# Copyright 2015, Tresys Technology, LLC
# Copyright 2018, Chris PeBenito <pebenito@ieee.org>
#
# SPDX-License-Identifier: LGPL-2.1-only
#
from collections import defaultdict
from typing import NamedTuple, Set, Union
from ..policyrep import Type, TypeAttribute, TypeOrAttr
from .descriptors import DiffResultDescriptor
from .difference import Difference, SymbolWrapper
from .typeattr import typeattr_wrapper_factory
from .typing import SymbolCache
_types_cache: SymbolCache[Type] = defaultdict(dict)
class ModifiedType(NamedTuple):
"""Difference details for a modified type."""
added_attributes: Set[TypeAttribute]
removed_attributes: Set[TypeAttribute]
matched_attributes: Set[TypeAttribute]
modified_permissive: bool
permissive: bool
added_aliases: Set[str]
removed_aliases: Set[str]
matched_aliases: Set[str]
def type_wrapper_factory(type_: Type) -> SymbolWrapper[Type]:
"""
Wrap types from the specified policy.
This caches results to prevent duplicate wrapper
objects in memory.
"""
try:
return _types_cache[type_.policy][type_]
except KeyError:
t = SymbolWrapper(type_)
_types_cache[type_.policy][type_] = t
return t
def type_or_attr_wrapper_factory(type_: TypeOrAttr) -> \
Union[SymbolWrapper[Type], SymbolWrapper[TypeAttribute]]:
"""
Wrap types or attributes from the specified policy.
This caches results to prevent duplicate wrapper
objects in memory.
"""
if isinstance(type_, Type):
return type_wrapper_factory(type_)
else:
return typeattr_wrapper_factory(type_)
class TypesDifference(Difference):
"""Determine the difference in types between two policies."""
added_types = DiffResultDescriptor("diff_types")
removed_types = DiffResultDescriptor("diff_types")
modified_types = DiffResultDescriptor("diff_types")
def diff_types(self) -> None:
"""Generate the difference in types between the policies."""
self.log.info(
"Generating type differences from {0.left_policy} to {0.right_policy}".format(self))
self.added_types, self.removed_types, matched_types = self._set_diff(
(SymbolWrapper(t) for t in self.left_policy.types()),
(SymbolWrapper(t) for t in self.right_policy.types()))
self.modified_types = dict()
for left_type, right_type in matched_types:
# Criteria for modified types
# 1. change to attribute set, or
# 2. change to alias set, or
# 3. different permissive setting
added_attr, removed_attr, matched_attr = self._set_diff(
(SymbolWrapper(a) for a in left_type.attributes()),
(SymbolWrapper(a) for a in right_type.attributes()))
added_aliases, removed_aliases, matched_aliases = self._set_diff(left_type.aliases(),
right_type.aliases(),
unwrap=False)
left_permissive = left_type.ispermissive
right_permissive = right_type.ispermissive
mod_permissive = left_permissive != right_permissive
if added_attr or removed_attr or added_aliases or removed_aliases or mod_permissive:
self.modified_types[left_type] = ModifiedType(added_attr,
removed_attr,
matched_attr,
mod_permissive,
left_permissive,
added_aliases,
removed_aliases,
matched_aliases)
#
# Internal functions
#
def _reset_diff(self) -> None:
"""Reset diff results on policy changes."""
self.log.debug("Resetting type differences")
self.added_types = None
self.removed_types = None
self.modified_types = None
