sysdeps/unix/common/tcsendbrk.c

   1 /* Send break to terminal.
   2 Copyright (C) 1996 Free Software Foundation, Inc.
   3 This file is part of the GNU C Library.
   4
   5 The GNU C Library is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 License, or (at your option) any later version.
   9
  10 The GNU C Library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <errno.h>
  21 #include <stddef.h>
  22 #include <termios.h>
  23 #include <sys/ioctl.h>
  24
  25 /* Send zero bits on FD.  */
  26 int
  27 tcsendbreak (int fd, int duration)
  28 {
  29   /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
  30      and an implementation-defined period if DURATION is nonzero.
  31      We define a positive DURATION to be number of milliseconds to break.  */
  32   if (duration <= 0)
  33     return __ioctl (fd, TCSBRK, 0);
  34
  35 #ifdef TCSBRKP
  36   /* Probably Linux-specific: a positive third TCSBRKP ioctl argument is
  37      defined to be the number of 100ms units to break.  */
  38   return __ioctl (fd, TCSBRKP, (duration + 99) / 100);
  39 #else
  40   /* ioctl can't send a break of any other duration for us.
  41      This could be changed to use trickery (e.g. lower speed and
  42      send a '\0') to send the break, but for now just return an error.  */
  43   __set_errno (EINVAL);
  44   return -1;
  45 #endif
  46 }