How to get the requested file in a Linux Samba Server?

Question

I need to process a file before it is requested via smb. Actually I am not able to get the information about the requested path directly. It is only possible over the Syslogs in the Samba Logs.

In the samba.conf I am using the root preexec statement and want to parse the requested file into my script. I searched in the samba conf, but I could not find any environment variable to realize this.