Commit 7d2ef6dcc1cf ("hmp: Simplify qom-set") switched to the json
parser, making it possible to specify complex types. However, with this
change it is no longer possible to specify proper sizes (e.g., 2G, 128M),
turning the interface harder to use for properties that consume sizes.

Let's switch back to the previous handling and allow to specify passing
json via the "-j" parameter.

Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---

An alternative would be to teach the json parser about sizes. But I am not
completely sure if that is desirable.

I make excessive use of qom-set with size properties in virtio-mem.

---
 hmp-commands.hx    |  7 ++++---
 qom/qom-hmp-cmds.c | 20 ++++++++++++++++----
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 28256209b5..b44f220c3e 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1806,9 +1806,10 @@ ERST
 
     {
         .name       = "qom-set",
-        .args_type  = "path:s,property:s,value:S",
-        .params     = "path property value",
-        .help       = "set QOM property",
+        .args_type  = "json:-j,path:s,property:s,value:s",
+        .params     = "[-j] path property value",
+        .help       = "set QOM property.\n\t\t\t"
+                      "-j: the property is specified in json format.",
         .cmd        = hmp_qom_set,
         .flags      = "p",
     },
diff --git a/qom/qom-hmp-cmds.c b/qom/qom-hmp-cmds.c
index f704b6949a..a794e62f0b 100644
--- a/qom/qom-hmp-cmds.c
+++ b/qom/qom-hmp-cmds.c
@@ -44,15 +44,27 @@ void hmp_qom_list(Monitor *mon, const QDict *qdict)
 
 void hmp_qom_set(Monitor *mon, const QDict *qdict)
 {
+    const bool json = qdict_get_try_bool(qdict, "json", false);
     const char *path = qdict_get_str(qdict, "path");
     const char *property = qdict_get_str(qdict, "property");
     const char *value = qdict_get_str(qdict, "value");
     Error *err = NULL;
-    QObject *obj;
 
-    obj = qobject_from_json(value, &err);
-    if (err == NULL) {
-        qmp_qom_set(path, property, obj, &err);
+    if (!json) {
+        Object *obj = object_resolve_path(path, NULL);
+
+        if (!obj) {
+            error_set(&err, ERROR_CLASS_DEVICE_NOT_FOUND,
+                      "Device '%s' not found", path);
+        } else {
+            object_property_parse(obj, value, property, &err);
+        }
+    } else {
+        QObject *obj = qobject_from_json(value, &err);
+
+        if (!err) {
+            qmp_qom_set(path, property, obj, &err);
+        }
     }
 
     hmp_handle_error(mon, err);
-- 
2.26.2

On 08/06/20 16:06, David Hildenbrand wrote:
>      {
>          .name       = "qom-set",
> -        .args_type  = "path:s,property:s,value:S",
> -        .params     = "path property value",
> -        .help       = "set QOM property",
> +        .args_type  = "json:-j,path:s,property:s,value:s",

I think this should remain an uppercase "S", so that it grabs the rest
of the input rather than stop at the first space.

Paolo

> +        .params     = "[-j] path property value",
> +        .help       = "set QOM property.\n\t\t\t"
> +                      "-j: the property is specified in json format.",
>          .cmd        = hmp_qom_set,
>          .flags      = "p",
>      },
> diff --git a/qom/qom-hmp-cmds.c b/qom/qom-hmp-cmds.c

> Am 08.06.2020 um 16:16 schrieb Paolo Bonzini <pbonzini@redhat.com>:
> 
> On 08/06/20 16:06, David Hildenbrand wrote:
>>     {
>>         .name       = "qom-set",
>> -        .args_type  = "path:s,property:s,value:S",
>> -        .params     = "path property value",
>> -        .help       = "set QOM property",
>> +        .args_type  = "json:-j,path:s,property:s,value:s",
> 
> I think this should remain an uppercase "S", so that it grabs the rest
> of the input rather than stop at the first space.
> 

Yes, changed by mistake (while working on a revert). Thanks!

> Paolo
> 
>> +        .params     = "[-j] path property value",
>> +        .help       = "set QOM property.\n\t\t\t"
>> +                      "-j: the property is specified in json format.",
>>         .cmd        = hmp_qom_set,
>>         .flags      = "p",
>>     },
>> diff --git a/qom/qom-hmp-cmds.c b/qom/qom-hmp-cmds.c
>