Re: [Qemu-devel] [PATCH] qdev-monitor.c: Add device id generation

[Programmingkid]

On Aug 24, 2015, at 6:21 PM, Eric Blake wrote:

> On 08/24/2015 12:53 PM, Programmingkid wrote:
>> Add device ID generation to each device if an ID isn't given.
>> 
>> Signed-off-by: John Arbuckle <address@hidden>
>> 
>> ---
> 
>>         dev->id = id;
>> +    } else { /* create an id for a device if none is provided */
>> +        static int device_id_count;
>> +
>> +        /* Add one for '\0' character */
>> +        char *device_id = (char *) malloc(sizeof(char) *
>> +                                            MAX_NUM_DIGITS_FOR_USB_ID + 1);
>> +        sprintf(device_id, "%d", device_id_count++);
> 
> g_strdup_printf() is a lot nicer about avoiding the risk of arbitrary
> overflow...
I prefer to use well known functions that work well, but I guess it shouldn't 
be too
painful to use the g_strdup_printf() function. Do you really think there is a 
possible
overflow condition here?


> 
>> +        dev->id = (const char *) device_id;
>> +
>> +        /* if device_id_count >= 10^MAX_NUM_DIGITS_FOR_USB_ID */
>> +        if (device_id_count >= pow(10, MAX_NUM_DIGITS_FOR_USB_ID)) {
>> +            printf("Warning: Maximum number of device ID's generated!\n\a");
>> +            printf("Time for you to make your own device ID's.\n");
> 
> besides, printf() is probably the wrong way to do error reporting, and
Why do you believe this? 

> we don't use \a BEL sequences anywhere else in qemu code.
Innovation has to start somewhere :)


> 
>> +        }
>>     }
>> 
>>     if (dev->id) {
> 
> This if would now be a dead check if your patch is applied.
I think you are right. It will be removed.

> 
>>         object_property_add_child(qdev_get_peripheral(), dev->id,
>>                                   OBJECT(dev), NULL);
>> -    } else {
>> -        static int anon_count;
>> -        gchar *name = g_strdup_printf("device[%d]", anon_count++);
>> -        object_property_add_child(qdev_get_peripheral_anon(), name,
>> -                                  OBJECT(dev), NULL);
>> -        g_free(name);
>>     }
> 
> It looks like your goal was to move this code earlier, but you changed
> enough aspects of it that I'm not sure what the right fix should be.

I didn't want to move the code. It just was in a condition that would never
be true, so I thought why keep it.

> -- 
> Eric Blake   eblake redhat com    +1-919-301-3266

Thank you very much for reviewing my patch. 

> Libvirt virtualization library http://libvirt.org

You work with this project? Any chance libvirt could support Mac OS X?