gh-133562: Skip security descriptors on unsupported Windows API partitions (GH-133563)

Author: maxbachmann

Misc/NEWS.d/next/Windows/2025-05-07-09-02-19.gh-issue-133562.lqqNW1.rst

@@ -0,0 +1 @@
+Disable handling of security descriptors by :func:`os.mkdir` with mode ``0o700`` on WinAPI partitions that do not support it. This only affects custom builds for specialized targets.

Modules/posixmodule.c

@@ -5736,6 +5736,9 @@ os_mkdir_impl(PyObject *module, path_t *path, int mode, int dir_fd)
 
 #ifdef MS_WINDOWS
     Py_BEGIN_ALLOW_THREADS
+    // For API sets that don't support these APIs, we have no choice
+    // but to silently create a directory with default ACL.
+#if defined(MS_WINDOWS_APP) || defined(MS_WINDOWS_SYSTEM)
     if (mode == 0700 /* 0o700 */) {
         ULONG sdSize;
         pSecAttr = &secAttr;
@@ -5751,6 +5754,7 @@ os_mkdir_impl(PyObject *module, path_t *path, int mode, int dir_fd)
             error = GetLastError();
         }
     }
+#endif
     if (!error) {
         result = CreateDirectoryW(path->wide, pSecAttr);
         if (secAttr.lpSecurityDescriptor &&