Very Computer

I am hoping to have a socket question answered for me in something I'm trying
to fix at work.

Recently we have been going over our socket/TN3270 communication section of
our product.  We have have noticed that the select() function has been has
been triggering but none of the FD's are true when you do the FD_ISSET.  We
are guessing that it has something to do with the exception and have set
the mask to see it when it occurs.

The problem we're having is that one of our books tell us what happens when
this mask is set.  We are unsure how to proceed with this when it happens.

Any help in this matter in the way of pointers, books to get, or the like
would be greatly appreciated.

Thanks,
Brian Gansle

Quote:>What value is select() returning, are you checking this?  It might be
>returning -1 (error) and errno set to EINTR, in which case a signal
>interrupted the call.  Another possibility, if you are using timeout
>value, is that it is returning 0, in which case the timeout expired.

BTW, my post should have said that NONE of our books tell us what happens
when an exception hits.

--Raja

-=-

Ohio Supercomputer Center               http://www.osc.edu/lam.html

Things to check:
        1. you are initializing the write & exception descriptor sets via
           FD_ZERO().
        2. The return value from select() > 0.
        3. The bit-width of the descriptor sets you pass to select() is
           correct. (are you calling ulimit(3C) ?)

If all these are correct, yet FD_ISSET() says there are no fds ready to
read after select has returned, it sounds like your select() could be
broken. Especially if you see exception activity yet you did not
specifically select for it.

For the record, exception conditions on sockets under SunOS 4.1 are only
meant to occur on tcp stream sockets to indicate the presence of
out-of-band data. OOB data may be transmitted via send(2) and received via
recv(2).

Hope this helps,
Nick