Python points-to: Handle old-style classes correctly.

markshannon · markshannon · commit dfc0a80cc546 · 2019-04-29T16:40:46.000+01:00
diff --git a/python/ql/src/semmle/python/objects/ObjectInternal.qll b/python/ql/src/semmle/python/objects/ObjectInternal.qll
@@ -410,6 +410,10 @@ module ObjectInternal {
         result = TBuiltinClassObject(Builtin::special("NoneType"))
     }
 
+    ObjectInternal type() {
+        result = TBuiltinClassObject(Builtin::special("type"))
+    }
+
     ObjectInternal property() {
         result = TBuiltinClassObject(Builtin::special("property"))
     }
diff --git a/python/ql/src/semmle/python/objects/TObject.qll b/python/ql/src/semmle/python/objects/TObject.qll
@@ -331,7 +331,7 @@ library class ClassDecl extends @py_object {
         result = "ClassDecl"
     }
 
-    private Class getClass() {
+    Class getClass() {
         result = this.(ControlFlowNode).getNode().(ClassExpr).getInnerScope()
     }
 
diff --git a/python/ql/src/semmle/python/pointsto/PointsTo.qll b/python/ql/src/semmle/python/pointsto/PointsTo.qll
@@ -1610,21 +1610,45 @@ cached module Types {
     }
 
     cached predicate isOldStyle(ClassObjectInternal cls) {
-        //To do...
-        none()
+        newStylePython2(cls, 0) = false
     }
 
     cached predicate isNewStyle(ClassObjectInternal cls) {
-        //To do...
-        any()
+        major_version() = 3
+        or
+        cls.isBuiltin()
+        or
+        newStylePython2(cls, 0) = true
+    }
+
+    private boolean newStylePython2(ClassObjectInternal cls, int n) {
+        major_version() = 2 and
+        (
+            hasDeclaredMetaclass(cls) = false and
+            exists(Class pycls |
+                pycls = cls.getClassDeclaration().getClass() and
+                n = count(pycls.getABase()) and result = false
+            )
+            or
+            hasDeclaredMetaclass(cls) = false and
+            exists(ClassObjectInternal base |
+                base = getBase(cls, n) |
+                isOldStyle(base) and result = newStylePython2(cls, n+1)
+                or
+                isNewStyle(base) and result = true
+            )
+            or
+            getMro(declaredMetaClass(cls)).contains(ObjectInternal::type()) and
+            n = 0 and result = true
+        )
     }
 
     cached ClassList getMro(ClassObjectInternal cls) {
         isNewStyle(cls) and
         result = Mro::newStyleMro(cls)
         or
-        // To do, old-style
-        none()
+        isOldStyle(cls) and
+        result = Mro::oldStyleMro(cls)
     }
 
     cached predicate declaredAttribute(ClassObjectInternal cls, string name, ObjectInternal value, CfgOrigin origin) {

Original file line number	Diff line number	Diff line change
`@@ -410,6 +410,10 @@ module ObjectInternal {`
`410`	`410`	`result = TBuiltinClassObject(Builtin::special("NoneType"))`
`411`	`411`	`}`
`412`	`412`
	`413`	`+ ObjectInternal type() {`
	`414`	`+ result = TBuiltinClassObject(Builtin::special("type"))`
	`415`	`+ }`
	`416`	`+`
`413`	`417`	`ObjectInternal property() {`
`414`	`418`	`result = TBuiltinClassObject(Builtin::special("property"))`
`415`	`419`	`}`
Original file line number	Diff line number	Diff line change
`@@ -331,7 +331,7 @@ library class ClassDecl extends @py_object {`
`331`	`331`	`result = "ClassDecl"`
`332`	`332`	`}`
`333`	`333`
`334`		`- private Class getClass() {`
	`334`	`+ Class getClass() {`
`335`	`335`	`result = this.(ControlFlowNode).getNode().(ClassExpr).getInnerScope()`
`336`	`336`	`}`
`337`	`337`