ntdll: check for string and stringlength in _wcslwr and _wcsupr

[Nikolay Sivov]

2011/9/7 André Hentschel <nerv at dawncrow.de>:
> Fixes http://bugs.winehq.org/show_bug.cgi?id=28303 (str="")
> ---
>  dlls/ntdll/wcstring.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/dlls/ntdll/wcstring.c b/dlls/ntdll/wcstring.c
> index 7f0035d..d75f10e 100644
> --- a/dlls/ntdll/wcstring.c
> +++ b/dlls/ntdll/wcstring.c
> @@ -47,6 +47,7 @@ INT __cdecl NTDLL__wcsicmp( LPCWSTR str1, LPCWSTR str2 )
>  */
>  LPWSTR __cdecl NTDLL__wcslwr( LPWSTR str )
>  {
> +    if (!str || !*str) return NULL;
>     return strlwrW( str );
>  }
>
> @@ -65,6 +66,7 @@ INT __cdecl NTDLL__wcsnicmp( LPCWSTR str1, LPCWSTR str2, INT n )
>  */
>  LPWSTR __cdecl NTDLL__wcsupr( LPWSTR str )
>  {
> +    if (!str || !*str) return NULL;
>     return struprW( str );
>  }
>

Please add tests for that.