bpo-42955: Add sys.modules_names (GH-24238)

Add sys.module_names, containing the list of the standard library
module names.

1 files changed, 47 insertions, 15 deletions

diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 720532e..e2f7e39 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -29,6 +29,7 @@ Data members:
 #include "frameobject.h"          // PyFrame_GetBack()
 #include "pydtrace.h"
 #include "osdefs.h"               // DELIM
+#include "module_names.h"         // _Py_module_names
 #include <locale.h>
 
 #ifdef MS_WINDOWS
@@ -2020,33 +2021,63 @@ static PyMethodDef sys_methods[] = {
     {NULL,              NULL}           /* sentinel */
 };
 
+
 static PyObject *
 list_builtin_module_names(void)
 {
     PyObject *list = PyList_New(0);
-    int i;
-    if (list == NULL)
+    if (list == NULL) {
         return NULL;
-    for (i = 0; PyImport_Inittab[i].name != NULL; i++) {
-        PyObject *name = PyUnicode_FromString(
-            PyImport_Inittab[i].name);
-        if (name == NULL)
-            break;
-        PyList_Append(list, name);
+    }
+    for (Py_ssize_t i = 0; PyImport_Inittab[i].name != NULL; i++) {
+        PyObject *name = PyUnicode_FromString(PyImport_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) {
-        Py_DECREF(list);
-        list = NULL;
+        goto error;
+    }
+    PyObject *tuple = PyList_AsTuple(list);
+    Py_DECREF(list);
+    return tuple;
+
+error:
+    Py_DECREF(list);
+    return NULL;
+}
+
+
+static PyObject *
+list_module_names(void)
+{
+    Py_ssize_t len = Py_ARRAY_LENGTH(_Py_module_names);
+    PyObject *names = PyTuple_New(len);
+    if (names == NULL) {
+        return NULL;
     }
-    if (list) {
-        PyObject *v = PyList_AsTuple(list);
-        Py_DECREF(list);
-        list = v;
+
+    for (Py_ssize_t i = 0; i < len; i++) {
+        PyObject *name = PyUnicode_FromString(_Py_module_names[i]);
+        if (name == NULL) {
+            Py_DECREF(names);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(names, i, name);
     }
-    return list;
+
+    PyObject *set = PyObject_CallFunction((PyObject *)&PyFrozenSet_Type,
+                                          "(O)", names);
+    Py_DECREF(names);
+    return set;
 }
 
+
 /* Pre-initialization support for sys.warnoptions and sys._xoptions
  *
  * Modern internal code paths:
@@ -2753,6 +2784,7 @@ _PySys_InitCore(PyThreadState *tstate, PyObject *sysdict)
     SET_SYS("hash_info", get_hash_info(tstate));
     SET_SYS("maxunicode", PyLong_FromLong(0x10FFFF));
     SET_SYS("builtin_module_names", list_builtin_module_names());
+    SET_SYS("module_names", list_module_names());
 #if PY_BIG_ENDIAN
     SET_SYS_FROM_STRING("byteorder", "big");
 #else