nvi: Bring in version 2.1.3 (update from 2.1.1)

[dragonfly.git] / contrib / nvi / vi / v_txt.c

/*-
 * Copyright (c) 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1992, 1993, 1994, 1995, 1996
 *      Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 */

#include "config.h"

#ifndef lint
static const char sccsid[] = "$Id: v_txt.c,v 11.5 2013/05/19 20:37:45 bentley Exp $";
#endif /* not lint */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/stat.h>

#include <bitstring.h>
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "../common/common.h"
#include "vi.h"

static int       txt_abbrev __P((SCR *, TEXT *, CHAR_T *, int, int *, int *));
static void      txt_ai_resolve __P((SCR *, TEXT *, int *));
static TEXT     *txt_backup __P((SCR *, TEXTH *, TEXT *, u_int32_t *));
static int       txt_dent __P((SCR *, TEXT *, int));
static int       txt_emark __P((SCR *, TEXT *, size_t));
static void      txt_err __P((SCR *, TEXTH *));
static int       txt_fc __P((SCR *, TEXT *, int *));
static int       txt_fc_col __P((SCR *, int, ARGS **));
static int       txt_hex __P((SCR *, TEXT *));
static int       txt_insch __P((SCR *, TEXT *, CHAR_T *, u_int));
static int       txt_isrch __P((SCR *, VICMD *, TEXT *, u_int8_t *));
static int       txt_map_end __P((SCR *));
static int       txt_map_init __P((SCR *));
static int       txt_margin __P((SCR *, TEXT *, TEXT *, int *, u_int32_t));
static void      txt_nomorech __P((SCR *));
static void      txt_Rresolve __P((SCR *, TEXTH *, TEXT *, const size_t));
static int       txt_resolve __P((SCR *, TEXTH *, u_int32_t));
static int       txt_showmatch __P((SCR *, TEXT *));
static void      txt_unmap __P((SCR *, TEXT *, u_int32_t *));

/* Cursor character (space is hard to track on the screen). */
#if defined(DEBUG) && 0
#undef  CH_CURSOR
#define CH_CURSOR       '+'
#endif

/*
 * v_tcmd --
 *      Fill a buffer from the terminal for vi.
 *
 * PUBLIC: int v_tcmd __P((SCR *, VICMD *, ARG_CHAR_T, u_int));
 */
int
v_tcmd(SCR *sp, VICMD *vp, ARG_CHAR_T prompt, u_int flags)
{
        /* Normally, we end up where we started. */
        vp->m_final.lno = sp->lno;
        vp->m_final.cno = sp->cno;

        /* Initialize the map. */
        if (txt_map_init(sp))
                return (1);

        /* Move to the last line. */
        sp->lno = TMAP[0].lno;
        sp->cno = 0;

        /* Don't update the modeline for now. */
        F_SET(sp, SC_TINPUT_INFO);

        /* Set the input flags. */
        LF_SET(TXT_APPENDEOL |
            TXT_CR | TXT_ESCAPE | TXT_INFOLINE | TXT_MAPINPUT);
        if (O_ISSET(sp, O_ALTWERASE))
                LF_SET(TXT_ALTWERASE);
        if (O_ISSET(sp, O_TTYWERASE))
                LF_SET(TXT_TTYWERASE);

        /* Do the input thing. */
        if (v_txt(sp, vp, NULL, NULL, 0, prompt, 0, 1, flags))
                return (1);

        /* Reenable the modeline updates. */
        F_CLR(sp, SC_TINPUT_INFO);

        /* Clean up the map. */
        if (txt_map_end(sp))
                return (1);

        if (IS_ONELINE(sp))
                F_SET(sp, SC_SCR_REDRAW);       /* XXX */

        /* Set the cursor to the resulting position. */
        sp->lno = vp->m_final.lno;
        sp->cno = vp->m_final.cno;

        return (0);
}

/*
 * txt_map_init
 *      Initialize the screen map for colon command-line input.
 */
static int
txt_map_init(SCR *sp)
{
        SMAP *esmp;
        VI_PRIVATE *vip;

        vip = VIP(sp);
        if (!IS_ONELINE(sp)) {
                /*
                 * Fake like the user is doing input on the last line of the
                 * screen.  This makes all of the scrolling work correctly,
                 * and allows us the use of the vi text editing routines, not
                 * to mention practically infinite length ex commands.
                 *
                 * Save the current location.
                 */
                vip->sv_tm_lno = TMAP->lno;
                vip->sv_tm_soff = TMAP->soff;
                vip->sv_tm_coff = TMAP->coff;
                vip->sv_t_maxrows = sp->t_maxrows;
                vip->sv_t_minrows = sp->t_minrows;
                vip->sv_t_rows = sp->t_rows;

                /*
                 * If it's a small screen, TMAP may be small for the screen.
                 * Fix it, filling in fake lines as we go.
                 */
                if (IS_SMALL(sp))
                        for (esmp =
                            HMAP + (sp->t_maxrows - 1); TMAP < esmp; ++TMAP) {
                                TMAP[1].lno = TMAP[0].lno + 1;
                                TMAP[1].coff = HMAP->coff;
                                TMAP[1].soff = 1;
                        }

                /* Build the fake entry. */
                TMAP[1].lno = TMAP[0].lno + 1;
                TMAP[1].soff = 1;
                TMAP[1].coff = 0;
                SMAP_FLUSH(&TMAP[1]);
                ++TMAP;

                /* Reset the screen information. */
                sp->t_rows = sp->t_minrows = ++sp->t_maxrows;
        }
        return (0);
}

/*
 * txt_map_end
 *      Reset the screen map for colon command-line input.
 */
static int
txt_map_end(SCR *sp)
{
        VI_PRIVATE *vip;
        size_t cnt;

        vip = VIP(sp);
        if (!IS_ONELINE(sp)) {
                /* Restore the screen information. */
                sp->t_rows = vip->sv_t_rows;
                sp->t_minrows = vip->sv_t_minrows;
                sp->t_maxrows = vip->sv_t_maxrows;

                /*
                 * If it's a small screen, TMAP may be wrong.  Clear any
                 * lines that might have been overwritten.
                 */
                if (IS_SMALL(sp)) {
                        for (cnt = sp->t_rows; cnt <= sp->t_maxrows; ++cnt) {
                                (void)sp->gp->scr_move(sp, cnt, 0);
                                (void)sp->gp->scr_clrtoeol(sp);
                        }
                        TMAP = HMAP + (sp->t_rows - 1);
                } else
                        --TMAP;

                /*
                 * The map may be wrong if the user entered more than one
                 * (logical) line.  Fix it.  If the user entered a whole
                 * screen, this will be slow, but we probably don't care.
                 */
                if (!O_ISSET(sp, O_LEFTRIGHT))
                        while (vip->sv_tm_lno != TMAP->lno ||
                            vip->sv_tm_soff != TMAP->soff)
                                if (vs_sm_1down(sp))
                                        return (1);
        }

        /*
         * Invalidate the cursor and the line size cache, the line never
         * really existed.  This fixes bugs where the user searches for
         * the last line on the screen + 1 and the refresh routine thinks
         * that's where we just were.
         */
        VI_SCR_CFLUSH(vip);
        F_SET(vip, VIP_CUR_INVALID);

        return (0);
}

/*
 * If doing input mapping on the colon command line, may need to unmap
 * based on the command.
 */
#define UNMAP_TST                                                       \
        FL_ISSET(ec_flags, EC_MAPINPUT) && LF_ISSET(TXT_INFOLINE)

/* 
 * Internally, we maintain tp->lno and tp->cno, externally, everyone uses
 * sp->lno and sp->cno.  Make them consistent as necessary.
 */
#define UPDATE_POSITION(sp, tp) {                                       \
        (sp)->lno = (tp)->lno;                                          \
        (sp)->cno = (tp)->cno;                                          \
}

/*
 * v_txt --
 *      Vi text input.
 *
 * PUBLIC: int v_txt __P((SCR *, VICMD *, MARK *,
 * PUBLIC:    const CHAR_T *, size_t, ARG_CHAR_T, recno_t, u_long, u_int32_t));
 */
int
v_txt(
        SCR *sp,
        VICMD *vp,
        MARK *tm,               /* To MARK. */
        const CHAR_T *lp,       /* Input line. */
        size_t len,             /* Input line length. */
        ARG_CHAR_T prompt,      /* Prompt to display. */
        recno_t ai_line,        /* Line number to use for autoindent count. */
        u_long rcount,          /* Replay count. */
        u_int32_t flags)        /* TXT_* flags. */
{
        EVENT ev, *evp = NULL;  /* Current event. */
        EVENT fc;               /* File name completion event. */
        GS *gp;
        TEXT *ntp, *tp;         /* Input text structures. */
        TEXT ait;               /* Autoindent text structure. */
        TEXT wmt = {{ 0 }};     /* Wrapmargin text structure. */
        TEXTH *tiqh;
        VI_PRIVATE *vip;
        abb_t abb;              /* State of abbreviation checks. */
        carat_t carat;          /* State of the "[^0]^D" sequences. */
        quote_t quote;          /* State of quotation. */
        size_t owrite, insert;  /* Temporary copies of TEXT fields. */
        size_t margin;          /* Wrapmargin value. */
        size_t rcol;            /* 0-N: insert offset in the replay buffer. */
        size_t tcol;            /* Temporary column. */
        u_int32_t ec_flags;     /* Input mapping flags. */
#define IS_RESTART      0x01    /* Reset the incremental search. */
#define IS_RUNNING      0x02    /* Incremental search turned on. */
        u_int8_t is_flags;
        int abcnt, ab_turnoff;  /* Abbreviation character count, switch. */
        int filec_redraw;       /* Redraw after the file completion routine. */
        int hexcnt;             /* Hex character count. */
        int showmatch;          /* Showmatch set on this character. */
        int wm_set, wm_skip;    /* Wrapmargin happened, blank skip flags. */
        int max, tmp;
        int nochange;
        CHAR_T *p;

        gp = sp->gp;
        vip = VIP(sp);

        /*
         * Set the input flag, so tabs get displayed correctly
         * and everyone knows that the text buffer is in use.
         */
        F_SET(sp, SC_TINPUT);

        /*
         * Get one TEXT structure with some initial buffer space, reusing
         * the last one if it's big enough.  (All TEXT bookkeeping fields
         * default to 0 -- text_init() handles this.)  If changing a line,
         * copy it into the TEXT buffer.
         */
        tiqh = sp->tiq;
        if (!TAILQ_EMPTY(tiqh)) {
                tp = TAILQ_FIRST(tiqh);
                if (TAILQ_NEXT(tp, q) != NULL || tp->lb_len < len + 32) {
                        text_lfree(tiqh);
                        goto newtp;
                }
                tp->ai = tp->insert = tp->offset = tp->owrite = 0;
                if (lp != NULL) {
                        tp->len = len;
                        BINC_RETW(sp, tp->lb, tp->lb_len, len);
                        MEMMOVE(tp->lb, lp, len);
                } else
                        tp->len = 0;
        } else {
newtp:          if ((tp = text_init(sp, lp, len, len + 32)) == NULL)
                        return (1);
                TAILQ_INSERT_HEAD(tiqh, tp, q);
        }

        /* Set default termination condition. */
        tp->term = TERM_OK;

        /* Set the starting line, column. */
        tp->lno = sp->lno;
        tp->cno = sp->cno;

        /*
         * Set the insert and overwrite counts.  If overwriting characters,
         * do insertion afterward.  If not overwriting characters, assume
         * doing insertion.  If change is to a mark, emphasize it with an
         * CH_ENDMARK character.
         */
        if (len) {
                if (LF_ISSET(TXT_OVERWRITE)) {
                        tp->owrite = (tm->cno - tp->cno) + 1;
                        tp->insert = (len - tm->cno) - 1;
                } else
                        tp->insert = len - tp->cno;

                if (LF_ISSET(TXT_EMARK) && txt_emark(sp, tp, tm->cno))
                        return (1);
        }

        /*
         * Many of the special cases in text input are to handle autoindent
         * support.  Somebody decided that it would be a good idea if "^^D"
         * and "0^D" deleted all of the autoindented characters.  In an editor
         * that takes single character input from the user, this beggars the
         * imagination.  Note also, "^^D" resets the next lines' autoindent,
         * but "0^D" doesn't.
         *
         * We assume that autoindent only happens on empty lines, so insert
         * and overwrite will be zero.  If doing autoindent, figure out how
         * much indentation we need and fill it in.  Update input column and
         * screen cursor as necessary.
         */
        if (LF_ISSET(TXT_AUTOINDENT) && ai_line != OOBLNO) {
                if (v_txt_auto(sp, ai_line, NULL, 0, tp))
                        return (1);
                tp->cno = tp->ai;
        } else {
                /*
                 * The cc and S commands have a special feature -- leading
                 * <blank> characters are handled as autoindent characters.
                 * Beauty!
                 */
                if (LF_ISSET(TXT_AICHARS)) {
                        tp->offset = 0;
                        tp->ai = tp->cno;
                } else
                        tp->offset = tp->cno;
        }

        /* If getting a command buffer from the user, there may be a prompt. */
        if (LF_ISSET(TXT_PROMPT)) {
                tp->lb[tp->cno++] = prompt;
                ++tp->len;
                ++tp->offset;
        }

        /*
         * If appending after the end-of-line, add a space into the buffer
         * and move the cursor right.  This space is inserted, i.e. pushed
         * along, and then deleted when the line is resolved.  Assumes that
         * the cursor is already positioned at the end of the line.  This
         * avoids the nastiness of having the cursor reside on a magical
         * column, i.e. a column that doesn't really exist.  The only down
         * side is that we may wrap lines or scroll the screen before it's
         * strictly necessary.  Not a big deal.
         */
        if (LF_ISSET(TXT_APPENDEOL)) {
                tp->lb[tp->cno] = CH_CURSOR;
                ++tp->len;
                ++tp->insert;
                (void)vs_change(sp, tp->lno, LINE_RESET);
        }

        /*
         * Historic practice is that the wrapmargin value was a distance
         * from the RIGHT-HAND margin, not the left.  It's more useful to
         * us as a distance from the left-hand margin, i.e. the same as
         * the wraplen value.  The wrapmargin option is historic practice.
         * Nvi added the wraplen option so that it would be possible to
         * edit files with consistent margins without knowing the number of
         * columns in the window.
         *
         * XXX
         * Setting margin causes a significant performance hit.  Normally
         * we don't update the screen if there are keys waiting, but we
         * have to if margin is set, otherwise the screen routines don't
         * know where the cursor is.
         *
         * !!!
         * Abbreviated keys were affected by the wrapmargin option in the
         * historic 4BSD vi.  Mapped keys were usually, but sometimes not.
         * See the comment in vi/v_text():set_txt_std for more information.
         *
         * !!!
         * One more special case.  If an inserted <blank> character causes
         * wrapmargin to split the line, the next user entered character is
         * discarded if it's a <space> character.
         */
        wm_set = wm_skip = 0;
        if (LF_ISSET(TXT_WRAPMARGIN))
                if ((margin = O_VAL(sp, O_WRAPMARGIN)) != 0)
                        margin = sp->cols - margin;
                else
                        margin = O_VAL(sp, O_WRAPLEN);
        else
                margin = 0;

        /* Initialize abbreviation checks. */
        abcnt = ab_turnoff = 0;
        abb = F_ISSET(gp, G_ABBREV) &&
            LF_ISSET(TXT_MAPINPUT) ? AB_INWORD : AB_NOTSET;

        /*
         * Set up the dot command.  Dot commands are done by saving the actual
         * characters and then reevaluating them so that things like wrapmargin
         * can change between the insert and the replay.
         *
         * !!!
         * Historically, vi did not remap or reabbreviate replayed input.  (It
         * did beep at you if you changed an abbreviation and then replayed the
         * input.  We're not that compatible.)  We don't have to do anything to
         * avoid remapping, as we're not getting characters from the terminal
         * routines.  Turn the abbreviation check off.
         *
         * XXX
         * It would be nice if we could swallow backspaces and such, but it's
         * not all that easy to do.  What we can do is turn off the common
         * error messages during the replay.  Otherwise, when the user enters
         * an illegal command, e.g., "Ia<erase><erase><erase><erase>b<escape>",
         * and then does a '.', they get a list of error messages after command
         * completion.
         */
        rcol = 0;
        if (LF_ISSET(TXT_REPLAY)) {
                abb = AB_NOTSET;
                LF_CLR(TXT_RECORD);
        }

        /* Other text input mode setup. */
        quote = Q_NOTSET;
        carat = C_NOTSET;
        nochange = 0;
        FL_INIT(is_flags,
            LF_ISSET(TXT_SEARCHINCR) ? IS_RESTART | IS_RUNNING : 0);
        filec_redraw = hexcnt = showmatch = 0;

        /* Initialize input flags. */
        ec_flags = LF_ISSET(TXT_MAPINPUT) ? EC_MAPINPUT : 0;

        /* Refresh the screen. */
        UPDATE_POSITION(sp, tp);
        if (vs_refresh(sp, 1))
                return (1);

        /* If it's dot, just do it now. */
        if (F_ISSET(vp, VC_ISDOT))
                goto replay;

        /* Get an event. */
        evp = &ev;
next:   if (v_event_get(sp, evp, 0, ec_flags))
                return (1);

        /*
         * If file completion overwrote part of the screen and nothing else has
         * been displayed, clean up.  We don't do this as part of the normal
         * message resolution because we know the user is on the colon command
         * line and there's no reason to enter explicit characters to continue.
         */
        if (filec_redraw && !F_ISSET(sp, SC_SCR_EXWROTE)) {
                filec_redraw = 0;

                fc.e_event = E_REPAINT;
                fc.e_flno = vip->totalcount >=
                    sp->rows ? 1 : sp->rows - vip->totalcount;
                fc.e_tlno = sp->rows;
                vip->linecount = vip->lcontinue = vip->totalcount = 0;
                (void)vs_repaint(sp, &fc);
                (void)vs_refresh(sp, 1);
        }

        /* Deal with all non-character events. */
        switch (evp->e_event) {
        case E_CHARACTER:
                break;
        case E_ERR:
        case E_EOF:
                F_SET(sp, SC_EXIT_FORCE);
                return (1);
        case E_INTERRUPT:
                /*
                 * !!!
                 * Historically, <interrupt> exited the user from text input
                 * mode or cancelled a colon command, and returned to command
                 * mode.  It also beeped the terminal, but that seems a bit
                 * excessive.
                 */
                goto k_escape;
        case E_REPAINT:
                if (vs_repaint(sp, &ev))
                        return (1);
                goto next;
        case E_WRESIZE:
                /* <resize> interrupts the input mode. */
                v_emsg(sp, NULL, VIM_WRESIZE);
                goto k_escape;
        default:
                v_event_err(sp, evp);
                goto k_escape;
        }

        /*
         * !!!
         * If the first character of the input is a nul, replay the previous
         * input.  (Historically, it's okay to replay non-existent input.)
         * This was not documented as far as I know, and is a great test of vi
         * clones.
         */
        if (LF_ISSET(TXT_RECORD) && rcol == 0 && evp->e_c == '\0') {
                if (vip->rep == NULL)
                        goto done;

                abb = AB_NOTSET;
                LF_CLR(TXT_RECORD);
                LF_SET(TXT_REPLAY);
                goto replay;
        }

        /*
         * File name completion and colon command-line editing.   We don't
         * have enough meta characters, so we expect people to overload
         * them.  If the two characters are the same, then we do file name
         * completion if the cursor is past the first column, and do colon
         * command-line editing if it's not.
         */
        if (quote == Q_NOTSET) {
                int L__cedit, L__filec;

                L__cedit = L__filec = 0;
                if (LF_ISSET(TXT_CEDIT) && O_STR(sp, O_CEDIT) != NULL &&
                    O_STR(sp, O_CEDIT)[0] == evp->e_c)
                        L__cedit = 1;
                if (LF_ISSET(TXT_FILEC) && O_STR(sp, O_FILEC) != NULL &&
                    O_STR(sp, O_FILEC)[0] == evp->e_c)
                        L__filec = 1;
                if (L__cedit == 1 && (L__filec == 0 || tp->cno == tp->offset)) {
                        tp->term = TERM_CEDIT;
                        goto k_escape;
                }
                if (L__filec == 1) {
                        if (txt_fc(sp, tp, &filec_redraw))
                                goto err;
                        goto resolve;
                }
        }

        /* Abbreviation overflow check.  See comment in txt_abbrev(). */
#define MAX_ABBREVIATION_EXPANSION      256
        if (F_ISSET(&evp->e_ch, CH_ABBREVIATED)) {
                if (++abcnt > MAX_ABBREVIATION_EXPANSION) {
                        if (v_event_flush(sp, CH_ABBREVIATED))
                                msgq(sp, M_ERR,
"191|Abbreviation exceeded expansion limit: characters discarded");
                        abcnt = 0;
                        if (LF_ISSET(TXT_REPLAY))
                                goto done;
                        goto resolve;
                }
        } else
                abcnt = 0;

        /* Check to see if the character fits into the replay buffers. */
        if (LF_ISSET(TXT_RECORD)) {
                BINC_GOTO(sp, EVENT, vip->rep,
                    vip->rep_len, (rcol + 1) * sizeof(EVENT));
                vip->rep[rcol++] = *evp;
        }

replay: if (LF_ISSET(TXT_REPLAY)) {
                if (rcol == vip->rep_cnt)
                        goto k_escape;
                evp = vip->rep + rcol++;
        }

        /* Wrapmargin check for leading space. */
        if (wm_skip) {
                wm_skip = 0;
                if (evp->e_c == ' ')
                        goto resolve;
        }

        /* If quoted by someone else, simply insert the character. */
        if (F_ISSET(&evp->e_ch, CH_QUOTED))
                goto insq_ch;

        /*
         * !!!
         * If this character was quoted by a K_VLNEXT or a backslash, replace
         * the placeholder (a carat or a backslash) with the new character.
         * If it was quoted by a K_VLNEXT, we've already adjusted the cursor
         * because it has to appear on top of the placeholder character.  If
         * it was quoted by a backslash, adjust the cursor now, the cursor
         * doesn't appear on top of it.  Historic practice in both cases.
         *
         * Skip tests for abbreviations; ":ab xa XA" followed by "ixa^V<space>"
         * doesn't perform an abbreviation.  Special case, ^V^J (not ^V^M) is
         * the same as ^J, historically.
         */
        if (quote == Q_BTHIS || quote == Q_VTHIS) {
                FL_CLR(ec_flags, EC_QUOTED);
                if (LF_ISSET(TXT_MAPINPUT))
                        FL_SET(ec_flags, EC_MAPINPUT);

                if (quote == Q_BTHIS &&
                    (evp->e_value == K_VERASE || evp->e_value == K_VKILL)) {
                        quote = Q_NOTSET;
                        --tp->cno;
                        ++tp->owrite;
                        goto insl_ch;
                }
                if (quote == Q_VTHIS && evp->e_value != K_NL) {
                        quote = Q_NOTSET;
                        goto insl_ch;
                }
                quote = Q_NOTSET;
        }

        /*
         * !!!
         * Translate "<CH_HEX>[isxdigit()]*" to a character with a hex value:
         * this test delimits the value by any non-hex character.  Offset by
         * one, we use 0 to mean that we've found <CH_HEX>.
         */
        if (hexcnt > 1 && !ISXDIGIT(evp->e_c)) {
                hexcnt = 0;
                if (txt_hex(sp, tp))
                        goto err;
        }

        switch (evp->e_value) {
        case K_CR:                              /* Carriage return. */
        case K_NL:                              /* New line. */
                /* Return in script windows and the command line. */
k_cr:           if (LF_ISSET(TXT_CR)) {
                        /*
                         * If this was a map, we may have not displayed
                         * the line.  Display it, just in case.
                         *
                         * If a script window and not the colon line,
                         * push a <cr> so it gets executed.
                         */
                        if (LF_ISSET(TXT_INFOLINE)) {
                                if (vs_change(sp, tp->lno, LINE_RESET))
                                        goto err;
                        } else if (F_ISSET(sp, SC_SCRIPT))
                                (void)v_event_push(sp, NULL, L("\r"), 1, CH_NOMAP);

                        /* Set term condition: if empty. */
                        if (tp->cno <= tp->offset)
                                tp->term = TERM_CR;
                        /*
                         * Set term condition: if searching incrementally and
                         * the user entered a pattern, return a completed
                         * search, regardless if the entire pattern was found.
                         */
                        if (FL_ISSET(is_flags, IS_RUNNING) &&
                            tp->cno >= tp->offset + 1)
                                tp->term = TERM_SEARCH;

                        goto k_escape;
                }

#define LINE_RESOLVE {                                                  \
                /*                                                      \
                 * Handle abbreviations.  If there was one, discard the \
                 * replay characters.                                   \
                 */                                                     \
                if (abb == AB_INWORD &&                                 \
                    !LF_ISSET(TXT_REPLAY) && F_ISSET(gp, G_ABBREV)) {   \
                        if (txt_abbrev(sp, tp, &evp->e_c,               \
                            LF_ISSET(TXT_INFOLINE), &tmp,               \
                            &ab_turnoff))                               \
                                goto err;                               \
                        if (tmp) {                                      \
                                if (LF_ISSET(TXT_RECORD))               \
                                        rcol -= tmp + 1;                \
                                goto resolve;                           \
                        }                                               \
                }                                                       \
                if (abb != AB_NOTSET)                                   \
                        abb = AB_NOTWORD;                               \
                if (UNMAP_TST)                                          \
                        txt_unmap(sp, tp, &ec_flags);                   \
                /*                                                      \
                 * Delete any appended cursor.  It's possible to get in \
                 * situations where TXT_APPENDEOL is set but tp->insert \
                 * is 0 when using the R command and all the characters \
                 * are tp->owrite characters.                           \
                 */                                                     \
                if (LF_ISSET(TXT_APPENDEOL) && tp->insert > 0) {        \
                        --tp->len;                                      \
                        --tp->insert;                                   \
                }                                                       \
}
                LINE_RESOLVE;

                /*
                 * Save the current line information for restoration in
                 * txt_backup(), and set the line final length.
                 */
                tp->sv_len = tp->len;
                tp->sv_cno = tp->cno;
                tp->len = tp->cno;

                /* Update the old line. */
                if (vs_change(sp, tp->lno, LINE_RESET))
                        goto err;

                /*
                 * Historic practice, when the autoindent edit option was set,
                 * was to delete <blank> characters following the inserted
                 * newline.  This affected the 'R', 'c', and 's' commands; 'c'
                 * and 's' retained the insert characters only, 'R' moved the
                 * overwrite and insert characters into the next TEXT structure.
                 * We keep track of the number of characters erased for the 'R'
                 * command so that the final resolution of the line is correct.
                 */
                tp->R_erase = 0;
                owrite = tp->owrite;
                insert = tp->insert;
                if (LF_ISSET(TXT_REPLACE) && owrite != 0) {
                        for (p = tp->lb + tp->cno; owrite > 0 && isblank(*p);
                            ++p, --owrite, ++tp->R_erase);
                        if (owrite == 0)
                                for (; insert > 0 && isblank(*p);
                                    ++p, ++tp->R_erase, --insert);
                } else {
                        p = tp->lb + tp->cno + owrite;
                        if (O_ISSET(sp, O_AUTOINDENT))
                                for (; insert > 0 &&
                                    isblank(*p); ++p, --insert);
                        owrite = 0;
                }

                /*
                 * !!!
                 * Create a new line and insert the new TEXT into the queue.
                 * DON'T insert until the old line has been updated, or the
                 * inserted line count in line.c:db_get() will be wrong.
                 */
                if ((ntp = text_init(sp, p,
                    insert + owrite, insert + owrite + 32)) == NULL)
                        goto err;
                TAILQ_INSERT_TAIL(sp->tiq, ntp, q);

                /* Set up bookkeeping for the new line. */
                ntp->insert = insert;
                ntp->owrite = owrite;
                ntp->lno = tp->lno + 1;

                /*
                 * Reset the autoindent line value.  0^D keeps the autoindent
                 * line from changing, ^D changes the level, even if there were
                 * no characters in the old line.  Note, if using the current
                 * tp structure, use the cursor as the length, the autoindent
                 * characters may have been erased.
                 */
                if (LF_ISSET(TXT_AUTOINDENT)) {
                        if (nochange) {
                                nochange = 0;
                                if (v_txt_auto(sp, OOBLNO, &ait, ait.ai, ntp))
                                        goto err;
                                FREE_SPACEW(sp, ait.lb, ait.lb_len);
                        } else
                                if (v_txt_auto(sp, OOBLNO, tp, tp->cno, ntp))
                                        goto err;
                        carat = C_NOTSET;
                }

                /* Reset the cursor. */
                ntp->cno = ntp->ai;

                /*
                 * If we're here because wrapmargin was set and we've broken a
                 * line, there may be additional information (i.e. the start of
                 * a line) in the wmt structure.
                 */
                if (wm_set) {
                        if (wmt.offset != 0 ||
                            wmt.owrite != 0 || wmt.insert != 0) {
#define WMTSPACE        wmt.offset + wmt.owrite + wmt.insert
                                BINC_GOTOW(sp, ntp->lb,
                                    ntp->lb_len, ntp->len + WMTSPACE + 32);
                                MEMMOVE(ntp->lb + ntp->cno, wmt.lb, WMTSPACE);
                                ntp->len += WMTSPACE;
                                ntp->cno += wmt.offset;
                                ntp->owrite = wmt.owrite;
                                ntp->insert = wmt.insert;
                        }
                        wm_set = 0;
                }

                /* New lines are TXT_APPENDEOL. */
                if (ntp->owrite == 0 && ntp->insert == 0) {
                        BINC_GOTOW(sp, ntp->lb, ntp->lb_len, ntp->len + 1);
                        LF_SET(TXT_APPENDEOL);
                        ntp->lb[ntp->cno] = CH_CURSOR;
                        ++ntp->insert;
                        ++ntp->len;
                }

                /* Swap old and new TEXT's, and update the new line. */
                tp = ntp;
                if (vs_change(sp, tp->lno, LINE_INSERT))
                        goto err;

                goto resolve;
        case K_ESCAPE:                          /* Escape. */
                if (!LF_ISSET(TXT_ESCAPE))
                        goto ins_ch;

                /* If we have a count, start replaying the input. */
                if (rcount > 1) {
                        --rcount;

                        vip->rep_cnt = rcol;
                        rcol = 0;
                        abb = AB_NOTSET;
                        LF_CLR(TXT_RECORD);
                        LF_SET(TXT_REPLAY);

                        /*
                         * Some commands (e.g. 'o') need a <newline> for each
                         * repetition.
                         */
                        if (LF_ISSET(TXT_ADDNEWLINE))
                                goto k_cr;

                        /*
                         * The R command turns into the 'a' command after the
                         * first repetition.
                         */
                        if (LF_ISSET(TXT_REPLACE)) {
                                tp->insert = tp->owrite;
                                tp->owrite = 0;
                                LF_CLR(TXT_REPLACE);
                        }
                        goto replay;
                }

                /* Set term condition: if empty. */
                if (tp->cno <= tp->offset)
                        tp->term = TERM_ESC;
                /*
                 * Set term condition: if searching incrementally and the user
                 * entered a pattern, return a completed search, regardless if
                 * the entire pattern was found.
                 */
                if (FL_ISSET(is_flags, IS_RUNNING) && tp->cno >= tp->offset + 1)
                        tp->term = TERM_SEARCH;

k_escape:       LINE_RESOLVE;

                /*
                 * Clean up for the 'R' command, restoring overwrite
                 * characters, and making them into insert characters.
                 */
                if (LF_ISSET(TXT_REPLACE))
                        txt_Rresolve(sp, sp->tiq, tp, len);

                /*
                 * If there are any overwrite characters, copy down
                 * any insert characters, and decrement the length.
                 */
                if (tp->owrite) {
                        if (tp->insert)
                                MEMMOVE(tp->lb + tp->cno,
                                    tp->lb + tp->cno + tp->owrite, tp->insert);
                        tp->len -= tp->owrite;
                }

                /*
                 * Optionally resolve the lines into the file.  If not
                 * resolving the lines into the file, end the line with
                 * a nul.  If the line is empty, then set the length to
                 * 0, the termination condition has already been set.
                 *
                 * XXX
                 * This is wrong, should pass back a length.
                 */
                if (LF_ISSET(TXT_RESOLVE)) {
                        if (txt_resolve(sp, sp->tiq, flags))
                                goto err;
                } else {
                        BINC_GOTOW(sp, tp->lb, tp->lb_len, tp->len + 1);
                        tp->lb[tp->len] = '\0';
                }

                /*
                 * Set the return cursor position to rest on the last
                 * inserted character.
                 */
                if (tp->cno != 0)
                        --tp->cno;

                /* Update the last line. */
                if (vs_change(sp, tp->lno, LINE_RESET))
                        return (1);
                goto done;
        case K_CARAT:                   /* Delete autoindent chars. */
                if (tp->cno <= tp->ai && LF_ISSET(TXT_AUTOINDENT))
                        carat = C_CARATSET;
                goto ins_ch;
        case K_ZERO:                    /* Delete autoindent chars. */
                if (tp->cno <= tp->ai && LF_ISSET(TXT_AUTOINDENT))
                        carat = C_ZEROSET;
                goto ins_ch;
        case K_CNTRLD:                  /* Delete autoindent char. */
                /*
                 * If in the first column or no characters to erase, ignore
                 * the ^D (this matches historic practice).  If not doing
                 * autoindent or already inserted non-ai characters, it's a
                 * literal.  The latter test is done in the switch, as the
                 * CARAT forms are N + 1, not N.
                 */
                if (!LF_ISSET(TXT_AUTOINDENT))
                        goto ins_ch;
                if (tp->cno == 0)
                        goto resolve;

                switch (carat) {
                case C_CARATSET:        /* ^^D */
                        if (tp->ai == 0 || tp->cno > tp->ai + tp->offset + 1)
                                goto ins_ch;

                        /* Save the ai string for later. */
                        ait.lb = NULL;
                        ait.lb_len = 0;
                        BINC_GOTOW(sp, ait.lb, ait.lb_len, tp->ai);
                        MEMMOVE(ait.lb, tp->lb, tp->ai);
                        ait.ai = ait.len = tp->ai;

                        carat = C_NOTSET;
                        nochange = 1;
                        goto leftmargin;
                case C_ZEROSET:         /* 0^D */
                        if (tp->ai == 0 || tp->cno > tp->ai + tp->offset + 1)
                                goto ins_ch;

                        carat = C_NOTSET;
leftmargin:             tp->lb[tp->cno - 1] = ' ';
                        tp->owrite += tp->cno - tp->offset;
                        tp->ai = 0;
                        tp->cno = tp->offset;
                        break;
                case C_NOTSET:          /* ^D */
                        if (tp->ai == 0 || tp->cno > tp->ai + tp->offset)
                                goto ins_ch;

                        (void)txt_dent(sp, tp, 0);
                        break;
                default:
                        abort();
                }
                break;
        case K_VERASE:                  /* Erase the last character. */
                /* If can erase over the prompt, return. */
                if (tp->cno <= tp->offset && LF_ISSET(TXT_BS)) {
                        tp->term = TERM_BS;
                        goto done;
                }

                /*
                 * If at the beginning of the line, try and drop back to a
                 * previously inserted line.
                 */
                if (tp->cno == 0) {
                        if ((ntp =
                            txt_backup(sp, sp->tiq, tp, &flags)) == NULL)
                                goto err;
                        tp = ntp;
                        break;
                }

                /* If nothing to erase, bell the user. */
                if (tp->cno <= tp->offset) {
                        if (!LF_ISSET(TXT_REPLAY))
                                txt_nomorech(sp);
                        break;
                }

                /* Drop back one character. */
                --tp->cno;

                /*
                 * Historically, vi didn't replace the erased characters with
                 * <blank>s, presumably because it's easier to fix a minor
                 * typing mistake and continue on if the previous letters are
                 * already there.  This is a problem for incremental searching,
                 * because the user can no longer tell where they are in the
                 * colon command line because the cursor is at the last search
                 * point in the screen.  So, if incrementally searching, erase
                 * the erased characters from the screen.
                 */
                if (FL_ISSET(is_flags, IS_RUNNING))
                        tp->lb[tp->cno] = ' ';

                /*
                 * Increment overwrite, decrement ai if deleted.
                 *
                 * !!!
                 * Historic vi did not permit users to use erase characters
                 * to delete autoindent characters.  We do.  Eat hot death,
                 * POSIX.
                 */
                ++tp->owrite;
                if (tp->cno < tp->ai)
                        --tp->ai;

                /* Reset if we deleted an incremental search character. */
                if (FL_ISSET(is_flags, IS_RUNNING))
                        FL_SET(is_flags, IS_RESTART);
                break;
        case K_VWERASE:                 /* Skip back one word. */
                /*
                 * If at the beginning of the line, try and drop back to a
                 * previously inserted line.
                 */
                if (tp->cno == 0) {
                        if ((ntp =
                            txt_backup(sp, sp->tiq, tp, &flags)) == NULL)
                                goto err;
                        tp = ntp;
                }

                /*
                 * If at offset, nothing to erase so bell the user.
                 */
                if (tp->cno <= tp->offset) {
                        if (!LF_ISSET(TXT_REPLAY))
                                txt_nomorech(sp);
                        break;
                }

                /*
                 * The first werase goes back to any autoindent column and the
                 * second werase goes back to the offset.
                 *
                 * !!!
                 * Historic vi did not permit users to use erase characters to
                 * delete autoindent characters.
                 */
                if (tp->ai && tp->cno > tp->ai)
                        max = tp->ai;
                else {
                        tp->ai = 0;
                        max = tp->offset;
                }

                /* Skip over trailing space characters. */
                while (tp->cno > max && ISBLANK(tp->lb[tp->cno - 1])) {
                        --tp->cno;
                        ++tp->owrite;
                }
                if (tp->cno == max)
                        break;
                /*
                 * There are three types of word erase found on UNIX systems.
                 * They can be identified by how the string /a/b/c is treated
                 * -- as 1, 3, or 6 words.  Historic vi had two classes of
                 * characters, and strings were delimited by them and
                 * <blank>'s, so, 6 words.  The historic tty interface used
                 * <blank>'s to delimit strings, so, 1 word.  The algorithm
                 * offered in the 4.4BSD tty interface (as stty altwerase)
                 * treats it as 3 words -- there are two classes of
                 * characters, and strings are delimited by them and
                 * <blank>'s.  The difference is that the type of the first
                 * erased character erased is ignored, which is exactly right
                 * when erasing pathname components.  The edit options
                 * TXT_ALTWERASE and TXT_TTYWERASE specify the 4.4BSD tty
                 * interface and the historic tty driver behavior,
                 * respectively, and the default is the same as the historic
                 * vi behavior.
                 *
                 * Overwrite erased characters if doing incremental search;
                 * see comment above.
                 */
                if (LF_ISSET(TXT_TTYWERASE))
                        while (tp->cno > max) {
                                if (ISBLANK(tp->lb[tp->cno - 1]))
                                        break;
                                --tp->cno;
                                ++tp->owrite;
                                if (FL_ISSET(is_flags, IS_RUNNING))
                                        tp->lb[tp->cno] = ' ';
                        }
                else {
                        if (LF_ISSET(TXT_ALTWERASE)) {
                                --tp->cno;
                                ++tp->owrite;
                                if (FL_ISSET(is_flags, IS_RUNNING))
                                        tp->lb[tp->cno] = ' ';
                        }
                        if (tp->cno > max)
                                tmp = inword(tp->lb[tp->cno - 1]);
                        while (tp->cno > max) {
                                if (tmp != inword(tp->lb[tp->cno - 1])
                                    || ISBLANK(tp->lb[tp->cno - 1]))
                                        break;
                                --tp->cno;
                                ++tp->owrite;
                                if (FL_ISSET(is_flags, IS_RUNNING))
                                        tp->lb[tp->cno] = ' ';
                        }
                }

                /* Reset if we deleted an incremental search character. */
                if (FL_ISSET(is_flags, IS_RUNNING))
                        FL_SET(is_flags, IS_RESTART);
                break;
        case K_VKILL:                   /* Restart this line. */
                /*
                 * !!!
                 * If at the beginning of the line, try and drop back to a
                 * previously inserted line.  Historic vi did not permit
                 * users to go back to previous lines.
                 */
                if (tp->cno == 0) {
                        if ((ntp =
                            txt_backup(sp, sp->tiq, tp, &flags)) == NULL)
                                goto err;
                        tp = ntp;
                }

                /* If at offset, nothing to erase so bell the user. */
                if (tp->cno <= tp->offset) {
                        if (!LF_ISSET(TXT_REPLAY))
                                txt_nomorech(sp);
                        break;
                }

                /*
                 * First kill goes back to any autoindent and second kill goes
                 * back to the offset.
                 *
                 * !!!
                 * Historic vi did not permit users to use erase characters to
                 * delete autoindent characters.
                 */
                if (tp->ai && tp->cno > tp->ai)
                        max = tp->ai;
                else {
                        tp->ai = 0;
                        max = tp->offset;
                }
                tp->owrite += tp->cno - max;

                /*
                 * Overwrite erased characters if doing incremental search;
                 * see comment above.
                 */
                if (FL_ISSET(is_flags, IS_RUNNING))
                        do {
                                tp->lb[--tp->cno] = ' ';
                        } while (tp->cno > max);
                else
                        tp->cno = max;

                /* Reset if we deleted an incremental search character. */
                if (FL_ISSET(is_flags, IS_RUNNING))
                        FL_SET(is_flags, IS_RESTART);
                break;
        case K_CNTRLT:                  /* Add autoindent characters. */
                if (!LF_ISSET(TXT_CNTRLT))
                        goto ins_ch;
                if (txt_dent(sp, tp, 1))
                        goto err;
                goto ebuf_chk;
        case K_BACKSLASH:               /* Quote next erase/kill. */
                /*
                 * !!!
                 * Historic vi tried to make abbreviations after a backslash
                 * escape work.  If you did ":ab x y", and inserted "x\^H",
                 * (assuming the erase character was ^H) you got "x^H", and
                 * no abbreviation was done.  If you inserted "x\z", however,
                 * it tried to back up and do the abbreviation, i.e. replace
                 * 'x' with 'y'.  The problem was it got it wrong, and you
                 * ended up with "zy\".
                 *
                 * This is really hard to do (you have to remember the
                 * word/non-word state, for example), and doesn't make any
                 * sense to me.  Both backslash and the characters it
                 * (usually) escapes will individually trigger the
                 * abbreviation, so I don't see why the combination of them
                 * wouldn't.  I don't expect to get caught on this one,
                 * particularly since it never worked right, but I've been
                 * wrong before.
                 *
                 * Do the tests for abbreviations, so ":ab xa XA",
                 * "ixa\<K_VERASE>" performs the abbreviation.
                 */
                quote = Q_BNEXT;
                goto insq_ch;
        case K_VLNEXT:                  /* Quote next character. */
                evp->e_c = '^';
                quote = Q_VNEXT;
                /*
                 * Turn on the quote flag so that the underlying routines
                 * quote the next character where it's possible. Turn off
                 * the input mapbiting flag so that we don't remap the next
                 * character.
                 */
                FL_SET(ec_flags, EC_QUOTED);
                FL_CLR(ec_flags, EC_MAPINPUT);

                /*
                 * !!!
                 * Skip the tests for abbreviations, so ":ab xa XA",
                 * "ixa^V<space>" doesn't perform the abbreviation.
                 */
                goto insl_ch;
        case K_HEXCHAR:
                hexcnt = 1;
                goto insq_ch;
        default:                        /* Insert the character. */
                if (LF_ISSET(TXT_SHOWMATCH)) {
                        CHAR_T *match_chars, *cp;

                        match_chars = VIP(sp)->mcs;
                        cp = STRCHR(match_chars, evp->e_c);
                        if (cp != NULL && (cp - match_chars) & 1)
                                showmatch = 1;
                }
ins_ch:         /*
                 * Historically, vi eliminated nul's out of hand.  If the
                 * beautify option was set, it also deleted any unknown
                 * ASCII value less than space (040) and the del character
                 * (0177), except for tabs.  Unknown is a key word here.
                 * Most vi documentation claims that it deleted everything
                 * but <tab>, <nl> and <ff>, as that's what the original
                 * 4BSD documentation said.  This is obviously wrong,
                 * however, as <esc> would be included in that list.  What
                 * we do is eliminate any unquoted, iscntrl() character that
                 * wasn't a replay and wasn't handled specially, except
                 * <tab> or <ff>.
                 */
                if (LF_ISSET(TXT_BEAUTIFY) && ISCNTRL(evp->e_c) &&
                    evp->e_value != K_FORMFEED && evp->e_value != K_TAB) {
                        msgq(sp, M_BERR,
                            "192|Illegal character; quote to enter");
                        if (LF_ISSET(TXT_REPLAY))
                                goto done;
                        break;
                }

insq_ch:        /*
                 * If entering a non-word character after a word, check for
                 * abbreviations.  If there was one, discard replay characters.
                 * If entering a blank character, check for unmap commands,
                 * as well.
                 */
                if (!inword(evp->e_c)) {
                        if (abb == AB_INWORD &&
                            !LF_ISSET(TXT_REPLAY) && F_ISSET(gp, G_ABBREV)) {
                                if (txt_abbrev(sp, tp, &evp->e_c,
                                    LF_ISSET(TXT_INFOLINE), &tmp, &ab_turnoff))
                                        goto err;
                                if (tmp) {
                                        if (LF_ISSET(TXT_RECORD))
                                                rcol -= tmp + 1;
                                        goto resolve;
                                }
                        }
                        if (isblank(evp->e_c) && UNMAP_TST)
                                txt_unmap(sp, tp, &ec_flags);
                }
                if (abb != AB_NOTSET)
                        abb = inword(evp->e_c) ? AB_INWORD : AB_NOTWORD;

insl_ch:        if (txt_insch(sp, tp, &evp->e_c, flags))
                        goto err;

                /*
                 * If we're using K_VLNEXT to quote the next character, then
                 * we want the cursor to position itself on the ^ placeholder
                 * we're displaying, to match historic practice.
                 */
                if (quote == Q_VNEXT) {
                        --tp->cno;
                        ++tp->owrite;
                }

                /*
                 * !!!
                 * Translate "<CH_HEX>[isxdigit()]*" to a character with
                 * a hex value: this test delimits the value by the max
                 * number of hex bytes.  Offset by one, we use 0 to mean
                 * that we've found <CH_HEX>.
                 */
                if (hexcnt != 0 && hexcnt++ == 3) {
                        hexcnt = 0;
                        if (txt_hex(sp, tp))
                                goto err;
                }

                /*
                 * Check to see if we've crossed the margin.
                 *
                 * !!!
                 * In the historic vi, the wrapmargin value was figured out
                 * using the display widths of the characters, i.e. <tab>
                 * characters were counted as two characters if the list edit
                 * option is set, but as the tabstop edit option number of
                 * characters otherwise.  That's what the vs_column() function
                 * gives us, so we use it.
                 */
                if (margin != 0) {
                        if (vs_column(sp, &tcol))
                                goto err;
                        if (tcol >= margin) {
                                if (txt_margin(sp, tp, &wmt, &tmp, flags))
                                        goto err;
                                if (tmp) {
                                        if (isblank(evp->e_c))
                                                wm_skip = 1;
                                        wm_set = 1;
                                        goto k_cr;
                                }
                        }
                }

                /*
                 * If we've reached the end of the buffer, then we need to
                 * switch into insert mode.  This happens when there's a
                 * change to a mark and the user puts in more characters than
                 * the length of the motion.
                 */
ebuf_chk:       if (tp->cno >= tp->len) {
                        BINC_GOTOW(sp, tp->lb, tp->lb_len, tp->len + 1);
                        LF_SET(TXT_APPENDEOL);

                        tp->lb[tp->cno] = CH_CURSOR;
                        ++tp->insert;
                        ++tp->len;
                }

                /* Step the quote state forward. */
                if (quote != Q_NOTSET) {
                        if (quote == Q_BNEXT)
                                quote = Q_BTHIS;
                        if (quote == Q_VNEXT)
                                quote = Q_VTHIS;
                }
                break;
        }

#ifdef DEBUG
        if (tp->cno + tp->insert + tp->owrite != tp->len) {
                msgq(sp, M_ERR,
                    "len %zu != cno: %zu ai: %zu insert %zu overwrite %zu",
                    tp->len, tp->cno, tp->ai, tp->insert, tp->owrite);
                if (LF_ISSET(TXT_REPLAY))
                        goto done;
                tp->len = tp->cno + tp->insert + tp->owrite;
        }
#endif

resolve:/*
         * 1: If we don't need to know where the cursor really is and we're
         *    replaying text, keep going.
         */
        if (margin == 0 && LF_ISSET(TXT_REPLAY))
                goto replay;

        /*
         * 2: Reset the line.  Don't bother unless we're about to wait on
         *    a character or we need to know where the cursor really is.
         *    We have to do this before showing matching characters so the
         *    user can see what they're matching.
         */
        if ((margin != 0 || !KEYS_WAITING(sp)) &&
            vs_change(sp, tp->lno, LINE_RESET))
                return (1);

        /*
         * 3: If there aren't keys waiting, display the matching character.
         *    We have to do this before resolving any messages, otherwise
         *    the error message from a missing match won't appear correctly.
         */
        if (showmatch) {
                if (!KEYS_WAITING(sp) && txt_showmatch(sp, tp))
                        return (1);
                showmatch = 0;
        }

        /*
         * 4: If there have been messages and we're not editing on the colon
         *    command line or doing file name completion, resolve them.
         */
        if ((vip->totalcount != 0 || F_ISSET(gp, G_BELLSCHED)) &&
            !F_ISSET(sp, SC_TINPUT_INFO) && !filec_redraw &&
            vs_resolve(sp, NULL, 0))
                return (1);

        /*
         * 5: Refresh the screen if we're about to wait on a character or we
         *    need to know where the cursor really is.
         */
        if (margin != 0 || !KEYS_WAITING(sp)) {
                UPDATE_POSITION(sp, tp);
                if (vs_refresh(sp, margin != 0))
                        return (1);
        }

        /* 6: Proceed with the incremental search. */
        if (FL_ISSET(is_flags, IS_RUNNING) && txt_isrch(sp, vp, tp, &is_flags))
                return (1);

        /* 7: Next character... */
        if (LF_ISSET(TXT_REPLAY))
                goto replay;
        goto next;

done:   /* Leave input mode. */
        F_CLR(sp, SC_TINPUT);

        /* If recording for playback, save it. */
        if (LF_ISSET(TXT_RECORD))
                vip->rep_cnt = rcol;

        /*
         * If not working on the colon command line, set the final cursor
         * position.
         */
        if (!F_ISSET(sp, SC_TINPUT_INFO)) {
                vp->m_final.lno = tp->lno;
                vp->m_final.cno = tp->cno;
        }
        return (0);

err:
alloc_err:
        F_CLR(sp, SC_TINPUT);
        txt_err(sp, sp->tiq);
        return (1);
}

/*
 * txt_abbrev --
 *      Handle abbreviations.
 */
static int
txt_abbrev(SCR *sp, TEXT *tp, CHAR_T *pushcp, int isinfoline, int *didsubp, int *turnoffp)
{
        VI_PRIVATE *vip;
        CHAR_T ch, *p;
        SEQ *qp;
        size_t len, off;

        /* Check to make sure we're not at the start of an append. */
        *didsubp = 0;
        if (tp->cno == tp->offset)
                return (0);

        vip = VIP(sp);

        /*
         * Find the start of the "word".
         *
         * !!!
         * We match historic practice, which, as far as I can tell, had an
         * off-by-one error.  The way this worked was that when the inserted
         * text switched from a "word" character to a non-word character,
         * vi would check for possible abbreviations.  It would then take the
         * type (i.e. word/non-word) of the character entered TWO characters
         * ago, and move backward in the text until reaching a character that
         * was not that type, or the beginning of the insert, the line, or
         * the file.  For example, in the string "abc<space>", when the <space>
         * character triggered the abbreviation check, the type of the 'b'
         * character was used for moving through the string.  Maybe there's a
         * reason for not using the first (i.e. 'c') character, but I can't
         * think of one.
         *
         * Terminate at the beginning of the insert or the character after the
         * offset character -- both can be tested for using tp->offset.
         */
        off = tp->cno - 1;                      /* Previous character. */
        p = tp->lb + off;
        len = 1;                                /* One character test. */
        if (off == tp->offset || isblank(p[-1]))
                goto search;
        if (inword(p[-1]))                      /* Move backward to change. */
                for (;;) {
                        --off; --p; ++len;
                        if (off == tp->offset || !inword(p[-1]))
                                break;
                }
        else
                for (;;) {
                        --off; --p; ++len;
                        if (off == tp->offset ||
                            inword(p[-1]) || isblank(p[-1]))
                                break;
                }

        /*
         * !!!
         * Historic vi exploded abbreviations on the command line.  This has
         * obvious problems in that unabbreviating the string can be extremely
         * tricky, particularly if the string has, say, an embedded escape
         * character.  Personally, I think it's a stunningly bad idea.  Other
         * examples of problems this caused in historic vi are:
         *      :ab foo bar
         *      :ab foo baz
         * results in "bar" being abbreviated to "baz", which wasn't what the
         * user had in mind at all.  Also, the commands:
         *      :ab foo bar
         *      :unab foo<space>
         * resulted in an error message that "bar" wasn't mapped.  Finally,
         * since the string was already exploded by the time the unabbreviate
         * command got it, all it knew was that an abbreviation had occurred.
         * Cleverly, it checked the replacement string for its unabbreviation
         * match, which meant that the commands:
         *      :ab foo1 bar
         *      :ab foo2 bar
         *      :unab foo2
         * unabbreviate "foo1", and the commands:
         *      :ab foo bar
         *      :ab bar baz
         * unabbreviate "foo"!
         *
         * Anyway, people neglected to first ask my opinion before they wrote
         * macros that depend on this stuff, so, we make this work as follows.
         * When checking for an abbreviation on the command line, if we get a
         * string which is <blank> terminated and which starts at the beginning
         * of the line, we check to see it is the abbreviate or unabbreviate
         * commands.  If it is, turn abbreviations off and return as if no
         * abbreviation was found.  Note also, minor trickiness, so that if
         * the user erases the line and starts another command, we turn the
         * abbreviations back on.
         *
         * This makes the layering look like a Nachos Supreme.
         */
search: if (isinfoline)
                if (off == tp->ai || off == tp->offset)
                        if (ex_is_abbrev(p, len)) {
                                *turnoffp = 1;
                                return (0);
                        } else
                                *turnoffp = 0;
                else
                        if (*turnoffp)
                                return (0);

        /* Check for any abbreviations. */
        if ((qp = seq_find(sp, NULL, NULL, p, len, SEQ_ABBREV, NULL)) == NULL)
                return (0);

        /*
         * Push the abbreviation onto the tty stack.  Historically, characters
         * resulting from an abbreviation expansion were themselves subject to
         * map expansions, O_SHOWMATCH matching etc.  This means the expanded
         * characters will be re-tested for abbreviations.  It's difficult to
         * know what historic practice in this case was, since abbreviations
         * were applied to :colon command lines, so entering abbreviations that
         * looped was tricky, although possible.  In addition, obvious loops
         * didn't work as expected.  (The command ':ab a b|ab b c|ab c a' will
         * silently only implement and/or display the last abbreviation.)
         *
         * This implementation doesn't recover well from such abbreviations.
         * The main input loop counts abbreviated characters, and, when it
         * reaches a limit, discards any abbreviated characters on the queue.
         * It's difficult to back up to the original position, as the replay
         * queue would have to be adjusted, and the line state when an initial
         * abbreviated character was received would have to be saved.
         */
        ch = *pushcp;
        if (v_event_push(sp, NULL, &ch, 1, CH_ABBREVIATED))
                return (1);
        if (v_event_push(sp, NULL, qp->output, qp->olen, CH_ABBREVIATED))
                return (1);

        /*
         * If the size of the abbreviation is larger than or equal to the size
         * of the original text, move to the start of the replaced characters,
         * and add their length to the overwrite count.
         *
         * If the abbreviation is smaller than the original text, we have to
         * delete the additional overwrite characters and copy down any insert
         * characters.
         */
        tp->cno -= len;
        if (qp->olen >= len)
                tp->owrite += len;
        else {
                if (tp->insert)
                        MEMMOVE(tp->lb + tp->cno + qp->olen,
                            tp->lb + tp->cno + tp->owrite + len, tp->insert);
                tp->owrite += qp->olen;
                tp->len -= len - qp->olen;
        }

        /*
         * We return the length of the abbreviated characters.  This is so
         * the calling routine can replace the replay characters with the
         * abbreviation.  This means that subsequent '.' commands will produce
         * the same text, regardless of intervening :[un]abbreviate commands.
         * This is historic practice.
         */
        *didsubp = len;
        return (0);
}

/*
 * txt_unmap --
 *      Handle the unmap command.
 */
static void
txt_unmap(SCR *sp, TEXT *tp, u_int32_t *ec_flagsp)
{
        size_t len, off;
        CHAR_T *p;

        /* Find the beginning of this "word". */
        for (off = tp->cno - 1, p = tp->lb + off, len = 0;; --p, --off) {
                if (isblank(*p)) {
                        ++p;
                        break;
                }
                ++len;
                if (off == tp->ai || off == tp->offset)
                        break;
        }

        /*
         * !!!
         * Historic vi exploded input mappings on the command line.  See the
         * txt_abbrev() routine for an explanation of the problems inherent
         * in this.
         *
         * We make this work as follows.  If we get a string which is <blank>
         * terminated and which starts at the beginning of the line, we check
         * to see it is the unmap command.  If it is, we return that the input
         * mapping should be turned off.  Note also, minor trickiness, so that
         * if the user erases the line and starts another command, we go ahead
         * an turn mapping back on.
         */
        if ((off == tp->ai || off == tp->offset) && ex_is_unmap(p, len))
                FL_CLR(*ec_flagsp, EC_MAPINPUT);
        else
                FL_SET(*ec_flagsp, EC_MAPINPUT);
}

/*
 * txt_ai_resolve --
 *      When a line is resolved by <esc>, review autoindent characters.
 */
static void
txt_ai_resolve(SCR *sp, TEXT *tp, int *changedp)
{
        u_long ts;
        int del;
        size_t cno, len, new, old, scno, spaces, tab_after_sp, tabs;
        CHAR_T *p;

        *changedp = 0;

        /*
         * If the line is empty, has an offset, or no autoindent
         * characters, we're done.
         */
        if (!tp->len || tp->offset || !tp->ai)
                return;

        /*
         * If the length is less than or equal to the autoindent
         * characters, delete them.
         */
        if (tp->len <= tp->ai) {
                tp->ai = tp->cno = tp->len = 0;
                return;
        }

        /*
         * The autoindent characters plus any leading <blank> characters
         * in the line are resolved into the minimum number of characters.
         * Historic practice.
         */
        ts = O_VAL(sp, O_TABSTOP);

        /* Figure out the last <blank> screen column. */
        for (p = tp->lb, scno = 0, len = tp->len,
            spaces = tab_after_sp = 0; len-- && isblank(*p); ++p)
                if (*p == '\t') {
                        if (spaces)
                                tab_after_sp = 1;
                        scno += COL_OFF(scno, ts);
                } else {
                        ++spaces;
                        ++scno;
                }

        /*
         * If there are no spaces, or no tabs after spaces and less than
         * ts spaces, it's already minimal.
         */
        if (!spaces || (!tab_after_sp && spaces < ts))
                return;

        /* Count up spaces/tabs needed to get to the target. */
        for (cno = 0, tabs = 0; cno + COL_OFF(cno, ts) <= scno; ++tabs)
                cno += COL_OFF(cno, ts);
        spaces = scno - cno;

        /*
         * Figure out how many characters we're dropping -- if we're not
         * dropping any, it's already minimal, we're done.
         */
        old = p - tp->lb;
        new = spaces + tabs;
        if (old == new)
                return;

        /* Shift the rest of the characters down, adjust the counts. */
        del = old - new;
        MEMMOVE(p - del, p, tp->len - old);
        tp->len -= del;
        tp->cno -= del;

        /* Fill in space/tab characters. */
        for (p = tp->lb; tabs--;)
                *p++ = '\t';
        while (spaces--)
                *p++ = ' ';
        *changedp = 1;
}

/*
 * v_txt_auto --
 *      Handle autoindent.  If aitp isn't NULL, use it, otherwise,
 *      retrieve the line.
 *
 * PUBLIC: int v_txt_auto __P((SCR *, recno_t, TEXT *, size_t, TEXT *));
 */
int
v_txt_auto(SCR *sp, recno_t lno, TEXT *aitp, size_t len, TEXT *tp)
{
        size_t nlen;
        CHAR_T *p, *t;

        if (aitp == NULL) {
                /*
                 * If the ex append command is executed with an address of 0,
                 * it's possible to get here with a line number of 0.  Return
                 * an indent of 0.
                 */
                if (lno == 0) {
                        tp->ai = 0;
                        return (0);
                }
                if (db_get(sp, lno, DBG_FATAL, &t, &len))
                        return (1);
        } else
                t = aitp->lb;

        /* Count whitespace characters. */
        for (p = t; len > 0; ++p, --len)
                if (!isblank(*p))
                        break;

        /* Set count, check for no indentation. */
        if ((nlen = (p - t)) == 0)
                return (0);

        /* Make sure the buffer's big enough. */
        BINC_RETW(sp, tp->lb, tp->lb_len, tp->len + nlen);

        /* Copy the buffer's current contents up. */
        if (tp->len != 0)
                MEMMOVE(tp->lb + nlen, tp->lb, tp->len);
        tp->len += nlen;

        /* Copy the indentation into the new buffer. */
        MEMMOVE(tp->lb, t, nlen);

        /* Set the autoindent count. */
        tp->ai = nlen;
        return (0);
}

/*
 * txt_backup --
 *      Back up to the previously edited line.
 */
static TEXT *
txt_backup(SCR *sp, TEXTH *tiqh, TEXT *tp, u_int32_t *flagsp)
{
        VI_PRIVATE *vip;
        TEXT *ntp;

        /* Get a handle on the previous TEXT structure. */
        if ((ntp = TAILQ_PREV(tp, _texth, q)) == NULL) {
                if (!FL_ISSET(*flagsp, TXT_REPLAY))
                        msgq(sp, M_BERR,
                            "193|Already at the beginning of the insert");
                return (tp);
        }

        /* Bookkeeping. */
        ntp->len = ntp->sv_len;

        /* Handle appending to the line. */
        vip = VIP(sp);
        if (ntp->owrite == 0 && ntp->insert == 0) {
                ntp->lb[ntp->len] = CH_CURSOR;
                ++ntp->insert;
                ++ntp->len;
                FL_SET(*flagsp, TXT_APPENDEOL);
        } else
                FL_CLR(*flagsp, TXT_APPENDEOL);

        /* Release the current TEXT. */
        TAILQ_REMOVE(tiqh, tp, q);
        text_free(tp);

        /* Update the old line on the screen. */
        if (vs_change(sp, ntp->lno + 1, LINE_DELETE))
                return (NULL);

        /* Return the new/current TEXT. */
        return (ntp);
}

/*
 * Text indentation is truly strange.  ^T and ^D do movements to the next or
 * previous shiftwidth value, i.e. for a 1-based numbering, with shiftwidth=3,
 * ^T moves a cursor on the 7th, 8th or 9th column to the 10th column, and ^D
 * moves it back.
 *
 * !!!
 * The ^T and ^D characters in historical vi had special meaning only when they
 * were the first characters entered after entering text input mode.  As normal
 * erase characters couldn't erase autoindent characters (^T in this case), it
 * meant that inserting text into previously existing text was strange -- ^T
 * only worked if it was the first keystroke(s), and then could only be erased
 * using ^D.  This implementation treats ^T specially anywhere it occurs in the
 * input, and permits the standard erase characters to erase the characters it
 * inserts.
 *
 * !!!
 * A fun test is to try:
 *      :se sw=4 ai list
 *      i<CR>^Tx<CR>^Tx<CR>^Tx<CR>^Dx<CR>^Dx<CR>^Dx<esc>
 * Historic vi loses some of the '$' marks on the line ends, but otherwise gets
 * it right.
 *
 * XXX
 * Technically, txt_dent should be part of the screen interface, as it requires
 * knowledge of character sizes, including <space>s, on the screen.  It's here
 * because it's a complicated little beast, and I didn't want to shove it down
 * into the screen.  It's probable that KEY_COL will call into the screen once
 * there are screens with different character representations.
 *
 * txt_dent --
 *      Handle ^T indents, ^D outdents.
 *
 * If anything changes here, check the ex version to see if it needs similar
 * changes.
 */
static int
txt_dent(SCR *sp, TEXT *tp, int isindent)
{
        CHAR_T ch;
        u_long sw, ts;
        size_t cno, current, spaces, target, tabs;
        int ai_reset;

        ts = O_VAL(sp, O_TABSTOP);
        sw = O_VAL(sp, O_SHIFTWIDTH);

        /*
         * Since we don't know what precedes the character(s) being inserted
         * (or deleted), the preceding whitespace characters must be resolved.
         * An example is a <tab>, which doesn't need a full shiftwidth number
         * of columns because it's preceded by <space>s.  This is easy to get
         * if the user sets shiftwidth to a value less than tabstop (or worse,
         * something for which tabstop isn't a multiple) and then uses ^T to
         * indent, and ^D to outdent.
         *
         * Figure out the current and target screen columns.  In the historic
         * vi, the autoindent column was NOT determined using display widths
         * of characters as was the wrapmargin column.  For that reason, we
         * can't use the vs_column() function, but have to calculate it here.
         * This is slow, but it's normally only on the first few characters of
         * a line.
         */
        for (current = cno = 0; cno < tp->cno; ++cno)
                current += tp->lb[cno] == '\t' ?
                    COL_OFF(current, ts) : KEY_COL(sp, tp->lb[cno]);

        target = current;
        if (isindent)
                target += COL_OFF(target, sw);
        else {
                --target;
                target -= target % sw;
        }

        /*
         * The AI characters will be turned into overwrite characters if the
         * cursor immediately follows them.  We test both the cursor position
         * and the indent flag because there's no single test.  (^T can only
         * be detected by the cursor position, and while we know that the test
         * is always true for ^D, the cursor can be in more than one place, as
         * "0^D" and "^D" are different.)
         */
        ai_reset = !isindent || tp->cno == tp->ai + tp->offset;

        /*
         * Back up over any previous <blank> characters, changing them into
         * overwrite characters (including any ai characters).  Then figure
         * out the current screen column.
         */
        for (; tp->cno > tp->offset &&
            (tp->lb[tp->cno - 1] == ' ' || tp->lb[tp->cno - 1] == '\t');
            --tp->cno, ++tp->owrite);
        for (current = cno = 0; cno < tp->cno; ++cno)
                current += tp->lb[cno] == '\t' ?
                    COL_OFF(current, ts) : KEY_COL(sp, tp->lb[cno]);

        /*
         * If we didn't move up to or past the target, it's because there
         * weren't enough characters to delete, e.g. the first character
         * of the line was a tp->offset character, and the user entered
         * ^D to move to the beginning of a line.  An example of this is:
         *
         *      :set ai sw=4<cr>i<space>a<esc>i^T^D
         *
         * Otherwise, count up the total spaces/tabs needed to get from the
         * beginning of the line (or the last non-<blank> character) to the
         * target.
         */
        if (current >= target)
                spaces = tabs = 0;
        else {
                for (cno = current,
                    tabs = 0; cno + COL_OFF(cno, ts) <= target; ++tabs)
                        cno += COL_OFF(cno, ts);
                spaces = target - cno;
        }

        /* If we overwrote ai characters, reset the ai count. */
        if (ai_reset)
                tp->ai = tabs + spaces;

        /*
         * Call txt_insch() to insert each character, so that we get the
         * correct effect when we add a <tab> to replace N <spaces>.
         */
        for (ch = '\t'; tabs > 0; --tabs)
                (void)txt_insch(sp, tp, &ch, 0);
        for (ch = ' '; spaces > 0; --spaces)
                (void)txt_insch(sp, tp, &ch, 0);
        return (0);
}

/*
 * txt_fc --
 *      File name and ex command completion.
 */
static int
txt_fc(SCR *sp, TEXT *tp, int *redrawp)
{
        struct stat sb;
        ARGS **argv;
        EXCMD cmd;
        size_t indx, len, nlen, off;
        int argc;
        CHAR_T *p, *t, *bp;
        char *np, *epd = NULL;
        size_t nplen;
        int fstwd = 1;

        *redrawp = 0;
        ex_cinit(sp, &cmd, 0, 0, OOBLNO, OOBLNO, 0);

        /*
         * Find the beginning of this "word" -- if we're at the beginning
         * of the line, it's a special case.
         */
        if (tp->cno == 1) {
                len = 0;
                p = tp->lb;
        } else {
                CHAR_T *ap;

                for (len = 0,
                    off = MAX(tp->ai, tp->offset), ap = tp->lb + off, p = ap;
                    off < tp->cno; ++off, ++ap) {
                        if (IS_ESCAPE(sp, &cmd, *ap)) {
                                if (++off == tp->cno)
                                        break;
                                ++ap;
                                len += 2;
                        } else if (cmdskip(*ap)) {
                                p = ap + 1;
                                if (len > 0)
                                        fstwd = 0;
                                len = 0;
                        } else
                                ++len;
                }
        }

        /*
         * If we are at the first word, do ex command completion instead of
         * file name completion.
         */
        if (fstwd)
                (void)argv_flt_ex(sp, &cmd, p, len);
        else {
                if ((bp = argv_uesc(sp, &cmd, p, len)) == NULL)
                        return (1);
                if (argv_flt_path(sp, &cmd, bp, STRLEN(bp))) {
                        FREE_SPACEW(sp, bp, 0);
                        return (0);
                }
                FREE_SPACEW(sp, bp, 0);
        }
        argc = cmd.argc;
        argv = cmd.argv;

        switch (argc) {
        case 0:                         /* No matches. */
                (void)sp->gp->scr_bell(sp);
                return (0);
        case 1:                         /* One match. */
                /* Always overwrite the old text. */
                nlen = STRLEN(cmd.argv[0]->bp);
                break;
        default:                        /* Multiple matches. */
                *redrawp = 1;
                if (txt_fc_col(sp, argc, argv))
                        return (1);

                /* Find the length of the shortest match. */
                for (nlen = cmd.argv[0]->len; --argc > 0;) {
                        if (cmd.argv[argc]->len < nlen)
                                nlen = cmd.argv[argc]->len;
                        for (indx = 0; indx < nlen &&
                            cmd.argv[argc]->bp[indx] == cmd.argv[0]->bp[indx];
                            ++indx);
                        nlen = indx;
                }
                break;
        }

        /* Escape the matched part of the path. */
        if (fstwd)
                bp = cmd.argv[0]->bp;
        else {
                if ((bp = argv_esc(sp, &cmd, cmd.argv[0]->bp, nlen)) == NULL)
                        return (1);
                nlen = STRLEN(bp);
        }

        /* Overwrite the expanded text first. */
        for (t = bp; len > 0 && nlen > 0; --len, --nlen)
                *p++ = *t++;

        /* If lost text, make the remaining old text overwrite characters. */
        if (len) {
                tp->cno -= len;
                tp->owrite += len;
        }

        /* Overwrite any overwrite characters next. */
        for (; nlen > 0 && tp->owrite > 0; --nlen, --tp->owrite, ++tp->cno)
                *p++ = *t++;

        /* Shift remaining text up, and move the cursor to the end. */
        if (nlen) {
                off = p - tp->lb;
                BINC_RETW(sp, tp->lb, tp->lb_len, tp->len + nlen);
                p = tp->lb + off;

                tp->cno += nlen;
                tp->len += nlen;

                if (tp->insert != 0)
                        (void)MEMMOVE(p + nlen, p, tp->insert);
                while (nlen--)
                        *p++ = *t++;
        }

        if (!fstwd)
                FREE_SPACEW(sp, bp, 0);

        /* If not a single match of path, we've done. */
        if (argc != 1 || fstwd)
                return (0);

        /* If a single match and it's a directory, append a '/'. */
        INT2CHAR(sp, cmd.argv[0]->bp, cmd.argv[0]->len + 1, np, nplen);
        if ((epd = expanduser(np)) != NULL)
                np = epd;
        if (!stat(np, &sb) && S_ISDIR(sb.st_mode)) {
                if (tp->owrite == 0) {
                        off = p - tp->lb;
                        BINC_RETW(sp, tp->lb, tp->lb_len, tp->len + 1);
                        p = tp->lb + off;
                        if (tp->insert != 0)
                                (void)MEMMOVE(p + 1, p, tp->insert);
                        ++tp->len;
                } else
                        --tp->owrite;

                ++tp->cno;
                *p++ = '/';
        }
        free(epd);
        return (0);
}

/*
 * txt_fc_col --
 *      Display file names for file name completion.
 */
static int
txt_fc_col(SCR *sp, int argc, ARGS **argv)
{
        ARGS **av;
        CHAR_T *p;
        GS *gp;
        size_t base, cnt, col, colwidth, numrows, numcols, prefix, row;
        int ac, nf, reset;
        char *np, *pp;
        size_t nlen;

        gp = sp->gp;

        /* Trim any directory prefix common to all of the files. */
        INT2CHAR(sp, argv[0]->bp, argv[0]->len + 1, np, nlen);
        if ((pp = strrchr(np, '/')) == NULL)
                prefix = 0;
        else {
                prefix = (pp - np) + 1;
                for (ac = argc - 1, av = argv + 1; ac > 0; --ac, ++av)
                        if (av[0]->len < prefix ||
                            MEMCMP(av[0]->bp, argv[0]->bp, 
                                   prefix)) {
                                prefix = 0;
                                break;
                        }
        }

        /*
         * Figure out the column width for the longest name.  Output is done on
         * 6 character "tab" boundaries for no particular reason.  (Since we
         * don't output tab characters, we ignore the terminal's tab settings.)
         * Ignore the user's tab setting because we have no idea how reasonable
         * it is.
         */
        for (ac = argc, av = argv, colwidth = 0; ac > 0; --ac, ++av) {
                for (col = 0, p = av[0]->bp + prefix; *p != '\0'; ++p)
                        col += KEY_COL(sp, *p);
                if (col > colwidth)
                        colwidth = col;
        }
        colwidth += COL_OFF(colwidth, 6);

        /*
         * Writing to the bottom line of the screen is always turned off when
         * SC_TINPUT_INFO is set.  Turn it back on, we know what we're doing.
         */
        if (F_ISSET(sp, SC_TINPUT_INFO)) {
                reset = 1;
                F_CLR(sp, SC_TINPUT_INFO);
        } else
                reset = 0;

#define CHK_INTR                                                        \
        if (F_ISSET(gp, G_INTERRUPTED))                                 \
                goto intr;

        /* If the largest file name is too large, just print them. */
        if (colwidth >= sp->cols) {
                for (ac = argc, av = argv; ac > 0; --ac, ++av) {
                        INT2CHAR(sp, av[0]->bp+prefix, av[0]->len+1-prefix,
                                 np, nlen);
                        pp = msg_print(sp, np, &nf);
                        (void)ex_printf(sp, "%s\n", pp);
                        if (nf)
                                FREE_SPACE(sp, pp, 0);
                        if (F_ISSET(gp, G_INTERRUPTED))
                                break;
                }
                CHK_INTR;
        } else {
                /* Figure out the number of columns. */
                numcols = (sp->cols - 1) / colwidth;
                if (argc > numcols) {
                        numrows = argc / numcols;
                        if (argc % numcols)
                                ++numrows;
                } else
                        numrows = 1;

                /* Display the files in sorted order. */
                for (row = 0; row < numrows; ++row) {
                        for (base = row, col = 0; col < numcols; ++col) {
                                INT2CHAR(sp, argv[base]->bp+prefix, 
                                        argv[base]->len+1-prefix, np, nlen);
                                pp = msg_print(sp, np, &nf);
                                cnt = ex_printf(sp, "%s", pp);
                                if (nf)
                                        FREE_SPACE(sp, pp, 0);
                                CHK_INTR;
                                if ((base += numrows) >= argc)
                                        break;
                                (void)ex_printf(sp,
                                    "%*s", (int)(colwidth - cnt), "");
                                CHK_INTR;
                        }
                        (void)ex_puts(sp, "\n");
                        CHK_INTR;
                }
                (void)ex_puts(sp, "\n");
                CHK_INTR;
        }
        (void)ex_fflush(sp);

        if (0) {
intr:           F_CLR(gp, G_INTERRUPTED);
        }
        if (reset)
                F_SET(sp, SC_TINPUT_INFO);

        return (0);
}

/*
 * txt_emark --
 *      Set the end mark on the line.
 */
static int
txt_emark(SCR *sp, TEXT *tp, size_t cno)
{
        CHAR_T ch;
        u_char *kp;
        size_t chlen, nlen, olen;
        CHAR_T *p;

        ch = CH_ENDMARK;

        /*
         * The end mark may not be the same size as the current character.
         * Don't let the line shift.
         */
        nlen = KEY_COL(sp, ch);
        if (tp->lb[cno] == '\t')
                (void)vs_columns(sp, tp->lb, tp->lno, &cno, &olen);
        else
                olen = KEY_COL(sp, tp->lb[cno]);

        /*
         * If the line got longer, well, it's weird, but it's easy.  If
         * it's the same length, it's easy.  If it got shorter, we have
         * to fix it up.
         */
        if (olen > nlen) {
                BINC_RETW(sp, tp->lb, tp->lb_len, tp->len + olen);
                chlen = olen - nlen;
                if (tp->insert != 0)
                        MEMMOVE(tp->lb + cno + 1 + chlen,
                            tp->lb + cno + 1, tp->insert);

                tp->len += chlen;
                tp->owrite += chlen;
                p = tp->lb + cno;
                if (tp->lb[cno] == '\t' ||
                    KEY_NEEDSWIDE(sp, tp->lb[cno]))
                        for (cno += chlen; chlen--;)
                                *p++ = ' ';
                else
                        for (kp = (u_char *)
                            KEY_NAME(sp, tp->lb[cno]),
                            cno += chlen; chlen--;)
                                *p++ = *kp++;
        }
        tp->lb[cno] = ch;
        return (vs_change(sp, tp->lno, LINE_RESET));
}

/*
 * txt_err --
 *      Handle an error during input processing.
 */
static void
txt_err(SCR *sp, TEXTH *tiqh)
{
        recno_t lno;

        /*
         * The problem with input processing is that the cursor is at an
         * indeterminate position since some input may have been lost due
         * to a malloc error.  So, try to go back to the place from which
         * the cursor started, knowing that it may no longer be available.
         *
         * We depend on at least one line number being set in the text
         * chain.
         */
        for (lno = TAILQ_FIRST(tiqh)->lno;
            !db_exist(sp, lno) && lno > 0; --lno);

        sp->lno = lno == 0 ? 1 : lno;
        sp->cno = 0;

        /* Redraw the screen, just in case. */
        F_SET(sp, SC_SCR_REDRAW);
}

/*
 * txt_hex --
 *      Let the user insert any character value they want.
 *
 * !!!
 * This is an extension.  The pattern "^X[0-9a-fA-F]*" is a way
 * for the user to specify a character value which their keyboard
 * may not be able to enter.
 */
static int
txt_hex(SCR *sp, TEXT *tp)
{
        CHAR_T savec;
        size_t len, off;
        u_long value;
        CHAR_T *p, *wp;

        /*
         * Null-terminate the string.  Since nul isn't a legal hex value,
         * this should be okay, and lets us use a local routine, which
         * presumably understands the character set, to convert the value.
         */
        savec = tp->lb[tp->cno];
        tp->lb[tp->cno] = 0;

        /* Find the previous CH_HEX character. */
        for (off = tp->cno - 1, p = tp->lb + off, len = 0;; --p, --off, ++len) {
                if (*p == CH_HEX) {
                        wp = p + 1;
                        break;
                }
                /* Not on this line?  Shouldn't happen. */
                if (off == tp->ai || off == tp->offset)
                        goto nothex;
        }

        /* If length of 0, then it wasn't a hex value. */
        if (len == 0)
                goto nothex;

        /* Get the value. */
        errno = 0;
        value = STRTOL(wp, NULL, 16);
        if (errno || value > UCHAR_MAX) {
nothex:         tp->lb[tp->cno] = savec;
                return (0);
        }

        /* Restore the original character. */
        tp->lb[tp->cno] = savec;

        /* Adjust the bookkeeping. */
        tp->cno -= len;
        tp->len -= len;
        tp->lb[tp->cno - 1] = value;

        /* Copy down any overwrite characters. */
        if (tp->owrite)
                MEMMOVE(tp->lb + tp->cno, tp->lb + tp->cno + len, 
                    tp->owrite);

        /* Copy down any insert characters. */
        if (tp->insert)
                MEMMOVE(tp->lb + tp->cno + tp->owrite,
                    tp->lb + tp->cno + tp->owrite + len, 
                    tp->insert);

        return (0);
}

/*
 * txt_insch --
 *
 * !!!
 * Historic vi did a special screen optimization for tab characters.  As an
 * example, for the keystrokes "iabcd<esc>0C<tab>", the tab overwrote the
 * rest of the string when it was displayed.
 *
 * Because early versions of this implementation redisplayed the entire line
 * on each keystroke, the "bcd" was pushed to the right as it ignored that
 * the user had "promised" to change the rest of the characters.  However,
 * the historic vi implementation had an even worse bug: given the keystrokes
 * "iabcd<esc>0R<tab><esc>", the "bcd" disappears, and magically reappears
 * on the second <esc> key.
 *
 * POSIX 1003.2 requires (will require) that this be fixed, specifying that
 * vi overwrite characters the user has committed to changing, on the basis
 * of the screen space they require, but that it not overwrite other characters.
 */
static int
txt_insch(SCR *sp, TEXT *tp, CHAR_T *chp, u_int flags)
{
        u_char *kp;
        CHAR_T savech;
        size_t chlen, cno, copydown, olen, nlen;
        CHAR_T *p;

        /*
         * The 'R' command does one-for-one replacement, because there's
         * no way to know how many characters the user intends to replace.
         */
        if (LF_ISSET(TXT_REPLACE)) {
                if (tp->owrite) {
                        --tp->owrite;
                        tp->lb[tp->cno++] = *chp;
                        return (0);
                }
        } else if (tp->owrite) {                /* Overwrite a character. */
                cno = tp->cno;

                /*
                 * If the old or new characters are tabs, then the length of the
                 * display depends on the character position in the display.  We
                 * don't even try to handle this here, just ask the screen.
                 */
                if (*chp == '\t') {
                        savech = tp->lb[cno];
                        tp->lb[cno] = '\t';
                        (void)vs_columns(sp, tp->lb, tp->lno, &cno, &nlen);
                        tp->lb[cno] = savech;
                } else
                        nlen = KEY_COL(sp, *chp);

                /*
                 * Eat overwrite characters until we run out of them or we've
                 * handled the length of the new character.  If we only eat
                 * part of an overwrite character, break it into its component
                 * elements and display the remaining components.
                 */
                for (copydown = 0; nlen != 0 && tp->owrite != 0;) {
                        --tp->owrite;

                        if (tp->lb[cno] == '\t')
                                (void)vs_columns(sp,
                                    tp->lb, tp->lno, &cno, &olen);
                        else
                                olen = KEY_COL(sp, tp->lb[cno]);

                        if (olen == nlen) {
                                nlen = 0;
                                break;
                        }
                        if (olen < nlen) {
                                ++copydown;
                                nlen -= olen;
                        } else {
                                BINC_RETW(sp,
                                    tp->lb, tp->lb_len, tp->len + olen);
                                chlen = olen - nlen;
                                MEMMOVE(tp->lb + cno + 1 + chlen,
                                    tp->lb + cno + 1, 
                                    tp->owrite + tp->insert);

                                tp->len += chlen;
                                tp->owrite += chlen;
                                if (tp->lb[cno] == '\t' ||
                                   KEY_NEEDSWIDE(sp, tp->lb[cno]))
                                        for (p = tp->lb + cno + 1; chlen--;)
                                                *p++ = ' ';
                                else
                                        for (kp = (u_char *)
                                            KEY_NAME(sp, tp->lb[cno]) + nlen,
                                            p = tp->lb + cno + 1; chlen--;)
                                                *p++ = *kp++;
                                nlen = 0;
                                break;
                        }
                }

                /*
                 * If had to erase several characters, we adjust the total
                 * count, and if there are any characters left, shift them
                 * into position.
                 */
                if (copydown != 0 && (tp->len -= copydown) != 0)
                        MEMMOVE(tp->lb + cno, tp->lb + cno + copydown,
                            tp->owrite + tp->insert + copydown);

                /* If we had enough overwrite characters, we're done. */
                if (nlen == 0) {
                        tp->lb[tp->cno++] = *chp;
                        return (0);
                }
        }

        /* Check to see if the character fits into the input buffer. */
        BINC_RETW(sp, tp->lb, tp->lb_len, tp->len + 1);

        ++tp->len;
        if (tp->insert) {                       /* Insert a character. */
                if (tp->insert == 1)
                        tp->lb[tp->cno + 1] = tp->lb[tp->cno];
                else
                        MEMMOVE(tp->lb + tp->cno + 1,
                            tp->lb + tp->cno, tp->owrite + tp->insert);
        }
        tp->lb[tp->cno++] = *chp;
        return (0);
}

/*
 * txt_isrch --
 *      Do an incremental search.
 */
static int
txt_isrch(SCR *sp, VICMD *vp, TEXT *tp, u_int8_t *is_flagsp)
{
        MARK start;
        recno_t lno;
        u_int sf;

        /* If it's a one-line screen, we don't do incrementals. */
        if (IS_ONELINE(sp)) {
                FL_CLR(*is_flagsp, IS_RUNNING);
                return (0);
        }

        /*
         * If the user erases back to the beginning of the buffer, there's
         * nothing to search for.  Reset the cursor to the starting point.
         */
        if (tp->cno <= 1) {
                vp->m_final = vp->m_start;
                return (0);
        }

        /*
         * If it's an RE quote character, and not quoted, ignore it until
         * we get another character.
         */
        if (tp->lb[tp->cno - 1] == '\\' &&
            (tp->cno == 2 || tp->lb[tp->cno - 2] != '\\'))
                return (0);

        /*
         * If it's a magic shell character, and not quoted, reset the cursor
         * to the starting point.
         */
        if (IS_SHELLMETA(sp, tp->lb[tp->cno - 1]) &&
            (tp->cno == 2 || tp->lb[tp->cno - 2] != '\\'))
                vp->m_final = vp->m_start;

        /*
         * If we see the search pattern termination character, then quit doing
         * an incremental search.  There may be more, e.g., ":/foo/;/bar/",
         * and we can't handle that incrementally.  Also, reset the cursor to
         * the original location, the ex search routines don't know anything
         * about incremental searches.
         */
        if (tp->lb[0] == tp->lb[tp->cno - 1] &&
            (tp->cno == 2 || tp->lb[tp->cno - 2] != '\\')) {
                vp->m_final = vp->m_start;
                FL_CLR(*is_flagsp, IS_RUNNING);
                return (0);
        }
                
        /*
         * Remember the input line and discard the special input map,
         * but don't overwrite the input line on the screen.
         */
        lno = tp->lno;
        F_SET(VIP(sp), VIP_S_MODELINE);
        F_CLR(sp, SC_TINPUT | SC_TINPUT_INFO);
        if (txt_map_end(sp))
                return (1);

        /*
         * Specify a starting point and search.  If we find a match, move to
         * it and refresh the screen.  If we didn't find the match, then we
         * beep the screen.  When searching from the original cursor position, 
         * we have to move the cursor, otherwise, we don't want to move the
         * cursor in case the text at the current position continues to match.
         */
        if (FL_ISSET(*is_flagsp, IS_RESTART)) {
                start = vp->m_start;
                sf = SEARCH_SET;
        } else {
                start = vp->m_final;
                sf = SEARCH_INCR | SEARCH_SET;
        }

        if (tp->lb[0] == '/' ?
            !f_search(sp,
            &start, &vp->m_final, tp->lb + 1, tp->cno - 1, NULL, sf) :
            !b_search(sp,
            &start, &vp->m_final, tp->lb + 1, tp->cno - 1, NULL, sf)) {
                sp->lno = vp->m_final.lno;
                sp->cno = vp->m_final.cno;
                FL_CLR(*is_flagsp, IS_RESTART);

                if (!KEYS_WAITING(sp) && vs_refresh(sp, 0))
                        return (1);
        } else
                FL_SET(*is_flagsp, IS_RESTART);

        /* Reinstantiate the special input map. */
        if (txt_map_init(sp))
                return (1);
        F_CLR(VIP(sp), VIP_S_MODELINE);
        F_SET(sp, SC_TINPUT | SC_TINPUT_INFO);

        /* Reset the line number of the input line. */
        tp->lno = TMAP[0].lno; 

        /*
         * If the colon command-line moved, i.e. the screen scrolled,
         * refresh the input line.
         *
         * XXX
         * We shouldn't be calling vs_line, here -- we need dirty bits
         * on entries in the SMAP array.
         */
        if (lno != TMAP[0].lno) {
                if (vs_line(sp, &TMAP[0], NULL, NULL))
                        return (1);
                (void)sp->gp->scr_refresh(sp, 0);
        }
        return (0);
}

/*
 * txt_resolve --
 *      Resolve the input text chain into the file.
 */
static int
txt_resolve(SCR *sp, TEXTH *tiqh, u_int32_t flags)
{
        VI_PRIVATE *vip;
        TEXT *tp;
        recno_t lno;
        int changed;

        /*
         * The first line replaces a current line, and all subsequent lines
         * are appended into the file.  Resolve autoindented characters for
         * each line before committing it.  If the latter causes the line to
         * change, we have to redisplay it, otherwise the information cached
         * about the line will be wrong.
         */
        vip = VIP(sp);
        tp = TAILQ_FIRST(tiqh);

        if (LF_ISSET(TXT_AUTOINDENT))
                txt_ai_resolve(sp, tp, &changed);
        else
                changed = 0;
        if (db_set(sp, tp->lno, tp->lb, tp->len) ||
            (changed && vs_change(sp, tp->lno, LINE_RESET)))
                return (1);

        for (lno = tp->lno; (tp = TAILQ_NEXT(tp, q)) != NULL; ++lno) {
                if (LF_ISSET(TXT_AUTOINDENT))
                        txt_ai_resolve(sp, tp, &changed);
                else
                        changed = 0;
                if (db_append(sp, 0, lno, tp->lb, tp->len) ||
                    (changed && vs_change(sp, tp->lno, LINE_RESET)))
                        return (1);
        }

        /*
         * Clear the input flag, the look-aside buffer is no longer valid.
         * Has to be done as part of text resolution, or upon return we'll
         * be looking at incorrect data.
         */
        F_CLR(sp, SC_TINPUT);

        return (0);
}

/*
 * txt_showmatch --
 *      Show a character match.
 *
 * !!!
 * Historic vi tried to display matches even in the :colon command line.
 * I think not.
 */
static int
txt_showmatch(SCR *sp, TEXT *tp)
{
        GS *gp;
        VCS cs;
        MARK m;
        int cnt, endc, startc;

        gp = sp->gp;

        /*
         * Do a refresh first, in case we haven't done one in awhile,
         * so the user can see what we're complaining about.
         */
        UPDATE_POSITION(sp, tp);
        if (vs_refresh(sp, 1))
                return (1);

        /*
         * We don't display the match if it's not on the screen.  Find
         * out what the first character on the screen is.
         */
        if (vs_sm_position(sp, &m, 0, P_TOP))
                return (1);

        /* Initialize the getc() interface. */
        cs.cs_lno = tp->lno;
        cs.cs_cno = tp->cno - 1;
        if (cs_init(sp, &cs))
                return (1);
        startc = STRCHR(VIP(sp)->mcs, endc = cs.cs_ch)[-1];

        /* Search for the match. */
        for (cnt = 1;;) {
                if (cs_prev(sp, &cs))
                        return (1);
                if (cs.cs_flags != 0) {
                        if (cs.cs_flags == CS_EOF || cs.cs_flags == CS_SOF) {
                                msgq(sp, M_BERR,
                                    "Unmatched %s", KEY_NAME(sp, endc));
                                return (0);
                        }
                        continue;
                }
                if (cs.cs_ch == endc)
                        ++cnt;
                else if (cs.cs_ch == startc && --cnt == 0)
                        break;
        }

        /* If the match is on the screen, move to it. */
        if (cs.cs_lno < m.lno || (cs.cs_lno == m.lno && cs.cs_cno < m.cno))
                return (0);
        sp->lno = cs.cs_lno;
        sp->cno = cs.cs_cno;
        if (vs_refresh(sp, 1))
                return (1);

        /* Wait for timeout or character arrival. */
        return (v_event_get(sp,
            NULL, O_VAL(sp, O_MATCHTIME) * 100, EC_TIMEOUT));
}

/*
 * txt_margin --
 *      Handle margin wrap.
 */
static int
txt_margin(SCR *sp, TEXT *tp, TEXT *wmtp, int *didbreak, u_int32_t flags)
{
        VI_PRIVATE *vip;
        size_t len, off;
        CHAR_T *p, *wp;

        /* Find the nearest previous blank. */
        for (off = tp->cno - 1, p = tp->lb + off, len = 0;; --off, --p, ++len) {
                if (isblank(*p)) {
                        wp = p + 1;
                        break;
                }

                /*
                 * If reach the start of the line, there's nowhere to break.
                 *
                 * !!!
                 * Historic vi belled each time a character was entered after
                 * crossing the margin until a space was entered which could
                 * be used to break the line.  I don't as it tends to wake the
                 * cats.
                 */
                if (off == tp->ai || off == tp->offset) {
                        *didbreak = 0;
                        return (0);
                }
        }

        /*
         * Store saved information about the rest of the line in the
         * wrapmargin TEXT structure.
         *
         * !!!
         * The offset field holds the length of the current characters
         * that the user entered, but which are getting split to the new
         * line -- it's going to be used to set the cursor value when we
         * move to the new line.
         */
        vip = VIP(sp);
        wmtp->lb = p + 1;
        wmtp->offset = len;
        wmtp->insert = LF_ISSET(TXT_APPENDEOL) ?  tp->insert - 1 : tp->insert;
        wmtp->owrite = tp->owrite;

        /* Correct current bookkeeping information. */
        tp->cno -= len;
        if (LF_ISSET(TXT_APPENDEOL)) {
                tp->len -= len + tp->owrite + (tp->insert - 1);
                tp->insert = 1;
        } else {
                tp->len -= len + tp->owrite + tp->insert;
                tp->insert = 0;
        }
        tp->owrite = 0;

        /*
         * !!!
         * Delete any trailing whitespace from the current line.
         */
        for (;; --p, --off) {
                if (!isblank(*p))
                        break;
                --tp->cno;
                --tp->len;
                if (off == tp->ai || off == tp->offset)
                        break;
        }
        *didbreak = 1;
        return (0);
}

/*
 * txt_Rresolve --
 *      Resolve the input line for the 'R' command.
 */
static void
txt_Rresolve(SCR *sp, TEXTH *tiqh, TEXT *tp, const size_t orig_len)
{
        TEXT *ttp;
        size_t input_len, retain;
        CHAR_T *p;

        /*
         * Check to make sure that the cursor hasn't moved beyond
         * the end of the line.
         */
        if (tp->owrite == 0)
                return;

        /*
         * Calculate how many characters the user has entered,
         * plus the blanks erased by <carriage-return>/<newline>s.
         */
        for (ttp = TAILQ_FIRST(tiqh), input_len = 0;;) {
                input_len += ttp == tp ? tp->cno : ttp->len + ttp->R_erase;
                if ((ttp = TAILQ_NEXT(ttp, q)) == NULL)
                        break;
        }

        /*
         * If the user has entered less characters than the original line
         * was long, restore any overwriteable characters to the original
         * characters.  These characters are entered as "insert characters",
         * because they're after the cursor and we don't want to lose them.
         * (This is okay because the R command has no insert characters.)
         * We set owrite to 0 so that the insert characters don't get copied
         * to somewhere else, which means that the line and the length have
         * to be adjusted here as well.
         *
         * We have to retrieve the original line because the original pinned
         * page has long since been discarded.  If it doesn't exist, that's
         * okay, the user just extended the file.
         */
        if (input_len < orig_len) {
                retain = MIN(tp->owrite, orig_len - input_len);
                if (db_get(sp,
                    TAILQ_FIRST(tiqh)->lno, DBG_FATAL | DBG_NOCACHE, &p, NULL))
                        return;
                MEMCPY(tp->lb + tp->cno, p + input_len, retain);
                tp->len -= tp->owrite - retain;
                tp->owrite = 0;
                tp->insert += retain;
        }
}

/*
 * txt_nomorech --
 *      No more characters message.
 */
static void
txt_nomorech(SCR *sp)
{
        msgq(sp, M_BERR, "194|No more characters to erase");
}