gdbus: Fix crash when calling g_dbus_add_service_watch
If g_dbus_add_service_watch is called for service which bus name is
already known the following crash can happen:
invalid read of size 1
at 0x4C2A2F2: strlen (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x4E97722: g_strdup (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x405B0C: update_name_cache (watch.c:435)
by 0x405C37: update_service (watch.c:593)
by 0x4E7A2A5: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E7A627: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E7AA39: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4038EA: client_ready (test-gdbus-client.c:1014)
by 0x4E9E5E0: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E9E7A5: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E9EB1A: g_test_run_suite (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x403614: main (test-gdbus-client.c:1058)
Address 0x5dbe5d0 is 0 bytes inside a block of size 7 free'd
at 0x4C28577: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x4E7FF7E: g_free (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x405B04: update_name_cache (watch.c:434)
by 0x405C37: update_service (watch.c:593)
by 0x4E7A2A5: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E7A627: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E7AA39: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4038EA: client_ready (test-gdbus-client.c:1014)
by 0x4E9E5E0: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E9E7A5: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x4E9EB1A: g_test_run_suite (in /usr/lib64/libglib-2.0.so.0.3800.2)
by 0x403614: main (test-gdbus-client.c:1058)
1 file changed
