qapi: Introduce change-vnc-password

New QMP command to change the VNC password.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

qapi-schema.json

@@ -1352,3 +1352,17 @@
 # Since: 0.14.0
 ##
 { 'command': 'eject', 'data': {'device': 'str', '*force': 'bool'} }
+
+##
+# @change-vnc-password:
+#
+# Change the VNC server password.
+#
+# @target:  the new password to use with VNC authentication
+#
+# Since: 1.1
+#
+# Notes:  An empty password in this command will set the password to the empty
+#         string.  Existing clients are unaffected by executing this command.
+##
+{ 'command': 'change-vnc-password', 'data': {'password': 'str'} }

qmp-commands.hx

@@ -2018,3 +2018,9 @@ EQMP
 	.args_type  = "path:s,property:s",
 	.mhandler.cmd_new = qmp_qom_get,
     },
+
+    {
+        .name       = "change-vnc-password",
+        .args_type  = "password:s",
+        .mhandler.cmd_new = qmp_marshal_input_change_vnc_password,
+    },

qmp.c

@@ -343,3 +343,10 @@ void qmp_expire_password(const char *protocol, const char *whenstr,
 
     error_set(errp, QERR_INVALID_PARAMETER, "protocol");
 }
+
+void qmp_change_vnc_password(const char *password, Error **errp)
+{
+    if (vnc_display_password(NULL, password) < 0) {
+        error_set(errp, QERR_SET_PASSWD_FAILED);
+    }
+}