Commit 56a6f02b authored by Eric Blake's avatar Eric Blake Committed by Markus Armbruster
Browse files

qmp: Tighten output visitor rules 



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: default avatarEric Blake <eblake@redhat.com>
Message-Id: <1461879932-9020-19-git-send-email-eblake@redhat.com>
Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
parent f2ff429b

qapi/qmp-output-visitor.c

+15 −15
Original line number Diff line number Diff line
@@ -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)