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().

1 files changed, 2 insertions, 2 deletions

diff --git a/Modules/getpath.c b/Modules/getpath.c
index 85e737b..e6a3e8e 100644
--- a/Modules/getpath.c
+++ b/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);