Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!mips!sgi!rpw3@rigden.wpd.sgi.com
From: rpw3@rigden.wpd.sgi.com (Rob Warnock)
Newsgroups: comp.sys.sgi
Subject: Re: ioctl
Message-ID: <105735@sgi.sgi.com>
Date: 23 May 91 03:20:58 GMT
References: <1991May21.224750.535@murdoch.acc.Virginia.EDU> <105553@sgi.sgi.com>
Sender: guest@sgi.sgi.com
Reply-To: rpw3@sgi.com (Rob Warnock)
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 23

In article <105553@sgi.sgi.com> I wrote:
+-+-------------
| | an ioctl call is giving me an "Invalid argument error".  The
| | call looks like this:
| | 	if (ioctl(trackerPtr->fileDescriptor, FIONREAD, &charsToRead) < 0)
| +---------------
| ... I just checked, and on Irix 3.3.2, FIONREAD is not supported on
| pipes or plain files. You get errno=25.
+---------------

As a work-around, you might try using select() in polling mode as a (partial)
replacement for icotl(,FIONREAD,). A select() "poll" can be done by providing
a "timeout" argument (a pointer to a "struct timeval"), but making the "timval"
structure pointed to contain all zeros. See the select(2) man page.


-Rob

-----
Rob Warnock, MS-1L/515		rpw3@sgi.com		rpw3@pei.com
Silicon Graphics, Inc.		(415)335-1673		Protocol Engines, Inc.
2011 N. Shoreline Blvd.
Mountain View, CA  94039-7311