c0086bf202
Just like the old TTY layer, the current MPSAFE TTY layer does not make any attempt to serialize calls of write(). Data is copied into the kernel in 256 (TTY_STACKBUF) byte chunks. If a write() call occurs at the same time, the data may interleave. This is especially likely when the TTY starts blocking, because the output queue reaches the high watermark. I've implemented this by adding a new flag, TTY_BUSY_OUT, which is used to mark a TTY as having a thread stuck in write(). Because I don't want non-blocking processes to be possibly blocked by a sleeping thread, I'm still allowing it to bypass the protection. According to this message, the Linux kernel returns EAGAIN in such cases, but I think that's a little too restrictive: http://kerneltrap.org/index.php?q=mailarchive/linux-kernel/2007/5/2/85418/thread PR: kern/118287
213 lines
7.9 KiB
C
213 lines
7.9 KiB
C
/*-
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* Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
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* All rights reserved.
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*
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* Portions of this software were developed under sponsorship from Snow
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* B.V., the Netherlands.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS_TTY_H_
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#define _SYS_TTY_H_
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#include <sys/param.h>
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#include <sys/queue.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/condvar.h>
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#include <sys/selinfo.h>
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#include <sys/termios.h>
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#include <sys/ttycom.h>
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#include <sys/ttyqueue.h>
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struct cdev;
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struct file;
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struct pgrp;
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struct session;
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struct ucred;
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struct ttydevsw;
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/*
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* Per-TTY structure, containing buffers, etc.
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*
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* List of locks
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* (t) locked by t_mtx
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* (l) locked by tty_list_sx
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* (c) const until freeing
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*/
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struct tty {
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struct mtx *t_mtx; /* TTY lock. */
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struct mtx t_mtxobj; /* Per-TTY lock (when not borrowing). */
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TAILQ_ENTRY(tty) t_list; /* (l) TTY list entry. */
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unsigned int t_flags; /* (t) Terminal option flags. */
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/* Keep flags in sync with db_show_tty and pstat(8). */
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#define TF_NOPREFIX 0x00001 /* Don't prepend "tty" to device name. */
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#define TF_INITLOCK 0x00002 /* Create init/lock state devices. */
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#define TF_CALLOUT 0x00004 /* Create "cua" devices. */
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#define TF_OPENED_IN 0x00008 /* "tty" node is in use. */
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#define TF_OPENED_OUT 0x00010 /* "cua" node is in use. */
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#define TF_OPENED_CONS 0x00020 /* Device in use as console. */
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#define TF_OPENED (TF_OPENED_IN|TF_OPENED_OUT|TF_OPENED_CONS)
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#define TF_GONE 0x00040 /* Device node is gone. */
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#define TF_OPENCLOSE 0x00080 /* Device is in open()/close(). */
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#define TF_ASYNC 0x00100 /* Asynchronous I/O enabled. */
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#define TF_LITERAL 0x00200 /* Accept the next character literally. */
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#define TF_HIWAT_IN 0x00400 /* We've reached the input watermark. */
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#define TF_HIWAT_OUT 0x00800 /* We've reached the output watermark. */
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#define TF_HIWAT (TF_HIWAT_IN|TF_HIWAT_OUT)
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#define TF_STOPPED 0x01000 /* Output flow control - stopped. */
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#define TF_EXCLUDE 0x02000 /* Exclusive access. */
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#define TF_BYPASS 0x04000 /* Optimized input path. */
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#define TF_ZOMBIE 0x08000 /* Modem disconnect received. */
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#define TF_HOOK 0x10000 /* TTY has hook attached. */
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#define TF_BUSY_IN 0x20000 /* Process busy in read() -- not supported. */
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#define TF_BUSY_OUT 0x40000 /* Process busy in write(). */
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#define TF_BUSY (TF_BUSY_IN|TF_BUSY_OUT)
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unsigned int t_revokecnt; /* (t) revoke() count. */
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/* Buffering mechanisms. */
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struct ttyinq t_inq; /* (t) Input queue. */
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size_t t_inlow; /* (t) Input low watermark. */
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struct ttyoutq t_outq; /* (t) Output queue. */
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size_t t_outlow; /* (t) Output low watermark. */
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/* Sleeping mechanisms. */
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struct cv t_inwait; /* (t) Input wait queue. */
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struct cv t_outwait; /* (t) Output wait queue. */
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struct cv t_bgwait; /* (t) Background wait queue. */
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struct cv t_dcdwait; /* (t) Carrier Detect wait queue. */
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/* Polling mechanisms. */
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struct selinfo t_inpoll; /* (t) Input poll queue. */
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struct selinfo t_outpoll; /* (t) Output poll queue. */
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struct sigio *t_sigio; /* (t) Asynchronous I/O. */
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struct termios t_termios; /* (t) I/O processing flags. */
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struct winsize t_winsize; /* (t) Window size. */
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unsigned int t_column; /* (t) Current cursor position. */
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unsigned int t_writepos; /* (t) Where input was interrupted. */
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int t_compatflags; /* (t) COMPAT_43TTY flags. */
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/* Init/lock-state devices. */
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struct termios t_termios_init_in; /* tty%s.init. */
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struct termios t_termios_lock_in; /* tty%s.lock. */
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struct termios t_termios_init_out; /* cua%s.init. */
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struct termios t_termios_lock_out; /* cua%s.lock. */
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struct ttydevsw *t_devsw; /* (c) Driver hooks. */
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struct ttyhook *t_hook; /* (t) Capture/inject hook. */
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/* Process signal delivery. */
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struct pgrp *t_pgrp; /* (t) Foreground process group. */
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struct session *t_session; /* (t) Associated session. */
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unsigned int t_sessioncnt; /* (t) Backpointing sessions. */
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void *t_devswsoftc; /* (c) Soft config, for drivers. */
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void *t_hooksoftc; /* (t) Soft config, for hooks. */
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struct cdev *t_dev; /* (c) Primary character device. */
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};
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/*
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* Userland version of struct tty, for sysctl kern.ttys
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*/
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struct xtty {
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size_t xt_size; /* Structure size. */
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size_t xt_insize; /* Input queue size. */
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size_t xt_incc; /* Canonicalized characters. */
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size_t xt_inlc; /* Input line charaters. */
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size_t xt_inlow; /* Input low watermark. */
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size_t xt_outsize; /* Output queue size. */
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size_t xt_outcc; /* Output queue usage. */
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size_t xt_outlow; /* Output low watermark. */
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unsigned int xt_column; /* Current column position. */
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pid_t xt_pgid; /* Foreground process group. */
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pid_t xt_sid; /* Session. */
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unsigned int xt_flags; /* Terminal option flags. */
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dev_t xt_dev; /* Userland device. */
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};
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#ifdef _KERNEL
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/* Allocation and deallocation. */
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struct tty *tty_alloc(struct ttydevsw *tsw, void *softc, struct mtx *mtx);
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void tty_rel_pgrp(struct tty *tp, struct pgrp *pgrp);
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void tty_rel_sess(struct tty *tp, struct session *sess);
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void tty_rel_gone(struct tty *tp);
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#define tty_lock(tp) mtx_lock((tp)->t_mtx)
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#define tty_unlock(tp) mtx_unlock((tp)->t_mtx)
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#define tty_lock_assert(tp,ma) mtx_assert((tp)->t_mtx, (ma))
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#define tty_getlock(tp) ((tp)->t_mtx)
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/* Device node creation. */
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void tty_makedev(struct tty *tp, struct ucred *cred, const char *fmt, ...)
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__printflike(3, 4);
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#define tty_makealias(tp,fmt,...) \
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make_dev_alias((tp)->t_dev, fmt, ## __VA_ARGS__)
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/* Signalling processes. */
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void tty_signal_sessleader(struct tty *tp, int signal);
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void tty_signal_pgrp(struct tty *tp, int signal);
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/* Waking up readers/writers. */
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int tty_wait(struct tty *tp, struct cv *cv);
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int tty_timedwait(struct tty *tp, struct cv *cv, int timo);
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void tty_wakeup(struct tty *tp, int flags);
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/* System messages. */
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int tty_checkoutq(struct tty *tp);
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int tty_putchar(struct tty *tp, char c);
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int tty_ioctl(struct tty *tp, u_long cmd, void *data, struct thread *td);
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int tty_ioctl_compat(struct tty *tp, u_long cmd, caddr_t data,
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struct thread *td);
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void tty_init_console(struct tty *tp, speed_t speed);
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void tty_flush(struct tty *tp, int flags);
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void tty_hiwat_in_block(struct tty *tp);
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void tty_hiwat_in_unblock(struct tty *tp);
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dev_t tty_udev(struct tty *tp);
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#define tty_opened(tp) ((tp)->t_flags & TF_OPENED)
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#define tty_gone(tp) ((tp)->t_flags & TF_GONE)
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#define tty_softc(tp) ((tp)->t_devswsoftc)
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#define tty_devname(tp) devtoname((tp)->t_dev)
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/* Status line printing. */
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void tty_info(struct tty *tp);
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/* /dev/console selection. */
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void ttyconsdev_select(const char *name);
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/* Pseudo-terminal hooks. */
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int pts_alloc_external(int fd, struct thread *td, struct file *fp,
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struct cdev *dev, const char *name);
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/* Drivers and line disciplines also need to call these. */
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#include <sys/ttydisc.h>
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#include <sys/ttydevsw.h>
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#include <sys/ttyhook.h>
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#endif /* _KERNEL */
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#endif /* !_SYS_TTY_H_ */
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