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Date: Wed, 14 Aug 2002 11:19:03 -0700
To: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Problem : can't make pipe non-blocking on 2.5.X
Message-ID: <20020814181902.GA24047@bougret.hpl.hp.com>
Reply-To: jt@hpl.hp.com
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Organisation: HP Labs Palo Alto
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E-mail: jt@hpl.hp.com
From: Jean Tourrilhes <jt@bougret.hpl.hp.com>
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	Hi,

	I've got the following problem : I can't make a pipe
non-blocking with 2.5.25.
	The various man pages don't mention anything
about it (actually, the "fifo" man page say that non-blocking mode
should succeed). And it seems to work fine on 2.4.20.
	Sorry if this has already been reported and fixed, but I
quicly searched the changelog and archive and found nothing.

	So, who should I complain to ?

------------- Setup ------------------------
	Kernel : 2.5.25 fails (but 2.4.20-pre2 works)
	Distrib : Debian 3.0
	libc : 2.2.5
------------- Test program -----------------
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>

int main()
{
  int trigger_pipe[2];
  int err;
  int flags;

  pipe(trigger_pipe);

  err = fcntl(trigger_pipe[0], F_GETFL, &flags);
  fprintf(stderr, "GET FLAGS : %d - %X\n", err, flags);
  if(err >= 0)
    {
      flags |= O_NONBLOCK;
      err = fcntl(trigger_pipe[0], F_SETFL, flags);
      fprintf(stderr, "SET FLAGS : %d - %d\n", err, errno);
    }
  return(0);
}
------------- Output 2.5.25 ----------------
GET FLAGS : 0 - 40045F18
SET FLAGS : -1 - 22
------------- Output 2.4.20-pre2 -----------
GET FLAGS : 0 - 40043F18
SET FLAGS : 0 - 0
--------------------------------------------

	Have fun...

	Jean