qmp: Improve QMP dispatch error messages

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1493282486-28338-2-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

qapi/qmp-dispatch.c

@@ -30,7 +30,7 @@ static QDict *qmp_dispatch_check_obj(const QObject *request, Error **errp)
 
     dict = qobject_to_qdict(request);
     if (!dict) {
-        error_setg(errp, "Expected '%s' in QMP input", "object");
+        error_setg(errp, "QMP input must be a JSON object");
         return NULL;
     }
 
@@ -41,26 +41,26 @@ static QDict *qmp_dispatch_check_obj(const QObject *request, Error **errp)
 
         if (!strcmp(arg_name, "execute")) {
             if (qobject_type(arg_obj) != QTYPE_QSTRING) {
-                error_setg(errp, "QMP input object member '%s' expects '%s'",
-                           "execute", "string");
+                error_setg(errp,
+                           "QMP input member 'execute' must be a string");
                 return NULL;
             }
             has_exec_key = true;
         } else if (!strcmp(arg_name, "arguments")) {
             if (qobject_type(arg_obj) != QTYPE_QDICT) {
-                error_setg(errp, "QMP input object member '%s' expects '%s'",
-                           "arguments", "object");
+                error_setg(errp,
+                           "QMP input member 'arguments' must be an object");
                 return NULL;
             }
         } else {
-            error_setg(errp, "QMP input object member '%s' is unexpected",
+            error_setg(errp, "QMP input member '%s' is unexpected",
                        arg_name);
             return NULL;
         }
     }
 
     if (!has_exec_key) {
-        error_setg(errp, "Expected '%s' in QMP input", "execute");
+        error_setg(errp, "QMP input lacks member 'execute'");
         return NULL;
     }