[libvirt] [RFC][PATCH] Revision for message payload encoding error when adding a large mount of virtio disks

[Michal Privoznik]

On 19.04.2012 14:45, Richard W.M. Jones wrote:
> On Thu, Apr 19, 2012 at 02:25:16PM +0800, Chen Hanxiao wrote:
>>   * This is an arbitrary limit designed to stop the decoder from trying
>>   * to allocate unbounded amounts of memory when fed with a bad message.
>>   */
>> -const REMOTE_STRING_MAX = 65536;
>> +const REMOTE_STRING_MAX = 80000;
> 
> Can this limit be changed?  I thought it would break existing clients
> or servers.
> 
> Rich.
> 

Yes & no. There are 4 possibilities:

- old both server & client: long string get dropped at server side and
"unable to encode string/payload" error is thrown.

- old server & new client: if server wants to send long string it's the
previous case; client will successfully retransmit message to the daemon
where it gets later dropped because of limit violation.

- new server & old client: see previous case

- new server & new client: nothing gets broken, everything works.

The only problem is with these gimme-list-of-* APIs. Because here you'll
get only partial result (first N entries - based on RPC limit).

Thus, changing this limit is okay.

Michal