from select(2): 	Any of readfds, writefds, and exceptfds may be given as nil 	pointers if no descriptors are of interest.
from select(2):
	Any of readfds, writefds, and exceptfds may be given as nil
	pointers if no descriptors are of interest.

neither wfds nor efds were of interest so now they are nil.

also, do a little better then making an educated guess for nfds.

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