Add _PyImport_GetBuiltinModuleNames().

Include/internal/pycore_import.h

@@ -46,6 +46,8 @@ extern PyStatus _PyImport_ReInitLock(void);
 #endif
 extern PyObject* _PyImport_BootstrapImp(PyThreadState *tstate);
 
+extern PyObject* _PyImport_GetBuiltinModuleNames(void);
+
 struct _module_alias {
     const char *name;                 /* ASCII encoded string */
     const char *orig;                 /* ASCII encoded string */

Python/import.c

@@ -1112,6 +1112,31 @@ PyImport_AppendInittab(const char *name, PyObject* (*initfunc)(void))
 }
 
 
+PyObject *
+_PyImport_GetBuiltinModuleNames(void)
+{
+    PyObject *list = PyList_New(0);
+    if (list == NULL) {
+        return NULL;
+    }
+    struct _inittab *inittab = _PyRuntime.imports.inittab;
+    for (Py_ssize_t i = 0; inittab[i].name != NULL; i++) {
+        PyObject *name = PyUnicode_FromString(inittab[i].name);
+        if (name == NULL) {
+            Py_DECREF(list);
+            return NULL;
+        }
+        if (PyList_Append(list, name) < 0) {
+            Py_DECREF(name);
+            Py_DECREF(list);
+            return NULL;
+        }
+        Py_DECREF(name);
+    }
+    return list;
+}
+
+
 /******************/
 /* frozen modules */
 /******************/

Python/sysmodule.c

@@ -2279,22 +2279,10 @@ static PyMethodDef sys_methods[] = {
 static PyObject *
 list_builtin_module_names(void)
 {
-    PyObject *list = PyList_New(0);
+    PyObject *list = _PyImport_GetBuiltinModuleNames();
     if (list == NULL) {
         return NULL;
     }
-    struct _inittab *inittab = _PyRuntime.imports.inittab;
-    for (Py_ssize_t i = 0; inittab[i].name != NULL; i++) {
-        PyObject *name = PyUnicode_FromString(inittab[i].name);
-        if (name == NULL) {
-            goto error;
-        }
-        if (PyList_Append(list, name) < 0) {
-            Py_DECREF(name);
-            goto error;
-        }
-        Py_DECREF(name);
-    }
     if (PyList_Sort(list) != 0) {
         goto error;
     }