[PATCH 1/2] mmdevapi: Truncate strings from PropertyStore's GetValue to 62 chars.

[Gabriel Ivăncescu]

On 23/05/2022 18:03, Andrew Eikum wrote:
> On Fri, May 20, 2022 at 08:40:18PM +0300, Gabriel Ivăncescu wrote:
>> @@ -1397,7 +1399,16 @@ static HRESULT WINAPI MMDevPropStore_GetValue(IPropertyStore *iface, REFPROPERTY
>>           return S_OK;
>>       }
>>   
>> -    return MMDevice_GetPropValue(&This->parent->devguid, This->parent->flow, key, pv);
>> +    hres = MMDevice_GetPropValue(&This->parent->devguid, This->parent->flow, key, pv);
>> +    if (FAILED(hres))
>> +        return hres;
>> +
>> +    /* Some broken apps and libs (e.g. Split/Second with fmodex)
>> +       can't deal with strings longer than 62 characters + NUL. */
>> +    if (pv->vt == VT_LPWSTR && wcslen(pv->pwszVal) > 62)
>> +        pv->pwszVal[62] = '\0';
>> +
> 
> I think we'd only want to do this for certain keys, not every returned
> string. But, Windows doesn't do this. You can edit the registry and
> put whatever you want into the device name, and it'll be returned
> unmodified:
> 
>      [HKLM\Software\Microsoft\Windows\CurrentVersion\MMDevices\Audio\Render\<device_guid>\Properties]
>      "{b3f8fa53-0004-438e-9003-51a46e139bfc},6"="A Very Long String...."
> 
> I don't immediately have the ability to check if the game crashes on
> Windows if I set the string very long, but that's what I would check
> next.
> 
> Andrew
> 

Thanks. I tested it on Windows 7 VM. Unfortunately, it crashes in the 
same way on Windows if I make a device name longer than 63 chars (for 
some reason, 63 instead of 62, but might have been a lucky run?).

So yes it's true that Windows doesn't do this, but it might also be that 
Windows doesn't have very long device names in the first place, so it's 
not a problem noticed "in the wild" there.

I don't really like truncation either, but since it makes the game 
unplayable it's kind of tough decision. Maybe use a registry setting? 
But then most users wouldn't know to try it...