From patchwork Mon Dec 21 17:08:27 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 559651 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id DC53D14018C for ; Tue, 22 Dec 2015 04:21:14 +1100 (AEDT) Received: from localhost ([::1]:46389 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aB492-0000in-Pr for incoming@patchwork.ozlabs.org; Mon, 21 Dec 2015 12:21:12 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51463) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aB3xE-00077k-5Y for qemu-devel@nongnu.org; Mon, 21 Dec 2015 12:09:01 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aB3xC-0006cb-Pn for qemu-devel@nongnu.org; Mon, 21 Dec 2015 12:09:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48424) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aB3xC-0006cN-JW for qemu-devel@nongnu.org; Mon, 21 Dec 2015 12:08:58 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 56DE514CAB2; Mon, 21 Dec 2015 17:08:58 +0000 (UTC) Received: from red.redhat.com (ovpn-113-139.phx2.redhat.com [10.3.113.139]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id tBLH8ge1008283; Mon, 21 Dec 2015 12:08:57 -0500 From: Eric Blake To: qemu-devel@nongnu.org Date: Mon, 21 Dec 2015 10:08:27 -0700 Message-Id: <1450717720-9627-23-git-send-email-eblake@redhat.com> In-Reply-To: <1450717720-9627-1-git-send-email-eblake@redhat.com> References: <1450717720-9627-1-git-send-email-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: armbru@redhat.com, Michael Roth Subject: [Qemu-devel] [PATCH v8 22/35] qapi: Add visit_type_null() visitor X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org 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 Reviewed-by: Marc-André Lureau --- 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) {