Signal SIGIO problems

[Susan Olivier]

I have encountered the following problem on both the Sun and Sequent, and
would appreciate any feedback as to how I can either get around the
problem, or preferably just fix it.  The problem involves IPC, and is
this:

I set up a socket with the call:

   if ((IpcManagerStream = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) >= 0).....

and set the signal SIGIO with the following two calls:

     SignalFunction = signal(SIGIO, IPCManagementHandler);
     res = fcntl(IpcManagerStream, F_SETFL, FASYNC);

With this set up I hope that when a packet arrives at the
IpcManagerStream, a signal will be generated, and the IPCManagementHandler
invoked.  To my chagrin, the expected doesn't happen on either the Sun or
the Sequent.  I have manually generated the SIGIO signal by doing a kill
-IO pid, and that works fine.  I have checked using the select(..) call
that there are in fact packets at the port, and there are.  And still no
signal is generated when these packets arrive. 

Has anyone tried to do something similar and succeeded?  If so, please let
me know how to do it.  Any solutions would be greatly appreciated.

Thank you.

Susan Olivier:  olivier at apple.com    
Apple Computer