Python points-to: Fix up metaclass determination for Python 2.

markshannon · markshannon · commit 1f00c3b24888 · 2019-05-13T14:34:33.000+01:00
diff --git a/python/ql/src/semmle/python/objects/ObjectInternal.qll b/python/ql/src/semmle/python/objects/ObjectInternal.qll
@@ -426,6 +426,11 @@ module ObjectInternal {
         result = TBuiltinClassObject(Builtin::special("super"))
     }
 
+    /** The old-style class type (Python 2 only) */
+    ObjectInternal classType() {
+        result = TBuiltinClassObject(Builtin::special("ClassType"))
+    }
+
 }
 
 /** Helper for boolean predicates returning both `true` and `false` */
diff --git a/python/ql/src/semmle/python/pointsto/PointsTo.qll b/python/ql/src/semmle/python/pointsto/PointsTo.qll
@@ -1692,9 +1692,9 @@ cached module Types {
     }
 
     cached ClassObjectInternal getMetaClass(PythonClassObjectInternal cls) {
-            result = declaredMetaClass(cls)
-            or
-            hasDeclaredMetaclass(cls) = false and result = getInheritedMetaclass(cls)
+        result = declaredMetaClass(cls)
+        or
+        hasDeclaredMetaclass(cls) = false and result = getInheritedMetaclass(cls)
     }
 
     private ClassObjectInternal declaredMetaClass(PythonClassObjectInternal cls) {
@@ -1799,7 +1799,9 @@ cached module Types {
             c = cls.(PythonClassObjectInternal).getScope() and
             n = count(c.getABase())
             |
-            result = ObjectInternal::builtin("type")
+            result = ObjectInternal::type() and major_version() = 3
+            or
+            result = ObjectInternal::classType() and major_version() = 2
         )
         or
         exists(ClassObjectInternal meta1, ClassObjectInternal meta2 |
@@ -1811,6 +1813,8 @@ cached module Types {
             or
             improperSuperType(meta2) = meta1 and result = meta2
             or
+            meta2 = ObjectInternal::classType() and result = meta1
+            or
             /* Make sure we have a metaclass, even if base is unknown */
             meta1 = ObjectInternal::unknownClass() and result = ObjectInternal::builtin("type")
             or
diff --git a/python/ql/test/2/library-tests/classes/mro/C3.ql b/python/ql/test/2/library-tests/classes/mro/C3.ql
@@ -1,15 +1,17 @@
 
 import python
 import semmle.python.pointsto.MRO
+import semmle.python.pointsto.PointsTo
+import semmle.python.objects.ObjectInternal
 
-ClassList mro(ClassObject cls) {
-    if cls.isNewStyle() then
-        result = new_style_mro(cls)
+ClassList mro(ClassObjectInternal cls) {
+    if Types::isNewStyle(cls) then
+        result = Mro::newStyleMro(cls)
     else
-        result = old_style_mro(cls)
+        result = Mro::oldStyleMro(cls)
 }
 
-from ClassObject cls
+from ClassObjectInternal cls
 where not cls.isBuiltin()
 
 select cls.toString(), mro(cls)
diff --git a/python/ql/test/2/library-tests/classes/mro/mro.ql b/python/ql/test/2/library-tests/classes/mro/mro.ql
@@ -1,8 +1,4 @@
-/**
- * @name class_attr
- * @kind test
- * @problem.severity warning
- */
+
 
 import python
 

Original file line number	Diff line number	Diff line change
`@@ -426,6 +426,11 @@ module ObjectInternal {`
`426`	`426`	`result = TBuiltinClassObject(Builtin::special("super"))`
`427`	`427`	`}`
`428`	`428`
	`429`	`+ /** The old-style class type (Python 2 only) */`
	`430`	`+ ObjectInternal classType() {`
	`431`	`+ result = TBuiltinClassObject(Builtin::special("ClassType"))`
	`432`	`+ }`
	`433`	`+`
`429`	`434`	`}`
`430`	`435`
`431`	`436`	/** Helper for boolean predicates returning both `true` and `false` */