To enforce capability negotiation before normal operation,
handle_qmp_command() inspects every command before it's handed off to
qmp_dispatch(). This is a bit of a layering violation, and results in
duplicated code.
Before capability negotiation (!cur_mon->in_command_mode), we fail
commands other than "qmp_capabilities". This is what enforces
capability negotiation.
Afterwards, we fail command "qmp_capabilities".
Clean this up as follows.
The obvious place to fail a command is the command itself, so move the
"afterwards" check to qmp_qmp_capabilities().
We do the "before" check in every other command, but that would be
bothersome. Instead, start without all the other commands, by
registering only qmp_qmp_capabilities(). Register the others in
qmp_qmp_capabilities().
Additionally, replace the generic human-readable error message for
CommandNotFound by one that reminds the user to run qmp_capabilities.
Without that, we'd regress commit 2d5a834.
Signed-off-by: Markus Armbruster <arm...@redhat.com>
---
monitor.c | 70 ++++++++++++++++++++++++++++++++++++---------------------------
1 file changed, 40 insertions(+), 30 deletions(-)
diff --git a/monitor.c b/monitor.c
index 5be71d6..dcf2de7 100644
--- a/monitor.c
+++ b/monitor.c
@@ -563,11 +563,6 @@ static void monitor_qapi_event_init(void)
qmp_event_set_func_emit(monitor_qapi_event_queue);
}
-void qmp_qmp_capabilities(Error **errp)
-{
- cur_mon->qmp.in_command_mode = true;
-}
-
static void handle_hmp_command(Monitor *mon, const char *cmdline);
static void monitor_data_init(Monitor *mon)
@@ -995,7 +990,7 @@ static void qmp_unregister_commands_hack(void)
#endif
}
-void monitor_init_qmp_commands(void)
+static void monitor_init_real_qmp_commands(void)
{
qmp_init_marshal();
@@ -1009,6 +1004,32 @@ void monitor_init_qmp_commands(void)
qmp_unregister_commands_hack();
}
+void monitor_init_qmp_commands(void)
+{
+ /*
+ * Start with just qmp_capabilities, to enforce capability
+ * negotiation. qmp_capabilities will register the other
+ * commands. See also the error message replacement hack in
+ * handle_qmp_command().
+ */
+ qmp_register_command("qmp_capabilities",
+ qmp_marshal_qmp_capabilities, QCO_NO_OPTIONS);
+}
+
+void qmp_qmp_capabilities(Error **errp)
+{
+ if (cur_mon->qmp.in_command_mode) {
+ error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
+ "Capabilities negotiation is already complete, command "
+ "ignored");
+ return;
+ }
+
+ cur_mon->qmp.in_command_mode = true;
+ qmp_unregister_command("qmp_capabilities");
+ monitor_init_real_qmp_commands();
+}
+
/* set the current CPU defined by the user */
int monitor_set_cpu(int cpu_index)
{
@@ -3676,26 +3697,6 @@ static int monitor_can_read(void *opaque)
return (mon->suspend_cnt == 0) ? 1 : 0;
}
-static bool invalid_qmp_mode(const Monitor *mon, const char *cmd,
- Error **errp)
-{
- bool is_cap = g_str_equal(cmd, "qmp_capabilities");
-
- if (is_cap && mon->qmp.in_command_mode) {
- error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
- "Capabilities negotiation is already complete, command "
- "'%s' ignored", cmd);
- return true;
- }
- if (!is_cap && !mon->qmp.in_command_mode) {
- error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
- "Expecting capabilities negotiation with "
- "'qmp_capabilities' before command '%s'", cmd);
- return true;
- }
- return false;
-}
-
/*
* Input object checking rules
*
@@ -3781,12 +3782,21 @@ static void handle_qmp_command(JSONMessageParser
*parser, GQueue *tokens)
cmd_name = qdict_get_str(qdict, "execute");
trace_handle_qmp_command(mon, cmd_name);
- if (invalid_qmp_mode(mon, cmd_name, &err)) {
- goto err_out;
- }
-
rsp = qmp_dispatch(req);
+ qdict = qdict_get_qdict(qobject_to_qdict(rsp), "error");
+ if (qdict) {
+ if (!mon->qmp.in_command_mode
+ && !strcmp(qdict_get_try_str(qdict, "class"),
+ QapiErrorClass_lookup[ERROR_CLASS_COMMAND_NOT_FOUND])) {
+ /* Provide a more useful error message */
+ qdict_del(qdict, "desc");
+ qdict_put(qdict, "desc",
+ qstring_from_str("Expecting capabilities negotiation"
+ " with 'qmp_capabilities'"));
+ }
+ }
+
err_out:
if (err) {
qdict = qdict_new();
--
2.7.4
