Re: [PATCH] schemas: Add vim modeline

[Nir Soffer]

On Mon, Aug 3, 2020 at 3:23 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> On Mon, Aug 03, 2020 at 02:16:19PM +0200, Paolo Bonzini wrote:
> > On 03/08/20 13:36, Daniel P. Berrangé wrote:
> > >>> Given that QEMU needs to pass
> > >>> uint64 values, JSON was simply the wrong choice of format for QMP.
> > >
> > > I wasn't refering to RFC7159. The problem of undefined integer precision
> > > with JSON came up right at the very start when QMP was first designed and
> > > implemented, and has come up again periodically ever since then. libvirt
> > > needed to do workarounds right at the start in 2009, in order to fully
> > > handle signed/unsigned 64-bit integers with QMP.
> >
> > I assume the workaround you refer to is to store the number as a string
> > and converting it lazily to either an integer or a floating-point type
> > in whoever uses the JSON API.  It may not be pretty but probably it
> > would have been the same for any text-based, schema-less protocol.  For
> > example, it didn't require writing your own parser.
>
> Yes, we get the raw values as a string, but not all parsers for C
> allow you to do this.  We'd really love to move off YAJL for JSON
> parsing, but the most viable alternatives don't have a way to let
> you get the string before they parse it as an integer and report
> errors.
>
> > It could be avoided by using a schema in Libvirt, just like QEMU has no
> > problem with it on the other side; it's just a different design choice
> > with different trade-offs, I don't think it's enough of an issue to
> > declare JSON "the wrong choice of format for QMP".
>
> The schema doesn't help - the problem is many JSON parsers don't allow
> use of full uint64 values when parsing - alot will simply report an
> error for anything bigger than LLONG_MAX and offer no workaround.

Jansson is considering this:
https://github.com/akheron/jansson/issues/69

The issue is 4 years old, but there is some activity lately. I guess
someone who wants this needs to invest the time.

>
> Regards,
> Daniel
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