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authorEric Blake <eblake@redhat.com>2016-06-09 10:48:43 -0600
committerMarkus Armbruster <armbru@redhat.com>2016-07-06 10:52:04 +0200
commit3b098d56979d2f7fd707c5be85555d114353a28d (patch)
tree85f234e99b363f4417c0b4a09971ad63935031d9 /qemu-img.c
parent23d1705f425ca847f11d92e4363cd7f67f369fd8 (diff)
downloadqemu-arm-3b098d56979d2f7fd707c5be85555d114353a28d.tar.gz
qapi: Add new visit_complete() function
Making each output visitor provide its own output collection function was the only remaining reason for exposing visitor sub-types to the rest of the code base. Add a polymorphic visit_complete() function which is a no-op for input visitors, and which populates an opaque pointer for output visitors. For maximum type-safety, also add a parameter to the output visitor constructors with a type-correct version of the output pointer, and assert that the two uses match. This approach was considered superior to either passing the output parameter only during construction (action at a distance during visit_free() feels awkward) or only during visit_complete() (defeating type safety makes it easier to use incorrectly). Most callers were function-local, and therefore a mechanical conversion; the testsuite was a bit trickier, but the previous cleanup patch minimized the churn here. The visit_complete() function may be called at most once; doing so lets us use transfer semantics rather than duplication or ref-count semantics to get the just-built output back to the caller, even though it means our behavior is not idempotent. Generated code is simplified as follows for events: |@@ -26,7 +26,7 @@ void qapi_event_send_acpi_device_ost(ACP | QDict *qmp; | Error *err = NULL; | QMPEventFuncEmit emit; |- QmpOutputVisitor *qov; |+ QObject *obj; | Visitor *v; | q_obj_ACPI_DEVICE_OST_arg param = { | info |@@ -39,8 +39,7 @@ void qapi_event_send_acpi_device_ost(ACP | | qmp = qmp_event_build_dict("ACPI_DEVICE_OST"); | |- qov = qmp_output_visitor_new(); |- v = qmp_output_get_visitor(qov); |+ v = qmp_output_visitor_new(&obj); | | visit_start_struct(v, "ACPI_DEVICE_OST", NULL, 0, &err); | if (err) { |@@ -55,7 +54,8 @@ void qapi_event_send_acpi_device_ost(ACP | goto out; | } | |- qdict_put_obj(qmp, "data", qmp_output_get_qobject(qov)); |+ visit_complete(v, &obj); |+ qdict_put_obj(qmp, "data", obj); | emit(QAPI_EVENT_ACPI_DEVICE_OST, qmp, &err); and for commands: | { | Error *err = NULL; |- QmpOutputVisitor *qov = qmp_output_visitor_new(); | Visitor *v; | |- v = qmp_output_get_visitor(qov); |+ v = qmp_output_visitor_new(ret_out); | visit_type_AddfdInfo(v, "unused", &ret_in, &err); |- if (err) { |- goto out; |+ if (!err) { |+ visit_complete(v, ret_out); | } |- *ret_out = qmp_output_get_qobject(qov); |- |-out: | error_propagate(errp, err); Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1465490926-28625-13-git-send-email-eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
Diffstat (limited to 'qemu-img.c')
-rw-r--r--qemu-img.c30
1 files changed, 15 insertions, 15 deletions
diff --git a/qemu-img.c b/qemu-img.c
index 728f471801..4dfb27df37 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -491,16 +491,16 @@ fail:
static void dump_json_image_check(ImageCheck *check, bool quiet)
{
QString *str;
- QmpOutputVisitor *ov = qmp_output_visitor_new();
QObject *obj;
- visit_type_ImageCheck(qmp_output_get_visitor(ov), NULL, &check,
- &error_abort);
- obj = qmp_output_get_qobject(ov);
+ Visitor *v = qmp_output_visitor_new(&obj);
+
+ visit_type_ImageCheck(v, NULL, &check, &error_abort);
+ visit_complete(v, &obj);
str = qobject_to_json_pretty(obj);
assert(str != NULL);
qprintf(quiet, "%s\n", qstring_get_str(str));
qobject_decref(obj);
- visit_free(qmp_output_get_visitor(ov));
+ visit_free(v);
QDECREF(str);
}
@@ -2181,32 +2181,32 @@ static void dump_snapshots(BlockDriverState *bs)
static void dump_json_image_info_list(ImageInfoList *list)
{
QString *str;
- QmpOutputVisitor *ov = qmp_output_visitor_new();
QObject *obj;
- visit_type_ImageInfoList(qmp_output_get_visitor(ov), NULL, &list,
- &error_abort);
- obj = qmp_output_get_qobject(ov);
+ Visitor *v = qmp_output_visitor_new(&obj);
+
+ visit_type_ImageInfoList(v, NULL, &list, &error_abort);
+ visit_complete(v, &obj);
str = qobject_to_json_pretty(obj);
assert(str != NULL);
printf("%s\n", qstring_get_str(str));
qobject_decref(obj);
- visit_free(qmp_output_get_visitor(ov));
+ visit_free(v);
QDECREF(str);
}
static void dump_json_image_info(ImageInfo *info)
{
QString *str;
- QmpOutputVisitor *ov = qmp_output_visitor_new();
QObject *obj;
- visit_type_ImageInfo(qmp_output_get_visitor(ov), NULL, &info,
- &error_abort);
- obj = qmp_output_get_qobject(ov);
+ Visitor *v = qmp_output_visitor_new(&obj);
+
+ visit_type_ImageInfo(v, NULL, &info, &error_abort);
+ visit_complete(v, &obj);
str = qobject_to_json_pretty(obj);
assert(str != NULL);
printf("%s\n", qstring_get_str(str));
qobject_decref(obj);
- visit_free(qmp_output_get_visitor(ov));
+ visit_free(v);
QDECREF(str);
}