Author: Luiz Augusto von Dentz
Author Date: 2018-12-05 23:57:51 UTC

gdbus: Make sure the object path and interface are valid

D-Bus object path and interface must be validate otherwise it can cause
errors as follow:

0 0xb7f67ab1 in __kernel_vsyscall ()
1 0xb7ca1cc1 in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
2 0xb7ca50ee in abort () at abort.c:92
3 0xb7e30ba5 in _dbus_abort () at dbus-sysdeps.c:94
4 0xb7e267a6 in _dbus_warn_check_failed (
    format=0xb7e36cd4 "arguments to %s() were incorrect, assertion \"%s\" failed in file %s line %d.\nThis is normally a bug in some application using the D-Bus library.\n") at dbus-internals.c:290
5 0xb7e16d9f in dbus_message_iter_append_basic (iter=0xbf864400, type=111,
    value=0xd70940) at dbus-message.c:2586
6 0x004fcdec in emit_interfaces_added (user_data=0xd70938)
    at gdbus/object.c:574