Add gc header size to returned sizeof information

Python/sysmodule.c

 
 /* System module */
 
 /*
 Various bits of information used by the interpreter are collected in
 module 'sys'.
 Function member:
 - exit(sts): raise SystemExit
 Data members:
 - stdin, stdout, stderr: standard file objects
@@ skipping 624 matching lines @@
                 return NULL;
         mallopt(M_DEBUG, flag);
         Py_INCREF(Py_None);
         return Py_None;
 }
 #endif /* USE_MALLOPT */
 
 static PyObject *
 sys_getsizeof(PyObject *self, PyObject *args)
 {
-        static PyObject * str__sizeof__ = NULL;
+        PyObject *res = NULL;
+        static PyObject *str__sizeof__ = NULL;
+        static PyObject *gc_head_size = NULL;
 
         /* Initialize static variable needed by _PyType_Lookup */
         if (str__sizeof__ == NULL) {
                 str__sizeof__ = PyString_InternFromString("__sizeof__");
                 if (str__sizeof__ == NULL)
                         return NULL;
         }
+
+        /* Initialize static variable for GC head size */
+        if (gc_head_size == NULL) {
+            gc_head_size = PyInt_FromSsize_t(sizeof(PyGC_Head));
+            if (gc_head_size == NULL) {
+                Py_DECREF(res);
+                return NULL;
+            }
+        }
 
         /* Type objects */
         if (PyType_Check(args)){
                 PyObject *method = _PyType_Lookup(Py_TYPE(args),
                                                   str__sizeof__);
                 if (method == NULL) {
                         PyErr_Format(PyExc_TypeError,
                                      "Type %.100s doesn't define __sizeof__",
                                      Py_TYPE(args)->tp_name);
                         return NULL;
                 }
-                return PyObject_CallFunctionObjArgs(method, args, NULL);
-        } 
+                res = PyObject_CallFunctionObjArgs(method, args, NULL);
+        }
         /* Instance of old-style classes */
         else if (PyInstance_Check(args))
-                return PyInt_FromSsize_t(PyInstance_Type.tp_basicsize);
+                res = PyInt_FromSsize_t(PyInstance_Type.tp_basicsize);
         /* Old-style classes */
         else if (PyClass_Check(args))
-                return PyInt_FromSsize_t(PyClass_Type.tp_basicsize);
+                res = PyInt_FromSsize_t(PyClass_Type.tp_basicsize);
         else
-                return PyObject_CallMethod(args, "__sizeof__", NULL);
+                res = PyObject_CallMethod(args, "__sizeof__", NULL);
+
+        /* add gc_head size if object is tracked by gc */
+        if (PyObject_IS_GC(args)) {
+            res = PyNumber_Add(res, gc_head_size);
+            Py_DECREF(gc_head_size);
+        }
+
+        return res;
 }
 
 PyDoc_STRVAR(getsizeof_doc,
 "getsizeof(object) -> int\n\
 \n\
 Return the size of object in bytes.");
 
 static PyObject *
 sys_getrefcount(PyObject *self, PyObject *arg)
 {
@@ skipping 992 matching lines @@
 
 void
 PySys_WriteStderr(const char *format, ...)
 {
         va_list va;
 
         va_start(va, format);
         mywrite("stderr", stderr, format, va);
         va_end(va);
 }