Source code for dfvfs.vfs.gpt_file_system

# -*- coding: utf-8 -*-
"""The GUID Partition Table (GPT) file system implementation."""

import pyvsgpt

from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import gpt_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import file_system
from dfvfs.vfs import gpt_file_entry


[docs] class GPTFileSystem(file_system.FileSystem): """File system that uses pyvsgpt.""" TYPE_INDICATOR = definitions.TYPE_INDICATOR_GPT
[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(GPTFileSystem, self).__init__(resolver_context, path_spec) self._file_object = None self._vsgpt_volume = None
def _Close(self): """Closes the file system object. Raises: IOError: if the close failed. """ self._vsgpt_volume.close() self._vsgpt_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) vsgpt_volume = pyvsgpt.volume() vsgpt_volume.open_file_object(file_object) self._file_object = file_object self._vsgpt_volume = vsgpt_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 = self.GetEntryIndexByPathSpec(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 self._vsgpt_volume.has_partition_with_identifier(entry_index)
[docs] def GetEntryIndexByPathSpec(self, path_spec): """Retrieves the entry index for a path specification. Args: path_spec (PathSpec): path specification. Returns: int: entry index or None if not available. """ entry_index = getattr(path_spec, 'entry_index', None) if entry_index is not None: return entry_index location = getattr(path_spec, 'location', None) if location is None: return None entry_index = None if location[:5] == '/gpt{' and location[-1] == '}': for vsgpt_partition in iter(self._vsgpt_volume.partitions): if vsgpt_partition.identifier == location[5:-1]: entry_index = vsgpt_partition.entry_index elif location[:2] == '/p': try: entry_index = int(location[2:], 10) - 1 except ValueError: pass if entry_index is None or entry_index < 0: return None return entry_index
[docs] def GetFileEntryByPathSpec(self, path_spec): """Retrieves a file entry for a path specification. Args: path_spec (PathSpec): path specification. Returns: GPTFileEntry: a file entry or None if not available. """ entry_index = self.GetEntryIndexByPathSpec(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 gpt_file_entry.GPTFileEntry( self._resolver_context, self, path_spec, is_root=True, is_virtual=True) if not self._vsgpt_volume.has_partition_with_identifier(entry_index): return None return gpt_file_entry.GPTFileEntry( self._resolver_context, self, path_spec, entry_index=entry_index)
[docs] def GetGPTPartitionByPathSpec(self, path_spec): """Retrieves a GPT partition for a path specification. Args: path_spec (PathSpec): path specification. Returns: pyvsgpt.partition: a GPT partition or None if not available. """ entry_index = self.GetEntryIndexByPathSpec(path_spec) if entry_index is None: return None return self._vsgpt_volume.get_partition_by_identifier(entry_index)
[docs] def GetGPTVolume(self): """Retrieves the GPT volume. Returns: pyvsgpt.volume: a GPT volume. """ return self._vsgpt_volume
[docs] def GetRootFileEntry(self): """Retrieves the root file entry. Returns: GPTFileEntry: root file entry or None if not available. """ path_spec = gpt_path_spec.GPTPathSpec( location=self.LOCATION_ROOT, parent=self._path_spec.parent) return self.GetFileEntryByPathSpec(path_spec)