bpo-42658: Using LCMapStringEx in ntpath.normcase

Lib/ntpath.py

@@ -23,6 +23,7 @@
 import genericpath
 from genericpath import *
 
+
 __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
  "basename","dirname","commonprefix","getsize","getmtime",
  "getatime","getctime", "islink","exists","lexists","isdir","isfile",
@@ -41,14 +42,39 @@ def _get_bothseps(path):
 # Other normalizations (such as optimizing '../' away) are not done
 # (this is done by normpath).
 
-def normcase(s):
- """Normalize case of pathname.
-
- Makes all characters lowercase and all slashes into backslashes."""
- s = os.fspath(s)
- if isinstance(s, bytes):
- return s.replace(b'/', b'\\').lower()
- else:
+try:
+ from _winapi import (
+ LCMapStringEx as _LCMapStringEx,
+ LOCALE_NAME_INVARIANT as _LOCALE_NAME_INVARIANT,
+ LCMAP_LOWERCASE as _LCMAP_LOWERCASE)
+
+ def normcase(s):
+ """Normalize case of pathname.
+
+ Makes all characters lowercase and all slashes into backslashes.
+ """
+ s = os.fspath(s)
+ if not s:
+ return s
+ if isinstance(s, bytes):
+ encoding = sys.getfilesystemencoding()
+ s = s.decode(encoding, 'surrogateescape').replace('/', '\\')
+ s = _LCMapStringEx(_LOCALE_NAME_INVARIANT,
+ _LCMAP_LOWERCASE, s)
+ return s.encode(encoding, 'surrogateescape')
+ else:
+ return _LCMapStringEx(_LOCALE_NAME_INVARIANT,
+ _LCMAP_LOWERCASE,
+ s.replace('/', '\\'))
+except ImportError:
+ def normcase(s):
+ """Normalize case of pathname.
+
+ Makes all characters lowercase and all slashes into backslashes.
+ """
+ s = os.fspath(s)
+ if isinstance(s, bytes):
+ return os.fsencode(os.fsdecode(s).replace('/', '\\').lower())
  return s.replace('/', '\\').lower()
 
 

Lib/test/test_ntpath.py

@@ -852,6 +852,8 @@ def _check_function(self, func):
 
  def test_path_normcase(self):
  self._check_function(self.path.normcase)
+ if sys.platform == 'win32':
+ self.assertEqual(ntpath.normcase('\u03a9\u2126'), 'ωΩ')
 
  def test_path_isabs(self):
  self._check_function(self.path.isabs)

Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst

@@ -0,0 +1,3 @@
+Support native Windows case-insensitive path comparisons by using
+``LCMapStringEx`` instead of :func:`str.lower` in :func:`ntpath.normcase`.
+Add ``LCMapStringEx`` to the :mod:`_winapi` module.

Modules/_winapi.c

@@ -1512,6 +1512,50 @@ _winapi_PeekNamedPipe_impl(PyObject *module, HANDLE handle, int size)
  }
 }
 
+/*[clinic input]
+_winapi.LCMapStringEx
+
+ locale: LPCWSTR
+ flags: DWORD
+ src: LPCWSTR
+
+[clinic start generated code]*/
+
+static PyObject *
+_winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
+ LPCWSTR src)
+/*[clinic end generated code: output=cf4713d80e2b47c9 input=9fe26f95d5ab0001]*/
+{
+ if (flags & (LCMAP_SORTHANDLE | LCMAP_HASH | LCMAP_BYTEREV |
+ LCMAP_SORTKEY)) {
+ return PyErr_Format(PyExc_ValueError, "unsupported flags");
+ }
+
+ int dest_size = LCMapStringEx(locale, flags, src, -1, NULL, 0,
+ NULL, NULL, 0);
+ if (dest_size == 0) {
+ return PyErr_SetFromWindowsErr(0);
+ }
+
+ wchar_t* dest = PyMem_NEW(wchar_t, dest_size);
+ if (dest == NULL) {
+ return PyErr_NoMemory();
+ }
+
+ int nmapped = LCMapStringEx(locale, flags, src, -1, dest, dest_size,
+ NULL, NULL, 0);
+ if (nmapped == 0) {
+ DWORD error = GetLastError();
+ PyMem_DEL(dest);
+ return PyErr_SetFromWindowsErr(error);
+ }
+
+ PyObject *ret = PyUnicode_FromWideChar(dest, dest_size - 1);
+ PyMem_DEL(dest);
+
+ return ret;
+}
+
 /*[clinic input]
 _winapi.ReadFile
 
@@ -2023,6 +2067,7 @@ static PyMethodDef winapi_functions[] = {
  _WINAPI_OPENFILEMAPPING_METHODDEF
  _WINAPI_OPENPROCESS_METHODDEF
  _WINAPI_PEEKNAMEDPIPE_METHODDEF
+ _WINAPI_LCMAPSTRINGEX_METHODDEF
  _WINAPI_READFILE_METHODDEF
  _WINAPI_SETNAMEDPIPEHANDLESTATE_METHODDEF
  _WINAPI_TERMINATEPROCESS_METHODDEF
@@ -2160,6 +2205,22 @@ static int winapi_exec(PyObject *m)
  WINAPI_CONSTANT(F_DWORD, FILE_TYPE_PIPE);
  WINAPI_CONSTANT(F_DWORD, FILE_TYPE_REMOTE);
 
+ WINAPI_CONSTANT("u", LOCALE_NAME_INVARIANT);
+ WINAPI_CONSTANT(F_DWORD, LOCALE_NAME_MAX_LENGTH);
+ WINAPI_CONSTANT("u", LOCALE_NAME_SYSTEM_DEFAULT);
+ WINAPI_CONSTANT("u", LOCALE_NAME_USER_DEFAULT);
+
+ WINAPI_CONSTANT(F_DWORD, LCMAP_FULLWIDTH);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_HALFWIDTH);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_HIRAGANA);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_KATAKANA);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_LINGUISTIC_CASING);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_LOWERCASE);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_SIMPLIFIED_CHINESE);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_TITLECASE);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_TRADITIONAL_CHINESE);
+ WINAPI_CONSTANT(F_DWORD, LCMAP_UPPERCASE);
+
  WINAPI_CONSTANT("i", NULL);
 
  return 0;