# -*- coding: utf-8 -*-
"""The compressed stream file system implementation."""
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import compressed_stream_path_spec
from dfvfs.vfs import compressed_stream_file_entry
from dfvfs.vfs import root_only_file_system
[docs]
class CompressedStreamFileSystem(root_only_file_system.RootOnlyFileSystem):
"""Compressed stream file system."""
TYPE_INDICATOR = definitions.TYPE_INDICATOR_COMPRESSED_STREAM
[docs]
def __init__(self, resolver_context, path_spec):
"""Initializes a compressed stream file system.
Args:
resolver_context (Context): a resolver context.
path_spec (PathSpec): a path specification.
"""
super(CompressedStreamFileSystem, self).__init__(
resolver_context, path_spec)
self._compression_method = None
def _Close(self):
"""Closes the file system.
Raises:
IOError: if the close failed.
"""
self._compression_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.')
compression_method = getattr(self._path_spec, 'compression_method', None)
if not compression_method:
raise errors.PathSpecError(
'Unsupported path specification without compression method.')
self._compression_method = compression_method
[docs]
def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): a path specification.
Returns:
CompressedStreamFileEntry: a file entry or None if not available.
"""
return compressed_stream_file_entry.CompressedStreamFileEntry(
self._resolver_context, self, path_spec, is_root=True, is_virtual=True)
[docs]
def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
CompressedStreamFileEntry: a file entry or None if not available.
"""
path_spec = compressed_stream_path_spec.CompressedStreamPathSpec(
compression_method=self._compression_method,
parent=self._path_spec.parent)
return self.GetFileEntryByPathSpec(path_spec)