(path_spec, 'location', None)
return location is not None and location == self.LOCATION_ROOT
return (
0 <= volume_index < self._fvde_volume_group.number_of_logical_volumes)
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def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
CSFileEntry: a file entry or None if not available.
"""
volume_index = cs_helper.CSPathSpecGetVolumeIndex(path_spec)
# The virtual root file has no corresponding volume index but
# should have a location.
if volume_index is None:
location = getattr(path_spec, 'location', None)
if location is None or location != self.LOCATION_ROOT:
return None
return cs_file_entry.CSFileEntry(
self._resolver_context, self, path_spec, is_root=True,
is_virtual=True)
if (volume_index < 0 or
volume_index >= self._fvde_volume_group.number_of_logical_volumes):
return None
return cs_file_entry.CSFileEntry(
self._resolver_context, self, path_spec)
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def GetFVDELogicalVolumeByPathSpec(self, path_spec):
"""Retrieves a Core Storage logical volume for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
pyfvde.logical_volume: a Core Storage logical volume or None if not
available.
"""
volume_index = cs_helper.CSPathSpecGetVolumeIndex(path_spec)
if volume_index is None:
return None
return self._fvde_volume_group.get_logical_volume(volume_index)
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def GetFVDEVolumeGroup(self):
"""Retrieves the Core Storage volume group.
Returns:
pyfvde.volume_group: a Core Storage volume group.
"""
return self._fvde_volume_group
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def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
CSFileEntry: root file entry or None if not available.
"""
path_spec = cs_path_spec.CSPathSpec(
location=self.LOCATION_ROOT, parent=self._path_spec.parent)
return self.GetFileEntryByPathSpec(path_spec)