glibc/sysdeps/unix/sysv/linux/tcsendbrk.c

45 lines
1.7 KiB
C

/* Send break to terminal.
Copyright (C) 1996-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <stddef.h>
#include <termios.h>
#include <sys/ioctl.h>
/* Send zero bits on FD. */
int
tcsendbreak (int fd, int duration)
{
/* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
and an implementation-defined period if DURATION is nonzero.
We define a positive DURATION to be number of milliseconds to break. */
if (duration <= 0)
return __ioctl (fd, TCSBRK, 0);
#ifdef TCSBRKP
/* Probably Linux-specific: a positive third TCSBRKP ioctl argument is
defined to be the number of 100ms units to break. */
return __ioctl (fd, TCSBRKP, (duration + 99) / 100);
#else
/* ioctl can't send a break of any other duration for us.
This could be changed to use trickery (e.g. lower speed and
send a '\0') to send the break, but for now just return an error. */
return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
#endif
}