Merge pull request github#1609 from markshannon/python-better-points-to-extensions

Python points-to: Remove negative recursion when using legacy points-to extensions

Author: taus-semmle

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

@@ -156,6 +156,8 @@ class PythonFunctionObjectInternal extends CallableObjectInternal, TPythonFuncti
         function = this and offset = 0
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 
@@ -277,6 +279,8 @@ class BuiltinFunctionObjectInternal extends CallableObjectInternal, TBuiltinFunc
         function = this and offset = 0
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** Class representing methods of built-in classes (otherwise known as method-descriptors) such as `list.append`.
@@ -367,6 +371,8 @@ class BuiltinMethodObjectInternal extends CallableObjectInternal, TBuiltinMethod
         function = this and offset = 0
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** Class representing bound-methods.
@@ -453,6 +459,8 @@ class BoundMethodObjectInternal extends CallableObjectInternal, TBoundMethod {
         function = this.getFunction() and offset = 1
     }
 
+    override predicate useOriginAsLegacyObject() { any() }
+
 }
 
 

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

@@ -89,6 +89,9 @@ abstract class ClassObjectInternal extends ObjectInternal {
     }
 
     override predicate subscriptUnknown() { none() }
+
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** Class representing Python source classes */

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

@@ -69,6 +69,8 @@ abstract class ConstantObjectInternal extends ObjectInternal {
 
     override string getName() { none() }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 private abstract class BooleanObjectInternal extends ConstantObjectInternal {

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

@@ -91,6 +91,7 @@ class PropertyInternal extends ObjectInternal, TProperty {
         )
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
 }
 
 /** A class representing classmethods in Python */
@@ -176,6 +177,8 @@ class ClassMethodObjectInternal extends ObjectInternal, TClassMethod {
         result = this.getFunction().getName()
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 class StaticMethodObjectInternal extends ObjectInternal, TStaticMethod {
@@ -247,4 +250,6 @@ class StaticMethodObjectInternal extends ObjectInternal, TStaticMethod {
         result = this.getFunction().getName()
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }

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

@@ -160,6 +160,8 @@ class SpecificInstanceInternal extends TSpecificInstance, InstanceObject {
         )
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** A class representing context-free instances represented by `self` in the source code
@@ -262,6 +264,8 @@ class SelfInstanceInternal extends TSelfInstance, InstanceObject {
         this.getClass().attribute("__init__", init, _)
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** A class representing a value that has a known class, but no other information */
@@ -366,6 +370,8 @@ class UnknownInstanceInternal extends TUnknownInstance, ObjectInternal {
 
     override string getName() { none() }
 
+    override predicate useOriginAsLegacyObject() { any() }
+
 }
 
 private int lengthFromClass(ClassObjectInternal cls) {
@@ -472,5 +478,7 @@ class SuperInstance extends TSuperInstance, ObjectInternal {
 
     override string getName() { none() }
 
+    override predicate useOriginAsLegacyObject() { any() }
+
 }
 

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

@@ -52,6 +52,8 @@ abstract class ModuleObjectInternal extends ObjectInternal {
         any(PackageObjectInternal package).getInitModule() = this
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** A class representing built-in modules */
@@ -308,10 +310,6 @@ class AbsentModuleObjectInternal extends ModuleObjectInternal, TAbsentModule {
         none()
     }
 
-    override predicate isMissing() {
-        any()
-    }
-
 }
 
 /** A class representing an attribute of a missing module. */
@@ -397,12 +395,10 @@ class AbsentModuleAttributeObjectInternal extends ObjectInternal, TAbsentModuleA
 
     override predicate subscriptUnknown() { any() }
 
-    override predicate isMissing() {
-        any()
-    }
-
     /* We know what this is called, but not its innate name */
     override string getName() { none() }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 

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

@@ -78,14 +78,6 @@ class Value extends TObject {
         this.(ObjectInternal).isBuiltin()
     }
 
-    /** Holds if this value represents an entity that is inferred to exist,
-     * but missing from the database.
-     * Most commonly, this is a module that is imported, but wasn't present during extraction.
-     */
-    predicate isMissing() {
-        this.(ObjectInternal).isMissing()
-    }
-
     predicate hasLocationInfo(string filepath, int bl, int bc, int el, int ec) {
         this.(ObjectInternal).getOrigin().getLocation().hasLocationInfo(filepath, bl, bc, el, ec)
         or

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

@@ -155,11 +155,12 @@ class ObjectInternal extends TObject {
      */
     predicate functionAndOffset(CallableObjectInternal function, int offset) { none() }
 
-    /** Holds if this 'object' represents an entity that is inferred to exist
-     * but is missing from the database */
-    predicate isMissing() {
-        none()
-    }
+    /** Holds if this 'object' represents an entity that should be exposed to the legacy points_to API
+     * This should hold for almost all objects that do not have an underlying DB object representing their source,
+     * for example `super` objects and bound-method. This should not hold for objects that are inferred to exists by
+     * an import statements or the like, but which aren't in the database. */
+     /* This predicate can be removed when the legacy points_to API is removed. */
+    abstract predicate useOriginAsLegacyObject();
 
     /** Gets the name of this of this object if it has a meaningful name.
      * Note that the name of an object is not necessarily the name by which it is called
@@ -249,6 +250,9 @@ class BuiltinOpaqueObjectInternal extends ObjectInternal, TBuiltinOpaqueObject {
     override string getName() {
         result = this.getBuiltin().getName()
     }
+
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 
@@ -326,6 +330,8 @@ class UnknownInternal extends ObjectInternal, TUnknown {
 
     override string getName() { none() }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 class UndefinedInternal extends ObjectInternal, TUndefined {
@@ -404,6 +410,8 @@ class UndefinedInternal extends ObjectInternal, TUndefined {
 
     override string getName() { none() }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 module ObjectInternal {
@@ -498,6 +506,7 @@ module ObjectInternal {
         result.(BuiltinTupleObjectInternal).length() = 0
     }
 
+
 }
 
 /** Helper for boolean predicates returning both `true` and `false` */

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

@@ -117,6 +117,9 @@ class BuiltinTupleObjectInternal extends TBuiltinTuple, TupleObjectInternal {
             result = count(int n | exists(b.getItem(n)))
         )
     }
+
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** A tuple declared by a tuple expression in the Python source code */
@@ -148,6 +151,8 @@ class PythonTupleObjectInternal extends TPythonTuple, TupleObjectInternal {
         )
     }
 
+    override predicate useOriginAsLegacyObject() { none() }
+
 }
 
 /** A tuple created by a `*` parameter */
@@ -176,6 +181,9 @@ class VarargsTupleObjectInternal extends TVarargsTuple,  TupleObjectInternal {
     override int length() {
         this = TVarargsTuple(_, _, _, result)
     }
+
+    override predicate useOriginAsLegacyObject() { any() }
+
 }
 
 
@@ -256,4 +264,6 @@ class SysVersionInfoObjectInternal extends TSysVersionInfo, SequenceObjectIntern
 
     override predicate functionAndOffset(CallableObjectInternal function, int offset) { none() }
 
+    override predicate useOriginAsLegacyObject() { any() }
+
 }

python/ql/src/semmle/python/pointsto/PointsTo.qll

@@ -130,7 +130,7 @@ module PointsTo {
             PointsToInternal::pointsTo(f, context, value, origin) and
             cls = value.getClass().getSource() |
             obj = value.getSource() or
-            not exists(value.getSource()) and not value.isMissing() and obj = origin
+            value.useOriginAsLegacyObject() and obj = origin
         )
         or
         /* Backwards compatibility for *args and **kwargs */
@@ -145,7 +145,7 @@ module PointsTo {
             PointsToInternal::pointsTo(f.(DefinitionNode).getValue(), context, value, origin) and
             cls = value.getClass().getSource() |
             obj = value.getSource() or
-            not exists(value.getSource()) and obj = origin
+            value.useOriginAsLegacyObject() and obj = origin
         )
     }