python/sepolicy: Update to work with setools-4.2.0

Change in internal setools API causes sepolicy to crash when processing
AVRules.

    File "python/sepolicy/sepolicy/__init__.py", line 277, in _setools_rule_to_dict
        if isinstance(rule, setools.policyrep.terule.AVRule):
    AttributeError: module 'setools.policyrep' has no attribute 'terule'

See https://github.com/SELinuxProject/setools/issues/8 for more details.

Stop using internal setools API:

- use AttributeError instead of setools specific exceptions
- evaluate conditional expressions using conditional.evaluate() instead
of qpol_symbol.is_enabled()

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>

python/sepolicy/sepolicy/__init__.py

@@ -272,34 +272,38 @@ def _setools_rule_to_dict(rule):
         'class': str(rule.tclass),
     }
 
+    # Evaluate boolean expression associated with given rule (if there is any)
     try:
-        enabled = bool(rule.qpol_symbol.is_enabled(rule.policy))
+        # Get state of all booleans in the conditional expression
+        boolstate = {}
+        for boolean in rule.conditional.booleans:
+            boolstate[str(boolean)] = boolean.state
+        # evaluate if the rule is enabled
+        enabled = rule.conditional.evaluate(**boolstate) == rule.conditional_block
     except AttributeError:
+        # non-conditional rules are always enabled
         enabled = True
 
-    if isinstance(rule, setools.policyrep.terule.AVRule):
-        d['enabled'] = enabled
+    d['enabled'] = enabled
 
     try:
         d['permlist'] = list(map(str, rule.perms))
-    except setools.policyrep.exception.RuleUseError:
+    except AttributeError:
         pass
 
     try:
         d['transtype'] = str(rule.default)
-    except setools.policyrep.exception.RuleUseError:
+    except AttributeError:
         pass
 
     try:
         d['boolean'] = [(str(rule.conditional), enabled)]
-    except (AttributeError, setools.policyrep.exception.RuleNotConditional):
+    except AttributeError:
         pass
 
     try:
         d['filename'] = rule.filename
-    except (AttributeError,
-            setools.policyrep.exception.RuleNotConditional,
-            setools.policyrep.exception.TERuleNoFilename):
+    except AttributeError:
         pass
 
     return d