Untested but you should be able to modify the logging to:

sub open
{

    # ... some logging happens here ...

    return CORE::open($_[0], @_[1..$#_]);
}
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The key is that variables are passed into functions by reference, so modifying the variable while it is still in @_ will be seen where the variable originally was.

Note that, as others have pointed out, it is a bad idea to just try to open files and not have an error check in case of failure. See perlstyle for details. Furthermore I think that it is a good idea to switch to 3-arg open: <code>open(my $AFILE, "<", $file)<code> which will keep metacharacters in $file from being wrongly interpreted.