@@ -76,7 +76,7 @@ struct Visitor
void (*type_any)(Visitor *v, const char *name, QObject **obj,
Error **errp);
/* Must be provided to visit explicit null values (right now, only the
- * dealloc visitor supports this). */
+ * dealloc and qmp-input visitors support this). */
void (*type_null)(Visitor *v, const char *name, Error **errp);
/* May be NULL; most useful for input visitors. */
@@ -315,6 +315,19 @@ static void qmp_input_type_any(Visitor *v, const char *name, QObject **obj,
*obj = qobj;
}
+static void qmp_input_type_null(Visitor *v, const char *name, Error **errp)
+{
+ QmpInputVisitor *qiv = to_qiv(v);
+ QObject *qobj = qmp_input_get_object(qiv, name, true);
+
+ if (qobject_type(qobj) == QTYPE_QNULL) {
+ return;
+ }
+
+ error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+ "null");
+}
+
static void qmp_input_optional(Visitor *v, const char *name, bool *present)
{
QmpInputVisitor *qiv = to_qiv(v);
@@ -358,6 +371,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
v->visitor.type_str = qmp_input_type_str;
v->visitor.type_number = qmp_input_type_number;
v->visitor.type_any = qmp_input_type_any;
+ v->visitor.type_null = qmp_input_type_null;
v->visitor.optional = qmp_input_optional;
v->visitor.get_next_type = qmp_input_get_next_type;
@@ -278,6 +278,30 @@ static void test_visitor_in_any(TestInputVisitorData *data,
qobject_decref(res);
}
+static void test_visitor_in_null(TestInputVisitorData *data,
+ const void *unused)
+{
+ Visitor *v;
+ QObject *null;
+
+ v = visitor_input_test_init(data, "null");
+ visit_type_null(v, NULL, &error_abort);
+
+ v = visitor_input_test_init(data, "{ 'a': null }");
+ visit_start_struct(v, NULL, NULL, 0, &error_abort);
+ visit_type_null(v, "a", &error_abort);
+ visit_end_struct(v, &error_abort);
+
+ /* Check that qnull reference counting is sane:
+ * 1 for global use, 1 for our qnull() use, and 1 still owned by 'v'
+ * until it is torn down */
+ null = qnull();
+ g_assert(null->refcnt == 3);
+ visitor_input_teardown(data, NULL);
+ g_assert(null->refcnt == 2);
+ qobject_decref(null);
+}
+
static void test_visitor_in_union_flat(TestInputVisitorData *data,
const void *unused)
{
@@ -792,6 +816,8 @@ int main(int argc, char **argv)
&in_visitor_data, test_visitor_in_list);
input_visitor_test_add("/visitor/input/any",
&in_visitor_data, test_visitor_in_any);
+ input_visitor_test_add("/visitor/input/null",
+ &in_visitor_data, test_visitor_in_null);
input_visitor_test_add("/visitor/input/union-flat",
&in_visitor_data, test_visitor_in_union_flat);
input_visitor_test_add("/visitor/input/alternate",
Implement the new type_null() callback for the qmp input visitor. While we don't yet have a use for this in qapi (the generator will need some tweaks first), one usage is already envisioned: when changing blockdev parameters, it would be nice to have a difference between leaving a tuning parameter unchanged (omit that parameter from the struct) and to explicitly reset the parameter to its default without having to know what the default value is (specify the parameter with an explicit null value, which will require us to allow a qapi alternate that chooses between the normal values and an explicit null). At any rate, we can test this without the use of generated qapi by manually using visit_start_struct()/visit_end_struct(). Signed-off-by: Eric Blake <eblake@redhat.com> --- v9: new patch --- include/qapi/visitor-impl.h | 2 +- qapi/qmp-input-visitor.c | 14 ++++++++++++++ tests/test-qmp-input-visitor.c | 26 ++++++++++++++++++++++++++ 3 files changed, 41 insertions(+), 1 deletion(-)