1/*-
2 * Copyright (c) 1991, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35#if 0
36static char sccsid[] = "@(#)util.c	8.3 (Berkeley) 4/2/94";
37#endif
38#endif /* not lint */
39#include <sys/cdefs.h>
40__RCSID("$FreeBSD: src/bin/stty/util.c,v 1.10 2002/06/30 05:15:04 obrien Exp $");
41
42#include <sys/types.h>
43#include <sys/stat.h>
44
45#include <err.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <unistd.h>
49
50#include "stty.h"
51#include "extern.h"
52
53/*
54 * Gross, but since we're changing the control descriptor from 1 to 0, most
55 * users will be probably be doing "stty > /dev/sometty" by accident.  If 1
56 * and 2 are both ttys, but not the same, assume that 1 was incorrectly
57 * redirected.
58 */
59void
60checkredirect(void)
61{
62	struct stat sb1, sb2;
63
64	if (isatty(STDOUT_FILENO) && isatty(STDERR_FILENO) &&
65	    !fstat(STDOUT_FILENO, &sb1) && !fstat(STDERR_FILENO, &sb2) &&
66	    (sb1.st_rdev != sb2.st_rdev))
67warnx("stdout appears redirected, but stdin is the control descriptor");
68}
69