From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48146) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a69NK-0004R8-B0 for qemu-devel@nongnu.org; Mon, 07 Dec 2015 22:55:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a69NI-0003bH-If for qemu-devel@nongnu.org; Mon, 07 Dec 2015 22:55:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57653) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a69NI-0003b6-Bm for qemu-devel@nongnu.org; Mon, 07 Dec 2015 22:55:36 -0500 From: Eric Blake Date: Mon, 7 Dec 2015 20:55:08 -0700 Message-Id: <1449546921-6378-19-git-send-email-eblake@redhat.com> In-Reply-To: <1449546921-6378-1-git-send-email-eblake@redhat.com> References: <1449546921-6378-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH v7 18/31] qapi: Add visit_type_null() visitor List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: armbru@redhat.com, Michael Roth 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 --- 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 27f776f..78a5ab1 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, QObject **obj, const char *name, 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, bool *present, const char *name); diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h index 96a9535..2592dd1 100644 --- a/include/qapi/visitor.h +++ b/include/qapi/visitor.h @@ -267,6 +267,14 @@ void visit_type_number(Visitor *v, double *obj, const char *name, void visit_type_any(Visitor *v, QObject **obj, const char *name, 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 e280d9f..e3a4493 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, QObject **obj, } } +static void qapi_dealloc_type_null(Visitor *v, const char *name, Error **errp) +{ +} + static void qapi_dealloc_type_enum(Visitor *v, int *obj, const char *const strings[], const char *name, Error **errp) @@ -223,6 +227,7 @@ 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 042ef07..36917f3 100644 --- a/qapi/qapi-visit-core.c +++ b/qapi/qapi-visit-core.c @@ -257,6 +257,11 @@ void visit_type_any(Visitor *v, QObject **obj, const char *name, v->type_any(v, obj, name, errp); } +void visit_type_null(Visitor *v, const char *name, Error **errp) +{ + v->type_null(v, name, errp); +} + void output_type_enum(Visitor *v, int *obj, const char *const strings[], const char *name, Error **errp) { -- 2.4.3