Issue #20437: Fixed 43 potential bugs when deleting objects references.

11 files changed, 35 insertions, 66 deletions

diff --git a/Modules/_bsddb.c b/Modules/_bsddb.c
index dad1dcd..203bba2 100644
--- a/Modules/_bsddb.c
+++ b/Modules/_bsddb.c
@@ -949,8 +949,7 @@ newDBObject(DBEnvObject* arg, int flags)
      * DBTxns and closing any open DBs first. */
     if (makeDBError(err)) {
         if (self->myenvobj) {
-            Py_DECREF(self->myenvobj);
-            self->myenvobj = NULL;
+            Py_CLEAR(self->myenvobj);
         }
         Py_DECREF(self);
         self = NULL;
@@ -982,20 +981,16 @@ DB_dealloc(DBObject* self)
         PyObject_ClearWeakRefs((PyObject *) self);
     }
     if (self->myenvobj) {
-        Py_DECREF(self->myenvobj);
-        self->myenvobj = NULL;
+        Py_CLEAR(self->myenvobj);
     }
     if (self->associateCallback != NULL) {
-        Py_DECREF(self->associateCallback);
-        self->associateCallback = NULL;
+        Py_CLEAR(self->associateCallback);
     }
     if (self->btCompareCallback != NULL) {
-        Py_DECREF(self->btCompareCallback);
-        self->btCompareCallback = NULL;
+        Py_CLEAR(self->btCompareCallback);
     }
     if (self->dupCompareCallback != NULL) {
-        Py_DECREF(self->dupCompareCallback);
-        self->dupCompareCallback = NULL;
+        Py_CLEAR(self->dupCompareCallback);
     }
     Py_DECREF(self->private_obj);
     PyObject_Del(self);
@@ -1160,8 +1155,7 @@ DBEnv_dealloc(DBEnvObject* self)
             PyErr_Clear();
     }
 
-    Py_XDECREF(self->event_notifyCallback);
-    self->event_notifyCallback = NULL;
+    Py_CLEAR(self->event_notifyCallback);
 
     if (self->in_weakreflist != NULL) {
         PyObject_ClearWeakRefs((PyObject *) self);
@@ -1640,8 +1634,7 @@ DB_associate(DBObject* self, PyObject* args, PyObject* kwargs)
     MYDB_END_ALLOW_THREADS;
 
     if (err) {
-        Py_XDECREF(secondaryDB->associateCallback);
-        secondaryDB->associateCallback = NULL;
+        Py_CLEAR(secondaryDB->associateCallback);
         secondaryDB->primaryDBType = 0;
     }
 
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 599d90a..8ba6443 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -194,10 +194,8 @@ _DictRemover_call(PyObject *_self, PyObject *args, PyObject *kw)
         if (-1 == PyDict_DelItem(self->dict, self->key))
             /* XXX Error context */
             PyErr_WriteUnraisable(Py_None);
-        Py_DECREF(self->key);
-        self->key = NULL;
-        Py_DECREF(self->dict);
-        self->dict = NULL;
+        Py_CLEAR(self->key);
+        Py_CLEAR(self->dict);
     }
     Py_INCREF(Py_None);
     return Py_None;
@@ -3040,10 +3038,8 @@ static int
 PyCFuncPtr_set_restype(PyCFuncPtrObject *self, PyObject *ob)
 {
     if (ob == NULL) {
-        Py_XDECREF(self->restype);
-        self->restype = NULL;
-        Py_XDECREF(self->checker);
-        self->checker = NULL;
+        Py_CLEAR(self->restype);
+        Py_CLEAR(self->checker);
         return 0;
     }
     if (ob != Py_None && !PyType_stgdict(ob) && !PyCallable_Check(ob)) {
@@ -3086,10 +3082,8 @@ PyCFuncPtr_set_argtypes(PyCFuncPtrObject *self, PyObject *ob)
     PyObject *converters;
 
     if (ob == NULL || ob == Py_None) {
-        Py_XDECREF(self->converters);
-        self->converters = NULL;
-        Py_XDECREF(self->argtypes);
-        self->argtypes = NULL;
+        Py_CLEAR(self->converters);
+        Py_CLEAR(self->argtypes);
     } else {
         converters = converters_from_argtypes(ob);
         if (!converters)
diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
index ae07ca3..3e9f9df 100644
--- a/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@ -2739,10 +2739,10 @@ xmlparser_setevents(XMLParserObject* self, PyObject* args)
     target->events = events;
 
     /* clear out existing events */
-    Py_XDECREF(target->start_event_obj); target->start_event_obj = NULL;
-    Py_XDECREF(target->end_event_obj); target->end_event_obj = NULL;
-    Py_XDECREF(target->start_ns_event_obj); target->start_ns_event_obj = NULL;
-    Py_XDECREF(target->end_ns_event_obj); target->end_ns_event_obj = NULL;
+    Py_CLEAR(target->start_event_obj);
+    Py_CLEAR(target->end_event_obj);
+    Py_CLEAR(target->start_ns_event_obj);
+    Py_CLEAR(target->end_ns_event_obj);
 
     if (event_set == Py_None) {
         /* default is "end" only */
diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index 59966dad..7a8a5a1 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -369,8 +369,7 @@ PyObject* pysqlite_connection_close(pysqlite_Connection* self, PyObject* args)
         if (self->apsw_connection) {
             ret = PyObject_CallMethod(self->apsw_connection, "close", "");
             Py_XDECREF(ret);
-            Py_XDECREF(self->apsw_connection);
-            self->apsw_connection = NULL;
+            Py_CLEAR(self->apsw_connection);
             self->db = NULL;
         } else {
             Py_BEGIN_ALLOW_THREADS
diff --git a/Modules/_sqlite/cursor.c b/Modules/_sqlite/cursor.c
index f06f92c..3b84484 100644
--- a/Modules/_sqlite/cursor.c
+++ b/Modules/_sqlite/cursor.c
@@ -231,8 +231,7 @@ int pysqlite_build_row_cast_map(pysqlite_Cursor* self)
             if (converter != Py_None) {
                 Py_DECREF(converter);
             }
-            Py_XDECREF(self->row_cast_map);
-            self->row_cast_map = NULL;
+            Py_CLEAR(self->row_cast_map);
 
             return -1;
         }
@@ -468,8 +467,7 @@ PyObject* _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject*
     allow_8bit_chars = ((self->connection->text_factory != (PyObject*)&PyUnicode_Type) &&
         (self->connection->text_factory != pysqlite_OptimizedUnicode));
 
-    Py_XDECREF(self->next_row);
-    self->next_row = NULL;
+    Py_CLEAR(self->next_row);
 
     if (multiple) {
         /* executemany() */
@@ -896,8 +894,7 @@ PyObject* pysqlite_cursor_iternext(pysqlite_Cursor *self)
     if (!self->next_row) {
          if (self->statement) {
             (void)pysqlite_statement_reset(self->statement);
-            Py_DECREF(self->statement);
-            self->statement = NULL;
+            Py_CLEAR(self->statement);
         }
         return NULL;
     }
diff --git a/Modules/cPickle.c b/Modules/cPickle.c
index 8145bbf..10199eb 100644
--- a/Modules/cPickle.c
+++ b/Modules/cPickle.c
@@ -324,8 +324,7 @@ Pdata_popList(Pdata *self, Py_ssize_t start)
 
 #define FREE_ARG_TUP(self) {                        \
     if (Py_REFCNT(self->arg) > 1) {                 \
-      Py_DECREF(self->arg);                         \
-      self->arg=NULL;                               \
+      Py_CLEAR(self->arg);                          \
     }                                               \
   }
 
diff --git a/Modules/cdmodule.c b/Modules/cdmodule.c
index 8dfb769..9ee9b0b 100644
--- a/Modules/cdmodule.c
+++ b/Modules/cdmodule.c
@@ -535,10 +535,8 @@ CD_deleteparser(cdparserobject *self, PyObject *args)
 
     /* no sense in keeping the callbacks, so remove them */
     for (i = 0; i < NCALLBACKS; i++) {
-        Py_XDECREF(self->ob_cdcallbacks[i].ob_cdcallback);
-        self->ob_cdcallbacks[i].ob_cdcallback = NULL;
-        Py_XDECREF(self->ob_cdcallbacks[i].ob_cdcallbackarg);
-        self->ob_cdcallbacks[i].ob_cdcallbackarg = NULL;
+        Py_CLEAR(self->ob_cdcallbacks[i].ob_cdcallback);
+        Py_CLEAR(self->ob_cdcallbacks[i].ob_cdcallbackarg);
     }
 
     Py_INCREF(Py_None);
@@ -588,11 +586,9 @@ CD_removecallback(cdparserobject *self, PyObject *args)
 
     CDremovecallback(self->ob_cdparser, (CDDATATYPES) type);
 
-    Py_XDECREF(self->ob_cdcallbacks[type].ob_cdcallback);
-    self->ob_cdcallbacks[type].ob_cdcallback = NULL;
+    Py_CLEAR(self->ob_cdcallbacks[type].ob_cdcallback);
 
-    Py_XDECREF(self->ob_cdcallbacks[type].ob_cdcallbackarg);
-    self->ob_cdcallbacks[type].ob_cdcallbackarg = NULL;
+    Py_CLEAR(self->ob_cdcallbacks[type].ob_cdcallbackarg);
 
     Py_INCREF(Py_None);
     return Py_None;
@@ -668,10 +664,8 @@ cdparser_dealloc(cdparserobject *self)
     int i;
 
     for (i = 0; i < NCALLBACKS; i++) {
-        Py_XDECREF(self->ob_cdcallbacks[i].ob_cdcallback);
-        self->ob_cdcallbacks[i].ob_cdcallback = NULL;
-        Py_XDECREF(self->ob_cdcallbacks[i].ob_cdcallbackarg);
-        self->ob_cdcallbacks[i].ob_cdcallbackarg = NULL;
+        Py_CLEAR(self->ob_cdcallbacks[i].ob_cdcallback);
+        Py_CLEAR(self->ob_cdcallbacks[i].ob_cdcallbackarg);
     }
     CDdeleteparser(self->ob_cdparser);
     PyObject_Del(self);
diff --git a/Modules/flmodule.c b/Modules/flmodule.c
index b5a78cf..0ddf600 100644
--- a/Modules/flmodule.c
+++ b/Modules/flmodule.c
@@ -97,10 +97,8 @@ forgetgeneric(genericobject *g)
 {
     int i, n;
 
-    Py_XDECREF(g->ob_callback);
-    g->ob_callback = NULL;
-    Py_XDECREF(g->ob_callback_arg);
-    g->ob_callback_arg = NULL;
+    Py_CLEAR(g->ob_callback);
+    Py_CLEAR(g->ob_callback_arg);
     if (allgenerics == NULL)
         return; /* No objects known yet */
     n = PyList_Size(allgenerics);
@@ -132,10 +130,8 @@ releaseobjects(FL_FORM *form)
             /* The object is now unreachable for
                do_forms and check_forms, so
                delete it from the list of known objects */
-            Py_XDECREF(g->ob_callback);
-            g->ob_callback = NULL;
-            Py_XDECREF(g->ob_callback_arg);
-            g->ob_callback_arg = NULL;
+            Py_CLEAR(g->ob_callback);
+            Py_CLEAR(g->ob_callback_arg);
             PyList_SetItem(allgenerics, i, (PyObject *)NULL);
             nfreeslots++;
         }
diff --git a/Modules/readline.c b/Modules/readline.c
index a5d48c9..f19fa0b 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -206,8 +206,7 @@ set_hook(const char *funcname, PyObject **hook_var, PyObject *args)
     if (!PyArg_ParseTuple(args, buf, &function))
         return NULL;
     if (function == Py_None) {
-        Py_XDECREF(*hook_var);
-        *hook_var = NULL;
+        Py_CLEAR(*hook_var);
     }
     else if (PyCallable_Check(function)) {
         PyObject *tmp = *hook_var;
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index 6071996..2707b05 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -71,8 +71,7 @@ reap_obj(pylist fd2obj[FD_SETSIZE + 1])
 {
     int i;
     for (i = 0; i < FD_SETSIZE + 1 && fd2obj[i].sentinel >= 0; i++) {
-        Py_XDECREF(fd2obj[i].obj);
-        fd2obj[i].obj = NULL;
+        Py_CLEAR(fd2obj[i].obj);
     }
     fd2obj[0].sentinel = -1;
 }
diff --git a/Modules/svmodule.c b/Modules/svmodule.c
index 6e419ce..1519065 100644
--- a/Modules/svmodule.c
+++ b/Modules/svmodule.c
@@ -279,8 +279,7 @@ capture_dealloc(captureobject *self)
             (void)svUnlockCaptureData(self->ob_svideo->ob_svideo,
                                       self->ob_capture);
         self->ob_capture = NULL;
-        Py_DECREF(self->ob_svideo);
-        self->ob_svideo = NULL;
+        Py_CLEAR(self->ob_svideo);
     }
     PyObject_Del(self);
 }