qapi: Flatten object-add

Mapping object-add to the command line as is doesn't result in nice
syntax because of the nesting introduced with 'props'. This becomes
nicer and more consistent with device_add and netdev_add when we accept
properties for the object on the top level instead.

'props' is still accepted after this patch, but marked as deprecated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200224143008.13362-8-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

docs/system/deprecated.rst

@@ -190,6 +190,11 @@ Use ``migrate-set-parameters`` instead.
 
 Use ``migrate-set-parameters`` and ``query-migrate-parameters`` instead.
 
+``object-add`` option ``props`` (since 5.0)
+'''''''''''''''''''''''''''''''''''''''''''
+
+Specify the properties for the object as top-level arguments instead.
+
 ``query-block`` result field ``dirty-bitmaps[i].status`` (since 4.0)
 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
 

hw/block/xen-block.c

@@ -18,6 +18,7 @@
 #include "qapi/visitor.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qstring.h"
+#include "qom/object_interfaces.h"
 #include "hw/xen/xen_common.h"
 #include "hw/block/xen_blkif.h"
 #include "hw/qdev-properties.h"
@@ -858,10 +859,18 @@ static XenBlockIOThread *xen_block_iothread_create(const char *id,
 {
     XenBlockIOThread *iothread = g_new(XenBlockIOThread, 1);
     Error *local_err = NULL;
+    QDict *opts;
+    QObject *ret_data;
 
     iothread->id = g_strdup(id);
 
-    qmp_object_add(TYPE_IOTHREAD, id, false, NULL, &local_err);
+    opts = qdict_new();
+    qdict_put_str(opts, "qom-type", TYPE_IOTHREAD);
+    qdict_put_str(opts, "id", id);
+    qmp_object_add(opts, &ret_data, &local_err);
+    qobject_unref(opts);
+    qobject_unref(ret_data);
+
     if (local_err) {
         error_propagate(errp, local_err);
 

include/qom/object_interfaces.h

@@ -162,4 +162,11 @@ void user_creatable_del(const char *id, Error **errp);
  */
 void user_creatable_cleanup(void);
 
+/**
+ * qmp_object_add:
+ *
+ * QMP command handler for object-add. See the QAPI schema for documentation.
+ */
+void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp);
+
 #endif

monitor/misc.c

@@ -248,6 +248,8 @@ static void monitor_init_qmp_commands(void)
                          QCO_NO_OPTIONS);
     qmp_register_command(&qmp_commands, "netdev_add", qmp_netdev_add,
                          QCO_NO_OPTIONS);
+    qmp_register_command(&qmp_commands, "object-add", qmp_object_add,
+                         QCO_NO_OPTIONS);
 
     QTAILQ_INIT(&qmp_cap_negotiation_commands);
     qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",

qapi/qom.json

@@ -210,7 +210,12 @@
 #
 # @id: the name of the new object
 #
-# @props: a dictionary of properties to be passed to the backend
+# @props: a dictionary of properties to be passed to the backend. Deprecated
+#         since 5.0, specify the properties on the top level instead. It is an
+#         error to specify the same option both on the top level and in @props.
+#
+# Additional arguments depend on qom-type and are passed to the backend
+# unchanged.
 #
 # Returns: Nothing on success
 #          Error if @qom-type is not a valid class name
@@ -221,12 +226,13 @@
 #
 # -> { "execute": "object-add",
 #      "arguments": { "qom-type": "rng-random", "id": "rng1",
-#                     "props": { "filename": "/dev/hwrng" } } }
+#                     "filename": "/dev/hwrng" } }
 # <- { "return": {} }
 #
 ##
 { 'command': 'object-add',
-  'data': {'qom-type': 'str', 'id': 'str', '*props': 'any'} }
+  'data': {'qom-type': 'str', 'id': 'str', '*props': 'any'},
+  'gen': false } # so we can get the additional arguments
 
 ##
 # @object-del:

qom/qom-qmp-cmds.c

@@ -14,6 +14,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "block/qdict.h"
 #include "hw/qdev-core.h"
 #include "qapi/error.h"
 #include "qapi/qapi-commands-qdev.h"
@@ -240,13 +241,34 @@ ObjectPropertyInfoList *qmp_qom_list_properties(const char *typename,
     return prop_list;
 }
 
-void qmp_object_add(const char *type, const char *id,
-                    bool has_props, QObject *props, Error **errp)
+void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp)
 {
+    QObject *props;
     QDict *pdict;
     Visitor *v;
     Object *obj;
+    const char *type;
+    const char *id;
 
+    type = qdict_get_try_str(qdict, "qom-type");
+    if (!type) {
+        error_setg(errp, QERR_MISSING_PARAMETER, "qom-type");
+        return;
+    } else {
+        type = g_strdup(type);
+        qdict_del(qdict, "qom-type");
+    }
+
+    id = qdict_get_try_str(qdict, "id");
+    if (!id) {
+        error_setg(errp, QERR_MISSING_PARAMETER, "id");
+        return;
+    } else {
+        id = g_strdup(id);
+        qdict_del(qdict, "id");
+    }
+
+    props = qdict_get(qdict, "props");
     if (props) {
         pdict = qobject_to(QDict, props);
         if (!pdict) {
@@ -254,17 +276,23 @@ void qmp_object_add(const char *type, const char *id,
             return;
         }
         qobject_ref(pdict);
-    } else {
-        pdict = qdict_new();
+        qdict_del(qdict, "props");
+        qdict_join(qdict, pdict, false);
+        if (qdict_size(pdict) != 0) {
+            error_setg(errp, "Option in 'props' conflicts with top level");
+            qobject_unref(pdict);
+            return;
+        }
+        qobject_unref(pdict);
     }
 
-    v = qobject_input_visitor_new(QOBJECT(pdict));
-    obj = user_creatable_add_type(type, id, pdict, v, errp);
+    v = qobject_input_visitor_new(QOBJECT(qdict));
+    obj = user_creatable_add_type(type, id, qdict, v, errp);
     visit_free(v);
     if (obj) {
         object_unref(obj);
     }
-    qobject_unref(pdict);
+    *ret_data = QOBJECT(qdict_new());
 }
 
 void qmp_object_del(const char *id, Error **errp)