bpo-41861: Convert _sqlite3 CursorType and ConnectionType to heap types (GH-22478)

Author: Erlend Egeberg Aasland

Modules/_sqlite/connection.c

@@ -220,6 +220,8 @@ void pysqlite_do_all_statements(pysqlite_Connection* self, int action, int reset
 
 void pysqlite_connection_dealloc(pysqlite_Connection* self)
 {
+    PyTypeObject *tp = Py_TYPE(self);
+
     Py_XDECREF(self->statement_cache);
 
     /* Clean up if user has not called .close() explicitly. */
@@ -236,7 +238,9 @@ void pysqlite_connection_dealloc(pysqlite_Connection* self)
     Py_XDECREF(self->collations);
     Py_XDECREF(self->statements);
     Py_XDECREF(self->cursors);
-    Py_TYPE(self)->tp_free((PyObject*)self);
+
+    tp->tp_free(self);
+    Py_DECREF(tp);
 }
 
 /*
@@ -281,13 +285,13 @@ PyObject* pysqlite_connection_cursor(pysqlite_Connection* self, PyObject* args,
     }
 
     if (factory == NULL) {
-        factory = (PyObject*)&pysqlite_CursorType;
+        factory = (PyObject*)pysqlite_CursorType;
     }
 
     cursor = PyObject_CallOneArg(factory, (PyObject *)self);
     if (cursor == NULL)
         return NULL;
-    if (!PyObject_TypeCheck(cursor, &pysqlite_CursorType)) {
+    if (!PyObject_TypeCheck(cursor, pysqlite_CursorType)) {
         PyErr_Format(PyExc_TypeError,
                      "factory must return a cursor, not %.100s",
                      Py_TYPE(cursor)->tp_name);
@@ -1494,7 +1498,7 @@ pysqlite_connection_backup(pysqlite_Connection *self, PyObject *args, PyObject *
     static char *keywords[] = {"target", "pages", "progress", "name", "sleep", NULL};
 
     if (!PyArg_ParseTupleAndKeywords(args, kwds, "O!|$iOsO:backup", keywords,
-                                     &pysqlite_ConnectionType, &target,
+                                     pysqlite_ConnectionType, &target,
                                      &pages, &progress, &name, &sleep_obj)) {
         return NULL;
     }
@@ -1831,50 +1835,32 @@ static struct PyMemberDef connection_members[] =
     {NULL}
 };
 
-PyTypeObject pysqlite_ConnectionType = {
-        PyVarObject_HEAD_INIT(NULL, 0)
-        MODULE_NAME ".Connection",                      /* tp_name */
-        sizeof(pysqlite_Connection),                    /* tp_basicsize */
-        0,                                              /* tp_itemsize */
-        (destructor)pysqlite_connection_dealloc,        /* tp_dealloc */
-        0,                                              /* tp_vectorcall_offset */
-        0,                                              /* tp_getattr */
-        0,                                              /* tp_setattr */
-        0,                                              /* tp_as_async */
-        0,                                              /* tp_repr */
-        0,                                              /* tp_as_number */
-        0,                                              /* tp_as_sequence */
-        0,                                              /* tp_as_mapping */
-        0,                                              /* tp_hash */
-        (ternaryfunc)pysqlite_connection_call,          /* tp_call */
-        0,                                              /* tp_str */
-        0,                                              /* tp_getattro */
-        0,                                              /* tp_setattro */
-        0,                                              /* tp_as_buffer */
-        Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE,         /* tp_flags */
-        connection_doc,                                 /* tp_doc */
-        0,                                              /* tp_traverse */
-        0,                                              /* tp_clear */
-        0,                                              /* tp_richcompare */
-        0,                                              /* tp_weaklistoffset */
-        0,                                              /* tp_iter */
-        0,                                              /* tp_iternext */
-        connection_methods,                             /* tp_methods */
-        connection_members,                             /* tp_members */
-        connection_getset,                              /* tp_getset */
-        0,                                              /* tp_base */
-        0,                                              /* tp_dict */
-        0,                                              /* tp_descr_get */
-        0,                                              /* tp_descr_set */
-        0,                                              /* tp_dictoffset */
-        (initproc)pysqlite_connection_init,             /* tp_init */
-        0,                                              /* tp_alloc */
-        0,                                              /* tp_new */
-        0                                               /* tp_free */
+static PyType_Slot connection_slots[] = {
+    {Py_tp_dealloc, pysqlite_connection_dealloc},
+    {Py_tp_doc, (void *)connection_doc},
+    {Py_tp_methods, connection_methods},
+    {Py_tp_members, connection_members},
+    {Py_tp_getset, connection_getset},
+    {Py_tp_new, PyType_GenericNew},
+    {Py_tp_init, pysqlite_connection_init},
+    {Py_tp_call, pysqlite_connection_call},
+    {0, NULL},
+};
+
+static PyType_Spec connection_spec = {
+    .name = MODULE_NAME ".Connection",
+    .basicsize = sizeof(pysqlite_Connection),
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .slots = connection_slots,
 };
 
-extern int pysqlite_connection_setup_types(void)
+PyTypeObject *pysqlite_ConnectionType = NULL;
+
+extern int pysqlite_connection_setup_types(PyObject *module)
 {
-    pysqlite_ConnectionType.tp_new = PyType_GenericNew;
-    return PyType_Ready(&pysqlite_ConnectionType);
+    pysqlite_ConnectionType = (PyTypeObject *)PyType_FromModuleAndSpec(module, &connection_spec, NULL);
+    if (pysqlite_ConnectionType == NULL) {
+        return -1;
+    }
+    return 0;
 }

Modules/_sqlite/connection.h

@@ -106,7 +106,7 @@ typedef struct
     PyObject* NotSupportedError;
 } pysqlite_Connection;
 
-extern PyTypeObject pysqlite_ConnectionType;
+extern PyTypeObject *pysqlite_ConnectionType;
 
 PyObject* pysqlite_connection_alloc(PyTypeObject* type, int aware);
 void pysqlite_connection_dealloc(pysqlite_Connection* self);
@@ -122,6 +122,6 @@ int pysqlite_connection_register_cursor(pysqlite_Connection* connection, PyObjec
 int pysqlite_check_thread(pysqlite_Connection* self);
 int pysqlite_check_connection(pysqlite_Connection* con);
 
-int pysqlite_connection_setup_types(void);
+int pysqlite_connection_setup_types(PyObject *module);
 
 #endif

Modules/_sqlite/cursor.c

@@ -33,7 +33,7 @@ static int pysqlite_cursor_init(pysqlite_Cursor* self, PyObject* args, PyObject*
 {
     pysqlite_Connection* connection;
 
-    if (!PyArg_ParseTuple(args, "O!", &pysqlite_ConnectionType, &connection))
+    if (!PyArg_ParseTuple(args, "O!", pysqlite_ConnectionType, &connection))
     {
         return -1;
     }
@@ -74,6 +74,8 @@ static int pysqlite_cursor_init(pysqlite_Cursor* self, PyObject* args, PyObject*
 
 static void pysqlite_cursor_dealloc(pysqlite_Cursor* self)
 {
+    PyTypeObject *tp = Py_TYPE(self);
+
     /* Reset the statement if the user has not closed the cursor */
     if (self->statement) {
         pysqlite_statement_reset(self->statement);
@@ -91,7 +93,8 @@ static void pysqlite_cursor_dealloc(pysqlite_Cursor* self)
         PyObject_ClearWeakRefs((PyObject*)self);
     }
 
-    Py_TYPE(self)->tp_free((PyObject*)self);
+    tp->tp_free(self);
+    Py_DECREF(tp);
 }
 
 static PyObject *
@@ -898,56 +901,39 @@ static struct PyMemberDef cursor_members[] =
     {"lastrowid", T_OBJECT, offsetof(pysqlite_Cursor, lastrowid), READONLY},
     {"rowcount", T_LONG, offsetof(pysqlite_Cursor, rowcount), READONLY},
     {"row_factory", T_OBJECT, offsetof(pysqlite_Cursor, row_factory), 0},
+    {"__weaklistoffset__", T_PYSSIZET, offsetof(pysqlite_Cursor, in_weakreflist), READONLY},
     {NULL}
 };
 
 static const char cursor_doc[] =
 PyDoc_STR("SQLite database cursor class.");
 
-PyTypeObject pysqlite_CursorType = {
-        PyVarObject_HEAD_INIT(NULL, 0)
-        MODULE_NAME ".Cursor",                          /* tp_name */
-        sizeof(pysqlite_Cursor),                        /* tp_basicsize */
-        0,                                              /* tp_itemsize */
-        (destructor)pysqlite_cursor_dealloc,            /* tp_dealloc */
-        0,                                              /* tp_vectorcall_offset */
-        0,                                              /* tp_getattr */
-        0,                                              /* tp_setattr */
-        0,                                              /* tp_as_async */
-        0,                                              /* tp_repr */
-        0,                                              /* tp_as_number */
-        0,                                              /* tp_as_sequence */
-        0,                                              /* tp_as_mapping */
-        0,                                              /* tp_hash */
-        0,                                              /* tp_call */
-        0,                                              /* tp_str */
-        0,                                              /* tp_getattro */
-        0,                                              /* tp_setattro */
-        0,                                              /* tp_as_buffer */
-        Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE, /* tp_flags */
-        cursor_doc,                                     /* tp_doc */
-        0,                                              /* tp_traverse */
-        0,                                              /* tp_clear */
-        0,                                              /* tp_richcompare */
-        offsetof(pysqlite_Cursor, in_weakreflist),      /* tp_weaklistoffset */
-        PyObject_SelfIter,                              /* tp_iter */
-        (iternextfunc)pysqlite_cursor_iternext,         /* tp_iternext */
-        cursor_methods,                                 /* tp_methods */
-        cursor_members,                                 /* tp_members */
-        0,                                              /* tp_getset */
-        0,                                              /* tp_base */
-        0,                                              /* tp_dict */
-        0,                                              /* tp_descr_get */
-        0,                                              /* tp_descr_set */
-        0,                                              /* tp_dictoffset */
-        (initproc)pysqlite_cursor_init,                 /* tp_init */
-        0,                                              /* tp_alloc */
-        0,                                              /* tp_new */
-        0                                               /* tp_free */
+static PyType_Slot cursor_slots[] = {
+    {Py_tp_dealloc, pysqlite_cursor_dealloc},
+    {Py_tp_doc, (void *)cursor_doc},
+    {Py_tp_iter, PyObject_SelfIter},
+    {Py_tp_iternext, pysqlite_cursor_iternext},
+    {Py_tp_methods, cursor_methods},
+    {Py_tp_members, cursor_members},
+    {Py_tp_new, PyType_GenericNew},
+    {Py_tp_init, pysqlite_cursor_init},
+    {0, NULL},
+};
+
+static PyType_Spec cursor_spec = {
+    .name = MODULE_NAME ".Cursor",
+    .basicsize = sizeof(pysqlite_Cursor),
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .slots = cursor_slots,
 };
 
-extern int pysqlite_cursor_setup_types(void)
+PyTypeObject *pysqlite_CursorType = NULL;
+
+extern int pysqlite_cursor_setup_types(PyObject *module)
 {
-    pysqlite_CursorType.tp_new = PyType_GenericNew;
-    return PyType_Ready(&pysqlite_CursorType);
+    pysqlite_CursorType = (PyTypeObject *)PyType_FromModuleAndSpec(module, &cursor_spec, NULL);
+    if (pysqlite_CursorType == NULL) {
+        return -1;
+    }
+    return 0;
 }

Modules/_sqlite/cursor.h

@@ -52,7 +52,7 @@ typedef struct
     PyObject* in_weakreflist; /* List of weak references */
 } pysqlite_Cursor;
 
-extern PyTypeObject pysqlite_CursorType;
+extern PyTypeObject *pysqlite_CursorType;
 
 PyObject* pysqlite_cursor_execute(pysqlite_Cursor* self, PyObject* args);
 PyObject* pysqlite_cursor_executemany(pysqlite_Cursor* self, PyObject* args);
@@ -64,7 +64,7 @@ PyObject* pysqlite_cursor_fetchall(pysqlite_Cursor* self, PyObject* args);
 PyObject* pysqlite_noop(pysqlite_Connection* self, PyObject* args);
 PyObject* pysqlite_cursor_close(pysqlite_Cursor* self, PyObject* args);
 
-int pysqlite_cursor_setup_types(void);
+int pysqlite_cursor_setup_types(PyObject *module);
 
 #define UNKNOWN (-1)
 #endif

Modules/_sqlite/module.c

@@ -82,7 +82,7 @@ static PyObject* module_connect(PyObject* self, PyObject* args, PyObject*
     }
 
     if (factory == NULL) {
-        factory = (PyObject*)&pysqlite_ConnectionType;
+        factory = (PyObject*)pysqlite_ConnectionType;
     }
 
     if (PySys_Audit("sqlite3.connect", "O", database) < 0) {
@@ -353,8 +353,8 @@ PyMODINIT_FUNC PyInit__sqlite3(void)
 
     if (!module ||
         (pysqlite_row_setup_types(module) < 0) ||
-        (pysqlite_cursor_setup_types() < 0) ||
-        (pysqlite_connection_setup_types() < 0) ||
+        (pysqlite_cursor_setup_types(module) < 0) ||
+        (pysqlite_connection_setup_types(module) < 0) ||
         (pysqlite_cache_setup_types(module) < 0) ||
         (pysqlite_statement_setup_types(module) < 0) ||
         (pysqlite_prepare_protocol_setup_types(module) < 0)
@@ -363,8 +363,8 @@ PyMODINIT_FUNC PyInit__sqlite3(void)
         return NULL;
     }
 
-    ADD_TYPE(module, pysqlite_ConnectionType);
-    ADD_TYPE(module, pysqlite_CursorType);
+    ADD_TYPE(module, *pysqlite_ConnectionType);
+    ADD_TYPE(module, *pysqlite_CursorType);
     ADD_TYPE(module, *pysqlite_PrepareProtocolType);
     ADD_TYPE(module, *pysqlite_RowType);
 

Modules/_sqlite/row.c

@@ -49,7 +49,7 @@ pysqlite_row_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
     if (!PyArg_ParseTuple(args, "OO", &cursor, &data))
         return NULL;
 
-    if (!PyObject_TypeCheck((PyObject*)cursor, &pysqlite_CursorType)) {
+    if (!PyObject_TypeCheck((PyObject*)cursor, pysqlite_CursorType)) {
         PyErr_SetString(PyExc_TypeError, "instance of cursor required for first argument");
         return NULL;
     }