From owner-freebsd-questions  Mon Aug 16 18:21:27 1999
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Date: Mon, 16 Aug 1999 21:07:57 -0400 (EDT)
From: Zhihui Zhang <zzhang@cs.binghamton.edu>
To: Danaii Maziar <dm@easynet.fr>
Cc: freebsd-questions@FreeBSD.ORG
Subject: Re: FIFO -- Device not configured
In-Reply-To: <14264.9594.118127.306139@golem.easynet.fr>
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On Mon, 16 Aug 1999, Danaii Maziar wrote:

> 
> 
> Hi,
> 
>   I've created a fifo (with mkfifo) and every time I try to open it I
> get -- Device not configured -- As I know Fifo is standard part of
> kernel and there is no need to add options.
> 
> Any suggestion.
> 
> Thanks.
> 
> # uname -a
> 2.2.8-STABLE FreeBSD 2.2.8-STABLE
> 
> # ls -l 
> prw-rw-rw-  1 root  wheel  0 Aug 16 16:25 radfifo
> 
> # cat xx.c
> #include <stdio.h>
> #include <fcntl.h>
> 
> main()
> {
>         int pokefd;
>         pokefd=open("radfifo", O_WRONLY|O_NONBLOCK);
>         if (pokefd < 0) {
>                 perror("open:");
>                 exit(1);
>         }
>         close(pokefd);
> }
> 
> # kdump
> 
> # kdump 
>   5343 ktrace   RET   ktrace 0
>   5343 ktrace   CALL  execve(0xefbfdcfb,0xefbfdc90,0xefbfdc98)
>   5343 ktrace   NAMI  "/tmp/xx"
>   5343 xx       RET   execve 0
>   5343 xx       CALL  open(0x10c0,0x5,0)
>   5343 xx       NAMI  "radfifo"
>   5343 xx       RET   open -1 errno 6 Device not configured
>   5343 xx       CALL  writev(0x2,0xefbfdc44,0x4)
>   5343 xx       GIO   fd 2 wrote 29 bytes
>        "open:: Device not configured
>        "
>   5343 xx       RET   writev 29/0x1d
>   5343 xx       CALL  exit(0x1)
> 
> -- 
> Easynet France
> 33 1.44.54.70.32
> 
From "Advanced Programming in the Unix Environment" by W. Richard Stevens,

"If O_NONBLOCK is specified, an open for read-only returns immediately.
But an open for write-only returns an error with an errno of ENXIO if no
process has the FIFO open for reading"  -- page 446.

-Zhihui



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