Re: [PATCH 3/3] vl: allow passing JSON to -object

[Eric Blake]

On 3/11/21 11:24 AM, Paolo Bonzini wrote:
> Extend the ObjectOption code that was added in the previous patch to
> enable passing JSON to -object.  Even though we cannot yet add
> non-scalar properties with the human-friendly comma-separated syntax,
> they can now be added as JSON.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  softmmu/vl.c | 27 ++++++++++++++++++---------
>  1 file changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index b245e912e5..7b07f19de7 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -31,6 +31,7 @@
>  #include "hw/qdev-properties.h"
>  #include "qapi/error.h"
>  #include "qapi/qmp/qdict.h"
> +#include "qapi/qmp/qjson.h"
>  #include "qemu-version.h"
>  #include "qemu/cutils.h"
>  #include "qemu/help_option.h"
> @@ -1714,19 +1715,27 @@ static void object_option_parse(const char *optarg)
>      const char *type;
>      Visitor *v;
>  
> -    opts = qemu_opts_parse_noisily(qemu_find_opts("object"),
> -                                   optarg, true);
> -    if (!opts) {
> -        exit(1);
> -    }
> +    if (optarg[0] == '{') {
> +        QObject *obj = qobject_from_json(optarg, &error_fatal);
>  
> -    type = qemu_opt_get(opts, "qom-type");
> -    if (user_creatable_print_help(type, opts)) {
> -        exit(0);
> +        v = qobject_input_visitor_new(obj);
> +        qobject_unref(obj);

Interesting note: the JSON form has no way to access help text.  But
that's not a show-stopper.

> +    } else {
> +        opts = qemu_opts_parse_noisily(qemu_find_opts("object"),
> +                                       optarg, true);
> +        if (!opts) {
> +            exit(1);
> +        }
> +
> +        type = qemu_opt_get(opts, "qom-type");
> +        if (user_creatable_print_help(type, opts)) {
> +            exit(0);
> +        }
> +
> +        v = opts_visitor_new(opts);
>      }
>  
>      opt = g_new0(ObjectOption, 1);
> -    v = opts_visitor_new(opts);
>      visit_type_ObjectOptions(v, NULL, &opt->opts, &error_fatal);
>      visit_free(v);

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org