bpo-29240: Fix locale encodings in UTF-8 Mode (#5170)

Modify locale.localeconv(), time.tzname, os.strerror() and other
functions to ignore the UTF-8 Mode: always use the current locale
encoding.

Changes:

* Add _Py_DecodeLocaleEx() and _Py_EncodeLocaleEx(). On decoding or
  encoding error, they return the position of the error and an error
  message which are used to raise Unicode errors in
  PyUnicode_DecodeLocale() and PyUnicode_EncodeLocale().
* Replace _Py_DecodeCurrentLocale() with _Py_DecodeLocaleEx().
* PyUnicode_DecodeLocale() now uses _Py_DecodeLocaleEx() for all
  cases, especially for the strict error handler.
* Add _Py_DecodeUTF8Ex(): return more information on decoding error
  and supports the strict error handler.
* Rename _Py_EncodeUTF8_surrogateescape() to _Py_EncodeUTF8Ex().
* Replace _Py_EncodeCurrentLocale() with _Py_EncodeLocaleEx().
* Ignore the UTF-8 mode to encode/decode localeconv(), strerror()
  and time zone name.
* Remove PyUnicode_DecodeLocale(), PyUnicode_DecodeLocaleAndSize()
  and PyUnicode_EncodeLocale() now ignore the UTF-8 mode: always use
  the "current" locale.
* Remove _PyUnicode_DecodeCurrentLocale(),
  _PyUnicode_DecodeCurrentLocaleAndSize() and
  _PyUnicode_EncodeCurrentLocale().

Modules/_datetimemodule.c

@@ -696,7 +696,7 @@ static int parse_isoformat_date(const char *dtstr,
     if (NULL == p) {
         return -1;
     }
-    
+
     if (*(p++) != '-') {
         return -2;
     }

Modules/_localemodule.c

@@ -572,8 +572,9 @@ PyIntl_bind_textdomain_codeset(PyObject* self,PyObject*args)
     if (!PyArg_ParseTuple(args, "sz", &domain, &codeset))
         return NULL;
     codeset = bind_textdomain_codeset(domain, codeset);
-    if (codeset)
+    if (codeset) {
         return PyUnicode_DecodeLocale(codeset, NULL);
+    }
     Py_RETURN_NONE;
 }
 #endif

Modules/getpath.c

@@ -449,8 +449,8 @@ search_for_exec_prefix(const _PyCoreConfig *core_config,
             n = fread(buf, 1, MAXPATHLEN, f);
             buf[n] = '\0';
             fclose(f);
-            rel_builddir_path = _Py_DecodeUTF8_surrogateescape(buf, n, NULL);
-            if (rel_builddir_path != NULL) {
+            rel_builddir_path = _Py_DecodeUTF8_surrogateescape(buf, n);
+            if (rel_builddir_path) {
                 wcsncpy(exec_prefix, calculate->argv0_path, MAXPATHLEN);
                 exec_prefix[MAXPATHLEN] = L'\0';
                 joinpath(exec_prefix, rel_builddir_path);

Modules/readline.c

@@ -132,13 +132,13 @@ static PyModuleDef readlinemodule;
 static PyObject *
 encode(PyObject *b)
 {
-    return _PyUnicode_EncodeCurrentLocale(b, "surrogateescape");
+    return PyUnicode_EncodeLocale(b, "surrogateescape");
 }
 
 static PyObject *
 decode(const char *s)
 {
-    return _PyUnicode_DecodeCurrentLocale(s, "surrogateescape");
+    return PyUnicode_DecodeLocale(s, "surrogateescape");
 }
 
 

Modules/timemodule.c

@@ -418,11 +418,11 @@ tmtotuple(struct tm *p
     SET(8, p->tm_isdst);
 #ifdef HAVE_STRUCT_TM_TM_ZONE
     PyStructSequence_SET_ITEM(v, 9,
-        _PyUnicode_DecodeCurrentLocale(p->tm_zone, "surrogateescape"));
+        PyUnicode_DecodeLocale(p->tm_zone, "surrogateescape"));
     SET(10, p->tm_gmtoff);
 #else
     PyStructSequence_SET_ITEM(v, 9,
-        _PyUnicode_DecodeCurrentLocale(zone, "surrogateescape"));
+        PyUnicode_DecodeLocale(zone, "surrogateescape"));
     PyStructSequence_SET_ITEM(v, 10, _PyLong_FromTime_t(gmtoff));
 #endif /* HAVE_STRUCT_TM_TM_ZONE */
 #undef SET
@@ -809,8 +809,7 @@ time_strftime(PyObject *self, PyObject *args)
 #ifdef HAVE_WCSFTIME
             ret = PyUnicode_FromWideChar(outbuf, buflen);
 #else
-            ret = _PyUnicode_DecodeCurrentLocaleAndSize(outbuf, buflen,
-                                                        "surrogateescape");
+            ret = PyUnicode_DecodeLocaleAndSize(outbuf, buflen, "surrogateescape");
 #endif
             PyMem_Free(outbuf);
             break;
@@ -1541,8 +1540,8 @@ PyInit_timezone(PyObject *m) {
     PyModule_AddIntConstant(m, "altzone", timezone-3600);
 #endif
     PyModule_AddIntConstant(m, "daylight", daylight);
-    otz0 = _PyUnicode_DecodeCurrentLocale(tzname[0], "surrogateescape");
-    otz1 = _PyUnicode_DecodeCurrentLocale(tzname[1], "surrogateescape");
+    otz0 = PyUnicode_DecodeLocale(tzname[0], "surrogateescape");
+    otz1 = PyUnicode_DecodeLocale(tzname[1], "surrogateescape");
     PyModule_AddObject(m, "tzname", Py_BuildValue("(NN)", otz0, otz1));
 #else /* !HAVE_TZNAME || __GLIBC__ || __CYGWIN__*/
     {