Add no-op tp_clear to Exception

Author: msimacek

graalpython/com.oracle.graal.python.cext/src/capi.c

@@ -839,6 +839,10 @@ PyAPI_FUNC(void*) truffle_convert_pointer(Py_ssize_t value) {
 	return (void*) value;
 }
 
+PyAPI_FUNC(int) truffle_no_op_clear(PyObject* o) {
+    return 0;
+}
+
 // defined in 'exceptions.c'
 void initialize_exceptions();
 // defined in 'pyhash.c'

graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_err.py

@@ -812,3 +812,19 @@ def gen():
         e = ExceptionSubclass()
         e1 = g.throw(e)
         assert e1 is e
+
+    def test_tp_clear(self):
+        # psycopg2 calls ((PyTypeObject *)PyExc_Exception)->tp_clear from their exception subclass's dealloc
+        # We need to make sure it doesn't segfault
+        Tester = CPyExtType(
+            "TpClearTester",
+            code="""
+            static PyObject* test(PyObject* unused, PyObject* unused2) {
+                PyBaseExceptionObject o = {0};
+                ((PyTypeObject *)PyExc_Exception)->tp_clear((PyObject*)&o);
+                Py_RETURN_NONE;
+            }
+            """,
+            tp_methods='{"test", (PyCFunction)test, METH_NOARGS | METH_STATIC, ""}',
+        )
+        Tester.test()

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/capi/CExtNodes.java

@@ -41,6 +41,7 @@
 package com.oracle.graal.python.builtins.objects.cext.capi;
 
 import static com.oracle.graal.python.builtins.objects.PNone.NO_VALUE;
+import static com.oracle.graal.python.builtins.objects.cext.capi.NativeCAPISymbol.FUN_NO_OP_CLEAR;
 import static com.oracle.graal.python.builtins.objects.cext.capi.NativeCAPISymbol.FUN_PTR_ADD;
 import static com.oracle.graal.python.builtins.objects.cext.capi.NativeCAPISymbol.FUN_PTR_COMPARE;
 import static com.oracle.graal.python.builtins.objects.cext.capi.NativeCAPISymbol.FUN_PY_DEALLOC;
@@ -136,6 +137,7 @@
 import com.oracle.graal.python.builtins.objects.type.PythonBuiltinClass;
 import com.oracle.graal.python.builtins.objects.type.PythonClass;
 import com.oracle.graal.python.builtins.objects.type.PythonManagedClass;
+import com.oracle.graal.python.builtins.objects.type.TypeFlags;
 import com.oracle.graal.python.builtins.objects.type.TypeNodes;
 import com.oracle.graal.python.builtins.objects.type.TypeNodes.GetBaseClassNode;
 import com.oracle.graal.python.builtins.objects.type.TypeNodes.GetMroStorageNode;
@@ -890,19 +892,24 @@ public static PCallCapiFunction getUncached() {
      */
     @TruffleBoundary
     public static Object lookupNativeMemberInMRO(PythonManagedClass cls, @SuppressWarnings("unused") CFields nativeMemberName, HiddenAttr managedMemberName) {
-        if (cls instanceof PythonClass && (managedMemberName == HiddenAttr.ALLOC || managedMemberName == HiddenAttr.FREE)) {
-            Object func = HiddenAttr.ReadNode.executeUncached(cls, managedMemberName, null);
-            if (func != null) {
-                return func;
-            }
+        if (cls instanceof PythonClass) {
+            NativeCAPISymbol symbol = null;
             // We need to point to PyType_GenericAlloc or PyObject_GC_Del
-            NativeCAPISymbol symbol;
             if (managedMemberName == HiddenAttr.ALLOC) {
                 symbol = FUN_PY_TYPE_GENERIC_ALLOC;
-            } else {
+            } else if (managedMemberName == HiddenAttr.FREE) {
                 symbol = FUN_PY_OBJECT_GC_DEL;
+            } else if (managedMemberName == HiddenAttr.CLEAR) {
+                // This will need to be subtype_clear when we implement native GC
+                symbol = FUN_NO_OP_CLEAR;
+            }
+            if (symbol != null) {
+                Object func = HiddenAttr.ReadNode.executeUncached(cls, managedMemberName, null);
+                if (func != null) {
+                    return func;
+                }
+                return CApiContext.getNativeSymbol(null, symbol);
             }
-            return CApiContext.getNativeSymbol(null, symbol);
         }
         MroSequenceStorage mroStorage = GetMroStorageNode.executeUncached(cls);
         int n = mroStorage.length();
@@ -921,6 +928,9 @@ public static Object lookupNativeMemberInMRO(PythonManagedClass cls, @SuppressWa
                 }
             }
         }
+        if (managedMemberName == HiddenAttr.CLEAR && (TypeNodes.GetTypeFlagsNode.executeUncached(cls) & TypeFlags.HAVE_GC) != 0) {
+            return CApiContext.getNativeSymbol(null, FUN_NO_OP_CLEAR);
+        }
         return HiddenAttr.ReadNode.executeUncached(PythonContext.get(null).lookupType(PythonBuiltinClassType.PythonObject), managedMemberName, NO_VALUE);
     }
 

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/capi/NativeCAPISymbol.java

@@ -70,6 +70,7 @@ public enum NativeCAPISymbol implements NativeCExtSymbol {
 
     FUN_VA_ARG_POINTER("truffle_va_arg_pointer", Pointer, Pointer),
     FUN_CONVERT_POINTER("truffle_convert_pointer", Pointer, Py_ssize_t),
+    FUN_NO_OP_CLEAR("truffle_no_op_clear", Int, PyObject),
 
     FUN_PYTRUFFLE_CONSTANTS("PyTruffle_constants", PY_SSIZE_T_PTR),
     FUN_PYTRUFFLE_STRUCT_OFFSETS("PyTruffle_struct_offsets", PY_SSIZE_T_PTR),