qom: add QObject-based property get/set wrappers

Move the creation of QmpInputVisitor and QmpOutputVisitor from qmp.c
to qom/object.c, since it's the only practical way to access object
properties.

Keep this isolated such that it's easy to remove.  At some point, we need
to remove all usage of QObject in the tree and replace it with GVariant.

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

4 files changed, 90 insertions, 16 deletions

diff --git a/include/qemu/qom-qobject.h b/include/qemu/qom-qobject.h
new file mode 100644
index 0000000..f9dff12
--- /dev/null
+++ b/include/qemu/qom-qobject.h
@@ -0,0 +1,42 @@
+/*
+ * QEMU Object Model - QObject wrappers
+ *
+ * Copyright (C) 2012 Red Hat, Inc.
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_QOM_QOBJECT_H
+#define QEMU_QOM_QOBJECT_H
+
+#include "qemu/object.h"
+
+/*
+ * object_property_get_qobject:
+ * @obj: the object
+ * @name: the name of the property
+ * @errp: returns an error if this function fails
+ *
+ * Returns: the value of the property, converted to QObject, or NULL if
+ * an error occurs.
+ */
+struct QObject *object_property_get_qobject(Object *obj, const char *name,
+                                            struct Error **errp);
+
+/**
+ * object_property_set_qobject:
+ * @obj: the object
+ * @ret: The value that will be written to the property.
+ * @name: the name of the property
+ * @errp: returns an error if this function fails
+ *
+ * Writes a property to a object.
+ */
+void object_property_set_qobject(Object *obj, struct QObject *qobj,
+                                 const char *name, struct Error **errp);
+
+#endif
diff --git a/qmp.c b/qmp.c
index 45052cc..1f64844 100644
--- a/qmp.c
+++ b/qmp.c
@@ -21,9 +21,8 @@
 #include "kvm.h"
 #include "arch_init.h"
 #include "hw/qdev.h"
-#include "qapi/qmp-input-visitor.h"
-#include "qapi/qmp-output-visitor.h"
 #include "blockdev.h"
+#include "qemu/qom-qobject.h"
 
 NameInfo *qmp_query_name(Error **errp)
 {
@@ -198,7 +197,6 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret)
     const char *property = qdict_get_str(qdict, "property");
     QObject *value = qdict_get(qdict, "value");
     Error *local_err = NULL;
-    QmpInputVisitor *mi;
     Object *obj;
 
     obj = object_resolve_path(path, NULL);
@@ -207,10 +205,7 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret)
         goto out;
     }
 
-    mi = qmp_input_visitor_new(value);
-    object_property_set(obj, qmp_input_get_visitor(mi), property, &local_err);
-
-    qmp_input_visitor_cleanup(mi);
+    object_property_set_qobject(obj, value, property, &local_err);
 
 out:
     if (local_err) {
@@ -227,7 +222,6 @@ int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret)
     const char *path = qdict_get_str(qdict, "path");
     const char *property = qdict_get_str(qdict, "property");
     Error *local_err = NULL;
-    QmpOutputVisitor *mo;
     Object *obj;
 
     obj = object_resolve_path(path, NULL);
@@ -236,13 +230,7 @@ int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret)
         goto out;
     }
 
-    mo = qmp_output_visitor_new();
-    object_property_get(obj, qmp_output_get_visitor(mo), property, &local_err);
-    if (!local_err) {
-        *ret = qmp_output_get_qobject(mo);
-    }
-
-    qmp_output_visitor_cleanup(mo);
+    *ret = object_property_get_qobject(obj, property, &local_err);
 
 out:
     if (local_err) {
diff --git a/qom/Makefile b/qom/Makefile
index f33f0be..885a263 100644
--- a/qom/Makefile
+++ b/qom/Makefile
@@ -1 +1 @@
-qom-y = object.o container.o
+qom-y = object.o container.o qom-qobject.o
diff --git a/qom/qom-qobject.c b/qom/qom-qobject.c
new file mode 100644
index 0000000..0689914
--- /dev/null
+++ b/qom/qom-qobject.c
@@ -0,0 +1,44 @@
+/*
+ * QEMU Object Model - QObject wrappers
+ *
+ * Copyright (C) 2012 Red Hat, Inc.
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu-common.h"
+#include "qemu/object.h"
+#include "qemu/qom-qobject.h"
+#include "qapi/qapi-visit-core.h"
+#include "qapi/qmp-input-visitor.h"
+#include "qapi/qmp-output-visitor.h"
+
+void object_property_set_qobject(Object *obj, QObject *value,
+                                 const char *name, Error **errp)
+{
+    QmpInputVisitor *mi;
+    mi = qmp_input_visitor_new(value);
+    object_property_set(obj, qmp_input_get_visitor(mi), name, errp);
+
+    qmp_input_visitor_cleanup(mi);
+}
+
+QObject *object_property_get_qobject(Object *obj, const char *name,
+                                     Error **errp)
+{
+    QObject *ret = NULL;
+    Error *local_err = NULL;
+    QmpOutputVisitor *mo;
+
+    mo = qmp_output_visitor_new();
+    object_property_get(obj, qmp_output_get_visitor(mo), name, &local_err);
+    if (!local_err) {
+        ret = qmp_output_get_qobject(mo);
+    }
+    error_propagate(errp, local_err);
+    qmp_output_visitor_cleanup(mo);
+    return ret;
+}