gh-84419: Fix the execute permissions in os.stat() on Windows

Lib/test/test_os/test_windows.py

@@ -608,5 +608,43 @@ def cleanup():
  self.assertGreaterEqual(stat1.st_atime, stat2.st_atime)
 
 
+class Win32StatExecutableTests(unittest.TestCase):
+ # gh-84419: Windows strips trailing dots and spaces from the last
+ # component of the path, so they should be ignored when guessing
+ # the execute permissions from the file extension.
+
+ SUFFIXES = ['', ' ', ' ', '.', '..', ' . .']
+
+ def check(self, ext, mask):
+ filename = os_helper.TESTFN + ext
+ create_file(filename)
+ try:
+ for suffix in self.SUFFIXES:
+ with self.subTest(suffix=suffix):
+ mode = os.stat(filename + suffix).st_mode
+ self.assertEqual(mode & 0o111, mask)
+ finally:
+ os_helper.unlink(filename)
+
+ def test_executable_extension(self):
+ for ext in '.exe', '.bat', '.cmd', '.com', '.EXE', '.Bat':
+ with self.subTest(ext=ext):
+ self.check(ext, 0o111)
+
+ def test_not_executable_extension(self):
+ for ext in '.txt', '.py', '.exe.txt', '':
+ with self.subTest(ext=ext):
+ self.check(ext, 0)
+
+ def test_extended_path(self):
+ # The \\?\ prefix disables normalization: trailing spaces and dots
+ # are part of the file name.
+ filename = os.path.abspath(os_helper.TESTFN + '.exe')
+ create_file(filename)
+ self.addCleanup(os_helper.unlink, filename)
+ self.assertEqual(os.stat('\\\\?\\' + filename).st_mode & 0o111, 0o111)
+ self.assertRaises(OSError, os.stat, '\\\\?\\' + filename + ' ')
+
+
 if __name__ == "__main__":
  unittest.main()

Misc/NEWS.d/next/Library/2026-08-08-21-40-00.gh-issue-84419.statexe.rst

@@ -0,0 +1,3 @@
+Fix :func:`os.stat` on Windows: trailing dots and spaces, which are ignored
+by the operating system, are no longer taken into account when the execute
+permissions are guessed from the file extension.

Modules/posixmodule.c

@@ -2035,6 +2035,14 @@ win32_wchdir(LPCWSTR path)
 #define HAVE_STRUCT_STAT_ST_FILE_ATTRIBUTES 1
 #define HAVE_STRUCT_STAT_ST_REPARSE_TAG 1
 
+/* The \\?\ prefix disables the path normalization, in particular
+ stripping of trailing dots and spaces. */
+static int
+is_extended_path(const wchar_t *path)
+{
+ return wcsncmp(path, L"\\\\?\\", 4) == 0;
+}
+
 static void
 find_data_to_file_info(WIN32_FIND_DATAW *pFileData,
  FILE_BASIC_INFO* basic_info,
@@ -2108,12 +2116,20 @@ update_st_mode_from_path(const wchar_t *path, DWORD attr,
  GetSecurityInfo, OpenThreadToken/OpenProcessToken, and
  AccessCheck to check for generic read, write, and execute
  access. */
- const wchar_t *fileExtension = wcsrchr(path, '.');
- if (fileExtension) {
- if (_wcsicmp(fileExtension, L".exe") == 0 ||
- _wcsicmp(fileExtension, L".bat") == 0 ||
- _wcsicmp(fileExtension, L".cmd") == 0 ||
- _wcsicmp(fileExtension, L".com") == 0) {
+ size_t len = wcslen(path);
+ if (!is_extended_path(path)) {
+ /* Trailing dots and spaces are stripped from the last component
+ of the path. */
+ while (len > 0 && (path[len - 1] == L'.' || path[len - 1] == L' ')) {
+ len--;
+ }
+ }
+ if (len >= 4) {
+ const wchar_t *fileExtension = path + len - 4;
+ if (_wcsnicmp(fileExtension, L".exe", 4) == 0 ||
+ _wcsnicmp(fileExtension, L".bat", 4) == 0 ||
+ _wcsnicmp(fileExtension, L".cmd", 4) == 0 ||
+ _wcsnicmp(fileExtension, L".com", 4) == 0) {
  result->st_mode |= 0111;
  }
  }
@@ -16711,12 +16727,6 @@ static PyType_Spec DirEntryType_spec = {
 
 #ifdef MS_WINDOWS
 
-static int
-is_extended_path(const wchar_t *path)
-{
- return wcsncmp(path, L"\\\\?\\", 4) == 0;
-}
-
 static wchar_t *
 join_path_filenameW(const wchar_t *path_wide, const wchar_t *filename,
  int normalize)