Re: [v2 2/2] winejoystick.drv: Disable joysticks via wine registry on Mac

[Ken Thomases]

Hi,

On Aug 29, 2016, at 6:03 AM, David Lawrie  wrote:
> +static void char_device_name_length(IOHIDDeviceRef device, char *name, int max_length)
> +{
> - CFStringRef str = copy_device_name(device);
> - CFIndex len = CFStringGetLength(str);
> -
> - if (name)
> -
>    name[0] = 0;
> -
> - if (max_length >= len)
> - {
> -
>    CFStringGetCString(str,name,max_length,kCFStringEncodingASCII);
> -
>    CFRelease(str);
> - }
> - else
> - {
> -
>    CFStringRef substr = CFStringCreateWithSubstring(kCFAllocatorDefault, str, CFRangeMake(0, max_length));
> -
>    CFRelease(str);
> -
>    CFStringGetCString(substr,name,max_length,kCFStringEncodingASCII);
> -
>    CFRelease(substr);
> - }
>
> +}

I realize you based this function on code from DInput.  Unfortunately, that code is pretty badly broken.  CFStringGetLength() returns the length of the string in UTF-16 code units, which is basically the same as WCHARs.  It's not meaningful to compare that to a buffer size that's in ASCII chars.

Using ASCII is wrong, too.  If the name has any non-ASCII characters in it, the conversion will just fail.  Second, it's potentially unnecessarily restrictive.  Your device_disabled_registry() function, by virtue of using the "A" variant RegQueryValueEx(), uses the ANSI code page, not ASCII.  The ANSI code page could maybe handle more names than ASCII would.

You could get a wide string and then use WideCharToMultiByte() to convert it to CP_ACP, but since you control all of the relevant code, it's just better to work with wide strings throughout.  Change your device_disabled_registry() and get_config_key() functions to accept a wide string.  Then, you can safely use CFStringGetLength() and CFStringGetCharacters() to acquire the WCHAR-based wide string from the CFString.  You can just cast a WCHAR* to a UniChar*.

-Ken