Re: [PATCH v6 08/11] libxl: QEMU startup sync based on QMP

From: Anthony PERARD <anthony.perard@citrix.com>
To: Ian Jackson <ian.jackson@citrix.com>
Cc: xen-devel@lists.xenproject.org, "Wei Liu" <wei.liu2@citrix.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH v6 08/11] libxl: QEMU startup sync based on QMP
Date: Thu, 22 Nov 2018 14:37:55 +0000	[thread overview]
Message-ID: <20181122143755.GG2448@perard.uk.xensource.com> (raw)
In-Reply-To: <20181121164906.GC2448@perard.uk.xensource.com>

On Wed, Nov 21, 2018 at 04:49:06PM +0000, Anthony PERARD wrote:
> On Fri, Nov 16, 2018 at 12:14:43PM +0000, Ian Jackson wrote:
> > Anthony PERARD writes ("[PATCH v6 08/11] libxl: QEMU startup sync based on QMP"):
> > > +        LOGD(DEBUG, ev->domid, ".. instead, got: %s",
> > > +             libxl__json_object_to_json(gc, response));
> > 
> > The doc comments for libxl__json_object_to_json don't say whether it
> > can fail.  So I assume it can, in which case you will pass NULL to %s
> > which is (sadly) nowadays illegal (although in practice probably
> > safe).
> 
> I wounder what to do for this.
> Maybe invent a JSON macro which would be:
>     JSON(o) (libxl__json_object_to_json(gc, (o)) : ? "\"null\"")
>     ("null" would actually be valid json)
> Or do it without the macro, but there are plenty of other caller's of
> libxl__json_object_to_json in libxl__ev_qmp implementation.

Or simply change libxl__json_object_to_json to always return a valid
json string. There are no user yet, so it is probably fine to make that
change.

What do you think?

Thanks,

-- 
Anthony PERARD

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