msvcrt: Implement _wperror

[Hugh McMaster]

On Tuesday, 21 June 2016 7:04 PM UTC+10, Piotr Caban wrote:
>    
>On 06/21/16 10:09, Hugh McMaster wrote:
>>  dlls/msvcrt/msvcrt.spec |  2 +-
>>  2 files changed, 36 insertions(+), 1 deletion(-)
>Please also update other msvc*/ucrtbase spec files as well.

Okay, will do.

>>  /*********************************************************************
>> + *           _wperror (MSVCRT.@)
>> + */
>> +void CDECL MSVCRT__wperror(const MSVCRT_wchar_t* str)
>> +{
>> +    int err, size, len;
>> +    static const WCHAR colon_spaceW[] = {':',' ',0};
>> +    static const WCHAR newlineW[] = {'\n',0};
>> +    MSVCRT_wchar_t *buffer = NULL;
>> +
>> +    err = *MSVCRT__errno();
>> +    if (err < 0 || err > MSVCRT__sys_nerr) err = MSVCRT__sys_nerr;
>> +
>> +    size = MultiByteToWideChar(CP_ACP, 0, MSVCRT__sys_errlist[err], -1, NULL, 0) + 1 /* add \n */;
>> +
>> +    if (str && *str)
>> +        size += lstrlenW(str) + 2; /* add str length, colon and space */
>> +
>> +    buffer = MSVCRT_malloc(size * sizeof(MSVCRT_wchar_t));
>> +    if (!buffer) return;
>> +
>> +    if (str && *str)
>> +    {
>> +        lstrcpyW(buffer, str);
>> +        lstrcatW(buffer, colon_spaceW);
>> +    }
>> +    else buffer[0] = 0;
>> +
>> +    len = lstrlenW(buffer);
>> +    MultiByteToWideChar(CP_ACP, 0, MSVCRT__sys_errlist[err], -1, buffer + len, size - len);
>> +    lstrcatW(buffer, newlineW);
>> +    MSVCRT__write(2, buffer, lstrlenW(buffer) * sizeof(MSVCRT_wchar_t));
>> +    MSVCRT_free(buffer);
>> +}
>This is not how the function works. It shouldn't print wchar_t string to 
>stderr. Probably the simplest implementation is to convert input 
>parameter and call _perror (CP_ACP is not the correct encoding, you can 
>use MSVCRT_wcstombs).

I don't understand. The MSDN page [1] contradicts your statement.
"The perror function prints an error message to stderr. _wperror is a wide-character version
of _perror; the string argument to _wperror is a wide-character string. _wperror and _perror
behave identically otherwise."

There is nothing in that quote to suggest _wperror does operate like my implementation.

Also, if we convert the wide string to multibyte, there is a risk any non-Unicode characters
supplied as input will not display correctly. So, IMHO converting to a multibyte string is a
bad approach.

Still, if that's what you want, I'll do it.

[1] https://msdn.microsoft.com/en-us/library/9t0e6085.aspx