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From: "Miquel van Smoorenburg" <miquels@cistron.nl>
Subject: Re: Writing as init without /dev/console?
Date: Thu, 23 Jun 2005 08:27:50 +0000 (UTC)
Organization: Cistron
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References: <20050620135132.GB2779@schottelius.org>
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In article <20050620135132.GB2779@schottelius.org>,
Nico Schottelius  <nico-kernel@schottelius.org> wrote:
>Currently I do not open /dev/console in cinit, but currently
>I do see very strange behaviour:
>
>If the first printf() in the following code (from serv/cinit.c) is
>enabled, the socket communication will later fail:

printf() prints to stdout i.e. filedescriptor #1. If you do not
open stdin/stdout/stderr in your program, you do not know what
is going to be fd #1 later on .. in your case, the socket probably
is fd #1 and the printf() is happily printing to it.

To prevent this, do something like this at the start of your program:

	int n;

	do {
		n = open("/dev/null", O_RDWR);
	} while (n >= 0 && n <= 2);
	close(n);

Mike.