qjson: Have qobject_from_json() & friends reject empty and blank
The last case where qobject_from_json() & friends return null without
setting an error is empty or blank input. Callers:
* block.c's parse_json_protocol() reports "Could not parse the JSON
options". It's marked as a work-around, because it also covered
actual bugs, but they got fixed in the previous few commits.
* qobject_input_visitor_new_str() reports "JSON parse error". Also
marked as work-around. The recent fixes have made this unreachable,
because it currently gets called only for input starting with '{'.
* check-qjson.c's empty_input() and blank_input() demonstrate the
behavior.
* The other callers are not affected since they only pass input with
exactly one JSON value or, in the case of negative tests, one error.
Fail with "Expecting a JSON value" instead of returning null, and
simplify callers.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-48-armbru@redhat.com>
diff --git a/qobject/qjson.c b/qobject/qjson.c
index 7f69036..b9ccae2 100644
--- a/qobject/qjson.c
+++ b/qobject/qjson.c
@@ -70,6 +70,10 @@
json_message_parser_flush(&state.parser);
json_message_parser_destroy(&state.parser);
+ if (!state.result && !state.err) {
+ error_setg(&state.err, "Expecting a JSON value");
+ }
+
error_propagate(errp, state.err);
return state.result;
}
