sysdeps/unix/sysv/tcsendbrk.c

   1 /* Copyright (C) 1992, 1996, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <stddef.h>
  21 #include <signal.h>
  22 #include <termios.h>
  23 #include <unistd.h>
  24 #include <sysv_termio.h>
  25 #include <sys/ioctl.h>
  26
  27 /* Send zero bits on FD.  */
  28 int
  29 tcsendbreak (fd, duration)
  30      int fd;
  31      int duration;
  32 {
  33   /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
  34      and an implementation-defined period if DURATION is nonzero.
  35      We define a positive DURATION to be number of milliseconds to break.  */
  36   if (duration <= 0)
  37     return __ioctl (fd, _TCSBRK, 0);
  38
  39   /* ioctl can't send a break of any other duration for us.
  40      This could be changed to use trickery (e.g. lower speed and
  41      send a '\0') to send the break, but for now just return an error.  */
  42   __set_errno (EINVAL);
  43   return -1;
  44 }