libxl: Add a version check of QEMU for QMP commands

On connection to QEMU via QMP, the version of QEMU is provided, store it
for later use.

Add a function qmp_qemu_check_version that can be used to check if QEMU
is new enough for certain fonctionnality. This will be used in a moment.

As it's a static function, it is commented out until first use, which is
in the next patch.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index eab993aca93c9529914e793cc51f1ef3decf86ca..b1c6598cf7da1c684ec6de36e2a6f1fdf120d930 100644 (file)
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -75,6 +75,11 @@ struct libxl__qmp_handler {
 
     int last_id_used;
     LIBXL_STAILQ_HEAD(callback_list, callback_id_pair) callback_list;
+    struct {
+        int major;
+        int minor;
+        int micro;
+    } version;
 };
 
 static int qmp_send(libxl__qmp_handler *qmp,
@@ -296,9 +301,22 @@ static int qmp_handle_response(libxl__gc *gc, libxl__qmp_handler *qmp,
     LOGD(DEBUG, qmp->domid, "message type: %s", libxl__qmp_message_type_to_string(type));
 
     switch (type) {
-    case LIBXL__QMP_MESSAGE_TYPE_QMP:
+    case LIBXL__QMP_MESSAGE_TYPE_QMP: {
+        const libxl__json_object *o;
+        o = libxl__json_map_get("QMP", resp, JSON_MAP);
+        o = libxl__json_map_get("version", o, JSON_MAP);
+        o = libxl__json_map_get("qemu", o, JSON_MAP);
+        qmp->version.major = libxl__json_object_get_integer(
+            libxl__json_map_get("major", o, JSON_INTEGER));
+        qmp->version.minor = libxl__json_object_get_integer(
+            libxl__json_map_get("minor", o, JSON_INTEGER));
+        qmp->version.micro = libxl__json_object_get_integer(
+            libxl__json_map_get("micro", o, JSON_INTEGER));
+        LOGD(DEBUG, qmp->domid, "QEMU version: %d.%d.%d",
+             qmp->version.major, qmp->version.minor, qmp->version.micro);
         /* On the greeting message from the server, enable QMP capabilities */
         return enable_qmp_capabilities(qmp);
+    }
     case LIBXL__QMP_MESSAGE_TYPE_RETURN: {
         callback_id_pair *pp = qmp_get_callback_from_id(qmp, resp);
 
@@ -332,6 +350,17 @@ static int qmp_handle_response(libxl__gc *gc, libxl__qmp_handler *qmp,
     return 0;
 }
 
+#if 0
+static bool qmp_qemu_check_version(libxl__qmp_handler *qmp, int major,
+                                   int minor, int micro)
+{
+    return qmp->version.major > major ||
+        (qmp->version.major == major &&
+            (qmp->version.minor > minor ||
+             (qmp->version.minor == minor && qmp->version.micro >= micro)));
+}
+#endif
+
 /*
  * Handler functions
  */