1  /* Copyright (C) 1991-2023 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, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <stddef.h>
      20  #include <signal.h>
      21  #include <termios.h>
      22  #include <unistd.h>
      23  #include "bsdtty.h"
      24  #include <sys/file.h>
      25  #include <sys/time.h>
      26  #include <sys/types.h>
      27  
      28  /* Send zero bits on FD.  */
      29  int
      30  tcsendbreak (int fd, int duration)
      31  {
      32    struct timeval delay;
      33  
      34    /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
      35       and an implementation-defined period if DURATION is nonzero.
      36       We define a positive DURATION to be number of microseconds to break.  */
      37    if (duration <= 0)
      38      duration = 400000;
      39  
      40    delay.tv_sec = 0;
      41    delay.tv_usec = duration;
      42  
      43    /* Starting sending break.  */
      44    if (__ioctl (fd, TIOCSBRK, (void *) NULL) < 0)
      45      return -1;
      46  
      47    /* Wait DURATION microseconds.  */
      48    (void) __select (0, (fd_set *) NULL, (fd_set *) NULL, (fd_set *) NULL,
      49  		   &delay);
      50  
      51    /* Turn off the break.  */
      52    return __ioctl (fd, TIOCCBRK, (void *) NULL);
      53  }