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[Qemu-devel] [PATCH v8 22/35] qapi: Add visit_type_null() visitor
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH v8 22/35] qapi: Add visit_type_null() visitor |
Date: |
Mon, 21 Dec 2015 10:08:27 -0700 |
Right now, qmp-output-visitor happens to produce a QNull result
if nothing is actually visited between the creation of the visitor
and the request for the resulting QObject. A stronger protocol
would require that a QMP output visit MUST visit something. But
to still be able to produce a JSON 'null' output, we need a new
visitor function that states our intentions.
This patch introduces the new visit_type_null() interface, and
a later patch will then wire it up into the qmp output visitor.
Signed-off-by: Eric Blake <address@hidden>
---
v8: rebase to 'name' motion
v7: new patch, based on discussion about spapr_drc.c
---
include/qapi/visitor-impl.h | 3 +++
include/qapi/visitor.h | 8 ++++++++
qapi/qapi-dealloc-visitor.c | 5 +++++
qapi/qapi-visit-core.c | 5 +++++
4 files changed, 21 insertions(+)
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 8110ebd..d301901 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -75,6 +75,9 @@ struct Visitor
* visitors do not currently visit arbitrary types). */
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). */
+ void (*type_null)(Visitor *v, const char *name, Error **errp);
/* May be NULL; most useful for input visitors. */
void (*optional)(Visitor *v, const char *name, bool *present);
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 5349a64..6e49b51 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -267,6 +267,14 @@ void visit_type_number(Visitor *v, const char *name,
double *obj,
void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
/**
+ * Visit a JSON null value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * No obj parameter is needed; rather, this is a witness that an
+ * explicit null value is expected rather than any other type.
+ */
+void visit_type_null(Visitor *v, const char *name, Error **errp);
+
+/**
* Mark the start of visiting the branches of a union. Return true if
* @data_present.
* FIXME: Should not be needed
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 560feb3..ede1703 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -162,6 +162,10 @@ static void qapi_dealloc_type_anything(Visitor *v, const
char *name,
}
}
+static void qapi_dealloc_type_null(Visitor *v, const char *name, Error **errp)
+{
+}
+
static void qapi_dealloc_type_enum(Visitor *v, const char *name, int *obj,
const char * const strings[], Error **errp)
{
@@ -222,6 +226,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
v->visitor.type_str = qapi_dealloc_type_str;
v->visitor.type_number = qapi_dealloc_type_number;
v->visitor.type_any = qapi_dealloc_type_anything;
+ v->visitor.type_null = qapi_dealloc_type_null;
v->visitor.start_union = qapi_dealloc_start_union;
QTAILQ_INIT(&v->stack);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 1612d0d..399256b 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -262,6 +262,11 @@ void visit_type_any(Visitor *v, const char *name, QObject
**obj, Error **errp)
v->type_any(v, name, obj, errp);
}
+void visit_type_null(Visitor *v, const char *name, Error **errp)
+{
+ v->type_null(v, name, errp);
+}
+
void output_type_enum(Visitor *v, const char *name, int *obj,
const char * const strings[], Error **errp)
{
--
2.4.3
- [Qemu-devel] [PATCH v8 09/35] qapi: Prefer type_int64 over type_int in visitors, (continued)
- [Qemu-devel] [PATCH v8 09/35] qapi: Prefer type_int64 over type_int in visitors, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 10/35] qapi: Make all visitors supply uint64 callbacks, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 11/35] qapi: Consolidate visitor small integer callbacks, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 07/35] qapi: Improve generated event use of qapi visitor, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 17/35] qapi: Drop unused 'kind' for struct/enum visit, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 13/35] qom: Use typedef for Visitor, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 20/35] qmp: Don't abuse stack to track qmp-output root, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 18/35] qapi: Drop unused error argument for list and implicit struct, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 27/35] qapi: Fix command with named empty argument type, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 01/35] qobject: Document more shortcomings in our number handling, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 22/35] qapi: Add visit_type_null() visitor,
Eric Blake <=
- [Qemu-devel] [PATCH v8 25/35] qapi: Simplify excess input reporting in input visitors, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 19/35] qmp: Fix reference-counting of qnull on empty output visit, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 21/35] qapi: Document visitor interfaces, add assertions, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 28/35] qapi: Eliminate empty visit_type_FOO_fields, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 24/35] spapr_drc: Expose 'null' in qom-get when there is no fdt, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 31/35] qapi: Rework deallocation of partial struct, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 34/35] qapi: Change visit_type_FOO() to no longer return partial objects, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 32/35] qapi: Split visit_end_struct() into pieces, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 35/35] RFC: qapi: Adjust layout of FooList types, Eric Blake, 2015/12/21
- [Qemu-devel] [PATCH v8 23/35] qmp: Tighten output visitor rules, Eric Blake, 2015/12/21