Issue #26200: Added Py_SETREF and replaced Py_XSETREF with Py_SETREF

in places where Py_DECREF was used.

Author: serhiy-storchaka

Include/object.h

@@ -851,18 +851,28 @@ PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
  *
  * As in case of Py_CLEAR "the obvious" code can be deadly:
  *
- *     Py_XDECREF(op);
+ *     Py_DECREF(op);
  *     op = op2;
  *
  * The safe way is:
  *
- *      Py_XSETREF(op, op2);
+ *      Py_SETREF(op, op2);
  *
  * That arranges to set `op` to `op2` _before_ decref'ing, so that any code
  * triggered as a side-effect of `op` getting torn down no longer believes
  * `op` points to a valid object.
+ *
+ * Py_XSETREF is a variant of Py_SETREF that uses Py_XDECREF instead of
+ * Py_DECREF.
  */
 
+#define Py_SETREF(op, op2)                      \
+    do {                                        \
+        PyObject *_py_tmp = (PyObject *)(op);   \
+        (op) = (op2);                           \
+        Py_DECREF(_py_tmp);                     \
+    } while (0)
+
 #define Py_XSETREF(op, op2)                     \
     do {                                        \
         PyObject *_py_tmp = (PyObject *)(op);   \

Modules/_ctypes/_ctypes.c

@@ -391,7 +391,7 @@ StructUnionType_new(PyTypeObject *type, PyObject *args, PyObject *kwds, int isSt
         Py_DECREF((PyObject *)dict);
         return NULL;
     }
-    Py_XSETREF(result->tp_dict, (PyObject *)dict);
+    Py_SETREF(result->tp_dict, (PyObject *)dict);
     dict->format = _ctypes_alloc_format_string(NULL, "B");
     if (dict->format == NULL) {
         Py_DECREF(result);
@@ -960,7 +960,7 @@ PyCPointerType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         Py_DECREF((PyObject *)stgdict);
         return NULL;
     }
-    Py_XSETREF(result->tp_dict, (PyObject *)stgdict);
+    Py_SETREF(result->tp_dict, (PyObject *)stgdict);
 
     return (PyObject *)result;
 }
@@ -1403,7 +1403,7 @@ PyCArrayType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     /* replace the class dict by our updated spam dict */
     if (-1 == PyDict_Update((PyObject *)stgdict, result->tp_dict))
         goto error;
-    Py_XSETREF(result->tp_dict, (PyObject *)stgdict);  /* steal the reference */
+    Py_SETREF(result->tp_dict, (PyObject *)stgdict);  /* steal the reference */
     stgdict = NULL;
 
     /* Special case for character arrays.
@@ -1816,7 +1816,7 @@ static PyObject *CreateSwappedType(PyTypeObject *type, PyObject *args, PyObject
         Py_DECREF((PyObject *)stgdict);
         return NULL;
     }
-    Py_XSETREF(result->tp_dict, (PyObject *)stgdict);
+    Py_SETREF(result->tp_dict, (PyObject *)stgdict);
 
     return (PyObject *)result;
 }
@@ -1944,7 +1944,7 @@ PyCSimpleType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         Py_DECREF((PyObject *)stgdict);
         return NULL;
     }
-    Py_XSETREF(result->tp_dict, (PyObject *)stgdict);
+    Py_SETREF(result->tp_dict, (PyObject *)stgdict);
 
     /* Install from_param class methods in ctypes base classes.
        Overrides the PyCSimpleType_from_param generic method.
@@ -2307,7 +2307,7 @@ PyCFuncPtrType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         Py_DECREF((PyObject *)stgdict);
         return NULL;
     }
-    Py_XSETREF(result->tp_dict, (PyObject *)stgdict);
+    Py_SETREF(result->tp_dict, (PyObject *)stgdict);
 
     if (-1 == make_funcptrtype_dict(stgdict)) {
         Py_DECREF(result);
@@ -5152,7 +5152,7 @@ comerror_init(PyObject *self, PyObject *args, PyObject *kwds)
 
     bself = (PyBaseExceptionObject *)self;
     Py_INCREF(args);
-    Py_XSETREF(bself->args, args);
+    Py_SETREF(bself->args, args);
 
     return 0;
 }

Modules/_curses_panel.c

@@ -313,7 +313,7 @@ PyCursesPanel_replace_panel(PyCursesPanelObject *self, PyObject *args)
         return NULL;
     }
     Py_INCREF(temp);
-    Py_XSETREF(po->wo, temp);
+    Py_SETREF(po->wo, temp);
     Py_INCREF(Py_None);
     return Py_None;
 }

Modules/_elementtree.c

@@ -1943,7 +1943,7 @@ element_setattro(ElementObject* self, PyObject* nameobj, PyObject* value)
 
     if (strcmp(name, "tag") == 0) {
         Py_INCREF(value);
-        Py_XSETREF(self->tag, value);
+        Py_SETREF(self->tag, value);
     } else if (strcmp(name, "text") == 0) {
         Py_DECREF(JOIN_OBJ(self->text));
         self->text = value;
@@ -1958,7 +1958,7 @@ element_setattro(ElementObject* self, PyObject* nameobj, PyObject* value)
                 return -1;
         }
         Py_INCREF(value);
-        Py_XSETREF(self->extra->attrib, value);
+        Py_SETREF(self->extra->attrib, value);
     } else {
         PyErr_SetString(PyExc_AttributeError,
             "Can't set arbitrary attributes on Element");
@@ -2551,9 +2551,9 @@ treebuilder_handle_start(TreeBuilderObject* self, PyObject* tag,
     self->index++;
 
     Py_INCREF(node);
-    Py_XSETREF(self->this, node);
+    Py_SETREF(self->this, node);
     Py_INCREF(node);
-    Py_XSETREF(self->last, node);
+    Py_SETREF(self->last, node);
 
     if (treebuilder_append_event(self, self->start_event_obj, node) < 0)
         goto error;

Modules/_sqlite/connection.c

@@ -204,7 +204,7 @@ void pysqlite_flush_statement_cache(pysqlite_Connection* self)
         node = node->next;
     }
 
-    Py_XSETREF(self->statement_cache,
+    Py_SETREF(self->statement_cache,
               (pysqlite_Cache *)PyObject_CallFunction((PyObject *)&pysqlite_CacheType, "O", self));
     Py_DECREF(self);
     self->statement_cache->decref_factory = 0;
@@ -794,7 +794,7 @@ static void _pysqlite_drop_unused_statement_references(pysqlite_Connection* self
         }
     }
 
-    Py_XSETREF(self->statements, new_list);
+    Py_SETREF(self->statements, new_list);
 }
 
 static void _pysqlite_drop_unused_cursor_references(pysqlite_Connection* self)
@@ -825,7 +825,7 @@ static void _pysqlite_drop_unused_cursor_references(pysqlite_Connection* self)
         }
     }
 
-    Py_XSETREF(self->cursors, new_list);
+    Py_SETREF(self->cursors, new_list);
 }
 
 PyObject* pysqlite_connection_create_function(pysqlite_Connection* self, PyObject* args, PyObject* kwargs)

Modules/_sqlite/cursor.c

@@ -510,7 +510,7 @@ PyObject* _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject*
 
     /* reset description and rowcount */
     Py_INCREF(Py_None);
-    Py_XSETREF(self->description, Py_None);
+    Py_SETREF(self->description, Py_None);
     self->rowcount = -1L;
 
     func_args = PyTuple_New(1);
@@ -535,7 +535,7 @@ PyObject* _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject*
     }
 
     if (self->statement->in_use) {
-        Py_XSETREF(self->statement,
+        Py_SETREF(self->statement,
                   PyObject_New(pysqlite_Statement, &pysqlite_StatementType));
         if (!self->statement) {
             goto error;
@@ -652,7 +652,7 @@ PyObject* _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject*
                 numcols = sqlite3_column_count(self->statement->st);
                 Py_END_ALLOW_THREADS
 
-                Py_XSETREF(self->description, PyTuple_New(numcols));
+                Py_SETREF(self->description, PyTuple_New(numcols));
                 if (!self->description) {
                     goto error;
                 }

Modules/_sre.c

@@ -756,7 +756,7 @@ deepcopy(PyObject** object, PyObject* memo)
     if (!copy)
         return 0;
 
-    Py_XSETREF(*object, copy);
+    Py_SETREF(*object, copy);
 
     return 1; /* success */
 }

Modules/_ssl.c

@@ -1589,7 +1589,7 @@ static int PySSL_set_context(PySSLSocket *self, PyObject *value,
         return -1;
 #else
         Py_INCREF(value);
-        Py_XSETREF(self->ctx, (PySSLContext *)value);
+        Py_SETREF(self->ctx, (PySSLContext *)value);
         SSL_set_SSL_CTX(self->ssl, self->ctx->ctx);
 #endif
     } else {

Modules/itertoolsmodule.c

@@ -631,7 +631,7 @@ tee_next(teeobject *to)
         link = teedataobject_jumplink(to->dataobj);
         if (link == NULL)
             return NULL;
-        Py_XSETREF(to->dataobj, (teedataobject *)link);
+        Py_SETREF(to->dataobj, (teedataobject *)link);
         to->index = 0;
     }
     value = teedataobject_getitem(to->dataobj, to->index);

Modules/signalmodule.c

@@ -1266,7 +1266,7 @@ PyInit__signal(void)
     if (Handlers[SIGINT].func == DefaultHandler) {
         /* Install default int handler */
         Py_INCREF(IntHandler);
-        Py_XSETREF(Handlers[SIGINT].func, IntHandler);
+        Py_SETREF(Handlers[SIGINT].func, IntHandler);
         old_siginthandler = PyOS_setsig(SIGINT, signal_handler);
     }