Currently object offsets are stored as integer (32 bit). However the PDF specification does not limit a PDF document to 2GB. The only restriction is the XREF table which supports 10 digit values for object offsets. Thus we could have offsets >2GB (<10GB). The attached patch changes all locations (as far as I could find them) dealing with object offsets to long type.
Since this is a rather small change which should not have greater performance/space impact I recommend to include it. Otherwise we would have to include checks that the parsed file is smaller then Integer.MAX_VALUE.