[KERNEL32_VISTA] Implement IsValidLocaleName

dll/win32/kernel32/kernel32_vista/CMakeLists.txt

@@ -14,6 +14,7 @@ list(APPEND SOURCE
     GetTickCount64.c
     GetUserDefaultLocaleName.c
     InitOnce.c
+    IsValidLocaleName.c
     LCIDToLocaleName.c
     LocaleNameToLCID.c
     sync.c

dll/win32/kernel32/kernel32_vista/IsValidLocaleName.c

@@ -0,0 +1,21 @@
+/*
+ * PROJECT:     ReactOS Win32 Base API
+ * LICENSE:     MIT (https://spdx.org/licenses/MIT)
+ * PURPOSE:     Implementation of IsValidLocaleName
+ * COPYRIGHT:   Copyright 2025 Timo Kreuzer <timo.kreuzer@reactos.org>
+ */
+
+#include "k32_vista.h"
+#include <winnls.h>
+
+#define NDEBUG
+#include <debug.h>
+
+BOOL
+WINAPI
+IsValidLocaleName(
+    LPCWSTR lpLocaleName)
+{
+    LCID lcid = LocaleNameToLCID(lpLocaleName, LOCALE_ALLOW_NEUTRAL_NAMES);
+    return lcid != 0;
+}

dll/win32/kernel32/kernel32_vista/kernel32_vista.spec

@@ -46,6 +46,7 @@
 @ stdcall GetUILanguageInfo(long wstr wstr ptr ptr)
 @ stdcall GetUserDefaultLocaleName(wstr long)
 @ stdcall GetUserPreferredUILanguages(long ptr wstr ptr)
+@ stdcall IsValidLocaleName(wstr)
 @ stdcall LCIDToLocaleName(long wstr long long)
 @ stdcall LocaleNameToLCID(wstr long)
 @ stdcall OpenFileById(ptr ptr long long ptr long)

dll/win32/kernel32/winnls/string/locale.c

@@ -1851,6 +1851,7 @@ INT WINAPI GetLocaleInfoEx(LPCWSTR locale, LCTYPE info, LPWSTR buffer, INT len)
 }
 #endif
 
+#if 0 // See kernel32_vista
 BOOL
 WINAPI
 IsValidLocaleName(
@@ -1861,6 +1862,7 @@ IsValidLocaleName(
     return TRUE;
 }
 #endif
+#endif
 
 /******************************************************************************
  *		SetLocaleInfoA	[KERNEL32.@]