Merge pull request #2978 from BekaValentine/python-objectapi-to-valueapi-illegalexceptionhandlertype

Python: ObjectAPI to ValueAPI: IllegalExceptionHandlerType

Author: tausbn

python/ql/src/Exceptions/IllegalExceptionHandlerType.ql

@@ -13,18 +13,18 @@
 
 import python
 
-from ExceptFlowNode ex, Object t, ClassObject c, ControlFlowNode origin, string what
-where ex.handledException(t, c, origin) and 
-(
-  exists(ClassObject x | x = t |
-    not x.isLegalExceptionType() and
-    not x.failedInference() and
-    what = "class '" + x.getName() + "'"
-  )
-  or
-  not t instanceof ClassObject and
-  what = "instance of '" + c.getName() + "'"
-)
-
-select ex.getNode(), "Non-exception $@ in exception handler which will never match raised exception.", origin, what
-
+from ExceptFlowNode ex, Value t, ClassValue c, ControlFlowNode origin, string what
+where
+    ex.handledException(t, c, origin) and
+    (
+        exists(ClassValue x | x = t |
+            not x.isLegalExceptionType() and
+            not x.failedInference(_) and
+            what = "class '" + x.getName() + "'"
+        )
+        or
+        not t instanceof ClassValue and
+        what = "instance of '" + c.getName() + "'"
+    )
+select ex.getNode(),
+    "Non-exception $@ in exception handler which will never match raised exception.", origin, what

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

@@ -44,6 +44,12 @@ class Value extends TObject {
         PointsToInternal::pointsTo(result, _, this, _)
     }
 
+    /** Gets the origin CFG node for this value. */
+    ControlFlowNode getOrigin() {
+        result = this.(ObjectInternal).getOrigin()
+    }
+
+
     /** Gets the class of this object.
      * Strictly, the `Value` representing the class of the objects
      * represented by this Value.

python/ql/src/semmle/python/types/Exceptions.qll

@@ -260,35 +260,58 @@ class ExceptFlowNode extends ControlFlowNode {
         )
     }
 
-    private predicate handledObject(Object obj, ClassObject cls, ControlFlowNode origin) {
+    private predicate handledObject_objectapi(Object obj, ClassObject cls, ControlFlowNode origin) {
         this.getType().refersTo(obj, cls, origin)
         or
         exists(Object tup |
-            this.handledObject(tup, theTupleType(), _) |
-            element_from_tuple(tup).refersTo(obj, cls, origin)
+            this.handledObject_objectapi(tup, theTupleType(), _) |
+            element_from_tuple_objectapi(tup).refersTo(obj, cls, origin)
+        )
+    }
+    
+    private predicate handledObject(Value val, ClassValue cls, ControlFlowNode origin) {
+        val.getClass() = cls and
+        (
+            this.getType().pointsTo(val, origin)
+            or
+            exists(TupleValue tup |
+                this.handledObject(tup, ClassValue::tuple(), _) |
+                val = tup.getItem(_) and origin = val.getOrigin()
+            )
         )
     }
 
     /** Gets the inferred type(s) that are handled by this node, splitting tuples if possible. */
     pragma [noinline]
-    predicate handledException(Object obj, ClassObject cls, ControlFlowNode origin) {
-        this.handledObject(obj, cls, origin) and not cls = theTupleType()
+    predicate handledException_objectapi(Object obj, ClassObject cls, ControlFlowNode origin) {
+        this.handledObject_objectapi(obj, cls, origin) and not cls = theTupleType()
         or
         not exists(this.getNode().(ExceptStmt).getType()) and obj = theBaseExceptionType() and cls = theTypeType() and
         origin = this
     }
+    
+    /** Gets the inferred type(s) that are handled by this node, splitting tuples if possible. */
+    pragma [noinline]
+    predicate handledException(Value val, ClassValue cls, ControlFlowNode origin) {
+        this.handledObject(val, cls, origin) and not cls = ClassValue::tuple()
+        or
+        not exists(this.getNode().(ExceptStmt).getType()) and val = ClassValue::baseException() and cls = ClassValue::type() and
+        origin = this
+    }
+    
+    
 
     /** Whether this `except` handles `cls` */
     predicate handles(ClassObject cls) {
         exists(ClassObject handled |
-            this.handledException(handled, _, _) |
+            this.handledException_objectapi(handled, _, _) |
             cls.getAnImproperSuperType() = handled
         )
     }
 
 }
 
-private ControlFlowNode element_from_tuple(Object tuple) {
+private ControlFlowNode element_from_tuple_objectapi(Object tuple) {
     exists(Tuple t |
         t = tuple.getOrigin() and result = t.getAnElt().getAFlowNode()
     )

python/ql/test/2/library-tests/ControlFlow/Exceptions/Handles.ql

@@ -2,5 +2,5 @@
 import python
 
 from ExceptFlowNode ex, Object obj
-where ex.handledException(obj, _, _)
+where ex.handledException_objectapi(obj, _, _)
 select ex.getLocation().getStartLine(), ex.toString(), obj.toString()

python/ql/test/3/library-tests/ControlFlow/Exceptions/Handles.ql

@@ -2,5 +2,5 @@
 import python
 
 from ExceptFlowNode ex, Object obj
-where ex.handledException(obj, _, _)
+where ex.handledException_objectapi(obj, _, _)
 select ex.getLocation().getStartLine(), ex.toString(), obj.toString()

python/ql/test/library-tests/exceptions/Handles.ql

@@ -1,5 +1,5 @@
 import python
 
 from ExceptFlowNode ex, Object t
-where ex.handledException(t,  _, _)
+where ex.handledException_objectapi(t,  _, _)
 select ex.getLocation().getStartLine(), ex.toString(), t.toString()