1/* Copyright (C) 1998-2020 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
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 <https://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <stdlib.h>
21#include <sys/ioctl.h>
22#include <termios.h>
23
24
25/* Unlock the slave pseudo terminal associated with the master pseudo
26 terminal specified by FD. */
27int
28unlockpt (int fd)
29{
30#ifdef TIOCSPTLCK
31 int save_errno = errno;
32 int unlock = 0;
33
34 if (__ioctl (fd, TIOCSPTLCK, &unlock))
35 {
36 if (errno == EINVAL)
37 {
38 __set_errno (save_errno);
39 return 0;
40 }
41 else
42 return -1;
43 }
44#endif
45 /* If we have no TIOCSPTLCK ioctl, all slave pseudo terminals are
46 unlocked by default. */
47 return 0;
48}
49