Get the im_file path

How can I get the filepath from im_file and pass it as variable in the Output.. as you can see i am using Recursive TRUE, want's to know which file from which directory, current message came from

<Input tst>
Module im_file
File "/home/*.log"
Recursive TRUE
</Input>

<Output tst_testfile>
Module om_file
File "/home/user/nxlogtest"
<Exec>
$tst_filepath = ??;
$Message = $raw_event; to_json();
</Exec>
</Output>

<Route tst_out>
Path maas => maas_testfile
</Route>