[Qemu-devel] [PATCH 01/11] QMP: Initial mode-oriented bits

[Luiz Capitulino <lcapitulino@redhat.com>]

In order to support 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, async
messages (as any other protocol capability) are disabled
by default

o Operational: regular Monitor operations. All handlers
(except the protocol configuration ones) are allowed and
async messages enabled in 'handshake' mode are delivered

This commit adds the initial infrastructure to implement this
design, basically it does:

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 cadf422..4b7067a 100644
--- a/monitor.c
+++ b/monitor.c
@@ -76,11 +76,16 @@
  *
  */
 
+/* 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);
@@ -98,8 +103,14 @@ 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;
@@ -2364,6 +2375,7 @@ 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,
     },
@@ -2372,6 +2384,7 @@ 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,
     },
@@ -4264,6 +4277,7 @@ void monitor_init(CharDriverState *chr, int flags)
 
     if (monitor_ctrl_mode(mon)) {
         mon->mc = qemu_mallocz(sizeof(MonitorControl));
+        mon->mc->mode = QMODE_HANDSHAKE;
         /* Control mode requires special handlers */
         qemu_chr_add_handlers(chr, monitor_can_read, monitor_control_read,
                               monitor_control_event, mon);
-- 
1.6.6