/*      $OpenBSD: tty.c,v 1.183 2026/04/16 14:51:36 deraadt Exp $       */
/*      $NetBSD: tty.c,v 1.68.4.2 1996/06/06 16:04:52 thorpej Exp $     */

/*-
 * Copyright (c) 1982, 1986, 1990, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)tty.c       8.8 (Berkeley) 1/21/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/proc.h>
#define TTYDEFCHARS
#include <sys/tty.h>
#undef  TTYDEFCHARS
#include <sys/fcntl.h>
#include <sys/conf.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/msgbuf.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/sysctl.h>
#include <sys/pool.h>
#include <sys/unistd.h>
#include <sys/pledge.h>

#include <sys/namei.h>

#include <uvm/uvm_extern.h>

#include <dev/cons.h>

#include "pty.h"

static int ttnread(struct tty *);
static void ttyblock(struct tty *);
void ttyunblock(struct tty *);
static void ttyecho(int, struct tty *);
static void ttyrubo(struct tty *, int);
int     filt_ttyread(struct knote *kn, long hint);
void    filt_ttyrdetach(struct knote *kn);
int     filt_ttywrite(struct knote *kn, long hint);
void    filt_ttywdetach(struct knote *kn);
int     filt_ttyexcept(struct knote *kn, long hint);
void    ttystats_init(struct itty **, int *, size_t *);
int     ttywait_nsec(struct tty *, uint64_t);

/* Symbolic sleep message strings. */
char ttclos[]   = "ttycls";
char ttopen[]   = "ttyopn";
char ttybg[]    = "ttybg";
char ttyin[]    = "ttyin";
char ttyout[]   = "ttyout";

/*
 * Table with character classes and parity. The 8th bit indicates parity,
 * the 7th bit indicates the character is an alphameric or underscore (for
 * ALTWERASE), and the low 6 bits indicate delay type.  If the low 6 bits
 * are 0 then the character needs no special processing on output; classes
 * other than 0 might be translated or (not currently) require delays.
 */
#define E       0x00    /* Even parity. */
#define O       0x80    /* Odd parity. */
#define PARITY(c)       (char_type[c] & O)

#define ALPHA   0x40    /* Alpha or underscore. */
#define ISALPHA(c)      (char_type[(c) & TTY_CHARMASK] & ALPHA)

#define CCLASSMASK      0x3f
#define CCLASS(c)       (char_type[c] & CCLASSMASK)

#define BS      BACKSPACE
#define CC      CONTROL
#define CR      RETURN
#define NA      ORDINARY | ALPHA
#define NL      NEWLINE
#define NO      ORDINARY
#define TB      TAB
#define VT      VTAB

u_char const char_type[] = {
        E|CC, O|CC, O|CC, E|CC, O|CC, E|CC, E|CC, O|CC, /* nul - bel */
        O|BS, E|TB, E|NL, O|CC, E|VT, O|CR, O|CC, E|CC, /* bs - si */
        O|CC, E|CC, E|CC, O|CC, E|CC, O|CC, O|CC, E|CC, /* dle - etb */
        E|CC, O|CC, O|CC, E|CC, O|CC, E|CC, E|CC, O|CC, /* can - us */
        O|NO, E|NO, E|NO, O|NO, E|NO, O|NO, O|NO, E|NO, /* sp - ' */
        E|NO, O|NO, O|NO, E|NO, O|NO, E|NO, E|NO, O|NO, /* ( - / */
        E|NA, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA, /* 0 - 7 */
        O|NA, E|NA, E|NO, O|NO, E|NO, O|NO, O|NO, E|NO, /* 8 - ? */
        O|NO, E|NA, E|NA, O|NA, E|NA, O|NA, O|NA, E|NA, /* @ - G */
        E|NA, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA, /* H - O */
        E|NA, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA, /* P - W */
        O|NA, E|NA, E|NA, O|NO, E|NO, O|NO, O|NO, O|NA, /* X - _ */
        E|NO, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA, /* ` - g */
        O|NA, E|NA, E|NA, O|NA, E|NA, O|NA, O|NA, E|NA, /* h - o */
        O|NA, E|NA, E|NA, O|NA, E|NA, O|NA, O|NA, E|NA, /* p - w */
        E|NA, O|NA, O|NA, E|NO, O|NO, E|NO, E|NO, O|CC, /* x - del */
        /*
         * Meta chars; should be settable per character set;
         * for now, treat them all as normal characters.
         */
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
        NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
};
#undef  BS
#undef  CC
#undef  CR
#undef  NA
#undef  NL
#undef  NO
#undef  TB
#undef  VT

#define islower(c)      ((c) >= 'a' && (c) <= 'z')
#define isupper(c)      ((c) >= 'A' && (c) <= 'Z')

#define tolower(c)      ((c) - 'A' + 'a')
#define toupper(c)      ((c) - 'a' + 'A')

struct ttylist_head ttylist;    /* TAILQ_HEAD */
int tty_count;
struct rwlock ttylist_lock = RWLOCK_INITIALIZER("ttylist");

int64_t tk_cancc, tk_nin, tk_nout, tk_rawcc;

/*
 * Initial open of tty, or (re)entry to standard tty line discipline.
 */
int
ttyopen(dev_t device, struct tty *tp, struct proc *p)
{
        int s;

        s = spltty();
        tp->t_dev = device;
        if (!ISSET(tp->t_state, TS_ISOPEN)) {
                SET(tp->t_state, TS_ISOPEN);
                memset(&tp->t_winsize, 0, sizeof(tp->t_winsize));
                tp->t_column = 0;
        }
        CLR(tp->t_state, TS_WOPEN);
        splx(s);
        return (0);
}

/*
 * Handle close() on a tty line: flush and set to initial state,
 * bumping generation number so that pending read/write calls
 * can detect recycling of the tty.
 */
int
ttyclose(struct tty *tp)
{
        if (constty == tp)
                constty = NULL;

        ttyflush(tp, FREAD | FWRITE);

        tp->t_gen++;
        tp->t_pgrp = NULL;
        if (tp->t_session)
                SESSRELE(tp->t_session);
        tp->t_session = NULL;
        tp->t_state = 0;
        return (0);
}

#define FLUSHQ(q) {                                                     \
        if ((q)->c_cc)                                                  \
                ndflush(q, (q)->c_cc);                                  \
}

/* Is 'c' a line delimiter ("break" character)? */
#define TTBREAKC(c, lflag)                                              \
        ((c) == '\n' || (((c) == cc[VEOF] || (c) == cc[VEOL] ||         \
        ((c) == cc[VEOL2] && (lflag & IEXTEN))) && (c) != _POSIX_VDISABLE))


/*
 * Process input of a single character received on a tty.  Returns 0 normally,
 * 1 if a costly operation was reached.
 */
int
ttyinput(int c, struct tty *tp)
{
        int iflag, lflag;
        u_char *cc;
        int i, error, ret = 0;
        int s;

        enqueue_randomness(tp->t_dev << 8 | c);
        /*
         * If receiver is not enabled, drop it.
         */
        if (!ISSET(tp->t_cflag, CREAD))
                return (0);

        /*
         * If input is pending take it first.
         */
        lflag = tp->t_lflag;
        s = spltty();
        if (ISSET(lflag, PENDIN))
                ttypend(tp);
        splx(s);
        /*
         * Gather stats.
         */
        if (ISSET(lflag, ICANON)) {
                ++tk_cancc;
                ++tp->t_cancc;
        } else {
                ++tk_rawcc;
                ++tp->t_rawcc;
        }
        ++tk_nin;

        /* Handle exceptional conditions (break, parity, framing). */
        cc = tp->t_cc;
        iflag = tp->t_iflag;
        if ((error = (ISSET(c, TTY_ERRORMASK))) != 0) {
                CLR(c, TTY_ERRORMASK);
                if (ISSET(error, TTY_FE) && !c) {       /* Break. */
                        if (ISSET(iflag, IGNBRK))
                                return (0);
                        ttyflush(tp, FREAD | FWRITE);
                        if (ISSET(iflag, BRKINT)) {
                            pgsignal(tp->t_pgrp, SIGINT, 1);
                            goto endcase;
                        }
                        else if (ISSET(iflag, PARMRK))
                                goto parmrk;
                } else if ((ISSET(error, TTY_PE) && ISSET(iflag, INPCK)) ||
                    ISSET(error, TTY_FE)) {
                        if (ISSET(iflag, IGNPAR))
                                goto endcase;
                        else if (ISSET(iflag, PARMRK)) {
parmrk:                         (void)putc(0377 | TTY_QUOTE, &tp->t_rawq);
                                if (ISSET(iflag, ISTRIP) || c != 0377)
                                        (void)putc(0 | TTY_QUOTE, &tp->t_rawq);
                                (void)putc(c | TTY_QUOTE, &tp->t_rawq);
                                goto endcase;
                        } else
                                c = 0;
                }
        }
        if (c == 0377 && !ISSET(iflag, ISTRIP) && ISSET(iflag, PARMRK))
                goto parmrk;

        /*
         * In tandem mode, check high water mark.
         */
        if (ISSET(iflag, IXOFF) || ISSET(tp->t_cflag, CHWFLOW))
                ttyblock(tp);
        if (!ISSET(tp->t_state, TS_TYPEN) && ISSET(iflag, ISTRIP))
                CLR(c, 0x80);
        if (!ISSET(lflag, EXTPROC)) {
                /*
                 * Check for literal nexting very first
                 */
                if (ISSET(tp->t_state, TS_LNCH)) {
                        SET(c, TTY_QUOTE);
                        CLR(tp->t_state, TS_LNCH);
                }
                /*
                 * Scan for special characters.  This code
                 * is really just a big case statement with
                 * non-constant cases.  The bottom of the
                 * case statement is labeled ``endcase'', so goto
                 * it after a case match, or similar.
                 */

                /*
                 * Control chars which aren't controlled
                 * by ICANON, ISIG, or IXON.
                 */
                if (ISSET(lflag, IEXTEN)) {
                        if (CCEQ(cc[VLNEXT], c)) {
                                if (ISSET(lflag, ECHO)) {
                                        if (ISSET(lflag, ECHOE)) {
                                                (void)ttyoutput('^', tp);
                                                (void)ttyoutput('\b', tp);
                                        } else
                                                ttyecho(c, tp);
                                }
                                SET(tp->t_state, TS_LNCH);
                                goto endcase;
                        }
                        if (CCEQ(cc[VDISCARD], c)) {
                                if (ISSET(lflag, FLUSHO))
                                        CLR(tp->t_lflag, FLUSHO);
                                else {
                                        ttyflush(tp, FWRITE);
                                        ttyecho(c, tp);
                                        if (tp->t_rawq.c_cc + tp->t_canq.c_cc)
                                                ret = ttyretype(tp);
                                        SET(tp->t_lflag, FLUSHO);
                                }
                                goto startoutput;
                        }
                }
                /*
                 * Signals.
                 */
                if (ISSET(lflag, ISIG)) {
                        if (CCEQ(cc[VINTR], c) || CCEQ(cc[VQUIT], c)) {
                                if (!ISSET(lflag, NOFLSH))
                                        ttyflush(tp, FREAD | FWRITE);
                                ttyecho(c, tp);
                                pgsignal(tp->t_pgrp,
                                    CCEQ(cc[VINTR], c) ? SIGINT : SIGQUIT, 1);
                                goto endcase;
                        }
                        if (CCEQ(cc[VSUSP], c)) {
                                if (!ISSET(lflag, NOFLSH))
                                        ttyflush(tp, FREAD);
                                ttyecho(c, tp);
                                pgsignal(tp->t_pgrp, SIGTSTP, 1);
                                goto endcase;
                        }
                }
                /*
                 * Handle start/stop characters.
                 */
                if (ISSET(iflag, IXON)) {
                        if (CCEQ(cc[VSTOP], c)) {
                                if (!ISSET(tp->t_state, TS_TTSTOP)) {
                                        SET(tp->t_state, TS_TTSTOP);
                                        (*cdevsw[major(tp->t_dev)].d_stop)(tp,
                                           0);
                                        return (0);
                                }
                                if (!CCEQ(cc[VSTART], c))
                                        return (0);
                                /*
                                 * if VSTART == VSTOP then toggle
                                 */
                                goto endcase;
                        }
                        if (CCEQ(cc[VSTART], c))
                                goto restartoutput;
                }
                /*
                 * IGNCR, ICRNL, & INLCR
                 */
                if (c == '\r') {
                        if (ISSET(iflag, IGNCR))
                                goto endcase;
                        else if (ISSET(iflag, ICRNL))
                                c = '\n';
                } else if (c == '\n' && ISSET(iflag, INLCR))
                        c = '\r';
        }
        if (!ISSET(tp->t_lflag, EXTPROC) && ISSET(lflag, ICANON)) {
                /*
                 * From here on down canonical mode character
                 * processing takes place.
                 */
                /*
                 * upper case or specials with IUCLC and XCASE
                 */
                if (ISSET(lflag, XCASE) && ISSET(iflag, IUCLC)) {
                        if (ISSET(tp->t_state, TS_BKSL)) {
                                CLR(tp->t_state, TS_BKSL);
                                switch (c) {
                                case '\'':
                                        c = '`';
                                        break;
                                case '!':
                                        c = '|';
                                        break;
                                case '^':
                                        c = '~';
                                        break;
                                case '(':
                                        c = '{';
                                        break;
                                case ')':
                                        c = '}';
                                        break;
                                }
                        }
                        else if (c == '\\') {
                                SET(tp->t_state, TS_BKSL);
                                goto endcase;
                        }
                        else if (isupper(c))
                                c = tolower(c);
                }
                else if (ISSET(iflag, IUCLC) && isupper(c))
                        c = tolower(c);
                /*
                 * erase (^H / ^?)
                 */
                if (CCEQ(cc[VERASE], c)) {
                        if (tp->t_rawq.c_cc)
                                ret = ttyrub(unputc(&tp->t_rawq), tp);
                        goto endcase;
                }
                /*
                 * kill (^U)
                 */
                if (CCEQ(cc[VKILL], c)) {
                        if (ISSET(lflag, ECHOKE) &&
                            tp->t_rawq.c_cc == tp->t_rocount &&
                            !ISSET(lflag, ECHOPRT)) {
                                while (tp->t_rawq.c_cc)
                                        if (ttyrub(unputc(&tp->t_rawq), tp))
                                                ret = 1;
                        } else {
                                ttyecho(c, tp);
                                if (ISSET(lflag, ECHOK) ||
                                    ISSET(lflag, ECHOKE))
                                        ttyecho('\n', tp);
                                FLUSHQ(&tp->t_rawq);
                                tp->t_rocount = 0;
                        }
                        CLR(tp->t_state, TS_LOCAL);
                        goto endcase;
                }
                /*
                 * word erase (^W)
                 */
                if (CCEQ(cc[VWERASE], c) && ISSET(lflag, IEXTEN)) {
                        int alt = ISSET(lflag, ALTWERASE);
                        int ctype;

                        /*
                         * erase whitespace
                         */
                        while ((c = unputc(&tp->t_rawq)) == ' ' || c == '\t')
                                if (ttyrub(c, tp))
                                        ret = 1;
                        if (c == -1)
                                goto endcase;
                        /*
                         * erase last char of word and remember the
                         * next chars type (for ALTWERASE)
                         */
                        if (ttyrub(c, tp))
                                ret = 1;
                        c = unputc(&tp->t_rawq);
                        if (c == -1)
                                goto endcase;
                        if (c == ' ' || c == '\t') {
                                (void)putc(c, &tp->t_rawq);
                                goto endcase;
                        }
                        ctype = ISALPHA(c);
                        /*
                         * erase rest of word
                         */
                        do {
                                if (ttyrub(c, tp))
                                        ret = 1;
                                c = unputc(&tp->t_rawq);
                                if (c == -1)
                                        goto endcase;
                        } while (c != ' ' && c != '\t' &&
                            (alt == 0 || ISALPHA(c) == ctype));
                        (void)putc(c, &tp->t_rawq);
                        goto endcase;
                }
                /*
                 * reprint line (^R)
                 */
                if (CCEQ(cc[VREPRINT], c) && ISSET(lflag, IEXTEN)) {
                        ret = ttyretype(tp);
                        goto endcase;
                }
                /*
                 * ^T - kernel info and generate SIGINFO
                 */
                if (CCEQ(cc[VSTATUS], c) && ISSET(lflag, IEXTEN)) {
                        if (ISSET(lflag, ISIG))
                                pgsignal(tp->t_pgrp, SIGINFO, 1);
                        if (!ISSET(lflag, NOKERNINFO))
                                ttyinfo(tp);
                        goto endcase;
                }
        }
        /*
         * Check for input buffer overflow
         */
        if (tp->t_rawq.c_cc + tp->t_canq.c_cc >= TTYHOG(tp)) {
                if (ISSET(iflag, IMAXBEL)) {
                        if (tp->t_outq.c_cc < tp->t_hiwat)
                                (void)ttyoutput(CTRL('g'), tp);
                } else
                        ttyflush(tp, FREAD | FWRITE);
                goto endcase;
        }
        /*
         * Put data char in q for user and
         * wakeup on seeing a line delimiter.
         */
        if (putc(c, &tp->t_rawq) >= 0) {
                if (!ISSET(lflag, ICANON)) {
                        ttwakeup(tp);
                        ttyecho(c, tp);
                        goto endcase;
                }
                if (TTBREAKC(c, lflag)) {
                        tp->t_rocount = 0;
                        catq(&tp->t_rawq, &tp->t_canq);
                        ttwakeup(tp);
                } else if (tp->t_rocount++ == 0)
                        tp->t_rocol = tp->t_column;
                if (ISSET(tp->t_state, TS_ERASE)) {
                        /*
                         * end of prterase \.../
                         */
                        CLR(tp->t_state, TS_ERASE);
                        (void)ttyoutput('/', tp);
                }
                i = tp->t_column;
                ttyecho(c, tp);
                if (CCEQ(cc[VEOF], c) && ISSET(lflag, ECHO)) {
                        /*
                         * Place the cursor over the '^' of the ^D.
                         */
                        i = min(2, tp->t_column - i);
                        while (i > 0) {
                                (void)ttyoutput('\b', tp);
                                i--;
                        }
                }
        }
endcase:
        /*
         * IXANY means allow any character to restart output.
         */
        if (ISSET(tp->t_state, TS_TTSTOP) &&
            !ISSET(iflag, IXANY) && cc[VSTART] != cc[VSTOP])
                return (ret);
restartoutput:
        CLR(tp->t_lflag, FLUSHO);
        CLR(tp->t_state, TS_TTSTOP);
startoutput:
        ttstart(tp);
        return (ret);
}

/*
 * Output a single character on a tty, doing output processing
 * as needed (expanding tabs, newline processing, etc.).
 * Returns < 0 if succeeds, otherwise returns char to resend.
 * Must be recursive.
 */
int
ttyoutput(int c, struct tty *tp)
{
        long oflag;
        int col, notout, s, c2;

        oflag = tp->t_oflag;
        if (!ISSET(oflag, OPOST)) {
                tk_nout++;
                tp->t_outcc++;
                if (!ISSET(tp->t_lflag, FLUSHO) && putc(c, &tp->t_outq))
                        return (c);
                return (-1);
        }
        /*
         * Do tab expansion if OXTABS is set.  Special case if we external
         * processing, we don't do the tab expansion because we'll probably
         * get it wrong.  If tab expansion needs to be done, let it happen
         * externally.
         */
        CLR(c, ~TTY_CHARMASK);
        if (c == '\t' &&
            ISSET(oflag, OXTABS) && !ISSET(tp->t_lflag, EXTPROC)) {
                c = 8 - (tp->t_column & 7);
                if (ISSET(tp->t_lflag, FLUSHO)) {
                        notout = 0;
                } else {
                        s = spltty();           /* Don't interrupt tabs. */
                        notout = b_to_q("        ", c, &tp->t_outq);
                        c -= notout;
                        tk_nout += c;
                        tp->t_outcc += c;
                        splx(s);
                }
                tp->t_column += c;
                return (notout ? '\t' : -1);
        }
        if (c == CEOT && ISSET(oflag, ONOEOT))
                return (-1);

        /*
         * Newline translation: if ONLCR is set,
         * translate newline into "\r\n".  If OCRNL
         * is set, translate '\r' into '\n'.
         */
        if (c == '\n' && ISSET(tp->t_oflag, ONLCR)) {
                tk_nout++;
                tp->t_outcc++;
                if (!ISSET(tp->t_lflag, FLUSHO) && putc('\r', &tp->t_outq))
                        return (c);
                tp->t_column = 0;
        }
        else if (c == '\r' && ISSET(tp->t_oflag, OCRNL))
                c = '\n';

        if (ISSET(tp->t_oflag, OLCUC) && islower(c))
                c = toupper(c);
        else if (ISSET(tp->t_oflag, OLCUC) && ISSET(tp->t_lflag, XCASE)) {
                c2 = c;
                switch (c) {
                case '`':
                        c2 = '\'';
                        break;
                case '|':
                        c2 = '!';
                        break;
                case '~':
                        c2 = '^';
                        break;
                case '{':
                        c2 = '(';
                        break;
                case '}':
                        c2 = ')';
                        break;
                }
                if (c == '\\' || isupper(c) || c != c2) {
                        tk_nout++;
                        tp->t_outcc++;
                        if (putc('\\', &tp->t_outq))
                                return (c);
                        c = c2;
                }
        }
        if (ISSET(tp->t_oflag, ONOCR) && c == '\r' && tp->t_column == 0)
                return (-1);

        tk_nout++;
        tp->t_outcc++;
        if (!ISSET(tp->t_lflag, FLUSHO) && putc(c, &tp->t_outq))
                return (c);

        col = tp->t_column;
        switch (CCLASS(c)) {
        case BACKSPACE:
                if (col > 0)
                        --col;
                break;
        case CONTROL:
                break;
        case NEWLINE:
                if (ISSET(tp->t_oflag, ONLRET) || ISSET(tp->t_oflag, OCRNL))
                        col = 0;
                break;
        case RETURN:
                col = 0;
                break;
        case ORDINARY:
                ++col;
                break;
        case TAB:
                col = (col + 8) & ~7;
                break;
        }
        tp->t_column = col;
        return (-1);
}

/*
 * Ioctls for all tty devices.  Called after line-discipline specific ioctl
 * has been called to do discipline-specific functions and/or reject any
 * of these ioctl commands.
 */
int
ttioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct proc *p)
{
        extern int nlinesw;
        struct process *pr = p->p_p;
        int s, error;

        /* If the ioctl involves modification, hang if in the background. */
        switch (cmd) {
        case  FIOSETOWN:
        case  TIOCFLUSH:
        case  TIOCDRAIN:
        case  TIOCSBRK:
        case  TIOCCBRK:
        case  TIOCSETA:
        case  TIOCSETD:
        case  TIOCSETAF:
        case  TIOCSETAW:
        case  TIOCSPGRP:
        case  TIOCSTAT:
        case  TIOCSWINSZ:
                while (isbackground(pr, tp) &&
                    (pr->ps_flags & PS_PPWAIT) == 0 &&
                    !sigismasked(p, SIGTTOU)) {
                        if (pr->ps_pgrp->pg_jobc == 0)
                                return (EIO);
                        pgsignal(pr->ps_pgrp, SIGTTOU, 1);
                        error = ttysleep_nsec(tp, &nowake, TTOPRI | PCATCH,
                                ttybg, SEC_TO_NSEC(1));
                        if (error)
                                return (error);
                }
                break;
        }

        switch (cmd) {                  /* Process the ioctl. */
        case FIOASYNC:                  /* set/clear async i/o */
                s = spltty();
                if (*(int *)data)
                        SET(tp->t_state, TS_ASYNC);
                else
                        CLR(tp->t_state, TS_ASYNC);
                splx(s);
                break;
        case FIONREAD:                  /* get # bytes to read */
                s = spltty();
                *(int *)data = ttnread(tp);
                splx(s);
                break;
        case TIOCEXCL:                  /* set exclusive use of tty */
                s = spltty();
                SET(tp->t_state, TS_XCLUDE);
                splx(s);
                break;
        case TIOCFLUSH: {               /* flush buffers */
                int flags = *(int *)data;

                if (flags == 0)
                        flags = FREAD | FWRITE;
                else
                        flags &= FREAD | FWRITE;
                ttyflush(tp, flags);
                break;
        }
        case TIOCCONS: {                /* become virtual console */
                if (*(int *)data) {
                        struct nameidata nid;

                        if (constty != NULL && constty != tp &&
                            ISSET(constty->t_state, TS_CARR_ON | TS_ISOPEN) ==
                            (TS_CARR_ON | TS_ISOPEN))
                                return (EBUSY);

                        /* ensure user can open the real console */
                        NDINIT(&nid, LOOKUP, FOLLOW, UIO_SYSSPACE, "/dev/console", p);
                        nid.ni_pledge = PLEDGE_RPATH | PLEDGE_WPATH;
                        nid.ni_unveil = UNVEIL_READ | UNVEIL_WRITE;
                        error = namei(&nid);
                        if (error)
                                return (error);
                        vn_lock(nid.ni_vp, LK_EXCLUSIVE | LK_RETRY);
                        error = VOP_ACCESS(nid.ni_vp, VREAD, p->p_ucred, p);
                        VOP_UNLOCK(nid.ni_vp);
                        vrele(nid.ni_vp);
                        if (error)
                                return (error);

                        constty = tp;
                } else if (tp == constty)
                        constty = NULL;
                break;
        }
        case TIOCDRAIN:                 /* wait till output drained */
                if ((error = ttywait(tp)) != 0)
                        return (error);
                break;
        case TIOCGETA: {                /* get termios struct */
                struct termios *t = (struct termios *)data;

                memcpy(t, &tp->t_termios, sizeof(struct termios));
                break;
        }
        case TIOCGETD:                  /* get line discipline */
                *(int *)data = tp->t_line;
                break;
        case TIOCGWINSZ:                /* get window size */
                *(struct winsize *)data = tp->t_winsize;
                break;
        case TIOCGTSTAMP:
                s = spltty();
                *(struct timeval *)data = tp->t_tv;
                splx(s);
                break;
        case FIOGETOWN:                 /* get pgrp of tty */
                if (!isctty(pr, tp) && suser(p))
                        return (ENOTTY);
                *(int *)data = tp->t_pgrp ? -tp->t_pgrp->pg_id : 0;
                break;
        case TIOCGPGRP:                 /* get pgrp of tty */
                if (!isctty(pr, tp) && suser(p))
                        return (ENOTTY);
                *(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PID;
                break;
        case TIOCGSID:                  /* get sid of tty */
                if (!isctty(pr, tp))
                        return (ENOTTY);
                *(int *)data = tp->t_session->s_leader->ps_pid;
                break;
        case TIOCNXCL:                  /* reset exclusive use of tty */
                s = spltty();
                CLR(tp->t_state, TS_XCLUDE);
                splx(s);
                break;
        case TIOCOUTQ:                  /* output queue size */
                *(int *)data = tp->t_outq.c_cc;
                break;
        case TIOCSETA:                  /* set termios struct */
        case TIOCSETAW:                 /* drain output, set */
        case TIOCSETAF: {               /* drn out, fls in, set */
                struct termios *t = (struct termios *)data;

                s = spltty();
                if (cmd == TIOCSETAW || cmd == TIOCSETAF) {
                        if ((error = ttywait(tp)) != 0) {
                                splx(s);
                                return (error);
                        }
                        if (cmd == TIOCSETAF)
                                ttyflush(tp, FREAD);
                }
                if (!ISSET(t->c_cflag, CIGNORE)) {
                        /*
                         * Some minor validation is necessary.
                         */
                        if (t->c_ispeed < 0 || t->c_ospeed < 0) {
                                splx(s);
                                return (EINVAL);
                        }
                        /*
                         * Set device hardware.
                         */
                        if (tp->t_param && (error = (*tp->t_param)(tp, t))) {
                                splx(s);
                                return (error);
                        } else {
                                if (!ISSET(tp->t_state, TS_CARR_ON) &&
                                    ISSET(tp->t_cflag, CLOCAL) &&
                                    !ISSET(t->c_cflag, CLOCAL)) {
                                        CLR(tp->t_state, TS_ISOPEN);
                                        SET(tp->t_state, TS_WOPEN);
                                        ttwakeup(tp);
                                }
                                tp->t_cflag = t->c_cflag;
                                tp->t_ispeed = t->c_ispeed;
                                tp->t_ospeed = t->c_ospeed;
                                if (t->c_ospeed == 0 && tp->t_session &&
                                    tp->t_session->s_leader)
                                        prsignal(tp->t_session->s_leader,
                                            SIGHUP);
                        }
                        ttsetwater(tp);
                }
                if (cmd != TIOCSETAF) {
                        if (ISSET(t->c_lflag, ICANON) !=
                            ISSET(tp->t_lflag, ICANON)) {
                                if (ISSET(t->c_lflag, ICANON)) {
                                        SET(tp->t_lflag, PENDIN);
                                        ttwakeup(tp);
                                } else {
                                        struct clist tq;

                                        catq(&tp->t_rawq, &tp->t_canq);
                                        tq = tp->t_rawq;
                                        tp->t_rawq = tp->t_canq;
                                        tp->t_canq = tq;
                                        CLR(tp->t_lflag, PENDIN);
                                }
                        }
                }
                tp->t_iflag = t->c_iflag;
                tp->t_oflag = t->c_oflag;
                /*
                 * Make the EXTPROC bit read only.
                 */
                if (ISSET(tp->t_lflag, EXTPROC))
                        SET(t->c_lflag, EXTPROC);
                else
                        CLR(t->c_lflag, EXTPROC);
                tp->t_lflag = t->c_lflag | ISSET(tp->t_lflag, PENDIN);
                memcpy(tp->t_cc, t->c_cc, sizeof(t->c_cc));
                splx(s);
                break;
        }
        case TIOCSETD: {                /* set line discipline */
                int t = *(int *)data;
                dev_t device = tp->t_dev;

                if ((u_int)t >= nlinesw)
                        return (ENXIO);
                if (t != tp->t_line) {
                        s = spltty();
                        (*linesw[tp->t_line].l_close)(tp, flag, p);
                        error = (*linesw[t].l_open)(device, tp, p);
                        if (error) {
                                (*linesw[tp->t_line].l_open)(device, tp, p);
                                splx(s);
                                return (error);
                        }
                        tp->t_line = t;
                        splx(s);
                }
                break;
        }
        case TIOCSTART:                 /* start output, like ^Q */
                s = spltty();
                if (ISSET(tp->t_state, TS_TTSTOP) ||
                    ISSET(tp->t_lflag, FLUSHO)) {
                        CLR(tp->t_lflag, FLUSHO);
                        CLR(tp->t_state, TS_TTSTOP);
                        ttstart(tp);
                }
                splx(s);
                break;
        case TIOCSTOP:                  /* stop output, like ^S */
                s = spltty();
                if (!ISSET(tp->t_state, TS_TTSTOP)) {
                        SET(tp->t_state, TS_TTSTOP);
                        (*cdevsw[major(tp->t_dev)].d_stop)(tp, 0);
                }
                splx(s);
                break;
        case TIOCSCTTY:                 /* become controlling tty */
                /* Session ctty vnode pointer set in vnode layer. */
                if (!SESS_LEADER(pr) ||
                    ((pr->ps_session->s_ttyvp || tp->t_session) &&
                     (tp->t_session != pr->ps_session)))
                        return (EPERM);
                if (tp->t_session)
                        SESSRELE(tp->t_session);
                SESSHOLD(pr->ps_session);
                tp->t_session = pr->ps_session;
                tp->t_pgrp = pr->ps_pgrp;
                pr->ps_session->s_ttyp = tp;
                atomic_setbits_int(&pr->ps_flags, PS_CONTROLT);
                break;
        case FIOSETOWN: {               /* set pgrp of tty */
                struct pgrp *pgrp;
                struct process *pr1;
                pid_t pgid = *(int *)data;

                if (!isctty(pr, tp))
                        return (ENOTTY);
                if (pgid < 0) {
                        pgrp = pgfind(-pgid);
                } else {
                        pr1 = prfind(pgid);
                        if (pr1 == NULL)
                                return (ESRCH);
                        pgrp = pr1->ps_pgrp;
                }
                if (pgrp == NULL)
                        return (EINVAL);
                else if (pgrp->pg_session != pr->ps_session)
                        return (EPERM);
                tp->t_pgrp = pgrp;
                break;
        }
        case TIOCSPGRP: {               /* set pgrp of tty */
                struct pgrp *pgrp = pgfind(*(int *)data);

                if (!isctty(pr, tp))
                        return (ENOTTY);
                else if (pgrp == NULL)
                        return (EINVAL);
                else if (pgrp->pg_session != pr->ps_session)
                        return (EPERM);
                tp->t_pgrp = pgrp;
                break;
        }
        case TIOCSTAT:                  /* get load avg stats */
                ttyinfo(tp);
                break;
        case TIOCSWINSZ:                /* set window size */
                if (bcmp((caddr_t)&tp->t_winsize, data,
                    sizeof (struct winsize))) {
                        tp->t_winsize = *(struct winsize *)data;
                        pgsignal(tp->t_pgrp, SIGWINCH, 1);
                }
                break;
        case TIOCSTSTAMP: {
                struct tstamps *ts = (struct tstamps *)data;

                s = spltty();
                CLR(tp->t_flags, TS_TSTAMPDCDSET);
                CLR(tp->t_flags, TS_TSTAMPCTSSET);
                CLR(tp->t_flags, TS_TSTAMPDCDCLR);
                CLR(tp->t_flags, TS_TSTAMPCTSCLR);
                if (ISSET(ts->ts_set, TIOCM_CAR))
                        SET(tp->t_flags, TS_TSTAMPDCDSET);
                if (ISSET(ts->ts_set, TIOCM_CTS))
                        SET(tp->t_flags, TS_TSTAMPCTSSET);
                if (ISSET(ts->ts_clr, TIOCM_CAR))
                        SET(tp->t_flags, TS_TSTAMPDCDCLR);
                if (ISSET(ts->ts_clr, TIOCM_CTS))
                        SET(tp->t_flags, TS_TSTAMPCTSCLR);
                splx(s);
                break;
        }
        default:
                return (-1);
        }
        return (0);
}

const struct filterops ttyread_filtops = {
        .f_flags        = FILTEROP_ISFD,
        .f_attach       = NULL,
        .f_detach       = filt_ttyrdetach,
        .f_event        = filt_ttyread,
};

const struct filterops ttywrite_filtops = {
        .f_flags        = FILTEROP_ISFD,
        .f_attach       = NULL,
        .f_detach       = filt_ttywdetach,
        .f_event        = filt_ttywrite,
};

const struct filterops ttyexcept_filtops = {
        .f_flags        = FILTEROP_ISFD,
        .f_attach       = NULL,
        .f_detach       = filt_ttyrdetach,
        .f_event        = filt_ttyexcept,
};

int
ttkqfilter(dev_t dev, struct knote *kn)
{
        struct tty *tp = (*cdevsw[major(dev)].d_tty)(dev);
        struct klist *klist;
        int s;

        switch (kn->kn_filter) {
        case EVFILT_READ:
                klist = &tp->t_rsel.si_note;
                kn->kn_fop = &ttyread_filtops;
                break;
        case EVFILT_WRITE:
                klist = &tp->t_wsel.si_note;
                kn->kn_fop = &ttywrite_filtops;
                break;
        case EVFILT_EXCEPT:
                if (kn->kn_flags & __EV_SELECT) {
                        /* Prevent triggering exceptfds. */
                        return (EPERM);
                }
                if ((kn->kn_flags & __EV_POLL) == 0) {
                        /* Disallow usage through kevent(2). */
                        return (EINVAL);
                }
                klist = &tp->t_rsel.si_note;
                kn->kn_fop = &ttyexcept_filtops;
                break;
        default:
                return (EINVAL);
        }

        kn->kn_hook = tp;

        s = spltty();
        klist_insert_locked(klist, kn);
        splx(s);

        return (0);
}

void
filt_ttyrdetach(struct knote *kn)
{
        struct tty *tp = kn->kn_hook;
        int s;

        s = spltty();
        klist_remove_locked(&tp->t_rsel.si_note, kn);
        splx(s);
}

int
filt_ttyread(struct knote *kn, long hint)
{
        struct tty *tp = kn->kn_hook;
        int active, s;

        s = spltty();
        kn->kn_data = ttnread(tp);
        active = (kn->kn_data > 0);
        if (!ISSET(tp->t_cflag, CLOCAL) && !ISSET(tp->t_state, TS_CARR_ON)) {
                kn->kn_flags |= EV_EOF;
                if (kn->kn_flags & __EV_POLL)
                        kn->kn_flags |= __EV_HUP;
                active = 1;
        } else {
                kn->kn_flags &= ~(EV_EOF | __EV_HUP);
        }
        splx(s);
        return (active);
}

void
filt_ttywdetach(struct knote *kn)
{
        struct tty *tp = kn->kn_hook;
        int s;

        s = spltty();
        klist_remove_locked(&tp->t_wsel.si_note, kn);
        splx(s);
}

int
filt_ttywrite(struct knote *kn, long hint)
{
        struct tty *tp = kn->kn_hook;
        int active, s;

        s = spltty();
        kn->kn_data = tp->t_outq.c_cn - tp->t_outq.c_cc;
        active = (tp->t_outq.c_cc <= tp->t_lowat);

        /* Write-side HUP condition is only for poll(2) and select(2). */
        if (kn->kn_flags & (__EV_POLL | __EV_SELECT)) {
                if (!ISSET(tp->t_cflag, CLOCAL) &&
                    !ISSET(tp->t_state, TS_CARR_ON)) {
                        kn->kn_flags |= __EV_HUP;
                        active = 1;
                } else {
                        kn->kn_flags &= ~__EV_HUP;
                }
        }
        splx(s);
        return (active);
}

int
filt_ttyexcept(struct knote *kn, long hint)
{
        struct tty *tp = kn->kn_hook;
        int active = 0;
        int s;

        s = spltty();
        if (kn->kn_flags & __EV_POLL) {
                if (!ISSET(tp->t_cflag, CLOCAL) &&
                    !ISSET(tp->t_state, TS_CARR_ON)) {
                        kn->kn_flags |= __EV_HUP;
                        active = 1;
                } else {
                        kn->kn_flags &= ~__EV_HUP;
                }
        }
        splx(s);
        return (active);
}

static int
ttnread(struct tty *tp)
{
        int nread;

        splassert(IPL_TTY);

        if (ISSET(tp->t_lflag, PENDIN))
                ttypend(tp);
        nread = tp->t_canq.c_cc;
        if (!ISSET(tp->t_lflag, ICANON)) {
                nread += tp->t_rawq.c_cc;
                if (nread < tp->t_cc[VMIN] && !tp->t_cc[VTIME])
                        nread = 0;
        }
        return (nread);
}

/*
 * Wait for output to drain, or if this times out, flush it.
 */
int
ttywait_nsec(struct tty *tp, uint64_t nsecs)
{
        int error, s;

        error = 0;
        s = spltty();
        while ((tp->t_outq.c_cc || ISSET(tp->t_state, TS_BUSY)) &&
            (ISSET(tp->t_state, TS_CARR_ON) || ISSET(tp->t_cflag, CLOCAL)) &&
            tp->t_oproc) {
                (*tp->t_oproc)(tp);
                if ((tp->t_outq.c_cc || ISSET(tp->t_state, TS_BUSY)) &&
                    (ISSET(tp->t_state, TS_CARR_ON) || ISSET(tp->t_cflag, CLOCAL))
                    && tp->t_oproc) {
                        SET(tp->t_state, TS_ASLEEP);
                        error = ttysleep_nsec(tp, &tp->t_outq, TTOPRI | PCATCH,
                            ttyout, nsecs);
                        if (error == EWOULDBLOCK)
                                ttyflush(tp, FWRITE);
                        if (error)
                                break;
                } else
                        break;
        }
        splx(s);
        return (error);
}

int
ttywait(struct tty *tp)
{
        return (ttywait_nsec(tp, INFSLP));
}

/*
 * Flush if successfully wait.
 */
int
ttywflush(struct tty *tp)
{
        int error;

        error = ttywait_nsec(tp, SEC_TO_NSEC(5));
        if (error == 0 || error == EWOULDBLOCK)
                ttyflush(tp, FREAD);
        return (error);
}

/*
 * Flush tty read and/or write queues, notifying anyone waiting.
 */
void
ttyflush(struct tty *tp, int rw)
{
        int s;

        s = spltty();
        if (rw & FREAD) {
                FLUSHQ(&tp->t_canq);
                FLUSHQ(&tp->t_rawq);
                tp->t_rocount = 0;
                tp->t_rocol = 0;
                CLR(tp->t_state, TS_LOCAL);
                ttyunblock(tp);
                ttwakeup(tp);
        }
        if (rw & FWRITE) {
                CLR(tp->t_state, TS_TTSTOP);
                (*cdevsw[major(tp->t_dev)].d_stop)(tp, rw);
                FLUSHQ(&tp->t_outq);
                wakeup((caddr_t)&tp->t_outq);
                selwakeup(&tp->t_wsel);
        }
        splx(s);
}

/*
 * Copy in the default termios characters.
 */
void
ttychars(struct tty *tp)
{

        memcpy(tp->t_cc, ttydefchars, sizeof(ttydefchars));
}

/*
 * Send stop character on input overflow.
 */
static void
ttyblock(struct tty *tp)
{
        int total;

        total = tp->t_rawq.c_cc + tp->t_canq.c_cc;
        if (tp->t_rawq.c_cc > TTYHOG(tp)) {
                ttyflush(tp, FREAD | FWRITE);
                CLR(tp->t_state, TS_TBLOCK);
        }
        /*
         * Block further input iff: current input > threshold
         * AND input is available to user program.
         */
        if ((total >= TTYHOG(tp) / 2 &&
             !ISSET(tp->t_state, TS_TBLOCK) &&
             !ISSET(tp->t_lflag, ICANON)) || tp->t_canq.c_cc > 0) {
                if (ISSET(tp->t_iflag, IXOFF) &&
                    tp->t_cc[VSTOP] != _POSIX_VDISABLE &&
                    putc(tp->t_cc[VSTOP], &tp->t_outq) == 0) {
                        SET(tp->t_state, TS_TBLOCK);
                        ttstart(tp);
                }
                /* Try to block remote output via hardware flow control. */
                if (ISSET(tp->t_cflag, CHWFLOW) && tp->t_hwiflow &&
                    (*tp->t_hwiflow)(tp, 1) != 0)
                        SET(tp->t_state, TS_TBLOCK);
        }
}

void
ttrstrt(void *arg)
{
        struct tty *tp = (struct tty *)arg;
        int s;

#ifdef DIAGNOSTIC
        if (tp == NULL)
                panic("ttrstrt");
#endif
        s = spltty();
        CLR(tp->t_state, TS_TIMEOUT);
        ttstart(tp);
        splx(s);
}

int
ttstart(struct tty *tp)
{

        if (tp->t_oproc != NULL)        /* XXX: Kludge for pty. */
                (*tp->t_oproc)(tp);
        return (0);
}

/*
 * "close" a line discipline
 */
int
ttylclose(struct tty *tp, int flag, struct proc *p)
{

        if (flag & FNONBLOCK)
                ttyflush(tp, FREAD | FWRITE);
        else
                ttywflush(tp);
        return (0);
}

/*
 * Handle modem control transition on a tty.
 * Flag indicates new state of carrier.
 * Returns 0 if the line should be turned off, otherwise 1.
 */
int
ttymodem(struct tty *tp, int flag)
{

        if (!ISSET(tp->t_state, TS_WOPEN) && ISSET(tp->t_cflag, MDMBUF)) {
                /*
                 * MDMBUF: do flow control according to carrier flag
                 */
                if (flag) {
                        CLR(tp->t_state, TS_TTSTOP);
                        ttstart(tp);
                } else if (!ISSET(tp->t_state, TS_TTSTOP)) {
                        SET(tp->t_state, TS_TTSTOP);
                        (*cdevsw[major(tp->t_dev)].d_stop)(tp, 0);
                }
        } else if (flag == 0) {
                /*
                 * Lost carrier.
                 */
                CLR(tp->t_state, TS_CARR_ON);
                if (ISSET(tp->t_state, TS_ISOPEN) &&
                    !ISSET(tp->t_cflag, CLOCAL)) {
                        if (tp->t_session && tp->t_session->s_leader)
                                prsignal(tp->t_session->s_leader, SIGHUP);
                        ttyflush(tp, FREAD | FWRITE);
                        return (0);
                }
        } else {
                /*
                 * Carrier now on.
                 */
                SET(tp->t_state, TS_CARR_ON);
                ttwakeup(tp);
        }
        return (1);
}

/*
 * Default modem control routine (for other line disciplines).
 * Return argument flag, to turn off device on carrier drop.
 */
int
nullmodem(struct tty *tp, int flag)
{

        if (flag)
                SET(tp->t_state, TS_CARR_ON);
        else {
                CLR(tp->t_state, TS_CARR_ON);
                if (ISSET(tp->t_state, TS_ISOPEN) &&
                    !ISSET(tp->t_cflag, CLOCAL)) {
                        if (tp->t_session && tp->t_session->s_leader)
                                prsignal(tp->t_session->s_leader, SIGHUP);
                        ttyflush(tp, FREAD | FWRITE);
                        return (0);
                }
        }
        return (1);
}

/*
 * Reinput pending characters after state switch
 * call at spltty().
 */
void
ttypend(struct tty *tp)
{
        struct clist tq;
        int c;

        splassert(IPL_TTY);

        CLR(tp->t_lflag, PENDIN);
        SET(tp->t_state, TS_TYPEN);
        tq = tp->t_rawq;
        tp->t_rawq.c_cc = 0;
        tp->t_rawq.c_cf = tp->t_rawq.c_cl = NULL;
        while ((c = getc(&tq)) >= 0)
                ttyinput(c, tp);
        CLR(tp->t_state, TS_TYPEN);
}

void ttvtimeout(void *);

void
ttvtimeout(void *arg)
{
        struct tty *tp = (struct tty *)arg;

        wakeup(&tp->t_rawq);
}

/*
 * Process a read call on a tty device.
 */
int
ttread(struct tty *tp, struct uio *uio, int flag)
{
        struct timeout *stime = NULL;
        struct proc *p = curproc;
        struct process *pr = p->p_p;
        int s, first, error = 0;
        u_char *cc = tp->t_cc;
        struct clist *qp;
        int last_cc = 0;
        long lflag;
        int c;

loop:   lflag = tp->t_lflag;
        s = spltty();
        /*
         * take pending input first
         */
        if (ISSET(lflag, PENDIN))
                ttypend(tp);
        splx(s);

        /*
         * Hang process if it's in the background.
         */
        if (isbackground(pr, tp)) {
                if (sigismasked(p, SIGTTIN) ||
                    pr->ps_flags & PS_PPWAIT || pr->ps_pgrp->pg_jobc == 0) {
                        error = EIO;
                        goto out;
                }
                pgsignal(pr->ps_pgrp, SIGTTIN, 1);
                error = ttysleep_nsec(tp, &nowake, TTIPRI | PCATCH, ttybg, 
                        SEC_TO_NSEC(1));
                if (error)
                        goto out;
                goto loop;
        }

        s = spltty();
        if (!ISSET(lflag, ICANON)) {
                int min = cc[VMIN];
                int time = cc[VTIME] * 100;     /* tenths of a second (ms) */

                qp = &tp->t_rawq;
                /*
                 * Check each of the four combinations.
                 * (min > 0 && time == 0) is the normal read case.
                 * It should be fairly efficient, so we check that and its
                 * companion case (min == 0 && time == 0) first.
                 */
                if (time == 0) {
                        if (qp->c_cc < min)
                                goto sleep;
                        goto read;
                }
                if (min > 0) {
                        if (qp->c_cc <= 0)
                                goto sleep;
                        if (qp->c_cc >= min)
                                goto read;
                        if (stime == NULL) {
alloc_timer:
                                stime = malloc(sizeof(*stime), M_TEMP, M_WAITOK);
                                timeout_set(stime, ttvtimeout, tp);
                                timeout_add_msec(stime, time);
                        } else if (qp->c_cc > last_cc) {
                                /* got a character, restart timer */
                                timeout_add_msec(stime, time);
                        }
                } else {        /* min == 0 */
                        if (qp->c_cc > 0)
                                goto read;
                        if (stime == NULL) {
                                goto alloc_timer;
                        }
                }
                last_cc = qp->c_cc;
                if (stime && !timeout_triggered(stime)) {
                        goto sleep;
                }
        } else if ((qp = &tp->t_canq)->c_cc <= 0) {
                int carrier;

sleep:
                /*
                 * If there is no input, sleep on rawq
                 * awaiting hardware receipt and notification.
                 * If we have data, we don't need to check for carrier.
                 */
                carrier = ISSET(tp->t_state, TS_CARR_ON) ||
                    ISSET(tp->t_cflag, CLOCAL);
                if (!carrier && ISSET(tp->t_state, TS_ISOPEN)) {
                        splx(s);
                        error = 0;
                        goto out;
                }
                if (flag & IO_NDELAY) {
                        splx(s);
                        error = EWOULDBLOCK;
                        goto out;
                }
                error = ttysleep(tp, &tp->t_rawq, TTIPRI | PCATCH,
                    carrier ? ttyin : ttopen);
                splx(s);
                if (stime && timeout_triggered(stime))
                        error = EWOULDBLOCK;
                if (cc[VMIN] == 0 && error == EWOULDBLOCK) {
                        error = 0;
                        goto out;
                }
                if (error && error != EWOULDBLOCK)
                        goto out;
                error = 0;
                goto loop;
        }
read:
        splx(s);

        /*
         * Input present, check for input mapping and processing.
         */
        first = 1;
        while ((c = getc(qp)) >= 0) {
                /*
                 * delayed suspend (^Y)
                 */
                if (CCEQ(cc[VDSUSP], c) &&
                    ISSET(lflag, IEXTEN | ISIG) == (IEXTEN | ISIG)) {
                        pgsignal(tp->t_pgrp, SIGTSTP, 1);
                        if (first) {
                                error = ttysleep_nsec(tp, &nowake, TTIPRI | PCATCH, 
                                        ttybg, SEC_TO_NSEC(1));
                                if (error)
                                        break;
                                goto loop;
                        }
                        break;
                }
                /*
                 * Interpret EOF only in canonical mode.
                 */
                if (CCEQ(cc[VEOF], c) && ISSET(lflag, ICANON))
                        break;
                /*
                 * Give user character.
                 */
                error = ureadc(c, uio);
                if (error)
                        break;
                if (uio->uio_resid == 0)
                        break;
                /*
                 * In canonical mode check for a "break character"
                 * marking the end of a "line of input".
                 */
                if (ISSET(lflag, ICANON) && TTBREAKC(c, lflag))
                        break;
                first = 0;
        }
        /*
         * Look to unblock output now that (presumably)
         * the input queue has gone down.
         */
        s = spltty();
        if (tp->t_rawq.c_cc < TTYHOG(tp)/5)
                ttyunblock(tp);
        splx(s);

out:
        if (stime) {
                timeout_del(stime);
                free(stime, M_TEMP, sizeof(*stime));
        }
        return (error);
}

/* Call at spltty */
void
ttyunblock(struct tty *tp)
{
        u_char *cc = tp->t_cc;

        splassert(IPL_TTY);

        if (ISSET(tp->t_state, TS_TBLOCK)) {
                if (ISSET(tp->t_iflag, IXOFF) &&
                    cc[VSTART] != _POSIX_VDISABLE &&
                    putc(cc[VSTART], &tp->t_outq) == 0) {
                        CLR(tp->t_state, TS_TBLOCK);
                        ttstart(tp);
                }
                /* Try to unblock remote output via hardware flow control. */
                if (ISSET(tp->t_cflag, CHWFLOW) && tp->t_hwiflow &&
                    (*tp->t_hwiflow)(tp, 0) != 0)
                        CLR(tp->t_state, TS_TBLOCK);
        }
}

/*
 * Check the output queue on tp for space for a kernel message (from uprintf
 * or tprintf).  Allow some space over the normal hiwater mark so we don't
 * lose messages due to normal flow control, but don't let the tty run amok.
 * Sleeps here are not interruptible, but we return prematurely if new signals
 * arrive.
 */
int
ttycheckoutq(struct tty *tp, int wait)
{
        int hiwat, s, oldsig;

        hiwat = tp->t_hiwat;
        s = spltty();
        oldsig = wait ? SIGPENDING(curproc) : 0;
        if (tp->t_outq.c_cc > hiwat + TTHIWATMINSPACE)
                while (tp->t_outq.c_cc > hiwat) {
                        ttstart(tp);
                        if (wait == 0 || SIGPENDING(curproc) != oldsig) {
                                splx(s);
                                return (0);
                        }
                        SET(tp->t_state, TS_ASLEEP);
                        tsleep_nsec(&tp->t_outq, PZERO - 1, "ttckoutq",
                            SEC_TO_NSEC(1));
                }
        splx(s);
        return (1);
}

/*
 * Process a write call on a tty device.
 */
int
ttwrite(struct tty *tp, struct uio *uio, int flag)
{
        u_char *cp = NULL;
        int cc, ce, obufcc = 0;
        struct proc *p;
        struct process *pr;
        int hiwat, error, s;
        size_t cnt;
        u_char obuf[OBUFSIZ];

        hiwat = tp->t_hiwat;
        cnt = uio->uio_resid;
        error = 0;
        cc = 0;
loop:
        s = spltty();
        if (!ISSET(tp->t_state, TS_CARR_ON) &&
            !ISSET(tp->t_cflag, CLOCAL)) {
                if (ISSET(tp->t_state, TS_ISOPEN)) {
                        splx(s);
                        error = EIO;
                        goto done;
                } else if (flag & IO_NDELAY) {
                        splx(s);
                        error = EWOULDBLOCK;
                        goto out;
                } else {
                        /* Sleep awaiting carrier. */
                        error = ttysleep(tp,
                            &tp->t_rawq, TTIPRI | PCATCH, ttopen);
                        splx(s);
                        if (error)
                                goto out;
                        goto loop;
                }
        }
        splx(s);
        /*
         * Hang the process if it's in the background.
         */
        p = curproc;
        pr = p->p_p;
        if (isbackground(pr, tp) &&
            ISSET(tp->t_lflag, TOSTOP) && (pr->ps_flags & PS_PPWAIT) == 0 &&
            !sigismasked(p, SIGTTOU)) {
                if (pr->ps_pgrp->pg_jobc == 0) {
                        error = EIO;
                        goto out;
                }
                pgsignal(pr->ps_pgrp, SIGTTOU, 1);
                error = ttysleep_nsec(tp, &nowake, TTIPRI | PCATCH, ttybg, 
                        SEC_TO_NSEC(1));
                if (error)
                        goto out;
                goto loop;
        }
        /*
         * Process the user's data in at most OBUFSIZ chunks.  Perform any
         * output translation.  Keep track of high water mark, sleep on
         * overflow awaiting device aid in acquiring new space.
         */
        while (uio->uio_resid > 0 || cc > 0) {
                if (ISSET(tp->t_lflag, FLUSHO)) {
                        uio->uio_resid = 0;
                        goto done;
                }
                if (tp->t_outq.c_cc > hiwat)
                        goto ovhiwat;
                /*
                 * Grab a hunk of data from the user, unless we have some
                 * leftover from last time.
                 */
                if (cc == 0) {
                        cc = MIN(uio->uio_resid, OBUFSIZ);
                        cp = obuf;
                        error = uiomove(cp, cc, uio);
                        if (error) {
                                cc = 0;
                                break;
                        }
                        if (cc > obufcc)
                                obufcc = cc;

                        /* duplicate /dev/console output into console buffer */
                        if (consbufp && cn_tab &&
                            cn_tab->cn_dev == tp->t_dev && tp->t_gen == 0) {
                                int i;
                                for (i = 0; i < cc; i++) {
                                        char c = cp[i];
                                        if (c != '\0' && c != '\r' && c != 0177)
                                                msgbuf_putchar(consbufp, c);
                                }
                        }
                }
                /*
                 * If nothing fancy need be done, grab those characters we
                 * can handle without any of ttyoutput's processing and
                 * just transfer them to the output q.  For those chars
                 * which require special processing (as indicated by the
                 * bits in char_type), call ttyoutput.  After processing
                 * a hunk of data, look for FLUSHO so ^O's will take effect
                 * immediately.
                 */
                while (cc > 0) {
                        int i;
                        if (!ISSET(tp->t_oflag, OPOST))
                                ce = cc;
                        else {
                                ce = cc - scanc((u_int)cc, cp, char_type,
                                    CCLASSMASK);
                                /*
                                 * If ce is zero, then we're processing
                                 * a special character through ttyoutput.
                                 */
                                if (ce == 0) {
                                        tp->t_rocount = 0;
                                        if (ttyoutput(*cp, tp) >= 0) {
                                                /* out of space */
                                                goto ovhiwat;
                                        }
                                        cp++;
                                        cc--;
                                        if (ISSET(tp->t_lflag, FLUSHO) ||
                                            tp->t_outq.c_cc > hiwat)
                                                goto ovhiwat;
                                        continue;
                                }
                        }
                        /*
                         * A bunch of normal characters have been found.
                         * Transfer them en masse to the output queue and
                         * continue processing at the top of the loop.
                         * If there are any further characters in this
                         * <= OBUFSIZ chunk, the first should be a character
                         * requiring special handling by ttyoutput.
                         */
                        tp->t_rocount = 0;
                        i = b_to_q(cp, ce, &tp->t_outq);
                        ce -= i;
                        tp->t_column += ce;
                        cp += ce, cc -= ce, tk_nout += ce;
                        tp->t_outcc += ce;
                        if (i > 0) {
                                /* out of space */
                                goto ovhiwat;
                        }
                        if (ISSET(tp->t_lflag, FLUSHO) ||
                            tp->t_outq.c_cc > hiwat)
                                break;
                }
                ttstart(tp);
        }
out:
        /*
         * If cc is nonzero, we leave the uio structure inconsistent, as the
         * offset and iov pointers have moved forward, but it doesn't matter
         * (the call will either return short or restart with a new uio).
         */
        uio->uio_resid += cc;
done:
        if (obufcc)
                explicit_bzero(obuf, obufcc);
        return (error);

ovhiwat:
        ttstart(tp);
        s = spltty();
        /*
         * This can only occur if FLUSHO is set in t_lflag,
         * or if ttstart/oproc is synchronous (or very fast).
         */
        if (tp->t_outq.c_cc <= hiwat) {
                splx(s);
                goto loop;
        }
        if (flag & IO_NDELAY) {
                splx(s);
                uio->uio_resid += cc;
                if (obufcc)
                        explicit_bzero(obuf, obufcc);
                return (uio->uio_resid == cnt ? EWOULDBLOCK : 0);
        }
        SET(tp->t_state, TS_ASLEEP);
        error = ttysleep(tp, &tp->t_outq, TTOPRI | PCATCH, ttyout);
        splx(s);
        if (error)
                goto out;
        goto loop;
}

/*
 * Rubout one character from the rawq of tp
 * as cleanly as possible.
 */
int
ttyrub(int c, struct tty *tp)
{
        u_char *cp;
        int savecol;
        int tabc, s, cc;

        if (!ISSET(tp->t_lflag, ECHO) || ISSET(tp->t_lflag, EXTPROC))
                return 0;
        CLR(tp->t_lflag, FLUSHO);
        if (ISSET(tp->t_lflag, ECHOE)) {
                if (tp->t_rocount == 0) {
                        /*
                         * Screwed by ttwrite; retype
                         */
                        return ttyretype(tp);
                }
                if (c == ('\t' | TTY_QUOTE) || c == ('\n' | TTY_QUOTE))
                        ttyrubo(tp, 2);
                else {
                        CLR(c, ~TTY_CHARMASK);
                        switch (CCLASS(c)) {
                        case ORDINARY:
                                ttyrubo(tp, 1);
                                break;
                        case BACKSPACE:
                        case CONTROL:
                        case NEWLINE:
                        case RETURN:
                        case VTAB:
                                if (ISSET(tp->t_lflag, ECHOCTL))
                                        ttyrubo(tp, 2);
                                break;
                        case TAB:
                                if (tp->t_rocount < tp->t_rawq.c_cc)
                                        return ttyretype(tp);
                                s = spltty();
                                savecol = tp->t_column;
                                SET(tp->t_state, TS_CNTTB);
                                SET(tp->t_lflag, FLUSHO);
                                tp->t_column = tp->t_rocol;
                                for (cp = firstc(&tp->t_rawq, &tabc, &cc); cp;
                                    cp = nextc(&tp->t_rawq, cp, &tabc, &cc))
                                        ttyecho(tabc, tp);
                                CLR(tp->t_lflag, FLUSHO);
                                CLR(tp->t_state, TS_CNTTB);
                                splx(s);

                                /* savecol will now be length of the tab. */
                                savecol -= tp->t_column;
                                tp->t_column += savecol;
                                if (savecol > 8)
                                        savecol = 8;    /* overflow screw */
                                while (--savecol >= 0)
                                        (void)ttyoutput('\b', tp);
                                break;
                        default:                        /* XXX */
#define PANICSTR        "ttyrub: would panic c = %d, val = %d"
                                (void)printf(PANICSTR "\n", c, CCLASS(c));
#ifdef notdef
                                panic(PANICSTR, c, CCLASS(c));
#endif
                        }
                }
        } else if (ISSET(tp->t_lflag, ECHOPRT)) {
                if (!ISSET(tp->t_state, TS_ERASE)) {
                        SET(tp->t_state, TS_ERASE);
                        (void)ttyoutput('\\', tp);
                }
                ttyecho(c, tp);
        } else
                ttyecho(tp->t_cc[VERASE], tp);
        --tp->t_rocount;
        return 0;
}

/*
 * Back over cnt characters, erasing them.
 */
static void
ttyrubo(struct tty *tp, int cnt)
{

        while (cnt-- > 0) {
                (void)ttyoutput('\b', tp);
                (void)ttyoutput(' ', tp);
                (void)ttyoutput('\b', tp);
        }
}

/*
 * ttyretype --
 *      Reprint the rawq line.  Note, it is assumed that c_cc has already
 *      been checked.
 */
int
ttyretype(struct tty *tp)
{
        u_char *cp;
        int s, c, cc;

        /* Echo the reprint character. */
        if (tp->t_cc[VREPRINT] != _POSIX_VDISABLE)
                ttyecho(tp->t_cc[VREPRINT], tp);

        (void)ttyoutput('\n', tp);

        s = spltty();
        for (cp = firstc(&tp->t_canq, &c, &cc); cp;
            cp = nextc(&tp->t_canq, cp, &c, &cc))
                ttyecho(c, tp);
        for (cp = firstc(&tp->t_rawq, &c, &cc); cp;
            cp = nextc(&tp->t_rawq, cp, &c, &cc))
                ttyecho(c, tp);
        CLR(tp->t_state, TS_ERASE);
        splx(s);

        tp->t_rocount = tp->t_rawq.c_cc;
        tp->t_rocol = 0;
        return (1);
}

/*
 * Echo a typed character to the terminal.
 */
static void
ttyecho(int c, struct tty *tp)
{

        if (!ISSET(tp->t_state, TS_CNTTB))
                CLR(tp->t_lflag, FLUSHO);
        if ((!ISSET(tp->t_lflag, ECHO) &&
            (!ISSET(tp->t_lflag, ECHONL) || c != '\n')) ||
            ISSET(tp->t_lflag, EXTPROC))
                return;
        if (((ISSET(tp->t_lflag, ECHOCTL) &&
             (ISSET(c, TTY_CHARMASK) <= 037 && c != '\t' && c != '\n')) ||
            ISSET(c, TTY_CHARMASK) == 0177)) {
                (void)ttyoutput('^', tp);
                CLR(c, ~TTY_CHARMASK);
                if (c == 0177)
                        c = '?';
                else
                        c += 'A' - 1;
        }
        (void)ttyoutput(c, tp);
}

/*
 * Wakeup any writers if necessary.
 */
void
ttwakeupwr(struct tty *tp)
{

        if (tp->t_outq.c_cc <= tp->t_lowat) {
                if (ISSET(tp->t_state, TS_ASLEEP)) {
                        CLR(tp->t_state, TS_ASLEEP);
                        wakeup(&tp->t_outq);
                }
                selwakeup(&tp->t_wsel);
        }
}

/*
 * Wake up any readers on a tty.
 */
void
ttwakeup(struct tty *tp)
{

        selwakeup(&tp->t_rsel);
        if (ISSET(tp->t_state, TS_ASYNC))
                pgsignal(tp->t_pgrp, SIGIO, 1);
        wakeup((caddr_t)&tp->t_rawq);
}

/*
 * Look up a code for a specified speed in a conversion table;
 * used by drivers to map software speed values to hardware parameters.
 */
int
ttspeedtab(int speed, const struct speedtab *table)
{

        for ( ; table->sp_speed != -1; table++)
                if (table->sp_speed == speed)
                        return (table->sp_code);
        return (-1);
}

/*
 * Set tty hi and low water marks.
 *
 * Try to arrange the dynamics so there's about one second
 * from hi to low water.
 */
void
ttsetwater(struct tty *tp)
{
        int cps, x;

#define CLAMP(x, h, l)  ((x) > h ? h : ((x) < l) ? l : (x))

        cps = tp->t_ospeed / 10;
        tp->t_lowat = x = CLAMP(cps / 2, TTMAXLOWAT, TTMINLOWAT);
        x += cps;
        tp->t_hiwat = CLAMP(x, tp->t_outq.c_cn - TTHIWATMINSPACE, TTMINHIWAT);
#undef  CLAMP
}

/*
 * Get the total estcpu for a process, summing across threads.
 * Returns true if at least one thread is runnable/running.
 */
static int
process_sum(struct process *pr, fixpt_t *pctcpup)
{
        struct proc *p;
        fixpt_t pctcpu;
        int ret;

        ret = 0;
        pctcpu = 0;
        TAILQ_FOREACH(p, &pr->ps_threads, p_thr_link) {
                if (p->p_stat == SRUN || p->p_stat == SONPROC)
                        ret = 1;
                pctcpu += p->p_pctcpu;
        }

        *pctcpup = pctcpu;
        return (ret);
}

/*
 * Report on state of foreground process group.
 */
void
ttyinfo(struct tty *tp)
{
        struct process *pr, *pickpr;
        struct proc *p, *pick;
        struct tusage tu;
        struct timespec utime, stime;
        int tmp;

        if (ttycheckoutq(tp,0) == 0)
                return;

        /* Print load average. */
        tmp = (averunnable.ldavg[0] * 100 + FSCALE / 2) >> FSHIFT;
        ttyprintf(tp, "load: %d.%02d ", tmp / 100, tmp % 100);

        if (tp->t_session == NULL)
                ttyprintf(tp, "not a controlling terminal\n");
        else if (tp->t_pgrp == NULL)
                ttyprintf(tp, "no foreground process group\n");
        else if ((pr = LIST_FIRST(&tp->t_pgrp->pg_members)) == NULL)
empty:          ttyprintf(tp, "empty foreground process group\n");
        else {
                const char *state;
                fixpt_t pctcpu, pctcpu2;
                int run, run2;
                int calc_pctcpu;
                long rss = 0;

                /*
                 * Pick the most active process:
                 *  - prefer at least one running/runnable thread
                 *  - prefer higher total pctcpu
                 *  - prefer non-zombie
                 * Otherwise take the most recently added to this process group
                 */
                pickpr = pr;
                run = process_sum(pickpr, &pctcpu);
                while ((pr = LIST_NEXT(pr, ps_pglist)) != NULL) {
                        run2 = process_sum(pr, &pctcpu2);
                        if (run) {
                                /*
                                 * pick is running; is p running w/same or
                                 * more cpu?
                                 */
                                if (run2 && pctcpu2 >= pctcpu)
                                        goto update_pickpr;
                                continue;
                        }
                        /* pick isn't running; is p running *or* w/more cpu? */
                        if (run2 || pctcpu2 > pctcpu)
                                goto update_pickpr;

                        /* if p has less cpu or is exiting, then it's worse */
                        if (pctcpu2 < pctcpu || (pr->ps_flags & PS_EXITING))
                                continue;
update_pickpr:
                        pickpr = pr;
                        run = run2;
                        pctcpu = pctcpu2;
                }

                /* Calculate percentage cpu, resident set size. */
                calc_pctcpu = (pctcpu * 10000 + FSCALE / 2) >> FSHIFT;
                if ((pickpr->ps_flags & (PS_EMBRYO | PS_EXITING)) == 0 &&
                    pickpr->ps_vmspace != NULL)
                        rss = vm_resident_count(pickpr->ps_vmspace);

                tuagg_get_process(&tu, pickpr);
                calctsru(&tu, &utime, &stime, NULL);

                /* Round up and print user time. */
                utime.tv_nsec += 5000000;
                if (utime.tv_nsec >= 1000000000) {
                        utime.tv_sec += 1;
                        utime.tv_nsec -= 1000000000;
                }

                /* Round up and print system time. */
                stime.tv_nsec += 5000000;
                if (stime.tv_nsec >= 1000000000) {
                        stime.tv_sec += 1;
                        stime.tv_nsec -= 1000000000;
                }

                /*
                 * Find the most active thread:
                 *  - prefer runnable
                 *  - prefer higher pctcpu
                 *  - prefer living
                 * Otherwise take the newest thread
                 */
                pick = p = TAILQ_FIRST(&pickpr->ps_threads);
                if (p == NULL)
                        goto empty;
                run = p->p_stat == SRUN || p->p_stat == SONPROC;
                pctcpu = p->p_pctcpu;
                while ((p = TAILQ_NEXT(p, p_thr_link)) != NULL) {
                        run2 = p->p_stat == SRUN || p->p_stat == SONPROC;
                        pctcpu2 = p->p_pctcpu;
                        if (run) {
                                /*
                                 * pick is running; is p running w/same or
                                 * more cpu?
                                 */
                                if (run2 && pctcpu2 >= pctcpu)
                                        goto update_pick;
                                continue;
                        }
                        /* pick isn't running; is p running *or* w/more cpu? */
                        if (run2 || pctcpu2 > pctcpu)
                                goto update_pick;

                        /* if p has less cpu or is exiting, then it's worse */
                        if (pctcpu2 < pctcpu || p->p_flag & P_WEXIT)
                                continue;
update_pick:
                        pick = p;
                        run = run2;
                        pctcpu = p->p_pctcpu;
                }
                state = pick->p_stat == SONPROC ? "running" :
                        pick->p_stat == SRUN ? "runnable" :
                        pick->p_wmesg ? pick->p_wmesg : "iowait";

                ttyprintf(tp,
                    " cmd: %s %d [%s] %lld.%02ldu %lld.%02lds %d%% %ldk\n",
                    pickpr->ps_comm, pickpr->ps_pid, state,
                    (long long)utime.tv_sec, utime.tv_nsec / 10000000,
                    (long long)stime.tv_sec, stime.tv_nsec / 10000000,
                    calc_pctcpu / 100, rss);
        }
        tp->t_rocount = 0;      /* so pending input will be retyped if BS */
}

/*
 * Output char to tty; console putchar style.
 */
int
tputchar(int c, struct tty *tp)
{
        int s;

        s = spltty();
        if (ISSET(tp->t_state, TS_ISOPEN) == 0 ||
            !(ISSET(tp->t_state, TS_CARR_ON) || ISSET(tp->t_cflag, CLOCAL))) {
                splx(s);
                return (-1);
        }
        if (c == '\n')
                (void)ttyoutput('\r', tp);
        (void)ttyoutput(c, tp);
        ttstart(tp);
        splx(s);
        return (0);
}

/*
 * Sleep on chan, returning ERESTART if tty changed while we napped and
 * returning any errors (e.g. EINTR/ETIMEDOUT) reported by tsleep.  If
 * the tty is revoked, restarting a pending call will redo validation done
 * at the start of the call.
 */
int
ttysleep(struct tty *tp, void *chan, int pri, char *wmesg)
{
        return (ttysleep_nsec(tp, chan, pri, wmesg, INFSLP));
}

int
ttysleep_nsec(struct tty *tp, void *chan, int pri, char *wmesg, uint64_t nsecs)
{
        int error;
        short gen;

        gen = tp->t_gen;
        if ((error = tsleep_nsec(chan, pri, wmesg, nsecs)) != 0)
                return (error);
        return (tp->t_gen == gen ? 0 : ERESTART);
}

/*
 * Initialise the global tty list.
 */
void
tty_init(void)
{

        TAILQ_INIT(&ttylist);
        tty_count = 0;
}

/*
 * Allocate a tty structure and its associated buffers, and attach it to the
 * tty list.
 */
struct tty *
ttymalloc(int baud)
{
        struct tty *tp;

        tp = malloc(sizeof(struct tty), M_TTYS, M_WAITOK|M_ZERO);

        if (baud == 0)
                baud = 115200;

        if (baud <= 9600)
                tp->t_qlen = 1024;
        else if (baud <= 115200)
                tp->t_qlen = 4096;
        else
                tp->t_qlen = 8192;
        clalloc(&tp->t_rawq, tp->t_qlen, 1);
        clalloc(&tp->t_canq, tp->t_qlen, 1);
        /* output queue doesn't need quoting */
        clalloc(&tp->t_outq, tp->t_qlen, 0);

        rw_enter_write(&ttylist_lock);
        TAILQ_INSERT_TAIL(&ttylist, tp, tty_link);
        ++tty_count;
        rw_exit_write(&ttylist_lock);

        timeout_set(&tp->t_rstrt_to, ttrstrt, tp);

        return(tp);
}


/*
 * Free a tty structure and its buffers, after removing it from the tty list.
 */
void
ttyfree(struct tty *tp)
{
        int s;

        rw_enter_write(&ttylist_lock);
        --tty_count;
#ifdef DIAGNOSTIC
        if (tty_count < 0)
                panic("ttyfree: tty_count < 0");
#endif
        TAILQ_REMOVE(&ttylist, tp, tty_link);
        rw_exit_write(&ttylist_lock);

        s = spltty();
        klist_invalidate(&tp->t_rsel.si_note);
        klist_invalidate(&tp->t_wsel.si_note);
        splx(s);

        clfree(&tp->t_rawq);
        clfree(&tp->t_canq);
        clfree(&tp->t_outq);
        free(tp, M_TTYS, sizeof(*tp));
}

void
ttystats_init(struct itty **ttystats, int *ttycp, size_t *ttystatssiz)
{
        int ntty = 0, ttyc;
        struct itty *itp;
        struct tty *tp;
        int show_pointers = suser(curproc) == 0;

        ttyc = tty_count;
        *ttystatssiz = ttyc * sizeof(struct itty);
        *ttystats = mallocarray(ttyc, sizeof(struct itty),
            M_SYSCTL, M_WAITOK|M_ZERO);

        rw_enter_write(&ttylist_lock);
        for (tp = TAILQ_FIRST(&ttylist), itp = *ttystats; tp && ntty++ < ttyc;
            tp = TAILQ_NEXT(tp, tty_link), itp++) {
                itp->t_dev = tp->t_dev;
                itp->t_rawq_c_cc = tp->t_rawq.c_cc;
                itp->t_canq_c_cc = tp->t_canq.c_cc;
                itp->t_outq_c_cc = tp->t_outq.c_cc;
                itp->t_hiwat = tp->t_hiwat;
                itp->t_lowat = tp->t_lowat;
                if (ISSET(tp->t_oflag, OPOST))
                        itp->t_column = tp->t_column;
                itp->t_state = tp->t_state;
                if (show_pointers)
                        itp->t_session = tp->t_session;
                if (tp->t_pgrp)
                        itp->t_pgrp_pg_id = tp->t_pgrp->pg_id;
                else
                        itp->t_pgrp_pg_id = 0;
                itp->t_line = tp->t_line;
        }
        rw_exit_write(&ttylist_lock);
        *ttycp = ntty;
}

#ifndef SMALL_KERNEL
/*
 * Return tty-related information.
 */
int
sysctl_tty(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
    size_t newlen)
{
        int err;

        if (namelen != 1)
                return (ENOTDIR);

        switch (name[0]) {
        case KERN_TTY_TKNIN:
                return (sysctl_rdquad(oldp, oldlenp, newp, tk_nin));
        case KERN_TTY_TKNOUT:
                return (sysctl_rdquad(oldp, oldlenp, newp, tk_nout));
        case KERN_TTY_TKRAWCC:
                return (sysctl_rdquad(oldp, oldlenp, newp, tk_rawcc));
        case KERN_TTY_TKCANCC:
                return (sysctl_rdquad(oldp, oldlenp, newp, tk_cancc));
        case KERN_TTY_INFO:
            {
                struct itty *ttystats;
                size_t ttystatssiz;
                int ttyc;

                ttystats_init(&ttystats, &ttyc, &ttystatssiz);
                err = sysctl_rdstruct(oldp, oldlenp, newp, ttystats,
                    ttyc * sizeof(struct itty));
                free(ttystats, M_SYSCTL, ttystatssiz);
                return (err);
            }
        default:
#if NPTY > 0
                return (sysctl_pty(name, namelen, oldp, oldlenp, newp, newlen));
#else
                return (EOPNOTSUPP);
#endif
        }
        /* NOTREACHED */
}
#endif

void
ttytstamp(struct tty *tp, int octs, int ncts, int odcd, int ndcd)
{
        int doit = 0;

        if (ncts ^ octs)
                doit |= ncts ? ISSET(tp->t_flags, TS_TSTAMPCTSSET) :
                    ISSET(tp->t_flags, TS_TSTAMPCTSCLR);
        if (ndcd ^ odcd)
                doit |= ndcd ? ISSET(tp->t_flags, TS_TSTAMPDCDSET) :
                    ISSET(tp->t_flags, TS_TSTAMPDCDCLR);

        if (doit)
                microtime(&tp->t_tv);
}