Re: [Qemu-block] [Qemu-devel] [PATCH v14 16/21] hmp: support non-scalar properties with object_add

[Markus Armbruster]

"Daniel P. Berrange" <address@hidden> writes:

> The current object_add HMP syntax only allows for
> creation of objects with scalar properties, or a list
> with a fixed scalar element type. Objects which have
> properties that are represented as structs in the QAPI
> schema cannot be created using -object.
>
> This is a design limitation of the way the OptsVisitor
> is written. It simply iterates over the QemuOpts values
> as a flat list. The support for lists is enabled by
> allowing the same key to be repeated in the opts string.
>
> The QObjectInputVisitor now has functionality that allows
> it to replace OptsVisitor, maintaining full backwards
> compatibility for previous CLI syntax, while also allowing
> use of new syntax for structs.
>
> Thus -object can now support non-scalar properties,
> for example the QMP object:
>
>   {
>     "execute": "object-add",
>     "arguments": {
>       "qom-type": "demo",
>       "id": "demo0",
>       "parameters": {
>         "foo": [
>           { "bar": "one", "wizz": "1" },
>           { "bar": "two", "wizz": "2" }
>         ]
>       }
>     }
>   }
>
> Would be creatable via the HMP now using
>
>    object_add demo,id=demo0,\
>               foo.0.bar=one,foo.0.wizz=1,\
>               foo.1.bar=two,foo.1.wizz=2
>
> Notice that this syntax is intentionally compatible
> with that currently used by block drivers. NB the
> indentation seen here after line continuations should
> not be used in reality, it is just for clarity in this
> commit message.
>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
>  hmp.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/hmp.c b/hmp.c
> index 336e7bf..b32d8c8 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -25,7 +25,7 @@
>  #include "qemu/sockets.h"
>  #include "monitor/monitor.h"
>  #include "monitor/qdev.h"
> -#include "qapi/opts-visitor.h"
> +#include "qapi/qobject-input-visitor.h"
>  #include "qapi/qmp/qerror.h"
>  #include "qapi/string-output-visitor.h"
>  #include "qapi/util.h"
> @@ -1696,21 +1696,30 @@ void hmp_netdev_del(Monitor *mon, const QDict *qdict)
>  void hmp_object_add(Monitor *mon, const QDict *qdict)
>  {
>      Error *err = NULL;
> -    QemuOpts *opts;
>      Visitor *v;
>      Object *obj = NULL;
> +    QObject *pobj;
>  
> -    opts = qemu_opts_from_qdict(qemu_find_opts("object"), qdict, &err);
> +    pobj = qdict_crumple(qdict, true, &err);
>      if (err) {
> -        hmp_handle_error(mon, &err);
> -        return;
> +        goto cleanup;
>      }
>  
> -    v = opts_visitor_new(opts);
> -    obj = user_creatable_add(qdict, v, &err);
> +    /*
> +     * We need autocreate_list=true + permit_int_ranges=true
> +     * in order to maintain compat with OptsVisitor creation
> +     * of the 'numa' object which had an int16List property.
> +     *
> +     * We need autocreate_structs=1, because at the CLI level

autocreate_struct_levels=1

Same in previous patch.

> +     * we have the object type + properties in the same flat
> +     * struct, even though at the QMP level they are nested.
> +     */
> +    v = qobject_input_visitor_new_autocast(pobj, true, 1, true);
> +    obj = user_creatable_add(qobject_to_qdict(pobj), v, &err);
>      visit_free(v);
> -    qemu_opts_del(opts);
>  
> + cleanup:
> +    qobject_decref(pobj);
>      if (err) {
>          hmp_handle_error(mon, &err);
>      }