# -*- coding: utf-8 -*-
"""The Apple Partition Map (APM) file system implementation."""
import pyvsapm
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.lib import apm_helper
from dfvfs.path import apm_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import file_system
from dfvfs.vfs import apm_file_entry
[docs]
class APMFileSystem(file_system.FileSystem):
"""File system that uses pyvsapm."""
TYPE_INDICATOR = definitions.TYPE_INDICATOR_APM
[docs]
def __init__(self, resolver_context, path_spec):
"""Initializes a file system.
Args:
resolver_context (Context): resolver context.
path_spec (PathSpec): a path specification.
"""
super(APMFileSystem, self).__init__(resolver_context, path_spec)
self._file_object = None
self._vsapm_volume = None
def _Close(self):
"""Closes the file system object.
Raises:
IOError: if the close failed.
"""
self._vsapm_volume.close()
self._vsapm_volume = None
self._file_object = None
def _Open(self, mode='rb'):
"""Opens the file system object defined by path specification.
Args:
mode (Optional[str]): file access mode. The default is 'rb' which
represents read-only binary.
Raises:
AccessError: if the access to open the file was denied.
IOError: if the file system object 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.')
file_object = resolver.Resolver.OpenFileObject(
self._path_spec.parent, resolver_context=self._resolver_context)
vsapm_volume = pyvsapm.volume()
vsapm_volume.open_file_object(file_object)
self._file_object = file_object
self._vsapm_volume = vsapm_volume
[docs]
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.
"""
entry_index = apm_helper.APMPathSpecGetEntryIndex(path_spec)
# The virtual root file has no corresponding partition entry index but
# should have a location.
if entry_index is None:
location = getattr(path_spec, 'location', None)
return location is not None and location == self.LOCATION_ROOT
return 0 <= entry_index < self._vsapm_volume.number_of_partitions
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def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
APMFileEntry: a file entry or None if not available.
"""
entry_index = apm_helper.APMPathSpecGetEntryIndex(path_spec)
# The virtual root file has no corresponding partition entry index but
# should have a location.
if entry_index is None:
location = getattr(path_spec, 'location', None)
if location is None or location != self.LOCATION_ROOT:
return None
return apm_file_entry.APMFileEntry(
self._resolver_context, self, path_spec, is_root=True,
is_virtual=True)
if (0 < entry_index or
entry_index >= self._vsapm_volume.number_of_partitions):
return None
return apm_file_entry.APMFileEntry(self._resolver_context, self, path_spec)
[docs]
def GetAPMPartitionByPathSpec(self, path_spec):
"""Retrieves a APM partition for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
pyvsapm.partition: a APM partition or None if not available.
"""
entry_index = apm_helper.APMPathSpecGetEntryIndex(path_spec)
if entry_index is None:
return None
return self._vsapm_volume.get_partition(entry_index)
[docs]
def GetAPMVolume(self):
"""Retrieves the APM volume.
Returns:
pyvsapm.volume: a APM volume.
"""
return self._vsapm_volume
[docs]
def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
APMFileEntry: root file entry or None if not available.
"""
path_spec = apm_path_spec.APMPathSpec(
location=self.LOCATION_ROOT, parent=self._path_spec.parent)
return self.GetFileEntryByPathSpec(path_spec)