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

[Daniel P. Berrange]

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
+     * 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);
     }
-- 
2.7.4