qom: Add an object_property_add_enum() helper function
A QOM property can be parsed as enum using the visit_type_enum()
helper function, but this forces callers to use the more complex
generic object_property_add() method when registering it. It
also requires that users of that object have access to the
string map when they want to read the property value.
This patch introduces a specialized object_property_add_enum()
method which simplifies the use of enum properties, so the
setters/getters directly get passed the int value.
typedef enum {
MYDEV_TYPE_FROG,
MYDEV_TYPE_ALLIGATOR,
MYDEV_TYPE_PLATYPUS,
MYDEV_TYPE_LAST
} MyDevType;
Then provide a table of enum <-> string mappings
static const char *const mydevtypemap[MYDEV_TYPE_LAST + 1] = {
[MYDEV_TYPE_FROG] = "frog",
[MYDEV_TYPE_ALLIGATOR] = "alligator",
[MYDEV_TYPE_PLATYPUS] = "platypus",
[MYDEV_TYPE_LAST] = NULL,
};
Assuming an object struct of
typedef struct {
Object parent_obj;
MyDevType devtype;
...other fields...
} MyDev;
The property can then be registered as follows:
static int mydev_prop_get_devtype(Object *obj,
Error **errp G_GNUC_UNUSED)
{
MyDev *dev = MYDEV(obj);
return dev->devtype;
}
static void mydev_prop_set_devtype(Object *obj,
int value,
Error **errp G_GNUC_UNUSED)
{
MyDev *dev = MYDEV(obj);
dev->devtype = value;
}
object_property_add_enum(obj, "devtype",
mydevtypemap, "MyDevType",
mydev_prop_get_devtype,
mydev_prop_set_devtype,
NULL);
Note there is no need to check the range of 'value' in
the setter, because the string->enum conversion code will
have already done that and reported an error as required.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
diff --git a/qom/object.c b/qom/object.c
index 523307d..8f0d8a7 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1069,6 +1069,12 @@
return retval;
}
+typedef struct EnumProperty {
+ const char * const *strings;
+ int (*get)(Object *, Error **);
+ void (*set)(Object *, int, Error **);
+} EnumProperty;
+
int object_property_get_enum(Object *obj, const char *name,
const char * const strings[], Error **errp)
{
@@ -1673,6 +1679,58 @@
}
}
+static void property_get_enum(Object *obj, Visitor *v, void *opaque,
+ const char *name, Error **errp)
+{
+ EnumProperty *prop = opaque;
+ int value;
+
+ value = prop->get(obj, errp);
+ visit_type_enum(v, &value, prop->strings, NULL, name, errp);
+}
+
+static void property_set_enum(Object *obj, Visitor *v, void *opaque,
+ const char *name, Error **errp)
+{
+ EnumProperty *prop = opaque;
+ int value;
+
+ visit_type_enum(v, &value, prop->strings, NULL, name, errp);
+ prop->set(obj, value, errp);
+}
+
+static void property_release_enum(Object *obj, const char *name,
+ void *opaque)
+{
+ EnumProperty *prop = opaque;
+ g_free(prop);
+}
+
+void object_property_add_enum(Object *obj, const char *name,
+ const char *typename,
+ const char * const *strings,
+ int (*get)(Object *, Error **),
+ void (*set)(Object *, int, Error **),
+ Error **errp)
+{
+ Error *local_err = NULL;
+ EnumProperty *prop = g_malloc(sizeof(*prop));
+
+ prop->strings = strings;
+ prop->get = get;
+ prop->set = set;
+
+ object_property_add(obj, name, typename,
+ get ? property_get_enum : NULL,
+ set ? property_set_enum : NULL,
+ property_release_enum,
+ prop, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ g_free(prop);
+ }
+}
+
typedef struct TMProperty {
void (*get)(Object *, struct tm *, Error **);
} TMProperty;