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Path: utzoo!linus!philabs!cmcl2!seismo!brl-tgr!tgr!jsol@bbnccv.ARPA
From: jsol@bbnccv.ARPA
Newsgroups: net.unix-wizards
Subject: select query
Message-ID: <7834@brl-tgr.ARPA>
Date: Tue, 29-Jan-85 18:25:56 EST
Article-I.D.: brl-tgr.7834
Posted: Tue Jan 29 18:25:56 1985
Date-Received: Sat, 2-Feb-85 23:35:25 EST
Sender: news@brl-tgr.ARPA
Organization: Ballistic Research Lab
Lines: 41
Xref: seismo net.unix-wizards:11712

The code is:

boolean io_haschar(infile)
FILE *infile;
{
  int readfds, nfound;
  struct timeval timeout;

  timeout.tv_sec = 10;
  timeout.tv_usec = 0;

  readfds = (1<<fileno(infile));
    
  nfound = select(1, &readfds, 0, 0, &timeout);

  if (nfound == 0)
	return(FALSE);
  if (readfds&(1<<fileno(infile)))
	return (TRUE);
  else
	return(FALSE);
}

timeval is declared in sys/time.h.

The problem is: When I call this peice of code, it times out,
claiming infile has no characters ready to read. Examination of the
data stream (with a line monitor) indicates that a character is being
sent to the program, but somehow the program doesn't notice.

We are running Ultrix-32, and note the following disclaimer in the
documentation for select(2).

STATUS
     SELECT(2) currently is not supported  by  Digital  Equipment
     Corporation.

Any hints as to what I'm doing wrong (if I am doing something wrong?)

Thanks,
--JSol