sysdeps/unix/sysv/linux/tcsendbrk.c

   1 /* Send break to terminal.
   2    Copyright (C) 1996-2015 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <stddef.h>
  21 #include <termios.h>
  22 #include <sys/ioctl.h>
  23
  24 /* Send zero bits on FD.  */
  25 int
  26 tcsendbreak (int fd, int duration)
  27 {
  28   /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
  29      and an implementation-defined period if DURATION is nonzero.
  30      We define a positive DURATION to be number of milliseconds to break.  */
  31   if (duration <= 0)
  32     return __ioctl (fd, TCSBRK, 0);
  33
  34 #ifdef TCSBRKP
  35   /* Probably Linux-specific: a positive third TCSBRKP ioctl argument is
  36      defined to be the number of 100ms units to break.  */
  37   return __ioctl (fd, TCSBRKP, (duration + 99) / 100);
  38 #else
  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 #endif
  45 }