Re: [Qemu-devel] [PATCH v4 2/8] Add socket_writev_buffer function

[Eric Blake]

On 03/22/2013 01:30 AM, Orit Wasserman wrote:

>>>  
>>> +static int socket_writev_buffer(void *opaque, struct iovec *iov, int 
>>> iovcnt)
>>
>> Returning int...
>>
>>> +{
>>> +    QEMUFileSocket *s = opaque;
>>> +    ssize_t len;
>>> +    ssize_t size = iov_size(iov, iovcnt);
>>> +
>>> +    len = iov_send(s->fd, iov, iovcnt, 0, size);
>>> +    if (len < size) {
>>> +        len = -socket_error();
>>> +    }
>>> +    return len;
>>
>> ...but len is an ssize_t.  If we send an iov with 2 gigabytes of data,
>> this can wrap around to a negative int even though we send a positive
>> amount of data.  Why not make the callback be typed to return ssize_t
>> from the beginning (affects patch 1/8)?
> At the moment it is not an issue but for the future we need to switch to 
> ssize_t 
> instead on int, I will change it.
> We actually need to replace it all around the migration code but this should
> be done in a different patch series.

I agree that the existing code base is in horrible shape with regards to
int instead of ssize_t, and that it will take a different patch series
to clean that up.  But why make that future patch harder?  New
interfaces might as well be designed correctly, to limit the cleanup to
the old interfaces, instead of making the cleanup job even harder.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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