ntdll: Implement wcsnlen().

dlls/ntdll/ntdll.spec

@@ -1609,6 +1609,7 @@
 @ cdecl wcsncat(wstr wstr long)
 @ cdecl wcsncmp(wstr wstr long)
 @ cdecl wcsncpy(ptr wstr long)
+@ cdecl wcsnlen(ptr long)
 @ cdecl wcspbrk(wstr wstr)
 @ cdecl wcsrchr(wstr long)
 @ cdecl wcsspn(wstr wstr)

dlls/ntdll/wcstring.c

@@ -252,6 +252,17 @@ LPWSTR __cdecl wcsncpy( LPWSTR s1, LPCWSTR s2, size_t n )
 
 
 /*********************************************************************
+ *           wcsnlen    (NTDLL.@)
+ */
+size_t __cdecl wcsnlen( const WCHAR *str, size_t len )
+{
+    const WCHAR *s = str;
+    for (s = str; len && *s; s++, len--) ;
+    return s - str;
+}
+
+
+/*********************************************************************
  *           wcspbrk    (NTDLL.@)
  */
 LPWSTR __cdecl wcspbrk( LPCWSTR str, LPCWSTR accept )