[Qemu-devel] [PATCH 1/8] QMP: Initial mode-oriented support

[Luiz Capitulino <lcapitulino@redhat.com>]

In order to have feature negotiation in QMP, the Monitor
has to be modified to support different modes of operation.

We need two modes:

o Handshake: where features are negotiated, only commands
which deal with protocol configuration are allowed

o Operational: regular Monitor operations, all handlers
(except the protocol configuration ones) are allowed

This commit does the following:

1. Adds the QMPMode data type to MonitorControl and sets
QMODE_HANDSHAKE as the default one

2. Grant permission to 'query-version' and 'query-commands'
to run on handshake mode

Note, however, that these changes are not visable yet and
thus QMP's behavior is still the same.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 monitor.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/monitor.c b/monitor.c
index fb7c572..baae9d0 100644
--- a/monitor.c
+++ b/monitor.c
@@ -82,11 +82,16 @@ struct MonitorCompletionData {
     void (*user_print)(Monitor *mon, const QObject *data);
 };
 
+/* Handler flags */
+#define HANDLER_HANDSHAKE      0x01 /* allowed to run on handshake mode */
+#define HANDLER_HANDSHAKE_ONLY 0x02 /* can ONLY run on handshake mode */
+
 typedef struct mon_cmd_t {
     const char *name;
     const char *args_type;
     const char *params;
     const char *help;
+    unsigned int flags;
     void (*user_print)(Monitor *mon, const QObject *data);
     union {
         void (*info)(Monitor *mon);
@@ -108,8 +113,14 @@ struct mon_fd_t {
     QLIST_ENTRY(mon_fd_t) next;
 };
 
+typedef enum QMPMode {
+    QMODE_OPERATIONAL,
+    QMODE_HANDSHAKE,
+} QMPMode;
+
 typedef struct MonitorControl {
     QObject *id;
+    QMPMode mode;
     int print_enabled;
     JSONMessageParser parser;
 } MonitorControl;
@@ -2471,6 +2482,7 @@ static const mon_cmd_t info_cmds[] = {
         .args_type  = "",
         .params     = "",
         .help       = "show the version of QEMU",
+        .flags      = HANDLER_HANDSHAKE,
         .user_print = do_info_version_print,
         .mhandler.info_new = do_info_version,
     },
@@ -2479,6 +2491,7 @@ static const mon_cmd_t info_cmds[] = {
         .args_type  = "",
         .params     = "",
         .help       = "list QMP available commands",
+        .flags      = HANDLER_HANDSHAKE,
         .user_print = monitor_user_noop,
         .mhandler.info_new = do_info_commands,
     },
@@ -4293,6 +4306,7 @@ static void monitor_control_event(void *opaque, int event)
         QObject *data;
         Monitor *mon = opaque;
 
+        mon->mc->mode = QMODE_HANDSHAKE;
         json_message_parser_init(&mon->mc->parser, handle_qmp_command);
 
         data = qobject_from_jsonf("{ 'QMP': { 'capabilities': [] } }");
-- 
1.6.6