Issue #20437: Fixed 21 potential bugs when deleting objects references.

9 files changed, 19 insertions, 37 deletions

diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 7d0d258..48351be 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -159,10 +159,8 @@ _DictRemover_call(PyObject *myself, 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;
@@ -2930,10 +2928,8 @@ 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)) {
@@ -2976,10 +2972,8 @@ 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/_sqlite/cursor.c b/Modules/_sqlite/cursor.c
index 4999415..09c13d4 100644
--- a/Modules/_sqlite/cursor.c
+++ b/Modules/_sqlite/cursor.c
@@ -230,8 +230,7 @@ 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;
         }
@@ -443,8 +442,7 @@ PyObject* _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject*
     self->locked = 1;
     self->reset = 0;
 
-    Py_XDECREF(self->next_row);
-    self->next_row = NULL;
+    Py_CLEAR(self->next_row);
 
     if (multiple) {
         /* executemany() */
@@ -860,8 +858,7 @@ 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/posixmodule.c b/Modules/posixmodule.c
index 4b077a0..e72fbcf 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -693,8 +693,7 @@ typedef struct {
 static void
 path_cleanup(path_t *path) {
     if (path->cleanup) {
-        Py_DECREF(path->cleanup);
-        path->cleanup = NULL;
+        Py_CLEAR(path->cleanup);
     }
 }
 
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index 7e51d35..45680ae 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -314,8 +314,7 @@ call_with_frame(PyCodeObject *c, PyObject* func, PyObject* args,
     }
     else {
         if (trace_frame(tstate, f, PyTrace_RETURN, res) < 0) {
-            Py_XDECREF(res);
-            res = NULL;
+            Py_CLEAR(res);
         }
     }
 #else
diff --git a/Modules/readline.c b/Modules/readline.c
index bcd34f7..8fac526 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -231,8 +231,7 @@ 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;
@@ -827,7 +826,7 @@ on_completion_display_matches_hook(char **matches,
         (r != Py_None && PyLong_AsLong(r) == -1 && PyErr_Occurred())) {
         goto error;
     }
-    Py_XDECREF(r); r=NULL;
+    Py_CLEAR(r);
 
     if (0) {
     error:
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index c492224..952a091 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -74,8 +74,7 @@ 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/signalmodule.c b/Modules/signalmodule.c
index fbe1bb7..704c9f5 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -1305,12 +1305,9 @@ finisignal(void)
         Py_XDECREF(func);
     }
 
-    Py_XDECREF(IntHandler);
-    IntHandler = NULL;
-    Py_XDECREF(DefaultHandler);
-    DefaultHandler = NULL;
-    Py_XDECREF(IgnoreHandler);
-    IgnoreHandler = NULL;
+    Py_CLEAR(IntHandler);
+    Py_CLEAR(DefaultHandler);
+    Py_CLEAR(IgnoreHandler);
 }
 
 
diff --git a/Modules/syslogmodule.c b/Modules/syslogmodule.c
index 8b877cf..fc3f375 100644
--- a/Modules/syslogmodule.c
+++ b/Modules/syslogmodule.c
@@ -197,8 +197,7 @@ syslog_closelog(PyObject *self, PyObject *unused)
 {
     if (S_log_open) {
         closelog();
-        Py_XDECREF(S_ident_o);
-        S_ident_o = NULL;
+        Py_CLEAR(S_ident_o);
         S_log_open = 0;
     }
     Py_INCREF(Py_None);
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index e718795..1d1072d 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -392,8 +392,7 @@ PyZlib_compressobj(PyObject *selfptr, PyObject *args, PyObject *kwargs)
     }
 
  error:
-    Py_XDECREF(self);
-    self = NULL;
+    Py_CLEAR(self);
  success:
     if (zdict.buf != NULL)
         PyBuffer_Release(&zdict);