bpo-42208: Add _Py_GetLocaleEncoding() (GH-23050)

_io.TextIOWrapper no longer calls getpreferredencoding(False) of
_bootlocale to get the locale encoding, but calls
_Py_GetLocaleEncoding() instead.

Add config_get_fs_encoding() sub-function. Reorganize also
config_get_locale_encoding() code.

3 files changed, 4 insertions, 48 deletions

diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
index e430352..9147648 100644
--- a/Modules/_io/_iomodule.c
+++ b/Modules/_io/_iomodule.c
@@ -593,31 +593,6 @@ _PyIO_get_module_state(void)
     return state;
 }
 
-PyObject *
-_PyIO_get_locale_module(_PyIO_State *state)
-{
-    PyObject *mod;
-    if (state->locale_module != NULL) {
-        assert(PyWeakref_CheckRef(state->locale_module));
-        mod = PyWeakref_GET_OBJECT(state->locale_module);
-        if (mod != Py_None) {
-            Py_INCREF(mod);
-            return mod;
-        }
-        Py_CLEAR(state->locale_module);
-    }
-    mod = PyImport_ImportModule("_bootlocale");
-    if (mod == NULL)
-        return NULL;
-    state->locale_module = PyWeakref_NewRef(mod, NULL);
-    if (state->locale_module == NULL) {
-        Py_DECREF(mod);
-        return NULL;
-    }
-    return mod;
-}
-
-
 static int
 iomodule_traverse(PyObject *mod, visitproc visit, void *arg) {
     _PyIO_State *state = get_io_state(mod);
diff --git a/Modules/_io/_iomodule.h b/Modules/_io/_iomodule.h
index a8f3951..638797f 100644
--- a/Modules/_io/_iomodule.h
+++ b/Modules/_io/_iomodule.h
@@ -150,7 +150,6 @@ typedef struct {
 #define IO_STATE() _PyIO_get_module_state()
 
 extern _PyIO_State *_PyIO_get_module_state(void);
-extern PyObject *_PyIO_get_locale_module(_PyIO_State *);
 
 #ifdef MS_WINDOWS
 extern char _PyIO_get_console_type(PyObject *);
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 699b7e9..2078bb3 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -10,6 +10,7 @@
 #include "Python.h"
 #include "pycore_interp.h"        // PyInterpreterState.fs_codec
 #include "pycore_long.h"          // _PyLong_GetZero()
+#include "pycore_fileutils.h"     // _Py_GetLocaleEncoding()
 #include "pycore_object.h"
 #include "pycore_pystate.h"       // _PyInterpreterState_GET()
 #include "structmember.h"         // PyMemberDef
@@ -27,7 +28,6 @@ _Py_IDENTIFIER(_dealloc_warn);
 _Py_IDENTIFIER(decode);
 _Py_IDENTIFIER(fileno);
 _Py_IDENTIFIER(flush);
-_Py_IDENTIFIER(getpreferredencoding);
 _Py_IDENTIFIER(isatty);
 _Py_IDENTIFIER(mode);
 _Py_IDENTIFIER(name);
@@ -1155,29 +1155,11 @@ _io_TextIOWrapper___init___impl(textio *self, PyObject *buffer,
         }
     }
     if (encoding == NULL && self->encoding == NULL) {
-        PyObject *locale_module = _PyIO_get_locale_module(state);
-        if (locale_module == NULL)
-            goto catch_ImportError;
-        self->encoding = _PyObject_CallMethodIdOneArg(
-            locale_module, &PyId_getpreferredencoding, Py_False);
-        Py_DECREF(locale_module);
+        self->encoding = _Py_GetLocaleEncoding();
         if (self->encoding == NULL) {
-          catch_ImportError:
-            /*
-             Importing locale can raise an ImportError because of
-             _functools, and locale.getpreferredencoding can raise an
-             ImportError if _locale is not available.  These will happen
-             during module building.
-            */
-            if (PyErr_ExceptionMatches(PyExc_ImportError)) {
-                PyErr_Clear();
-                self->encoding = PyUnicode_FromString("ascii");
-            }
-            else
-                goto error;
+            goto error;
         }
-        else if (!PyUnicode_Check(self->encoding))
-            Py_CLEAR(self->encoding);
+        assert(PyUnicode_Check(self->encoding));
     }
     if (self->encoding != NULL) {
         encoding = PyUnicode_AsUTF8(self->encoding);