I think that fib probably means "file information block". The P1 value for file open waits is a pointer into the "KGFF heap" which is a subheap of the shared pool. Each fib has its own extent in the KGFF heap. The subheap extent number seems to correspond to the file number, but I cannot guarantee that that will always be true.

You can map a decimal address (such as P1 in this case) to the containing shared pool chunk using containing_chunk.sql. That script is dependent on the rawtonum function which is declared in rawtonum.sql. In this case you'll need to hack containing_chunk.sql to return the KSMCHPAR column (the address of the heap descriptor for the KGFF heap) and join that to X$KSMHP with an explicit USE_NL hint to find the extent number for the chunk.

The P1 field in V$SESSION_WAIT for the event file open is fib. I'd like to associate this with a filename. Any ideas on how to do this? It's not V$DATAFILE.FILE#, I know that much.