Re: [PATCH] kernel32: Implement GetFinalPathNameByHandle

[Nikolay Sivov]

On 19.03.2015 18:22, Andrew Eikum wrote:
> +/*************************************************************************
> + *           GetFinalPathNameByHandleA   (KERNEL32.@)
> + */
> +DWORD WINAPI GetFinalPathNameByHandleA(HANDLE handle, char *outstr, DWORD len,
> +        DWORD flags)
> +{
> +    WCHAR *wstr;
> +    DWORD dw;
> +
> +    if (len > 0)
> +    {
> +        wstr = HeapAlloc( GetProcessHeap(), 0, len * sizeof(WCHAR) );
> +        if (!wstr)
> +        {
> +            SetLastError( ERROR_OUTOFMEMORY );
> +            return 0;
> +        }
> +    }
> +    else
> +        wstr = NULL;
> +
> +    dw = GetFinalPathNameByHandleW( handle, wstr, len, flags );
> +
> +    if (dw > 0 && dw < len)
> +    {
> +        /* success */
> +
> +        dw = WideCharToMultiByte( CP_ACP, 0, wstr, -1, NULL, 0, NULL, NULL );
> +        if (dw > len)
> +        {
> +            /* buffer too small */
> +            HeapFree( GetProcessHeap(), 0, wstr );
> +            return dw;
> +        }
> +
> +        dw = WideCharToMultiByte( CP_ACP, 0, wstr, -1, outstr, len, NULL, NULL );
> +        if (!dw)
> +        {
> +            HeapFree( GetProcessHeap(), 0, wstr );
> +            return 0;
> +        }
> +
> +        /* don't report NUL */
> +        dw = dw - 1;
> +    }
> +
> +    HeapFree( GetProcessHeap(), 0, wstr );
> +
> +    return dw;
> +}
> +

This doesn't look right. Proper way would be:

- call GetFinalPathNameByHandleW() with NULL buffer to get required length;
- allocated WCHAR buffer and get a path in it;
- call WideCharToMultiByte() with NULL output buffer to get required 
length for CP_ACP string;
- do what you need to do if A buffer length is too small.

Right now you're assuming that WCHAR representation has same number of 
characters as CP_ACP one, I don't think it's always a case.

[PATCH] kernel32: Implement GetFinalPathNameByHandle

[Andrew Eikum]

On Thu, Mar 19, 2015 at 06:29:50PM +0300, Nikolay Sivov wrote:
> This doesn't look right. Proper way would be:
>
> - call GetFinalPathNameByHandleW() with NULL buffer to get required length;
> - allocated WCHAR buffer and get a path in it;
> - call WideCharToMultiByte() with NULL output buffer to get required
> length for CP_ACP string;
> - do what you need to do if A buffer length is too small.
>
> Right now you're assuming that WCHAR representation has same number
> of characters as CP_ACP one, I don't think it's always a case.

Yeah, good point. I'll fix and resubmit.

Thanks!
Andrew