gh-152433: Windows: improve sys.getwindowsversion() fix return incorrect build number for Windows 11+ and fix errors in UWP

Author: thexai

Misc/NEWS.d/next/Windows/2026-06-29-17-17-10.gh-issue-152433.AhW--j.rst

@@ -0,0 +1,2 @@
+Improve :func:`sys.getwindowsversion`: fix return incorrect build number for
+Windows 11+ and fix errors in Universal Windows Platform.

Python/sysmodule.c

@@ -51,6 +51,7 @@ Data members:
 #  ifndef WIN32_LEAN_AND_MEAN
 #    define WIN32_LEAN_AND_MEAN
 #  endif
+#  define REG_CURRENT_VERSION L"Software\\Microsoft\\Windows NT\\CurrentVersion"
 #  include <windows.h>
 #endif /* MS_WINDOWS */
 
@@ -1645,13 +1646,10 @@ static PyStructSequence_Desc windows_version_desc = {
                                       via indexing, the rest are name only */
 };
 
+#ifdef MS_WINDOWS_DESKTOP
 static PyObject *
 _sys_getwindowsversion_from_kernel32(void)
 {
-#ifndef MS_WINDOWS_DESKTOP
-    PyErr_SetString(PyExc_OSError, "cannot read version info on this platform");
-    return NULL;
-#else
     HANDLE hKernel32;
     wchar_t kernel32_path[MAX_PATH];
     LPVOID verblock;
@@ -1687,9 +1685,21 @@ _sys_getwindowsversion_from_kernel32(void)
     realMinor = LOWORD(ffi->dwProductVersionMS);
     realBuild = HIWORD(ffi->dwProductVersionLS);
     PyMem_RawFree(verblock);
+
+    // Obtain the build number from Windows registry in case of Windows 10/11
+    if (realMajor == 10 && realMinor == 0) {
+        wchar_t currentBuild[32] = {0};
+        DWORD len = sizeof(currentBuild);
+        if (ERROR_SUCCESS == RegGetValueW(HKEY_LOCAL_MACHINE, REG_CURRENT_VERSION, L"CurrentBuild",
+            RRF_RT_REG_SZ, NULL, &currentBuild, &len))
+        {
+            realBuild = _wtol(currentBuild);
+        }
+    }
+
     return Py_BuildValue("(kkk)", realMajor, realMinor, realBuild);
-#endif /* !MS_WINDOWS_DESKTOP */
 }
+#endif /* MS_WINDOWS_DESKTOP */
 
 /* Disable deprecation warnings about GetVersionEx as the result is
    being passed straight through to the caller, who is responsible for
@@ -1719,7 +1729,6 @@ sys_getwindowsversion_impl(PyObject *module)
 {
     PyObject *version;
     int pos = 0;
-    OSVERSIONINFOEXW ver;
 
     if (PyObject_GetOptionalAttrString(module, "_cached_windows_version", &version) < 0) {
         return NULL;
@@ -1729,6 +1738,8 @@ sys_getwindowsversion_impl(PyObject *module)
     }
     Py_XDECREF(version);
 
+    OSVERSIONINFOEXW ver;
+    ZeroMemory(&ver, sizeof(ver));
     ver.dwOSVersionInfoSize = sizeof(ver);
     if (!GetVersionExW((OSVERSIONINFOW*) &ver))
         return PyErr_SetFromWindowsErr(0);
@@ -1756,10 +1767,12 @@ sys_getwindowsversion_impl(PyObject *module)
     SET_VERSION_INFO(PyLong_FromLong(ver.wSuiteMask));
     SET_VERSION_INFO(PyLong_FromLong(ver.wProductType));
 
+#ifdef MS_WINDOWS_DESKTOP
     // GetVersion will lie if we are running in a compatibility mode.
     // We need to read the version info from a system file resource
     // to accurately identify the OS version. If we fail for any reason,
     // just return whatever GetVersion said.
+    // UWP return correct version from GetVersionExW, this is not necessary.
     PyObject *realVersion = _sys_getwindowsversion_from_kernel32();
     if (!realVersion) {
         if (!PyErr_ExceptionMatches(PyExc_WindowsError)) {
@@ -1775,6 +1788,7 @@ sys_getwindowsversion_impl(PyObject *module)
     }
 
     SET_VERSION_INFO(realVersion);
+#endif
 
 #undef SET_VERSION_INFO