Python: Add PropertyValue

+ Extend PropertyInternal.getSetter to handle non-decorator
+ Add PropertyInternal.getDeleter

It seems like a bit hacky way to do things, since we're not using the
PropertySetterOrDeleter class at all, but for now I'll leave it be.

python/ql/src/semmle/python/objects/Descriptors.qll

@@ -20,13 +20,39 @@ class PropertyInternal extends ObjectInternal, TProperty {
         this = TProperty(_, _, result)
     }
 
+    private CallNode getCall() { this = TProperty(result, _, _) }
+
     /** Gets the setter function of this property */
     CallableObjectInternal getSetter() {
+        // @x.setter
         exists(CallNode call, AttrNode setter |
-            call.getFunction() = setter and 
+            call.getFunction() = setter and
             PointsToInternal::pointsTo(setter.getObject("setter"), this.getContext(), this, _) and
             PointsToInternal::pointsTo(call.getArg(0), this.getContext(), result, _)
         )
+        or
+        // x = property(getter, setter, deleter)
+        exists(ControlFlowNode setter_arg |
+            setter_arg = getCall().getArg(1) or setter_arg = getCall().getArgByName("fset")
+        |
+            PointsToInternal::pointsTo(setter_arg, this.getContext(), result, _)
+        )
+    }
+
+    /** Gets the setter function of this property */
+    CallableObjectInternal getDeleter() {
+        exists(CallNode call, AttrNode setter |
+            call.getFunction() = setter and
+            PointsToInternal::pointsTo(setter.getObject("deleter"), this.getContext(), this, _) and
+            PointsToInternal::pointsTo(call.getArg(0), this.getContext(), result, _)
+        )
+        or
+        // x = property(getter, setter, deleter)
+        exists(ControlFlowNode deleter_arg |
+            deleter_arg = getCall().getArg(2) or deleter_arg = getCall().getArgByName("fdel")
+        |
+            PointsToInternal::pointsTo(deleter_arg, this.getContext(), result, _)
+        )
     }
 
     private Context getContext() { this = TProperty(_,result,  _) }

python/ql/src/semmle/python/objects/ObjectAPI.qll

@@ -669,6 +669,34 @@ class NumericValue extends Value {
     }
 }
 
+/** A Python property:
+ *     @property
+ *     def f():
+ *         ....
+ *
+ * https://docs.python.org/3/howto/descriptor.html#properties
+ * https://docs.python.org/3/library/functions.html#property
+ */
+class PropertyValue extends Value {
+
+    PropertyValue() {
+        this instanceof PropertyInternal
+    }
+
+    CallableValue getGetter(){
+        result = this.(PropertyInternal).getGetter()
+    }
+
+    CallableValue getSetter(){
+        result = this.(PropertyInternal).getSetter()
+    }
+
+    CallableValue getDeleter(){
+        result = this.(PropertyInternal).getDeleter()
+    }
+
+}
+
 /** A method-resolution-order sequence of classes */
 class MRO extends TClassList {
 

python/ql/test/library-tests/descriptors/Properties.expected

@@ -1,8 +1,8 @@
-| test.py:6:5:6:16 | Function x | getter | test.py:5:6:5:13 | Property x |
-| test.py:11:5:11:23 | Function x | setter | test.py:5:6:5:13 | Property x |
-| test.py:15:5:15:16 | Function x | deleter | test.py:5:6:5:13 | Property x |
-| test.py:21:5:21:16 | Function x | getter | test.py:20:6:20:13 | Property x |
-| test.py:28:5:28:19 | Function getx | getter | test.py:37:9:37:59 | Property getx |
-| test.py:31:5:31:26 | Function setx | setter | test.py:37:9:37:59 | Property getx |
-| test.py:34:5:34:19 | Function delx | deleter | test.py:37:9:37:59 | Property getx |
-| test.py:41:5:41:19 | Function getx | getter | test.py:44:9:44:22 | Property getx |
+| test.py:6:5:6:16 | Function WithDecorator.x | getter | test.py:5:6:5:13 | property x |
+| test.py:11:5:11:23 | Function WithDecorator.x | setter | test.py:5:6:5:13 | property x |
+| test.py:15:5:15:16 | Function WithDecorator.x | deleter | test.py:5:6:5:13 | property x |
+| test.py:21:5:21:16 | Function WithDecoratorOnlyGetter.x | getter | test.py:20:6:20:13 | property x |
+| test.py:28:5:28:19 | Function WithoutDecorator.getx | getter | test.py:37:9:37:59 | property getx |
+| test.py:31:5:31:26 | Function WithoutDecorator.setx | setter | test.py:37:9:37:59 | property getx |
+| test.py:34:5:34:19 | Function WithoutDecorator.delx | deleter | test.py:37:9:37:59 | property getx |
+| test.py:41:5:41:19 | Function WithoutDecoratorOnlyGetter.getx | getter | test.py:44:9:44:22 | property getx |

python/ql/test/library-tests/descriptors/Properties.ql

@@ -1,7 +1,7 @@
 import python
 import semmle.python.types.Descriptors
 
-from PropertyObject p, string method_name, FunctionObject method
+from PropertyValue p, string method_name, FunctionValue method
 where
     method_name = "getter" and method = p.getGetter()
     or