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From: konczal@mail-gw.ncsl.nist.gov (Joseph C. Konczal)
Newsgroups: comp.unix.questions
Subject: Polling on a socket without select()...
Message-ID: <21411@adm.BRL.MIL>
Date: 9 Nov 89 16:50:28 GMT
Sender: news@adm.BRL.MIL
Lines: 28


| I am writing a program that needs to effect a poll on a udp/ip socket.  I am
| using recvfrom(2) to read data, but I would like it to return immediately if
| there is no data ready...  My SunOS4.x man page says that there is a method
| to make the recvfrom() call return immediately using ioctl(2) to set the
| socket to non-blocking...  I have looked in <sys/ioctl.h> and <sys/sockio.h>
| but have not found any ioctl capable of doing this...
| 
| I know of the method using select(2), but that seems like overkill if I only
| have one socket, it is not really a selection process...  Is there something
| in a man page someplace that would explain this in some more detail or is it
| a man page error?
| 
| Thanx!
| 
| Micky
| 
|   arpa: micky@cunixc.cc.columbia.edu
|   uucp: ...!rutgers!columbia!cunixc!micky
| bitnet: malua@cuvmc

It seems like a strange place for this information, but the socket(2)
man page refers you to fcntl(2v) where under F_SETFL it tells you that
using fcntl to set a certain flag will cause the desired ioctl to be
performed...  So look up FIONBIO in filio(4).

Joe
internet: konczal@mail-gw.ncsl.nist.gov