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  * 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  * @(#)util.c   8.3 (Berkeley) 4/2/94
  34  * $FreeBSD: src/bin/stty/util.c,v 1.8 1999/08/27 23:15:43 peter Exp $
  35  * $DragonFly: src/bin/stty/util.c,v 1.3 2003/09/28 14:39:15 hmp Exp $
  36  */
  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  */
  55 void
  56 checkredirect(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))
  63 warnx("stdout appears redirected, but stdin is the control descriptor");
  64 }