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# Copyright 2016, Tresys Technology, LLC
# Copyright 2018, Chris PeBenito <pebenito@ieee.org>
#
# This file is part of SETools.
#
# SETools is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as
# published by the Free Software Foundation, either version 2.1 of
# the License, or (at your option) any later version.
#
# SETools is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with SETools. If not, see
# <http://www.gnu.org/licenses/>.
#
from collections import defaultdict, namedtuple
from .descriptors import DiffResultDescriptor
from .difference import Difference, SymbolWrapper
modified_bool_record = namedtuple("modified_boolean", ["added_state", "removed_state"])
_bool_cache = defaultdict(dict)
def boolean_wrapper(policy, boolean):
"""
Wrap booleans from the specified policy.
This caches results to prevent duplicate wrapper
objects in memory.
"""
try:
return _bool_cache[policy][boolean]
except KeyError:
b = SymbolWrapper(boolean)
_bool_cache[policy][boolean] = b
return b
class BooleansDifference(Difference):
"""Determine the difference in type attributes between two policies."""
added_booleans = DiffResultDescriptor("diff_booleans")
removed_booleans = DiffResultDescriptor("diff_booleans")
modified_booleans = DiffResultDescriptor("diff_booleans")
def diff_booleans(self):
"""Generate the difference in type attributes between the policies."""
self.log.info("Generating Boolean differences from {0.left_policy} to {0.right_policy}".
format(self))
self.added_booleans, self.removed_booleans, matched_booleans = \
self._set_diff(
(SymbolWrapper(b) for b in self.left_policy.bools()),
(SymbolWrapper(b) for b in self.right_policy.bools()))
self.modified_booleans = dict()
for left_boolean, right_boolean in matched_booleans:
# Criteria for modified booleans
# 1. change to default state
if left_boolean.state != right_boolean.state:
self.modified_booleans[left_boolean] = modified_bool_record(right_boolean.state,
left_boolean.state)
#
# Internal functions
#
def _reset_diff(self):
"""Reset diff results on policy changes."""
self.log.debug("Resetting Boolean differences")
self.added_booleans = None
self.removed_booleans = None
self.modified_booleans = None