/bin/stty/util.c

 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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#ifndef lint
31#if 0
32static char sccsid[] = "@(#)util.c	8.3 (Berkeley) 4/2/94";
33#endif
34#endif /* not lint */
35#include <sys/cdefs.h>
36__FBSDID("$FreeBSD$");
37
38#include <sys/types.h>
39#include <sys/stat.h>
40
41#include <err.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <unistd.h>
45
46#include "stty.h"
47#include "extern.h"
48
49/*
50 * Gross, but since we're changing the control descriptor from 1 to 0, most
51 * users will be probably be doing "stty > /dev/sometty" by accident.  If 1
52 * and 2 are both ttys, but not the same, assume that 1 was incorrectly
53 * redirected.
54 */
55void
56checkredirect(void)
57{
58	struct stat sb1, sb2;
59
60	if (isatty(STDOUT_FILENO) && isatty(STDERR_FILENO) &&
61	    !fstat(STDOUT_FILENO, &sb1) && !fstat(STDERR_FILENO, &sb2) &&
62	    (sb1.st_rdev != sb2.st_rdev))
63warnx("stdout appears redirected, but stdin is the control descriptor");
64}