1/*-
2 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Portions of this software were developed under sponsorship from Snow
6 * B.V., the Netherlands.
7 *
8 * Redistribution and use in source and binary forms, with or without

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23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: stable/11/sys/dev/pty/pty.c 303432 2016-07-28 11:43:25Z kib $");
32
33#include <sys/param.h>
34#include <sys/conf.h>
35#include <sys/eventhandler.h>
36#include <sys/fcntl.h>
37#include <sys/kernel.h>
38#include <sys/module.h>
39#include <sys/proc.h>

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47 * the pts(4) driver. We just call into pts(4) to create the actual PTY.
48 * To make sure we don't use the same PTY multiple times, we abuse
49 * si_drv1 inside the cdev to mark whether the PTY is in use.
50 *
51 * It also implements a /dev/ptmx device node, which is useful for Linux
52 * binary emulation.
53 */
54
55static unsigned pty_warningcnt = 1;
56SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW,
57 &pty_warningcnt, 0,
58 "Warnings that will be triggered upon legacy PTY allocation");
59
60static int
61ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp)
62{
63 int error;
64 char name[6]; /* "ttyXX" */
65
66 if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1))

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72
73 error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name);
74 if (error != 0) {
75 destroy_dev_sched(dev);
76 return (error);
77 }
78
79 /* Raise a warning when a legacy PTY has been allocated. */
80 counted_warning(&pty_warningcnt, "is using legacy pty devices");
81
82 return (0);
83}
84
85static struct cdevsw ptydev_cdevsw = {
86 .d_version = D_VERSION,
87 .d_fdopen = ptydev_fdopen,
88 .d_name = "ptydev",

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