Re: [PATCH v2 0/4] MR8515: setupapi: Support in-built properties for device instances in SetupDiGetDevicePropertyW.

[Connor McAdams (＠cmcadams)]

Connor McAdams (@cmcadams) commented about dlls/setupapi/devinst.c:
> -
>        *prop_type = DEVPROP_TYPE_STRING_LIST;
> -
>        if (req_size)
> -
>            *req_size = size;
> -
>    }
> - }
> - else if (IsEqualDevPropKey( *prop_key, DEVPKEY_Device_ContainerId ))
> - {
> -
>    WCHAR id_str[39];
> -
>    if (!SetupDiGetDeviceRegistryPropertyW( devinfo, device_data, SPDRP_BASE_CONTAINERID, NULL, (BYTE *)id_str,
> -
>                                            sizeof(id_str), NULL ))
> -
>        return GetLastError() == ERROR_INVALID_DATA ? ERROR_NOT_FOUND : GetLastError();
> -
>    *prop_type = DEVPROP_TYPE_GUID;
> -
>    if (buf_size >= sizeof( GUID ))
> -
>    {
> -
>        GUID guid = {0};
> -
>        id_str[37] = 0;

Is it ever possible for this function to return an empty string, or a string not representing a GUID? Elsewhere in setupapi it seems there are checks to ensure the correct characters are there, i.e:
```
                if (szKeyName[0] == '{' && szKeyName[37] == '}')
```
If it's something that is only ever handled by us I guess we could do an assert to make sure it never gets messed up.