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 <ebl...@redhat.com>
---
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 <ebl...@redhat.com>
---
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)
--
2.5.5
