# -*- coding: utf-8 -*-
"""The encoded stream file system implementation."""
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import encoded_stream_path_spec
from dfvfs.vfs import encoded_stream_file_entry
from dfvfs.vfs import root_only_file_system
[docs]
class EncodedStreamFileSystem(root_only_file_system.RootOnlyFileSystem):
"""Encoded stream file system."""
TYPE_INDICATOR = definitions.TYPE_INDICATOR_ENCODED_STREAM
[docs]
def __init__(self, resolver_context, path_spec):
"""Initializes an encoded file system.
Args:
resolver_context (Context): a resolver context.
path_spec (PathSpec): a path specification.
"""
super(EncodedStreamFileSystem, self).__init__(resolver_context, path_spec)
self._encoding_method = None
def _Close(self):
"""Closes the file system.
Raises:
IOError: if the close failed.
"""
self._encoding_method = 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' which
represents 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.')
encoding_method = getattr(self._path_spec, 'encoding_method', None)
if not encoding_method:
raise errors.PathSpecError(
'Unsupported path specification without encoding method.')
self._encoding_method = encoding_method
[docs]
def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): a path specification.
Returns:
EncodedStreamFileEntry: a file entry or None if not available.
"""
return encoded_stream_file_entry.EncodedStreamFileEntry(
self._resolver_context, self, path_spec, is_root=True, is_virtual=True)
[docs]
def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
EncodedStreamFileEntry: a file entry or None if not available.
"""
path_spec = encoded_stream_path_spec.EncodedStreamPathSpec(
encoding_method=self._encoding_method,
parent=self._path_spec.parent)
return self.GetFileEntryByPathSpec(path_spec)