[Qemu-devel] [PATCH qemu v2] qmp: Add qom-list-properties to list QOM object properties

[Alexey Kardashevskiy <aik@ozlabs.ru>]

There is already 'device-list-properties' which does most of the job,
however it does not handle everything returned by qom-list-types such
as machines as they inherit directly from TYPE_OBJECT and not TYPE_DEVICE.
It does not handle abstract classes either.

This adds a new qom-list-properties command which prints properties
of a specific class and its instance. It is pretty much a simplified copy
of the device-list-properties handler.

Since it creates an object instance, device properties should appear
in the output as they are copied to QOM properties at the instance_init
hook.

This adds a object_class_property_iter_init() helper to allow class
properties enumeration uses it in the new QMP command to allow properties
listing for abstract classes.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v2:
* added abstract classes support, now things like "pci-device" or
"spapr-machine" show properties, previously these would produce
an "abstract class" error
---
 qapi-schema.json     | 29 +++++++++++++++++++++++++++++
 include/qom/object.h | 16 ++++++++++++++++
 qmp.c                | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 qom/object.c         |  7 +++++++
 4 files changed, 101 insertions(+)

diff --git a/qapi-schema.json b/qapi-schema.json
index 0262b9f..fa5f189 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1455,6 +1455,35 @@
   'returns': [ 'DevicePropertyInfo' ] }
 
 ##
+# @QOMPropertyInfo:
+#
+# Information about object properties.
+#
+# @name: the name of the property
+# @type: the typename of the property
+# @description: if specified, the description of the property.
+#
+# Since: 2.12
+##
+{ 'struct': 'QOMPropertyInfo',
+  'data': { 'name': 'str', 'type': 'str', '*description': 'str' } }
+
+##
+# @qom-list-properties:
+#
+# List properties associated with a QOM object.
+#
+# @typename: the type name of an object
+#
+# Returns: a list of QOMPropertyInfo describing object properties
+#
+# Since: 2.12
+##
+{ 'command': 'qom-list-properties',
+  'data': { 'typename': 'str'},
+  'returns': [ 'QOMPropertyInfo' ] }
+
+##
 # @xen-set-global-dirty-log:
 #
 # Enable or disable the global dirty log mode.
diff --git a/include/qom/object.h b/include/qom/object.h
index dc73d59..ef07d78 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -1017,6 +1017,22 @@ void object_property_iter_init(ObjectPropertyIterator *iter,
                                Object *obj);
 
 /**
+ * object_class_property_iter_init:
+ * @klass: the class
+ *
+ * Initializes an iterator for traversing all properties
+ * registered against an object class and all parent classes.
+ *
+ * It is forbidden to modify the property list while iterating,
+ * whether removing or adding properties.
+ *
+ * This can be used on abstract classes as it does not create a temporary
+ * instance.
+ */
+void object_class_property_iter_init(ObjectPropertyIterator *iter,
+                                     ObjectClass *klass);
+
+/**
  * object_property_iter_next:
  * @iter: the iterator instance
  *
diff --git a/qmp.c b/qmp.c
index 793f6f3..151d3d7 100644
--- a/qmp.c
+++ b/qmp.c
@@ -576,6 +576,55 @@ DevicePropertyInfoList *qmp_device_list_properties(const char *typename,
     return prop_list;
 }
 
+QOMPropertyInfoList *qmp_qom_list_properties(const char *typename,
+                                             Error **errp)
+{
+    ObjectClass *klass;
+    Object *obj = NULL;
+    ObjectProperty *prop;
+    ObjectPropertyIterator iter;
+    QOMPropertyInfoList *prop_list = NULL;
+
+    klass = object_class_by_name(typename);
+    if (klass == NULL) {
+        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
+                  "Class '%s' not found", typename);
+        return NULL;
+    }
+
+    klass = object_class_dynamic_cast(klass, TYPE_OBJECT);
+    if (klass == NULL) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "typename", TYPE_OBJECT);
+        return NULL;
+    }
+
+    if (object_class_is_abstract(klass)) {
+        object_class_property_iter_init(&iter, klass);
+    } else {
+        obj = object_new(typename);
+        object_property_iter_init(&iter, obj);
+    }
+    while ((prop = object_property_iter_next(&iter))) {
+        QOMPropertyInfo *info;
+        QOMPropertyInfoList *entry;
+
+        info = g_malloc0(sizeof(*info));
+        info->name = g_strdup(prop->name);
+        info->type = g_strdup(prop->type);
+        info->has_description = !!prop->description;
+        info->description = g_strdup(prop->description);
+
+        entry = g_malloc0(sizeof(*entry));
+        entry->value = info;
+        entry->next = prop_list;
+        prop_list = entry;
+    }
+
+    object_unref(obj);
+
+    return prop_list;
+}
+
 CpuDefinitionInfoList *qmp_query_cpu_definitions(Error **errp)
 {
     return arch_query_cpu_definitions(errp);
diff --git a/qom/object.c b/qom/object.c
index 5dcee46..e7978bd 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1037,6 +1037,13 @@ ObjectProperty *object_property_iter_next(ObjectPropertyIterator *iter)
     return val;
 }
 
+void object_class_property_iter_init(ObjectPropertyIterator *iter,
+                                     ObjectClass *klass)
+{
+    g_hash_table_iter_init(&iter->iter, klass->properties);
+    iter->nextclass = klass;
+}
+
 ObjectProperty *object_class_property_find(ObjectClass *klass, const char *name,
                                            Error **errp)
 {
-- 
2.11.0