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X-Authentication-Warning: makita.cygnus.com: keiths owned process doing -bs
Date: Tue, 14 Aug 2001 13:16:59 -0700 (PDT)
From: Keith Seitz <keiths AT cygnus DOT com>
To: Troy Noble <troy DOT noble AT channelpoint DOT com>
cc: Roderick Groesbeek <rgroesb AT triple-it DOT com>, <cygwin AT cygwin DOT com>
Subject: RE: 1.3.2: Cygwin && UDP && O_NONBLOCK
In-Reply-To: <8F23E55D511AD5119A6800D0B76FDDE1CA302A@cpex3.channelpoint.com>
Message-ID: <Pine.GSO.4.33.0108141306010.23565-100000@makita.cygnus.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Tue, 14 Aug 2001, Troy Noble wrote:

> Unless I misunderstood entirely, I think you've found a bug.

Ok, I see what has happened. The real assertion is that NONBLOCKING i/o on
udp doesn't work, not that blocking i/o doesn't work. This confused me
because the original poster wrote:

   [snip]
   flags = fcntl(sock, F_GETFL, 0);
   ret = fcntl(sock, F_SETFL, flags & ~O_NONBLOCK);
   [snip]

This certainly forces the socket to blocking mode.

   Under Linux:
   ~
   [root AT xml /tmp]# gcc -Wall -o server server.c
   [root AT xml /tmp]# ./server
   (ctrl + c)
   [root AT xml /tmp]#
   ~
   (Nice blocking..)

   Under Cygwin:
   ~
   Administrator AT PIGGY ~/cvsroot/blocktest
   $ gcc -Wall -o server server.c

   Administrator AT PIGGY ~/cvsroot/blocktest
   $ ./server.exe
   ret=0|
   recvfrom: Invalid argument
   len=-1|
   recvfrom: Invalid argument
   len=-1|

As my program demonstrated, this certainly does work.

However, as the original poster reports, NONBLOCKING i/o does NOT work.
The call to recvfrom DOES appear to block.

Sorry for the confusion. (Where's my diet coke?) :-)
Keith



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