[Qemu-devel] [PATCH v1 RFC 04/34] qom: add object_new_propv / object_new_proplist constructors

[Daniel P. Berrange]

It is reasonably common to want to create an object, set a
number of properties, register it in the hierarchy and then
mark it as complete (if a user creatable type). This requires
quite alot of error prone, verbose, boilerplate code to achieve.

The object_new_propv / object_new_proplist constructors will
simplify this task by performing all required steps in one go,
accepting the property names/values as variadic args.

Usage would be:

   Error *err = NULL;
   Object *obj;
   obj = object_new_propv(TYPE_MEMORY_BACKEND_FILE,
                          "hostmem0",
                          &err,
                          "share", "yes",
                          "mem-path", "/dev/shm/somefile",
                          "prealloc", "yes",
                          "size": "1048576",
                          NULL);

Note all property values are passed in string form and will
be parsed into their required data types.

Signed-off-by: Daniel P. Berrange <address@hidden>
---
 include/qom/object.h | 58 +++++++++++++++++++++++++++++++++++++++++++++++
 qom/object.c         | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/Makefile       |  2 +-
 3 files changed, 123 insertions(+), 1 deletion(-)

diff --git a/include/qom/object.h b/include/qom/object.h
index d2d7748..223b577 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -607,6 +607,64 @@ Object *object_new(const char *typename);
 Object *object_new_with_type(Type type);
 
 /**
+ * object_new_propv:
+ * @typename:  The name of the type of the object to instantiate.
+ * @id: The unique ID of the object
+ * @errp: pointer to error object
+ * @...: list of property names and values
+ *
+ * This function with initialize a new object using heap allocated memory.
+ * The returned object has a reference count of 1, and will be freed when
+ * the last reference is dropped.
+ *
+ * The @id parameter will be used to register the object in the /objects
+ * hierarchy.
+ *
+ * The variadic parameters are a list of pairs of (propname, propvalue)
+ * strings. The propname of NULL indicates the end of the property
+ * list. If the object implements the user creatable interface, the
+ * object will be marked complete once all the properties have been
+ * processed.
+ *
+ *   Error *err = NULL;
+ *   Object *obj;
+ *
+ *   obj = object_new_propv(TYPE_MEMORY_BACKEND_FILE,
+ *                          "hostmem0",
+ *                          &err,
+ *                          "share", "yes",
+ *                          "mem-path", "/dev/shm/somefile",
+ *                          "prealloc", "yes",
+ *                          "size": "1048576",
+ *                          NULL);
+ *
+ *   if (!obj) {
+ *     g_printerr("Cannot create memory backend: %s\n",
+ *                error_get_pretty(err));
+ *   }
+ *
+ * Returns: The newly allocated, instantiated & initialized object.
+ */
+Object *object_new_propv(const char *typename,
+                         const char *id,
+                         Error **errp,
+                         ...);
+
+/**
+ * object_new_proplist:
+ * @typename:  The name of the type of the object to instantiate.
+ * @id: The unique ID of the object
+ * @errp: pointer to error object
+ * @vargs: list of property names and values
+ *
+ * See object_new_propv for documentation.
+ */
+Object *object_new_proplist(const char *typename,
+                            const char *id,
+                            Error **errp,
+                            va_list vargs);
+
+/**
  * object_initialize_with_type:
  * @data: A pointer to the memory to be used for the object.
  * @size: The maximum size available at @data for the object.
diff --git a/qom/object.c b/qom/object.c
index b8dff43..29c7aea 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -11,6 +11,7 @@
  */
 
 #include "qom/object.h"
+#include "qom/object_interfaces.h"
 #include "qemu-common.h"
 #include "qapi/visitor.h"
 #include "qapi-visit.h"
@@ -439,6 +440,69 @@ Object *object_new(const char *typename)
     return object_new_with_type(ti);
 }
 
+Object *object_new_propv(const char *typename,
+                         const char *id,
+                         Error **errp,
+                         ...)
+{
+    va_list vargs;
+    Object *obj;
+
+    va_start(vargs, errp);
+    obj = object_new_proplist(typename, id, errp, vargs);
+    va_end(vargs);
+
+    return obj;
+}
+
+Object *object_new_proplist(const char *typename,
+                            const char *id,
+                            Error **errp,
+                            va_list vargs)
+{
+    Object *obj;
+    const char *propname;
+
+    obj = object_new(typename);
+
+    if (object_class_is_abstract(object_get_class(obj))) {
+        error_setg(errp, "object type '%s' is abstract", typename);
+        goto error;
+    }
+
+    propname = va_arg(vargs, char *);
+    while (propname != NULL) {
+        const char *value = va_arg(vargs, char *);
+
+        object_property_parse(obj, value, propname, errp);
+        if (*errp) {
+            goto error;
+        }
+        propname = va_arg(vargs, char *);
+    }
+
+    object_property_add_child(container_get(object_get_root(), "/objects"),
+                              id, obj, errp);
+    if (*errp) {
+        goto error;
+    }
+
+    if (object_dynamic_cast(obj, TYPE_USER_CREATABLE)) {
+        user_creatable_complete(obj, errp);
+        if (*errp) {
+            object_property_del(container_get(object_get_root(), "/objects"),
+                                id, &error_abort);
+            goto error;
+        }
+    }
+
+    return obj;
+
+ error:
+    object_unref(obj);
+    return NULL;
+}
+
 Object *object_dynamic_cast(Object *obj, const char *typename)
 {
     if (obj && object_class_dynamic_cast(object_get_class(obj), typename)) {
diff --git a/tests/Makefile b/tests/Makefile
index 55aa745..e212ba9 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -240,7 +240,7 @@ test-qapi-obj-y = tests/test-qapi-visit.o 
tests/test-qapi-types.o \
 
 $(test-obj-y): QEMU_INCLUDES += -Itests
 QEMU_CFLAGS += -I$(SRC_PATH)/tests
-qom-core-obj = qom/object.o qom/qom-qobject.o qom/container.o
+qom-core-obj = qom/object.o qom/qom-qobject.o qom/container.o 
qom/object_interfaces.o
 
 tests/check-qint$(EXESUF): tests/check-qint.o libqemuutil.a
 tests/check-qstring$(EXESUF): tests/check-qstring.o libqemuutil.a
-- 
2.1.0