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Thu, 28 Apr 2016 17:45:42 -0400 From: Eric Blake To: qemu-devel@nongnu.org Date: Thu, 28 Apr 2016 15:45:26 -0600 Message-Id: <1461879932-9020-19-git-send-email-eblake@redhat.com> In-Reply-To: <1461879932-9020-1-git-send-email-eblake@redhat.com> References: <1461879932-9020-1-git-send-email-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v16 18/24] qmp: Tighten output visitor rules X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: armbru@redhat.com, Michael Roth Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Tighten assertions in the QMP output visitor, so that: - qmp_output_get_qobject() can only be called after pairing a visit_end_* for every visit_start_* (rather than allowing it on a partially built object) - qmp_output_get_qobject() cannot be called unless at least one visit_type_* or visit_start/visit_end pair has occurred since creation/reset (the accidental return of NULL fixed by commit ab8bf1d7 would have been much easier to diagnose) - ensure that we are encountering the expected object or list type, to provide protection against mismatched push(struct)/ pop(list) or push(list)/pop(struct), similar to the qmp-input protection added in commit bdd8e6b5. - ensure that except for the root, 'name' is non-null inside a dict, and NULL inside a list (this may need changing later if we add "name.0" support for better error messages for a list, but for now it makes sure all users are at least consistent) Signed-off-by: Eric Blake --- v15: split off qmp_output_visitor_reset(), improve comments, use QTAILQ_EMPTY v14: no change v13: no change v12: rebase to latest, move type_null() into earlier patches, don't change signature of pop, don't auto-reset after a single get_qobject [no v10, v11] v9: rebase to added patch, squash in more sanity checks, drop Marc-Andre's R-b v8: rename qmp_output_reset to qmp_output_visitor_reset v7: new patch, based on discussion about spapr_drc.c Signed-off-by: Eric Blake --- qapi/qmp-output-visitor.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c index 6c44210..7155bde 100644 --- a/qapi/qmp-output-visitor.c +++ b/qapi/qmp-output-visitor.c @@ -82,9 +82,8 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name, QObject *cur = e ? e->value : NULL; if (!cur) { - /* FIXME we should require the user to reset the visitor, rather - * than throwing away the previous root */ - qobject_decref(qov->root); + /* Don't allow reuse of visitor on more than one root */ + assert(!qov->root); qov->root = value; } else { switch (qobject_type(cur)) { @@ -93,6 +92,7 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name, qdict_put_obj(qobject_to_qdict(cur), name, value); break; case QTYPE_QLIST: + assert(!name); qlist_append_obj(qobject_to_qlist(cur), value); break; default: @@ -114,7 +114,8 @@ static void qmp_output_start_struct(Visitor *v, const char *name, void **obj, static void qmp_output_end_struct(Visitor *v, Error **errp) { QmpOutputVisitor *qov = to_qov(v); - qmp_output_pop(qov); + QObject *value = qmp_output_pop(qov); + assert(qobject_type(value) == QTYPE_QDICT); } static void qmp_output_start_list(Visitor *v, const char *name, Error **errp) @@ -145,7 +146,8 @@ static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp, static void qmp_output_end_list(Visitor *v) { QmpOutputVisitor *qov = to_qov(v); - qmp_output_pop(qov); + QObject *value = qmp_output_pop(qov); + assert(qobject_type(value) == QTYPE_QLIST); } static void qmp_output_type_int64(Visitor *v, const char *name, int64_t *obj, @@ -202,18 +204,16 @@ static void qmp_output_type_null(Visitor *v, const char *name, Error **errp) qmp_output_add_obj(qov, name, qnull()); } -/* Finish building, and return the root object. Will not be NULL. */ +/* Finish building, and return the root object. + * The root object is never null. The caller becomes the object's + * owner, and should use qobject_decref() when done with it. */ QObject *qmp_output_get_qobject(QmpOutputVisitor *qov) { - /* FIXME: we should require that a visit occurred, and that it is - * complete (no starts without a matching end) */ - QObject *obj = qov->root; - if (obj) { - qobject_incref(obj); - } else { - obj = qnull(); - } - return obj; + /* A visit must have occurred, with each start paired with end. */ + assert(qov->root && QTAILQ_EMPTY(&qov->stack)); + + qobject_incref(qov->root); + return qov->root; } Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)