qom: Add "realized" property to Object

The Object::realized property can only be set once and, on setting it,
invokes the ObjectClass::realize callback.

Introduce QERR_OBJECT_REALIZE_FAILED for error handling.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>

include/qemu/object.h

@@ -239,6 +239,7 @@ struct ObjectClass
 {
     /*< private >*/
     Type type;
+    int (*realize)(Object *obj);
 };
 
 /**
@@ -264,6 +265,7 @@ struct Object
     QTAILQ_HEAD(, ObjectProperty) properties;
     uint32_t ref;
     Object *parent;
+    bool realized;
 };
 
 /**

qerror.c

@@ -216,6 +216,10 @@ static const QErrorStringTable qerror_table[] = {
         .error_fmt = QERR_NOT_SUPPORTED,
         .desc      = "Not supported",
     },
+    {
+        .error_fmt = QERR_OBJECT_REALIZE_FAILED,
+        .desc      = "Object of type '%(type)' could not be realized",
+    },
     {
         .error_fmt = QERR_OPEN_FILE_FAILED,
         .desc      = "Could not open '%(filename)'",

qerror.h

@@ -184,6 +184,9 @@ QError *qobject_to_qerror(const QObject *obj);
 #define QERR_NOT_SUPPORTED \
     "{ 'class': 'NotSupported', 'data': {} }"
 
+#define QERR_OBJECT_REALIZE_FAILED \
+    "{ 'class': 'ObjectRealizeFailed', 'data': { 'type': %s } }"
+
 #define QERR_OPEN_FILE_FAILED \
     "{ 'class': 'OpenFileFailed', 'data': { 'filename': %s } }"
 

qom/object.c

@@ -273,6 +273,34 @@ static void object_init_with_type(Object *obj, TypeImpl *ti)
     }
 }
 
+static void object_get_realized(Object *obj, Visitor *v, void *opaque,
+                                const char *name, Error **errp)
+{
+    visit_type_bool(v, &obj->realized, name, errp);
+}
+
+static void object_set_realized(Object *obj, Visitor *v, void *opaque,
+                                const char *name, Error **errp)
+{
+    bool value;
+
+    if (obj->realized) {
+        error_set(errp, QERR_PERMISSION_DENIED);
+        return;
+    }
+
+    visit_type_bool(v, &value, name, errp);
+    if (error_is_set(errp) || !value) {
+        return;
+    }
+
+    if (obj->class->realize != NULL && obj->class->realize(obj) != 0) {
+        error_set(errp, QERR_OBJECT_REALIZE_FAILED, object_get_typename(obj));
+        return;
+    }
+    obj->realized = true;
+}
+
 void object_initialize_with_type(void *data, TypeImpl *type)
 {
     Object *obj = data;
@@ -287,6 +315,9 @@ void object_initialize_with_type(void *data, TypeImpl *type)
     obj->class = type->class;
     QTAILQ_INIT(&obj->properties);
     object_init_with_type(obj, type);
+    object_property_add(obj, "realized", "boolean",
+                        object_get_realized, object_set_realized,
+                        NULL, NULL, NULL);
 }
 
 void object_initialize(void *data, const char *typename)