Re: [Qemu-devel] [PATCH 04/16] qapi: introduce OptsVisitor

[Laszlo Ersek]

Thank you very much for the review! One question below (and maybe some
more later in response to other parts of the review):

On 06/05/12 23:12, Paolo Bonzini wrote:
> Il 22/05/2012 12:45, Laszlo Ersek ha scritto:

>> Optarg values can be of scalar types str / bool / int / size.
> 
> Michael Roth recently added Visitor interfaces for uint*_t and int*_t,
> they look like they would simplify the patches very nicely.  They do the
> range checking automatically and only need a type_int callback in the
> visitor.
> 
> You can get the patch from http://patchwork.ozlabs.org/patch/150427/,
> feel free to include it at the beginning of your series.

The unsigned functions don't check if the int64_t value to be assigned is
negative. What happens in such a case is fully defined, but did Michael
really intend the wraparound to unsigned?

I thought it was a silent requirement for the int parser to return a
non-negative int (which is something I also implemented in
opts_type_int() [*]), but the signed visit_type_XXX() functions do check
for the negative limit. I'm confused.


[*] see the comment in opts-visitor.h: 

/* Contrarily to qemu-option.c::parse_option_number(), OptsVisitor's "int"
 * parser relies on strtoll() instead of strtoull(). Consequences:
 * - string representations of negative numbers are rejected (parsed values
 *   continue to be non-negative),
 * - values above INT64_MAX or LLONG_MAX are rejected.
 */

That's also why I dropped/omitted the "< 0" checks in net_init_nic() [v1
09/16], net_init_dump() [v1 10/16] and net_init_vde() [v1 13/16].

If you want I can go through all the integer fields I introduced in [v1
06/16] "qapi schema: add Netdev types" and classify each as strictly as
possible (and then remove the checks being obviated).

Thanks!
Laszlo