qapi: Implement deprecated-input=reject for QMP commands

This policy rejects deprecated input, and thus permits "testing the
future".  Implement it for QMP commands: make deprecated ones fail.
Example: when QEMU is run with -compat deprecated-input=reject, then

    {"execute": "query-cpus"}

fails like this

    {"error": {"class": "CommandNotFound", "desc": "Deprecated command query-cpus disabled by policy"}}

When the deprecated command is removed, the error will change to

    {"error": {"class": "CommandNotFound", "desc": "The command query-cpus has not been found"}}

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210318155519.1224118-10-armbru@redhat.com>
diff --git a/tests/unit/test-qmp-cmds.c b/tests/unit/test-qmp-cmds.c
index 1079d35..cba9821 100644
--- a/tests/unit/test-qmp-cmds.c
+++ b/tests/unit/test-qmp-cmds.c
@@ -281,6 +281,28 @@
     qobject_unref(ret3);
 }
 
+static void test_dispatch_cmd_deprecated(void)
+{
+    const char *cmd = "{ 'execute': 'test-command-features1' }";
+    QDict *ret;
+
+    memset(&compat_policy, 0, sizeof(compat_policy));
+
+    /* accept */
+    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
+    assert(ret && qdict_size(ret) == 0);
+    qobject_unref(ret);
+
+    compat_policy.has_deprecated_input = true;
+    compat_policy.deprecated_input = COMPAT_POLICY_INPUT_ACCEPT;
+    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
+    assert(ret && qdict_size(ret) == 0);
+    qobject_unref(ret);
+
+    compat_policy.deprecated_input = COMPAT_POLICY_INPUT_REJECT;
+    do_qmp_dispatch_error(false, ERROR_CLASS_COMMAND_NOT_FOUND, cmd);
+}
+
 static void test_dispatch_cmd_ret_deprecated(void)
 {
     const char *cmd = "{ 'execute': 'test-features0' }";
@@ -379,6 +401,8 @@
     g_test_add_func("/qmp/dispatch_cmd_io", test_dispatch_cmd_io);
     g_test_add_func("/qmp/dispatch_cmd_success_response",
                     test_dispatch_cmd_success_response);
+    g_test_add_func("/qmp/dispatch_cmd_deprecated",
+                    test_dispatch_cmd_deprecated);
     g_test_add_func("/qmp/dispatch_cmd_ret_deprecated",
                     test_dispatch_cmd_ret_deprecated);
     g_test_add_func("/qmp/dealloc_types", test_dealloc_types);