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      1 # Copyright 2015, Tresys Technology, LLC
      2 #
      3 # This file is part of SETools.
      4 #
      5 # SETools is free software: you can redistribute it and/or modify
      6 # it under the terms of the GNU Lesser General Public License as
      7 # published by the Free Software Foundation, either version 2.1 of
      8 # the License, or (at your option) any later version.
      9 #
     10 # SETools is distributed in the hope that it will be useful,
     11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
     12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     13 # GNU Lesser General Public License for more details.
     14 #
     15 # You should have received a copy of the GNU Lesser General Public
     16 # License along with SETools.  If not, see
     17 # <http://www.gnu.org/licenses/>.
     18 #
     19 from collections import namedtuple
     20 
     21 from .descriptors import DiffResultDescriptor
     22 from .difference import Difference, SymbolWrapper
     23 
     24 
     25 modified_types_record = namedtuple("modified_type", ["added_attributes",
     26                                                      "removed_attributes",
     27                                                      "matched_attributes",
     28                                                      "modified_permissive",
     29                                                      "permissive",
     30                                                      "added_aliases",
     31                                                      "removed_aliases",
     32                                                      "matched_aliases"])
     33 
     34 
     35 class TypesDifference(Difference):
     36 
     37     """Determine the difference in types between two policies."""
     38 
     39     added_types = DiffResultDescriptor("diff_types")
     40     removed_types = DiffResultDescriptor("diff_types")
     41     modified_types = DiffResultDescriptor("diff_types")
     42 
     43     def diff_types(self):
     44         """Generate the difference in types between the policies."""
     45 
     46         self.log.info(
     47             "Generating type differences from {0.left_policy} to {0.right_policy}".format(self))
     48 
     49         self.added_types, self.removed_types, matched_types = self._set_diff(
     50             (SymbolWrapper(t) for t in self.left_policy.types()),
     51             (SymbolWrapper(t) for t in self.right_policy.types()))
     52 
     53         self.modified_types = dict()
     54 
     55         for left_type, right_type in matched_types:
     56             # Criteria for modified types
     57             # 1. change to attribute set, or
     58             # 2. change to alias set, or
     59             # 3. different permissive setting
     60             added_attr, removed_attr, matched_attr = self._set_diff(
     61                 (SymbolWrapper(a) for a in left_type.attributes()),
     62                 (SymbolWrapper(a) for a in right_type.attributes()))
     63 
     64             added_aliases, removed_aliases, matched_aliases = self._set_diff(left_type.aliases(),
     65                                                                              right_type.aliases())
     66 
     67             left_permissive = left_type.ispermissive
     68             right_permissive = right_type.ispermissive
     69             mod_permissive = left_permissive != right_permissive
     70 
     71             if added_attr or removed_attr or added_aliases or removed_aliases or mod_permissive:
     72                 self.modified_types[left_type] = modified_types_record(added_attr,
     73                                                                        removed_attr,
     74                                                                        matched_attr,
     75                                                                        mod_permissive,
     76                                                                        left_permissive,
     77                                                                        added_aliases,
     78                                                                        removed_aliases,
     79                                                                        matched_aliases)
     80 
     81     #
     82     # Internal functions
     83     #
     84     def _reset_diff(self):
     85         """Reset diff results on policy changes."""
     86         self.log.debug("Resetting type differences")
     87         self.added_types = None
     88         self.removed_types = None
     89         self.modified_types = None
     90