DBUS? Then your question was more a XY question :).

While I can see shared memory to DBUS, my take of mmap is more about efficiency and accessing files other than with print&sysread. You might wish to post a separate question about DBUS.

CPAN offers at least one module for this: Net::DBus.

What I can offer on DBUS is a quick hack I did a while ago: check if I can see & send dbus events and somehow use them with waitcond - a rather primitive dbus example. Note that all I needed was the ability to grep and tail dbus, and thus a bit of glue, shell and an existing dbus monitoring tool was enough to conclude that experiment & obtain a useful but missing DBUS debug tool.