Modifying a built-in function for logging purposes

[qwweeeit at yahoo.it]

Hi all,
I wonder if it is possible to change (temporarily) a built-in function
for logging purposes.
Let me explain:
I want to log all the 'open' operations, recording the file to be
opened, the "mode" (r/w/a...) and (possibly) the module which made the
call.
After that the 'open' can carry on following the standard built-in
path.
Possibly I don't want to have to modify the source of the application
to be logged.
If there is another solution, I am open to any suggestion...

Bye.