sockets and select

[Nathaniel Ingersoll]

In article <4309 at helios.TAMU.EDU> dhess at cs.tamu.edu (David K Hess)
asks why select() for reading on an NDELAY socket always seems to
return a fact that the socket has data.

The manual page:
.
.     SELECT(S)		       UNIX System V		     SELECT(S)
.     ...
.     Description
.	  select examines the I/O descriptor sets whose	addresses are
.	  passed in readfds, writefds, and exceptfds to	see if some of
.	  their	descriptors are	ready for reading, are ready for
.	  writing, or have an exceptional condition pending,
.	  respectively.	 The first nfds	descriptors are	checked	in

"Ready" for reading/writing probably means that the read or the write
will filled without blocking, and since the NDELAY bit has been set,
read() will always work without blocking.

You should either
	(use NDELAY && not use select())
		||
	(use select() && not NDELAY)
-- 
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