sbin/hammer: Have consistent naming for buffer variables

[dragonfly.git] / contrib / nvi2 / vi / vs_msg.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: vs_msg.c,v 10.88 2013/03/19 09:59:03 zy Exp $";
#endif /* not lint */

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

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

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

typedef enum {
        SCROLL_W,                       /* User wait. */
        SCROLL_W_EX,                    /* User wait, or enter : to continue. */
        SCROLL_W_QUIT                   /* User wait, or enter q to quit. */
                                        /*
                                         * SCROLL_W_QUIT has another semantic
                                         * -- only wait if the screen is full
                                         */
} sw_t;

static void     vs_divider(SCR *);
static void     vs_msgsave(SCR *, mtype_t, char *, size_t);
static void     vs_output(SCR *, mtype_t, const char *, int);
static void     vs_scroll(SCR *, int *, sw_t);
static void     vs_wait(SCR *, int *, sw_t);

/*
 * vs_busy --
 *      Display, update or clear a busy message.
 *
 * This routine is the default editor interface for vi busy messages.  It
 * implements a standard strategy of stealing lines from the bottom of the
 * vi text screen.  Screens using an alternate method of displaying busy
 * messages, e.g. X11 clock icons, should set their scr_busy function to the
 * correct function before calling the main editor routine.
 *
 * PUBLIC: void vs_busy(SCR *, const char *, busy_t);
 */
void
vs_busy(SCR *sp, const char *msg, busy_t btype)
{
        GS *gp;
        VI_PRIVATE *vip;
        static const char flagc[] = "|/-\\";
        struct timespec ts, ts_diff;
        const struct timespec ts_min = { 0, 125000000 };
        size_t len, notused;
        const char *p;

        /* Ex doesn't display busy messages. */
        if (F_ISSET(sp, SC_EX | SC_SCR_EXWROTE))
                return;

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

        /*
         * Most of this routine is to deal with the screen sharing real estate
         * between the normal edit messages and the busy messages.  Logically,
         * all that's needed is something that puts up a message, periodically
         * updates it, and then goes away.
         */
        switch (btype) {
        case BUSY_ON:
                ++vip->busy_ref;
                if (vip->totalcount != 0 || vip->busy_ref != 1)
                        break;

                /* Initialize state for updates. */
                vip->busy_ch = 0;
                timepoint_steady(&vip->busy_ts);

                /* Save the current cursor. */
                (void)gp->scr_cursor(sp, &vip->busy_oldy, &vip->busy_oldx);

                /* Display the busy message. */
                p = msg_cat(sp, msg, &len);
                (void)gp->scr_move(sp, LASTLINE(sp), 0);
                (void)gp->scr_addstr(sp, p, len);
                (void)gp->scr_cursor(sp, &notused, &vip->busy_fx);
                (void)gp->scr_clrtoeol(sp);
                (void)gp->scr_move(sp, LASTLINE(sp), vip->busy_fx);
                break;
        case BUSY_OFF:
                if (vip->busy_ref == 0)
                        break;
                --vip->busy_ref;

                /*
                 * If the line isn't in use for another purpose, clear it.
                 * Always return to the original position.
                 */
                if (vip->totalcount == 0 && vip->busy_ref == 0) {
                        (void)gp->scr_move(sp, LASTLINE(sp), 0);
                        (void)gp->scr_clrtoeol(sp);
                }
                (void)gp->scr_move(sp, vip->busy_oldy, vip->busy_oldx);
                break;
        case BUSY_UPDATE:
                if (vip->totalcount != 0 || vip->busy_ref == 0)
                        break;

                /* Update no more than every 1/8 of a second. */
                timepoint_steady(&ts);
                ts_diff = ts;
                timespecsub(&ts_diff, &vip->busy_ts);
                if (timespeccmp(&ts_diff, &ts_min, <))
                        return;
                vip->busy_ts = ts;

                /* Display the update. */
                if (vip->busy_ch == sizeof(flagc) - 1)
                        vip->busy_ch = 0;
                (void)gp->scr_move(sp, LASTLINE(sp), vip->busy_fx);
                (void)gp->scr_addstr(sp, flagc + vip->busy_ch++, 1);
                (void)gp->scr_move(sp, LASTLINE(sp), vip->busy_fx);
                break;
        }
        (void)gp->scr_refresh(sp, 0);
}

/* 
 * vs_home --
 *      Home the cursor to the bottom row, left-most column.
 *
 * PUBLIC: void vs_home(SCR *);
 */
void
vs_home(SCR *sp)
{
        (void)sp->gp->scr_move(sp, LASTLINE(sp), 0);
        (void)sp->gp->scr_refresh(sp, 0);
}

/*
 * vs_update --
 *      Update a command.
 *
 * PUBLIC: void vs_update(SCR *, const char *, const CHAR_T *);
 */
void
vs_update(SCR *sp, const char *m1, const CHAR_T *m2)
{
        GS *gp;
        size_t len, mlen, oldx, oldy;
        CONST char *np;
        size_t nlen;

        gp = sp->gp;

        /*
         * This routine displays a message on the bottom line of the screen,
         * without updating any of the command structures that would keep it
         * there for any period of time, i.e. it is overwritten immediately.
         *
         * It's used by the ex read and ! commands when the user's command is
         * expanded, and by the ex substitution confirmation prompt.
         */
        if (F_ISSET(sp, SC_SCR_EXWROTE)) {
                if (m2 != NULL)
                        INT2CHAR(sp, m2, STRLEN(m2) + 1, np, nlen);
                (void)ex_printf(sp,
                    "%s\n", m1 == NULL? "" : m1, m2 == NULL ? "" : np);
                (void)ex_fflush(sp);
        }

        /*
         * Save the cursor position, the substitute-with-confirmation code
         * will have already set it correctly.
         */
        (void)gp->scr_cursor(sp, &oldy, &oldx);

        /* Clear the bottom line. */
        (void)gp->scr_move(sp, LASTLINE(sp), 0);
        (void)gp->scr_clrtoeol(sp);

        /*
         * XXX
         * Don't let long file names screw up the screen.
         */
        if (m1 != NULL) {
                mlen = len = strlen(m1);
                if (len > sp->cols - 2)
                        mlen = len = sp->cols - 2;
                (void)gp->scr_addstr(sp, m1, mlen);
        } else
                len = 0;
        if (m2 != NULL) {
                mlen = STRLEN(m2);
                if (len + mlen > sp->cols - 2)
                        mlen = (sp->cols - 2) - len;
                (void)gp->scr_waddstr(sp, m2, mlen);
        }

        (void)gp->scr_move(sp, oldy, oldx);
        (void)gp->scr_refresh(sp, 0);
}

/*
 * vs_msg --
 *      Display ex output or error messages for the screen.
 *
 * This routine is the default editor interface for all ex output, and all ex
 * and vi error/informational messages.  It implements the standard strategy
 * of stealing lines from the bottom of the vi text screen.  Screens using an
 * alternate method of displaying messages, e.g. dialog boxes, should set their
 * scr_msg function to the correct function before calling the editor.
 *
 * PUBLIC: void vs_msg(SCR *, mtype_t, char *, size_t);
 */
void
vs_msg(SCR *sp, mtype_t mtype, char *line, size_t len)
{
        GS *gp;
        VI_PRIVATE *vip;
        size_t maxcols, oldx, oldy, padding;
        const char *e, *s, *t;

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

        /*
         * Ring the bell if it's scheduled.
         *
         * XXX
         * Shouldn't we save this, too?
         */
        if (F_ISSET(sp, SC_TINPUT_INFO) || F_ISSET(gp, G_BELLSCHED))
                if (F_ISSET(sp, SC_SCR_VI)) {
                        F_CLR(gp, G_BELLSCHED);
                        (void)gp->scr_bell(sp);
                } else
                        F_SET(gp, G_BELLSCHED);

        /*
         * If vi is using the error line for text input, there's no screen
         * real-estate for the error message.  Nothing to do without some
         * information as to how important the error message is.
         */
        if (F_ISSET(sp, SC_TINPUT_INFO))
                return;

        /*
         * Ex or ex controlled screen output.
         *
         * If output happens during startup, e.g., a .exrc file, we may be
         * in ex mode but haven't initialized the screen.  Initialize here,
         * and in this case, stay in ex mode.
         *
         * If the SC_SCR_EXWROTE bit is set, then we're switching back and
         * forth between ex and vi, but the screen is trashed and we have
         * to respect that.  Switch to ex mode long enough to put out the
         * message.
         *
         * If the SC_EX_WAIT_NO bit is set, turn it off -- we're writing to
         * the screen, so previous opinions are ignored.
         */
        if (F_ISSET(sp, SC_EX | SC_SCR_EXWROTE)) {
                if (!F_ISSET(sp, SC_SCR_EX))
                        if (F_ISSET(sp, SC_SCR_EXWROTE)) {
                                if (sp->gp->scr_screen(sp, SC_EX))
                                        return;
                        } else
                                if (ex_init(sp))
                                        return;

                if (mtype == M_ERR)
                        (void)gp->scr_attr(sp, SA_INVERSE, 1);
                (void)printf("%.*s", (int)len, line);
                if (mtype == M_ERR)
                        (void)gp->scr_attr(sp, SA_INVERSE, 0);
                (void)fflush(stdout);

                F_CLR(sp, SC_EX_WAIT_NO);

                if (!F_ISSET(sp, SC_SCR_EX))
                        (void)sp->gp->scr_screen(sp, SC_VI);
                return;
        }

        /* If the vi screen isn't ready, save the message. */
        if (!F_ISSET(sp, SC_SCR_VI)) {
                (void)vs_msgsave(sp, mtype, line, len);
                return;
        }

        /* Save the cursor position. */
        (void)gp->scr_cursor(sp, &oldy, &oldx);

        /* If it's an ex output message, just write it out. */
        if (mtype == M_NONE) {
                vs_output(sp, mtype, line, len);
                goto ret;
        }

        /*
         * If it's a vi message, strip the trailing <newline> so we can
         * try and paste messages together.
         */
        if (line[len - 1] == '\n')
                --len;

        /*
         * If a message won't fit on a single line, try to split on a <blank>.
         * If a subsequent message fits on the same line, write a separator
         * and output it.  Otherwise, put out a newline.
         *
         * Need up to two padding characters normally; a semi-colon and a
         * separating space.  If only a single line on the screen, add some
         * more for the trailing continuation message.
         *
         * XXX
         * Assume that periods and semi-colons take up a single column on the
         * screen.
         *
         * XXX
         * There are almost certainly pathological cases that will break this
         * code.
         */
        if (IS_ONELINE(sp))
                (void)msg_cmsg(sp, CMSG_CONT_S, &padding);
        else
                padding = 0;
        padding += 2;

        maxcols = sp->cols - 1;
        if (vip->lcontinue != 0)
                if (len + vip->lcontinue + padding > maxcols)
                        vs_output(sp, vip->mtype, ".\n", 2);
                else  {
                        vs_output(sp, vip->mtype, ";", 1);
                        vs_output(sp, M_NONE, " ", 1);
                }
        vip->mtype = mtype;
        for (s = line;; s = t) {
                for (; len > 0 && isblank(*s); --len, ++s);
                if (len == 0)
                        break;
                if (len + vip->lcontinue > maxcols) {
                        for (e = s + (maxcols - vip->lcontinue);
                            e > s && !isblank(*e); --e);
                        if (e == s)
                                 e = t = s + (maxcols - vip->lcontinue);
                        else
                                for (t = e; isblank(e[-1]); --e);
                } else
                        e = t = s + len;

                /*
                 * If the message ends in a period, discard it, we want to
                 * gang messages where possible.
                 */
                len -= t - s;
                if (len == 0 && (e - s) > 1 && s[(e - s) - 1] == '.')
                        --e;
                vs_output(sp, mtype, s, e - s);

                if (len != 0)
                        vs_output(sp, M_NONE, "\n", 1);

                if (INTERRUPTED(sp))
                        break;
        }

ret:    (void)gp->scr_move(sp, oldy, oldx);
        (void)gp->scr_refresh(sp, 0);
}

/*
 * vs_output --
 *      Output the text to the screen.
 */
static void
vs_output(SCR *sp, mtype_t mtype, const char *line, int llen)
{
        GS *gp;
        VI_PRIVATE *vip;
        size_t notused;
        int len, rlen, tlen;
        const char *p, *t;
        char *cbp, *ecbp, cbuf[128];

        gp = sp->gp;
        vip = VIP(sp);
        for (p = line, rlen = llen; llen > 0;) {
                /* Get the next physical line. */
                if ((p = memchr(line, '\n', llen)) == NULL)
                        len = llen;
                else
                        len = p - line;

                /*
                 * The max is sp->cols characters, and we may have already
                 * written part of the line.
                 */
                if (len + vip->lcontinue > sp->cols)
                        len = sp->cols - vip->lcontinue;

                /*
                 * If the first line output, do nothing.  If the second line
                 * output, draw the divider line.  If drew a full screen, we
                 * remove the divider line.  If it's a continuation line, move
                 * to the continuation point, else, move the screen up.
                 */
                if (vip->lcontinue == 0) {
                        if (!IS_ONELINE(sp)) {
                                if (vip->totalcount == 1) {
                                        (void)gp->scr_move(sp,
                                            LASTLINE(sp) - 1, 0);
                                        (void)gp->scr_clrtoeol(sp);
                                        (void)vs_divider(sp);
                                        F_SET(vip, VIP_DIVIDER);
                                        ++vip->totalcount;
                                        ++vip->linecount;
                                }
                                if (vip->totalcount == sp->t_maxrows &&
                                    F_ISSET(vip, VIP_DIVIDER)) {
                                        --vip->totalcount;
                                        --vip->linecount;
                                        F_CLR(vip, VIP_DIVIDER);
                                }
                        }
                        if (vip->totalcount != 0)
                                vs_scroll(sp, NULL, SCROLL_W_QUIT);

                        (void)gp->scr_move(sp, LASTLINE(sp), 0);
                        ++vip->totalcount;
                        ++vip->linecount;

                        if (INTERRUPTED(sp))
                                break;
                } else
                        (void)gp->scr_move(sp, LASTLINE(sp), vip->lcontinue);

                /* Error messages are in inverse video. */
                if (mtype == M_ERR)
                        (void)gp->scr_attr(sp, SA_INVERSE, 1);

                /* Display the line, doing character translation. */
#define FLUSH {                                                         \
        *cbp = '\0';                                                    \
        (void)gp->scr_addstr(sp, cbuf, cbp - cbuf);                     \
        cbp = cbuf;                                                     \
}
                ecbp = (cbp = cbuf) + sizeof(cbuf) - 1;
                for (t = line, tlen = len; tlen--; ++t) {
                        /*
                         * Replace tabs with spaces, there are places in
                         * ex that do column calculations without looking
                         * at <tabs> -- and all routines that care about
                         * <tabs> do their own expansions.  This catches
                         * <tabs> in things like tag search strings.
                         */
                        if (cbp + 1 >= ecbp)
                                FLUSH;
                        *cbp++ = *t == '\t' ? ' ' : *t;
                }
                if (cbp > cbuf)
                        FLUSH;
                if (mtype == M_ERR)
                        (void)gp->scr_attr(sp, SA_INVERSE, 0);

                /* Clear the rest of the line. */
                (void)gp->scr_clrtoeol(sp);

                /* If we loop, it's a new line. */
                vip->lcontinue = 0;

                /* Reset for the next line. */
                line += len;
                llen -= len;
                if (p != NULL) {
                        ++line;
                        --llen;
                }
        }

        /* Set up next continuation line. */
        if (p == NULL)
                gp->scr_cursor(sp, &notused, &vip->lcontinue);
}

/*
 * vs_ex_resolve --
 *      Deal with ex message output.
 *
 * This routine is called when exiting a colon command to resolve any ex
 * output that may have occurred.
 *
 * PUBLIC: int vs_ex_resolve(SCR *, int *);
 */
int
vs_ex_resolve(SCR *sp, int *continuep)
{
        EVENT ev;
        GS *gp;
        VI_PRIVATE *vip;
        sw_t wtype;

        gp = sp->gp;
        vip = VIP(sp);
        *continuep = 0;

        /* If we ran any ex command, we can't trust the cursor position. */
        F_SET(vip, VIP_CUR_INVALID);

        /* Terminate any partially written message. */
        if (vip->lcontinue != 0) {
                vs_output(sp, vip->mtype, ".", 1);
                vip->lcontinue = 0;

                vip->mtype = M_NONE;
        }

        /*
         * If we switched out of the vi screen into ex, switch back while we
         * figure out what to do with the screen and potentially get another
         * command to execute.
         *
         * If we didn't switch into ex, we're not required to wait, and less
         * than 2 lines of output, we can continue without waiting for the
         * wait.
         *
         * Note, all other code paths require waiting, so we leave the report
         * of modified lines until later, so that we won't wait for no other
         * reason than a threshold number of lines were modified.  This means
         * we display cumulative line modification reports for groups of ex
         * commands.  That seems right to me (well, at least not wrong).
         */
        if (F_ISSET(sp, SC_SCR_EXWROTE)) {
                if (sp->gp->scr_screen(sp, SC_VI))
                        return (1);
        } else
                if (!F_ISSET(sp, SC_EX_WAIT_YES) && vip->totalcount < 2) {
                        F_CLR(sp, SC_EX_WAIT_NO);
                        return (0);
                }

        /* Clear the required wait flag, it's no longer needed. */
        F_CLR(sp, SC_EX_WAIT_YES);

        /*
         * Wait, unless explicitly told not to wait or the user interrupted
         * the command.  If the user is leaving the screen, for any reason,
         * they can't continue with further ex commands.
         */
        if (!F_ISSET(sp, SC_EX_WAIT_NO) && !INTERRUPTED(sp)) {
                wtype = F_ISSET(sp, SC_EXIT | SC_EXIT_FORCE |
                    SC_FSWITCH | SC_SSWITCH) ? SCROLL_W : SCROLL_W_EX;
                if (F_ISSET(sp, SC_SCR_EXWROTE))
                        vs_wait(sp, continuep, wtype);
                else
                        vs_scroll(sp, continuep, wtype);
                if (*continuep)
                        return (0);
        }

        /* If ex wrote on the screen, refresh the screen image. */
        if (F_ISSET(sp, SC_SCR_EXWROTE))
                F_SET(vip, VIP_N_EX_PAINT);

        /*
         * If we're not the bottom of the split screen stack, the screen
         * image itself is wrong, so redraw everything.
         */
        if (TAILQ_NEXT(sp, q) != NULL)
                F_SET(sp, SC_SCR_REDRAW);

        /* If ex changed the underlying file, the map itself is wrong. */
        if (F_ISSET(vip, VIP_N_EX_REDRAW))
                F_SET(sp, SC_SCR_REFORMAT);

        /* Ex may have switched out of the alternate screen, return. */
        (void)gp->scr_attr(sp, SA_ALTERNATE, 1);

        /*
         * Whew.  We're finally back home, after what feels like years.
         * Kiss the ground.
         */
        F_CLR(sp, SC_SCR_EXWROTE | SC_EX_WAIT_NO);

        /*
         * We may need to repaint some of the screen, e.g.:
         *
         *      :set
         *      :!ls
         *
         * gives us a combination of some lines that are "wrong", and a need
         * for a full refresh.
         */
        if (vip->totalcount > 1) {
                /* Set up the redraw of the overwritten lines. */
                ev.e_event = E_REPAINT;
                ev.e_flno = vip->totalcount >=
                    sp->rows ? 1 : sp->rows - vip->totalcount;
                ev.e_tlno = sp->rows;

                /* Reset the count of overwriting lines. */
                vip->linecount = vip->lcontinue = vip->totalcount = 0;

                /* Redraw. */
                (void)vs_repaint(sp, &ev);
        } else
                /* Reset the count of overwriting lines. */
                vip->linecount = vip->lcontinue = vip->totalcount = 0;

        return (0);
}

/*
 * vs_resolve --
 *      Deal with message output.
 *
 * PUBLIC: int vs_resolve(SCR *, SCR *, int);
 */
int
vs_resolve(SCR *sp, SCR *csp, int forcewait)
{
        EVENT ev;
        GS *gp;
        MSGS *mp;
        VI_PRIVATE *vip;
        size_t oldy, oldx;
        int redraw;

        /*
         * Vs_resolve is called from the main vi loop and the refresh function
         * to periodically ensure that the user has seen any messages that have
         * been displayed and that any status lines are correct.  The sp screen
         * is the screen we're checking, usually the current screen.  When it's
         * not, csp is the current screen, used for final cursor positioning.
         */
        gp = sp->gp;
        vip = VIP(sp);
        if (csp == NULL)
                csp = sp;

        /* Save the cursor position. */
        (void)gp->scr_cursor(csp, &oldy, &oldx);

        /* Ring the bell if it's scheduled. */
        if (F_ISSET(gp, G_BELLSCHED)) {
                F_CLR(gp, G_BELLSCHED);
                (void)gp->scr_bell(sp);
        }

        /* Display new file status line. */
        if (F_ISSET(sp, SC_STATUS)) {
                F_CLR(sp, SC_STATUS);
                msgq_status(sp, sp->lno, MSTAT_TRUNCATE);
        }

        /* Report on line modifications. */
        mod_rpt(sp);

        /*
         * Flush any saved messages.  If the screen isn't ready, refresh
         * it.  (A side-effect of screen refresh is that we can display
         * messages.)  Once this is done, don't trust the cursor.  That
         * extra refresh screwed the pooch.
         */
        if (!SLIST_EMPTY(gp->msgq)) {
                if (!F_ISSET(sp, SC_SCR_VI) && vs_refresh(sp, 1))
                        return (1);
                while ((mp = SLIST_FIRST(gp->msgq)) != NULL) {
                        gp->scr_msg(sp, mp->mtype, mp->buf, mp->len);
                        SLIST_REMOVE_HEAD(gp->msgq, q);
                        free(mp->buf);
                        free(mp);
                }
                F_SET(vip, VIP_CUR_INVALID);
        }

        switch (vip->totalcount) {
        case 0:
                redraw = 0;
                break;
        case 1:
                /*
                 * If we're switching screens, we have to wait for messages,
                 * regardless.  If we don't wait, skip updating the modeline.
                 */
                if (forcewait)
                        vs_scroll(sp, NULL, SCROLL_W);
                else
                        F_SET(vip, VIP_S_MODELINE);

                redraw = 0;
                break;
        default:
                /*
                 * If >1 message line in use, prompt the user to continue and
                 * repaint overwritten lines.
                 */
                vs_scroll(sp, NULL, SCROLL_W);

                ev.e_event = E_REPAINT;
                ev.e_flno = vip->totalcount >=
                    sp->rows ? 1 : sp->rows - vip->totalcount;
                ev.e_tlno = sp->rows;

                redraw = 1;
                break;
        }

        /* Reset the count of overwriting lines. */
        vip->linecount = vip->lcontinue = vip->totalcount = 0;

        /* Redraw. */
        if (redraw)
                (void)vs_repaint(sp, &ev);

        /* Restore the cursor position. */
        (void)gp->scr_move(csp, oldy, oldx);

        return (0);
}

/*
 * vs_scroll --
 *      Scroll the screen for output.
 */
static void
vs_scroll(SCR *sp, int *continuep, sw_t wtype)
{
        GS *gp;
        VI_PRIVATE *vip;

        gp = sp->gp;
        vip = VIP(sp);
        if (!IS_ONELINE(sp)) {
                /*
                 * Scroll the screen.  Instead of scrolling the entire screen,
                 * delete the line above the first line output so preserve the
                 * maximum amount of the screen.
                 */
                (void)gp->scr_move(sp, vip->totalcount <
                    sp->rows ? LASTLINE(sp) - vip->totalcount : 0, 0);
                (void)gp->scr_deleteln(sp);

                /* If there are screens below us, push them back into place. */
                if (TAILQ_NEXT(sp, q) != NULL) {
                        (void)gp->scr_move(sp, LASTLINE(sp), 0);
                        (void)gp->scr_insertln(sp);
                }
        }
        if (wtype == SCROLL_W_QUIT && vip->linecount < sp->t_maxrows)
                return;
        vs_wait(sp, continuep, wtype);
}

/*
 * vs_wait --
 *      Prompt the user to continue.
 */
static void
vs_wait(SCR *sp, int *continuep, sw_t wtype)
{
        EVENT ev;
        VI_PRIVATE *vip;
        const char *p;
        GS *gp;
        size_t len;

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

        (void)gp->scr_move(sp, LASTLINE(sp), 0);
        if (IS_ONELINE(sp))
                p = msg_cmsg(sp, CMSG_CONT_S, &len);
        else
                switch (wtype) {
                case SCROLL_W_QUIT:
                        p = msg_cmsg(sp, CMSG_CONT_Q, &len);
                        break;
                case SCROLL_W_EX:
                        p = msg_cmsg(sp, CMSG_CONT_EX, &len);
                        break;
                case SCROLL_W:
                        p = msg_cmsg(sp, CMSG_CONT, &len);
                        break;
                default:
                        abort();
                        /* NOTREACHED */
                }
        (void)gp->scr_addstr(sp, p, len);

        ++vip->totalcount;
        vip->linecount = 0;

        (void)gp->scr_clrtoeol(sp);
        (void)gp->scr_refresh(sp, 0);

        /* Get a single character from the terminal. */
        if (continuep != NULL)
                *continuep = 0;
        for (;;) {
                if (v_event_get(sp, &ev, 0, 0))
                        return;
                if (ev.e_event == E_CHARACTER)
                        break;
                if (ev.e_event == E_INTERRUPT) {
                        ev.e_c = CH_QUIT;
                        F_SET(gp, G_INTERRUPTED);
                        break;
                }
                (void)gp->scr_bell(sp);
        }
        switch (wtype) {
        case SCROLL_W_QUIT:
                if (ev.e_c == CH_QUIT)
                        F_SET(gp, G_INTERRUPTED);
                break;
        case SCROLL_W_EX:
                if (ev.e_c == ':' && continuep != NULL)
                        *continuep = 1;
                break;
        case SCROLL_W:
                break;
        }
}

/*
 * vs_divider --
 *      Draw a dividing line between the screen and the output.
 */
static void
vs_divider(SCR *sp)
{
        GS *gp;
        size_t len;

#define DIVIDESTR       "+=+=+=+=+=+=+=+"
        len =
            sizeof(DIVIDESTR) - 1 > sp->cols ? sp->cols : sizeof(DIVIDESTR) - 1;
        gp = sp->gp;
        (void)gp->scr_attr(sp, SA_INVERSE, 1);
        (void)gp->scr_addstr(sp, DIVIDESTR, len);
        (void)gp->scr_attr(sp, SA_INVERSE, 0);
}

/*
 * vs_msgsave --
 *      Save a message for later display.
 */
static void
vs_msgsave(SCR *sp, mtype_t mt, char *p, size_t len)
{
        GS *gp;
        MSGS *mp_c, *mp_n;

        /*
         * We have to handle messages before we have any place to put them.
         * If there's no screen support yet, allocate a msg structure, copy
         * in the message, and queue it on the global structure.  If we can't
         * allocate memory here, we're genuinely screwed, dump the message
         * to stderr in the (probably) vain hope that someone will see it.
         */
        CALLOC_GOTO(sp, mp_n, MSGS *, 1, sizeof(MSGS));
        MALLOC_GOTO(sp, mp_n->buf, char *, len);

        memmove(mp_n->buf, p, len);
        mp_n->len = len;
        mp_n->mtype = mt;

        gp = sp->gp;
        if (SLIST_EMPTY(gp->msgq)) {
                SLIST_INSERT_HEAD(gp->msgq, mp_n, q);
        } else {
                SLIST_FOREACH(mp_c, gp->msgq, q)
                        if (SLIST_NEXT(mp_c, q) == NULL)
                                break;
                SLIST_INSERT_AFTER(mp_c, mp_n, q);
        }
        return;

alloc_err:
        if (mp_n != NULL)
                free(mp_n);
        (void)fprintf(stderr, "%.*s\n", (int)len, p);
}