[Qemu-devel] [RFC][PATCH v6 16/23] virtagent: add agent_capabilities qmp/hmp commands

[Michael Roth <mdroth@linux.vnet.ibm.com>]

Call guest agent's built-in introspection functions to get a list of
supported RPCs, and re-negotiate guest agent capabilities to determine
what agent_* commands are supported.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hmp-commands.hx |   16 +++++++++
 qmp-commands.hx |   32 ++++++++++++++++++
 virtagent.c     |   98 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 virtagent.h     |    3 ++
 4 files changed, 149 insertions(+), 0 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 6679771..52d4821 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1392,6 +1392,22 @@ STEXI
 Ping a guest
 ETEXI
 
+    {
+        .name       = "agent_capabilities",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Fetch and re-negotiate guest agent capabilities",
+        .user_print = do_agent_capabilities_print,
+        .mhandler.cmd_async = do_agent_capabilities,
+        .flags      = MONITOR_CMD_ASYNC,
+    },
+
+STEXI
+@item agent_capabilities
+@findex agent_capabilities
+Fetch and re-negotiate guest agent capabilties
+ETEXI
+
 STEXI
 @end table
 ETEXI
diff --git a/qmp-commands.hx b/qmp-commands.hx
index be6f485..5a14191 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -927,6 +927,38 @@ Example:
 EQMP
 
     {
+        .name       = "agent_capabilities",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Fetch and re-negotiate guest agent capabilities",
+        .user_print = do_agent_capabilities_print,
+        .mhandler.cmd_async = do_agent_capabilities,
+        .flags      = MONITOR_CMD_ASYNC,
+    },
+
+STEXI
+@item agent_capabilities
+@findex agent_capabilities
+Fetch and re-negotiate guest agent capabilties
+ETEXI
+SQMP
+agent_capabilities
+--------
+
+Fetch and re-negotiate guest agent capabilities
+
+Arguments:
+
+(none)
+
+Example:
+
+-> { "execute": "agent_capabilities" }
+<- { "return":["va.shutdown", "va.getdmesg", "va.getfile", ... ] }
+
+EQMP
+
+    {
         .name       = "qmp_capabilities",
         .args_type  = "",
         .params     = "",
diff --git a/virtagent.c b/virtagent.c
index 4b6b7d1..99efe2b 100644
--- a/virtagent.c
+++ b/virtagent.c
@@ -477,3 +477,101 @@ int do_agent_ping(Monitor *mon, const QDict *mon_params,
     xmlrpc_DECREF(params);
     return ret;
 }
+
+static void va_print_capability_iter(QObject *obj, void *opaque)
+{
+    Monitor *mon = opaque;
+    QString *method = qobject_to_qstring(obj);
+    const char *method_str;
+
+    if (method) {
+        method_str = qstring_get_str(method);
+        monitor_printf(mon, "%s\n", method_str); 
+    }
+}
+
+void do_agent_capabilities_print(Monitor *mon, const QObject *data)
+{
+    QList *qlist;
+
+    TRACE("called");
+
+    monitor_printf(mon, "the following RPC methods are supported by the guest agent:\n");
+    qlist = qobject_to_qlist(data);
+    qlist_iter(qlist, va_print_capability_iter, mon);
+}
+
+static void do_agent_capabilities_cb(const char *resp_data,
+                                     size_t resp_data_len,
+                                     MonitorCompletion *mon_cb,
+                                     void *mon_data)
+{
+    xmlrpc_value *resp = NULL;
+    xmlrpc_value *cur_val = NULL;
+    const char *cur_method = NULL;
+    xmlrpc_env env;
+    QList *qlist = qlist_new();
+    int i;
+
+    TRACE("called");
+
+    if (resp_data == NULL) {
+        LOG("error handling RPC request");
+        goto out_no_resp;
+    }
+
+    TRACE("resp = %s\n", resp_data);
+
+    xmlrpc_env_init(&env);
+    resp = xmlrpc_parse_response(&env, resp_data, resp_data_len);
+    if (va_rpc_has_error(&env)) {
+        goto out_no_resp;
+    }
+
+    /* extract the list of supported RPCs */
+    for (i = 0; i < xmlrpc_array_size(&env, resp); i++) {
+        xmlrpc_array_read_item(&env, resp, i, &cur_val);
+        xmlrpc_read_string(&env, cur_val, &cur_method);
+        if (cur_method) {
+            TRACE("cur_method: %s", cur_method);
+            qlist_append_obj(qlist, QOBJECT(qstring_from_str(cur_method)));
+        }
+        xmlrpc_DECREF(cur_val);
+    }
+
+    /* set our client capabilities accordingly */
+    va_set_capabilities(qlist);
+
+    xmlrpc_DECREF(resp);
+out_no_resp:
+    if (mon_cb) {
+        mon_cb(mon_data, QOBJECT(qlist));
+    }
+    qobject_decref(QOBJECT(qlist));
+}
+
+/*
+ * do_agent_capabilities(): Fetch/re-negotiate guest agent capabilities
+ */
+int do_agent_capabilities(Monitor *mon, const QDict *mon_params,
+                          MonitorCompletion cb, void *opaque)
+{
+    xmlrpc_env env;
+    xmlrpc_value *params;
+    int ret;
+
+    xmlrpc_env_init(&env);
+
+    params = xmlrpc_build_value(&env, "()");
+    if (va_rpc_has_error(&env)) {
+        return -1;
+    }
+
+    ret = va_do_rpc(&env, "system.listMethods", params,
+                    do_agent_capabilities_cb, cb, opaque);
+    if (ret) {
+        qerror_report(QERR_VA_FAILED, ret, strerror(ret));
+    }
+    xmlrpc_DECREF(params);
+    return ret;
+}
diff --git a/virtagent.h b/virtagent.h
index 7d3a122..da70317 100644
--- a/virtagent.h
+++ b/virtagent.h
@@ -41,5 +41,8 @@ int do_agent_shutdown(Monitor *mon, const QDict *mon_params,
 void do_agent_ping_print(Monitor *mon, const QObject *qobject);
 int do_agent_ping(Monitor *mon, const QDict *mon_params,
                   MonitorCompletion cb, void *opaque);
+void do_agent_capabilities_print(Monitor *mon, const QObject *qobject);
+int do_agent_capabilities(Monitor *mon, const QDict *mon_params,
+                  MonitorCompletion cb, void *opaque);
 
 #endif /* VIRTAGENT_H */
-- 
1.7.0.4