[exim] acl_added_headers

I'm writing a dlfunc routine using local_scan.h and within it I need to access the headers that have been added in ACLs. From what I can tell these should be stored in a linked list called acl_added_headers, however that variable doesn't appear to be available to me.

I've tried using the Exim from Debian packages (versions 4.72 and 4.80) and neither work - the symbol acl_added_headers is not defined. I've checked for the string within the Exim file ('strings exim | grep acl_added_headers') and it's not there.

Is there a way to make this variable accessible to dlfunc code? Or is there an alternative method of getting the headers that have been added by ACLs?

Many thanks,

Simon