1/* Copyright (C) 1991-2022 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. */
29int
30tcsendbreak (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}
54

source code of glibc/sysdeps/unix/bsd/tcsendbrk.c