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

[Gabriel Ivăncescu]

On 23/05/2022 19:18, Andrew Eikum wrote:
> On Mon, May 23, 2022 at 06:50:16PM +0300, Gabriel Ivăncescu wrote:
>> 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...
> 
> We could try to acquire a shorter name for the underlying device,
> somehow, but I'm not sure what options PA and/or ALSA give us. Maybe
> use PA_PROP_DEVICE_PRODUCT_NAME instead, for example.
> 
> Andrew
> 

I experimented with a few options. Unfortunately, they don't really work.

PA_PROP_DEVICE_PRODUCT_NAME is either not available in most cases, or 
it's the same as the description (which is what is currently used), and 
when it is different, the returned name is way too short (e.g. just 
"D30"). However the problem is that it's not available for "virtual" 
sources (or sinks), and in this case those are the largest offenders, 
e.g. "Monitor of <some really long name>" which makes the long name even 
longer.

In the case of the linked bug, it's the builtin soundcard (on 
motherboard) that is too long and it seems the product name won't help 
there at all anyway, even without the "Monitor of" source.

I was thinking of using the pulse_name in case the description is longer 
than 62 chars, but apparently those can get pretty long too. Though I 
suppose using it as a fallback should work in most cases... And pick it 
if it's shorter in such case.

Thoughts?