/* $OpenBSD: tty.c,v 1.458 2026/03/23 08:48:32 nicm Exp $ */

/*
 * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/ioctl.h>

#include <netinet/in.h>

#include <curses.h>
#include <errno.h>
#include <fcntl.h>
#include <resolv.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>

#include "tmux.h"

static int      tty_log_fd = -1;

static void     tty_start_timer_callback(int, short, void *);
static void     tty_clipboard_query_callback(int, short, void *);
static void     tty_set_italics(struct tty *);
static int      tty_try_colour(struct tty *, int, const char *);
static void     tty_force_cursor_colour(struct tty *, int);
static void     tty_cursor_pane(struct tty *, const struct tty_ctx *, u_int,
                    u_int);
static void     tty_cursor_pane_unless_wrap(struct tty *,
                    const struct tty_ctx *, u_int, u_int);
static void     tty_colours(struct tty *, const struct grid_cell *);
static void     tty_check_fg(struct tty *, struct colour_palette *,
                    struct grid_cell *);
static void     tty_check_bg(struct tty *, struct colour_palette *,
                    struct grid_cell *);
static void     tty_check_us(struct tty *, struct colour_palette *,
                    struct grid_cell *);
static void     tty_colours_fg(struct tty *, const struct grid_cell *);
static void     tty_colours_bg(struct tty *, const struct grid_cell *);
static void     tty_colours_us(struct tty *, const struct grid_cell *);

static void     tty_region_pane(struct tty *, const struct tty_ctx *, u_int,
                    u_int);
static void     tty_region(struct tty *, u_int, u_int);
static void     tty_margin_pane(struct tty *, const struct tty_ctx *);
static void     tty_margin(struct tty *, u_int, u_int);
static int      tty_large_region(struct tty *, const struct tty_ctx *);
static void     tty_redraw_region(struct tty *, const struct tty_ctx *);
static void     tty_emulate_repeat(struct tty *, enum tty_code_code,
                    enum tty_code_code, u_int);
static void     tty_draw_pane(struct tty *, const struct tty_ctx *, u_int);
static int      tty_check_overlay(struct tty *, u_int, u_int);

#define tty_use_margin(tty) \
        (tty->term->flags & TERM_DECSLRM)
#define tty_full_width(tty, ctx) \
        ((ctx)->xoff == 0 && (ctx)->sx >= (tty)->sx)

#define TTY_BLOCK_INTERVAL (100000 /* 100 milliseconds */)
#define TTY_BLOCK_START(tty) (1 + ((tty)->sx * (tty)->sy) * 8)
#define TTY_BLOCK_STOP(tty) (1 + ((tty)->sx * (tty)->sy) / 8)

#define TTY_QUERY_TIMEOUT 5
#define TTY_REQUEST_LIMIT 30

void
tty_create_log(void)
{
        char    name[64];

        xsnprintf(name, sizeof name, "tmux-out-%ld.log", (long)getpid());

        tty_log_fd = open(name, O_WRONLY|O_CREAT|O_TRUNC, 0644);
        if (tty_log_fd != -1 && fcntl(tty_log_fd, F_SETFD, FD_CLOEXEC) == -1)
                fatal("fcntl failed");
}

int
tty_init(struct tty *tty, struct client *c)
{
        if (!isatty(c->fd))
                return (-1);

        memset(tty, 0, sizeof *tty);
        tty->client = c;

        tty->cstyle = SCREEN_CURSOR_DEFAULT;
        tty->ccolour = -1;
        tty->fg = tty->bg = -1;

        if (tcgetattr(c->fd, &tty->tio) != 0)
                return (-1);
        return (0);
}

void
tty_resize(struct tty *tty)
{
        struct client   *c = tty->client;
        struct winsize   ws;
        u_int            sx, sy, xpixel, ypixel;

        if (ioctl(c->fd, TIOCGWINSZ, &ws) != -1) {
                sx = ws.ws_col;
                if (sx == 0) {
                        sx = 80;
                        xpixel = 0;
                } else
                        xpixel = ws.ws_xpixel / sx;
                sy = ws.ws_row;
                if (sy == 0) {
                        sy = 24;
                        ypixel = 0;
                } else
                        ypixel = ws.ws_ypixel / sy;

                if ((xpixel == 0 || ypixel == 0) &&
                    tty->out != NULL &&
                    !(tty->flags & TTY_WINSIZEQUERY) &&
                    (tty->term->flags & TERM_VT100LIKE)) {
                        tty_puts(tty, "\033[18t\033[14t");
                        tty->flags |= TTY_WINSIZEQUERY;
                }
        } else {
                sx = 80;
                sy = 24;
                xpixel = 0;
                ypixel = 0;
        }
        log_debug("%s: %s now %ux%u (%ux%u)", __func__, c->name, sx, sy,
            xpixel, ypixel);
        tty_set_size(tty, sx, sy, xpixel, ypixel);
        tty_invalidate(tty);
}

void
tty_set_size(struct tty *tty, u_int sx, u_int sy, u_int xpixel, u_int ypixel)
{
        tty->sx = sx;
        tty->sy = sy;
        tty->xpixel = xpixel;
        tty->ypixel = ypixel;
}

static void
tty_read_callback(__unused int fd, __unused short events, void *data)
{
        struct tty      *tty = data;
        struct client   *c = tty->client;
        const char      *name = c->name;
        size_t           size = EVBUFFER_LENGTH(tty->in);
        int              nread;

        nread = evbuffer_read(tty->in, c->fd, -1);
        if (nread == 0 || nread == -1) {
                if (nread == 0)
                        log_debug("%s: read closed", name);
                else
                        log_debug("%s: read error: %s", name, strerror(errno));
                event_del(&tty->event_in);
                server_client_lost(tty->client);
                return;
        }
        log_debug("%s: read %d bytes (already %zu)", name, nread, size);

        while (tty_keys_next(tty))
                ;
}

static void
tty_timer_callback(__unused int fd, __unused short events, void *data)
{
        struct tty      *tty = data;
        struct client   *c = tty->client;
        struct timeval   tv = { .tv_usec = TTY_BLOCK_INTERVAL };

        log_debug("%s: %zu discarded", c->name, tty->discarded);

        c->flags |= CLIENT_ALLREDRAWFLAGS;
        c->discarded += tty->discarded;

        if (tty->discarded < TTY_BLOCK_STOP(tty)) {
                tty->flags &= ~TTY_BLOCK;
                tty_invalidate(tty);
                return;
        }
        tty->discarded = 0;
        evtimer_add(&tty->timer, &tv);
}

static int
tty_block_maybe(struct tty *tty)
{
        struct client   *c = tty->client;
        size_t           size = EVBUFFER_LENGTH(tty->out);
        struct timeval   tv = { .tv_usec = TTY_BLOCK_INTERVAL };

        if (size == 0)
                tty->flags &= ~TTY_NOBLOCK;
        else if (tty->flags & TTY_NOBLOCK)
                return (0);

        if (size < TTY_BLOCK_START(tty))
                return (0);

        if (tty->flags & TTY_BLOCK)
                return (1);
        tty->flags |= TTY_BLOCK;

        log_debug("%s: can't keep up, %zu discarded", c->name, size);

        evbuffer_drain(tty->out, size);
        c->discarded += size;

        tty->discarded = 0;
        evtimer_add(&tty->timer, &tv);
        return (1);
}

static void
tty_write_callback(__unused int fd, __unused short events, void *data)
{
        struct tty      *tty = data;
        struct client   *c = tty->client;
        size_t           size = EVBUFFER_LENGTH(tty->out);
        int              nwrite;

        nwrite = evbuffer_write(tty->out, c->fd);
        if (nwrite == -1)
                return;
        log_debug("%s: wrote %d bytes (of %zu)", c->name, nwrite, size);

        if (c->redraw > 0) {
                if ((size_t)nwrite >= c->redraw)
                        c->redraw = 0;
                else
                        c->redraw -= nwrite;
                log_debug("%s: waiting for redraw, %zu bytes left", c->name,
                    c->redraw);
        } else if (tty_block_maybe(tty))
                return;

        if (EVBUFFER_LENGTH(tty->out) != 0)
                event_add(&tty->event_out, NULL);
}

int
tty_open(struct tty *tty, char **cause)
{
        struct client   *c = tty->client;

        tty->term = tty_term_create(tty, c->term_name, c->term_caps,
            c->term_ncaps, &c->term_features, cause);
        if (tty->term == NULL) {
                tty_close(tty);
                return (-1);
        }
        tty->flags |= TTY_OPENED;

        tty->flags &= ~(TTY_NOCURSOR|TTY_FREEZE|TTY_BLOCK|TTY_TIMER);

        event_set(&tty->event_in, c->fd, EV_PERSIST|EV_READ,
            tty_read_callback, tty);
        tty->in = evbuffer_new();
        if (tty->in == NULL)
                fatal("out of memory");

        event_set(&tty->event_out, c->fd, EV_WRITE, tty_write_callback, tty);
        tty->out = evbuffer_new();
        if (tty->out == NULL)
                fatal("out of memory");

        evtimer_set(&tty->clipboard_timer, tty_clipboard_query_callback, tty);
        evtimer_set(&tty->start_timer, tty_start_timer_callback, tty);
        evtimer_set(&tty->timer, tty_timer_callback, tty);

        tty_start_tty(tty);
        tty_keys_build(tty);

        return (0);
}

static void
tty_start_timer_callback(__unused int fd, __unused short events, void *data)
{
        struct tty      *tty = data;
        struct client   *c = tty->client;

        log_debug("%s: start timer fired", c->name);

        if ((tty->flags & (TTY_HAVEDA|TTY_HAVEDA2|TTY_HAVEXDA)) == 0)
                tty_update_features(tty);
        tty->flags |= TTY_ALL_REQUEST_FLAGS;

        tty->flags &= ~(TTY_WAITBG|TTY_WAITFG);
}

static void
tty_start_start_timer(struct tty *tty)
{
        struct client   *c = tty->client;
        struct timeval   tv = { .tv_sec = TTY_QUERY_TIMEOUT };

        log_debug("%s: start timer started", c->name);
        evtimer_del(&tty->start_timer);
        evtimer_add(&tty->start_timer, &tv);
}

void
tty_start_tty(struct tty *tty)
{
        struct client   *c = tty->client;
        struct termios   tio;

        setblocking(c->fd, 0);
        event_add(&tty->event_in, NULL);

        memcpy(&tio, &tty->tio, sizeof tio);
        tio.c_iflag &= ~(IXON|IXOFF|ICRNL|INLCR|IGNCR|IMAXBEL|ISTRIP);
        tio.c_iflag |= IGNBRK;
        tio.c_oflag &= ~(OPOST|ONLCR|OCRNL|ONLRET);
        tio.c_lflag &= ~(IEXTEN|ICANON|ECHO|ECHOE|ECHONL|ECHOCTL|ECHOPRT|
            ECHOKE|ISIG);
        tio.c_cc[VMIN] = 1;
        tio.c_cc[VTIME] = 0;
        if (tcsetattr(c->fd, TCSANOW, &tio) == 0)
                tcflush(c->fd, TCOFLUSH);

        tty_putcode(tty, TTYC_SMCUP);

        tty_putcode(tty, TTYC_SMKX);
        tty_putcode(tty, TTYC_CLEAR);

        if (tty_acs_needed(tty)) {
                log_debug("%s: using capabilities for ACS", c->name);
                tty_putcode(tty, TTYC_ENACS);
        } else
                log_debug("%s: using UTF-8 for ACS", c->name);

        tty_putcode(tty, TTYC_CNORM);
        if (tty_term_has(tty->term, TTYC_KMOUS)) {
                tty_puts(tty, "\033[?1000l\033[?1002l\033[?1003l");
                tty_puts(tty, "\033[?1006l\033[?1005l");
        }
        if (tty_term_has(tty->term, TTYC_ENBP))
                tty_putcode(tty, TTYC_ENBP);

        if (tty->term->flags & TERM_VT100LIKE) {
                /* Subscribe to theme changes and request theme now. */
                tty_puts(tty, "\033[?2031h\033[?996n");
        }

        tty_start_start_timer(tty);

        tty->flags |= TTY_STARTED;
        tty_invalidate(tty);

        if (tty->ccolour != -1)
                tty_force_cursor_colour(tty, -1);

        tty->mouse_drag_flag = 0;
        tty->mouse_drag_update = NULL;
        tty->mouse_drag_release = NULL;
}

void
tty_send_requests(struct tty *tty)
{
        if (~tty->flags & TTY_STARTED)
                return;

        if (tty->term->flags & TERM_VT100LIKE) {
                if (~tty->flags & TTY_HAVEDA)
                        tty_puts(tty, "\033[c");
                if (~tty->flags & TTY_HAVEDA2)
                        tty_puts(tty, "\033[>c");
                if (~tty->flags & TTY_HAVEXDA)
                        tty_puts(tty, "\033[>q");
                tty_puts(tty, "\033]10;?\033\\\033]11;?\033\\");
                tty->flags |= (TTY_WAITBG|TTY_WAITFG);
        } else
                tty->flags |= TTY_ALL_REQUEST_FLAGS;
        tty->last_requests = time(NULL);
}

void
tty_repeat_requests(struct tty *tty, int force)
{
        struct client   *c = tty->client;
        time_t           t = time(NULL);
        u_int            n = t - tty->last_requests;

        if (~tty->flags & TTY_STARTED)
                return;

        if (!force && n <= TTY_REQUEST_LIMIT) {
                log_debug("%s: not repeating requests (%u seconds)", c->name,
                    n);
                return;
        }
        log_debug("%s: %srepeating requests (%u seconds)", c->name,
            force ? "(force) " : "" , n);
        tty->last_requests = t;

        if (tty->term->flags & TERM_VT100LIKE) {
                tty_puts(tty, "\033]10;?\033\\\033]11;?\033\\");
                tty->flags |= (TTY_WAITBG|TTY_WAITFG);
        }
        tty_start_start_timer(tty);
}

void
tty_stop_tty(struct tty *tty)
{
        struct client   *c = tty->client;
        struct winsize   ws;

        if (!(tty->flags & TTY_STARTED))
                return;
        tty->flags &= ~TTY_STARTED;

        evtimer_del(&tty->start_timer);
        evtimer_del(&tty->clipboard_timer);

        event_del(&tty->timer);
        tty->flags &= ~TTY_BLOCK;

        event_del(&tty->event_in);
        event_del(&tty->event_out);

        /*
         * Be flexible about error handling and try not kill the server just
         * because the fd is invalid. Things like ssh -t can easily leave us
         * with a dead tty.
         */
        if (ioctl(c->fd, TIOCGWINSZ, &ws) == -1)
                return;
        if (tcsetattr(c->fd, TCSANOW, &tty->tio) == -1)
                return;

        tty_raw(tty, tty_term_string_ii(tty->term, TTYC_CSR, 0, ws.ws_row - 1));
        if (tty_acs_needed(tty))
                tty_raw(tty, tty_term_string(tty->term, TTYC_RMACS));
        tty_raw(tty, tty_term_string(tty->term, TTYC_SGR0));
        tty_raw(tty, tty_term_string(tty->term, TTYC_RMKX));
        tty_raw(tty, tty_term_string(tty->term, TTYC_CLEAR));
        if (tty->cstyle != SCREEN_CURSOR_DEFAULT) {
                if (tty_term_has(tty->term, TTYC_SE))
                        tty_raw(tty, tty_term_string(tty->term, TTYC_SE));
                else if (tty_term_has(tty->term, TTYC_SS))
                        tty_raw(tty, tty_term_string_i(tty->term, TTYC_SS, 0));
        }
        if (tty->ccolour != -1)
                tty_raw(tty, tty_term_string(tty->term, TTYC_CR));

        tty_raw(tty, tty_term_string(tty->term, TTYC_CNORM));
        if (tty_term_has(tty->term, TTYC_KMOUS)) {
                tty_raw(tty, "\033[?1000l\033[?1002l\033[?1003l");
                tty_raw(tty, "\033[?1006l\033[?1005l");
        }
        if (tty_term_has(tty->term, TTYC_DSBP))
                tty_raw(tty, tty_term_string(tty->term, TTYC_DSBP));

        if (tty->term->flags & TERM_VT100LIKE)
                tty_raw(tty, "\033[?7727l");
        tty_raw(tty, tty_term_string(tty->term, TTYC_DSFCS));
        tty_raw(tty, tty_term_string(tty->term, TTYC_DSEKS));

        if (tty_use_margin(tty))
                tty_raw(tty, tty_term_string(tty->term, TTYC_DSMG));
        tty_raw(tty, tty_term_string(tty->term, TTYC_RMCUP));

        if (tty->term->flags & TERM_VT100LIKE)
                tty_raw(tty, "\033[?2031l");

        setblocking(c->fd, 1);
}

void
tty_close(struct tty *tty)
{
        if (event_initialized(&tty->key_timer))
                evtimer_del(&tty->key_timer);
        tty_stop_tty(tty);

        if (tty->flags & TTY_OPENED) {
                evbuffer_free(tty->in);
                event_del(&tty->event_in);
                evbuffer_free(tty->out);
                event_del(&tty->event_out);

                tty_term_free(tty->term);
                tty_keys_free(tty);

                tty->flags &= ~TTY_OPENED;
        }
}

void
tty_free(struct tty *tty)
{
        tty_close(tty);

        free(tty->r.ranges);
}

void
tty_update_features(struct tty *tty)
{
        struct client   *c = tty->client;

        if (tty_apply_features(tty->term, c->term_features))
                tty_term_apply_overrides(tty->term);

        if (tty_use_margin(tty))
                tty_putcode(tty, TTYC_ENMG);
        if (options_get_number(global_options, "extended-keys"))
                tty_puts(tty, tty_term_string(tty->term, TTYC_ENEKS));
        if (options_get_number(global_options, "focus-events"))
                tty_puts(tty, tty_term_string(tty->term, TTYC_ENFCS));
        if (tty->term->flags & TERM_VT100LIKE)
                tty_puts(tty, "\033[?7727h");

        /*
         * Features might have changed since the first draw during attach. For
         * example, this happens when DA responses are received.
         */
        server_redraw_client(c);

        tty_invalidate(tty);
}

void
tty_raw(struct tty *tty, const char *s)
{
        struct client   *c = tty->client;
        ssize_t          n, slen;
        u_int            i;

        slen = strlen(s);
        for (i = 0; i < 5; i++) {
                n = write(c->fd, s, slen);
                if (n >= 0) {
                        s += n;
                        slen -= n;
                        if (slen == 0)
                                break;
                } else if (n == -1 && errno != EAGAIN)
                        break;
                usleep(100);
        }
}

void
tty_putcode(struct tty *tty, enum tty_code_code code)
{
        tty_puts(tty, tty_term_string(tty->term, code));
}

void
tty_putcode_i(struct tty *tty, enum tty_code_code code, int a)
{
        if (a < 0)
                return;
        tty_puts(tty, tty_term_string_i(tty->term, code, a));
}

void
tty_putcode_ii(struct tty *tty, enum tty_code_code code, int a, int b)
{
        if (a < 0 || b < 0)
                return;
        tty_puts(tty, tty_term_string_ii(tty->term, code, a, b));
}

void
tty_putcode_iii(struct tty *tty, enum tty_code_code code, int a, int b, int c)
{
        if (a < 0 || b < 0 || c < 0)
                return;
        tty_puts(tty, tty_term_string_iii(tty->term, code, a, b, c));
}

void
tty_putcode_s(struct tty *tty, enum tty_code_code code, const char *a)
{
        if (a != NULL)
                tty_puts(tty, tty_term_string_s(tty->term, code, a));
}

void
tty_putcode_ss(struct tty *tty, enum tty_code_code code, const char *a,
    const char *b)
{
        if (a != NULL && b != NULL)
                tty_puts(tty, tty_term_string_ss(tty->term, code, a, b));
}

static void
tty_add(struct tty *tty, const char *buf, size_t len)
{
        struct client   *c = tty->client;

        if (tty->flags & TTY_BLOCK) {
                tty->discarded += len;
                return;
        }

        evbuffer_add(tty->out, buf, len);
        log_debug("%s: %.*s", c->name, (int)len, buf);
        c->written += len;

        if (tty_log_fd != -1)
                write(tty_log_fd, buf, len);
        if ((tty->flags & TTY_STARTED) &&
            !event_pending(&tty->event_out, EV_WRITE, NULL))
                event_add(&tty->event_out, NULL);
}

void
tty_puts(struct tty *tty, const char *s)
{
        if (*s != '\0')
                tty_add(tty, s, strlen(s));
}

void
tty_putc(struct tty *tty, u_char ch)
{
        const char      *acs;

        if ((tty->term->flags & TERM_NOAM) &&
            ch >= 0x20 && ch != 0x7f &&
            tty->cy == tty->sy - 1 &&
            tty->cx + 1 >= tty->sx)
                return;

        if (tty->cell.attr & GRID_ATTR_CHARSET) {
                acs = tty_acs_get(tty, ch);
                if (acs != NULL)
                        tty_add(tty, acs, strlen(acs));
                else
                        tty_add(tty, &ch, 1);
        } else
                tty_add(tty, &ch, 1);

        if (ch >= 0x20 && ch != 0x7f) {
                if (tty->cx >= tty->sx) {
                        tty->cx = 1;
                        if (tty->cy != tty->rlower)
                                tty->cy++;

                        /*
                         * On !am terminals, force the cursor position to where
                         * we think it should be after a line wrap - this means
                         * it works on sensible terminals as well.
                         */
                        if (tty->term->flags & TERM_NOAM)
                                tty_putcode_ii(tty, TTYC_CUP, tty->cy, tty->cx);
                } else
                        tty->cx++;
        }
}

void
tty_putn(struct tty *tty, const void *buf, size_t len, u_int width)
{
        if ((tty->term->flags & TERM_NOAM) &&
            tty->cy == tty->sy - 1 &&
            tty->cx + len >= tty->sx)
                len = tty->sx - tty->cx - 1;

        tty_add(tty, buf, len);
        if (tty->cx + width > tty->sx) {
                tty->cx = (tty->cx + width) - tty->sx;
                if (tty->cx <= tty->sx)
                        tty->cy++;
                else
                        tty->cx = tty->cy = UINT_MAX;
        } else
                tty->cx += width;
}

static void
tty_set_italics(struct tty *tty)
{
        const char      *s;

        if (tty_term_has(tty->term, TTYC_SITM)) {
                s = options_get_string(global_options, "default-terminal");
                if (strcmp(s, "screen") != 0 && strncmp(s, "screen-", 7) != 0) {
                        tty_putcode(tty, TTYC_SITM);
                        return;
                }
        }
        tty_putcode(tty, TTYC_SMSO);
}

void
tty_set_title(struct tty *tty, const char *title)
{
        if (!tty_term_has(tty->term, TTYC_TSL) ||
            !tty_term_has(tty->term, TTYC_FSL))
                return;

        tty_putcode(tty, TTYC_TSL);
        tty_puts(tty, title);
        tty_putcode(tty, TTYC_FSL);
}

void
tty_set_path(struct tty *tty, const char *title)
{
        if (!tty_term_has(tty->term, TTYC_SWD) ||
            !tty_term_has(tty->term, TTYC_FSL))
                return;

        tty_putcode(tty, TTYC_SWD);
        tty_puts(tty, title);
        tty_putcode(tty, TTYC_FSL);
}

static void
tty_force_cursor_colour(struct tty *tty, int c)
{
        u_char  r, g, b;
        char    s[13];

        if (c != -1)
                c = colour_force_rgb(c);
        if (c == tty->ccolour)
                return;
        if (c == -1)
                tty_putcode(tty, TTYC_CR);
        else {
                colour_split_rgb(c, &r, &g, &b);
                xsnprintf(s, sizeof s, "rgb:%02hhx/%02hhx/%02hhx", r, g, b);
                tty_putcode_s(tty, TTYC_CS, s);
        }
        tty->ccolour = c;
}

static int
tty_update_cursor(struct tty *tty, int mode, struct screen *s)
{
        enum screen_cursor_style        cstyle;
        int                             ccolour, changed, cmode = mode;

        /* Set cursor colour if changed. */
        if (s != NULL) {
                ccolour = s->ccolour;
                if (s->ccolour == -1)
                        ccolour = s->default_ccolour;
                tty_force_cursor_colour(tty, ccolour);
        }

        /* If cursor is off, set as invisible. */
        if (~cmode & MODE_CURSOR) {
                if (tty->mode & MODE_CURSOR)
                        tty_putcode(tty, TTYC_CIVIS);
                return (cmode);
        }

        /* Check if blinking or very visible flag changed or style changed. */
        if (s == NULL)
                cstyle = tty->cstyle;
        else {
                cstyle = s->cstyle;
                if (cstyle == SCREEN_CURSOR_DEFAULT) {
                        if (~cmode & MODE_CURSOR_BLINKING_SET) {
                                if (s->default_mode & MODE_CURSOR_BLINKING)
                                        cmode |= MODE_CURSOR_BLINKING;
                                else
                                        cmode &= ~MODE_CURSOR_BLINKING;
                        }
                        cstyle = s->default_cstyle;
                }
        }

        /* If nothing changed, do nothing. */
        changed = cmode ^ tty->mode;
        if ((changed & CURSOR_MODES) == 0 && cstyle == tty->cstyle)
                return (cmode);

        /*
         * Set cursor style. If an explicit style has been set with DECSCUSR,
         * set it if supported, otherwise send cvvis for blinking styles.
         *
         * If no style, has been set (SCREEN_CURSOR_DEFAULT), then send cvvis
         * if either the blinking or very visible flags are set.
         */
        tty_putcode(tty, TTYC_CNORM);
        switch (cstyle) {
        case SCREEN_CURSOR_DEFAULT:
                if (tty->cstyle != SCREEN_CURSOR_DEFAULT) {
                        if (tty_term_has(tty->term, TTYC_SE))
                                tty_putcode(tty, TTYC_SE);
                        else
                                tty_putcode_i(tty, TTYC_SS, 0);
                }
                if (cmode & (MODE_CURSOR_BLINKING|MODE_CURSOR_VERY_VISIBLE))
                        tty_putcode(tty, TTYC_CVVIS);
                break;
        case SCREEN_CURSOR_BLOCK:
                if (tty_term_has(tty->term, TTYC_SS)) {
                        if (cmode & MODE_CURSOR_BLINKING)
                                tty_putcode_i(tty, TTYC_SS, 1);
                        else
                                tty_putcode_i(tty, TTYC_SS, 2);
                } else if (cmode & MODE_CURSOR_BLINKING)
                        tty_putcode(tty, TTYC_CVVIS);
                break;
        case SCREEN_CURSOR_UNDERLINE:
                if (tty_term_has(tty->term, TTYC_SS)) {
                        if (cmode & MODE_CURSOR_BLINKING)
                                tty_putcode_i(tty, TTYC_SS, 3);
                        else
                                tty_putcode_i(tty, TTYC_SS, 4);
                } else if (cmode & MODE_CURSOR_BLINKING)
                        tty_putcode(tty, TTYC_CVVIS);
                break;
        case SCREEN_CURSOR_BAR:
                if (tty_term_has(tty->term, TTYC_SS)) {
                        if (cmode & MODE_CURSOR_BLINKING)
                                tty_putcode_i(tty, TTYC_SS, 5);
                        else
                                tty_putcode_i(tty, TTYC_SS, 6);
                } else if (cmode & MODE_CURSOR_BLINKING)
                        tty_putcode(tty, TTYC_CVVIS);
                break;
        }
        tty->cstyle = cstyle;
        return (cmode);
 }

void
tty_update_mode(struct tty *tty, int mode, struct screen *s)
{
        struct tty_term *term = tty->term;
        struct client   *c = tty->client;
        int              changed;

        if (tty->flags & TTY_NOCURSOR)
                mode &= ~MODE_CURSOR;

        if (tty_update_cursor(tty, mode, s) & MODE_CURSOR_BLINKING)
                mode |= MODE_CURSOR_BLINKING;
        else
                mode &= ~MODE_CURSOR_BLINKING;

        changed = mode ^ tty->mode;
        if (log_get_level() != 0 && changed != 0) {
                log_debug("%s: current mode %s", c->name,
                    screen_mode_to_string(tty->mode));
                log_debug("%s: setting mode %s", c->name,
                    screen_mode_to_string(mode));
        }

        if ((changed & ALL_MOUSE_MODES) && tty_term_has(term, TTYC_KMOUS)) {
                /*
                 * If the mouse modes have changed, clear then all and apply
                 * again. There are differences in how terminals track the
                 * various bits.
                 */
                tty_puts(tty, "\033[?1006l\033[?1000l\033[?1002l\033[?1003l");
                if (mode & ALL_MOUSE_MODES)
                        tty_puts(tty, "\033[?1006h");
                if (mode & MODE_MOUSE_ALL)
                        tty_puts(tty, "\033[?1000h\033[?1002h\033[?1003h");
                else if (mode & MODE_MOUSE_BUTTON)
                        tty_puts(tty, "\033[?1000h\033[?1002h");
                else if (mode & MODE_MOUSE_STANDARD)
                        tty_puts(tty, "\033[?1000h");
        }
        tty->mode = mode;
}

static void
tty_emulate_repeat(struct tty *tty, enum tty_code_code code,
    enum tty_code_code code1, u_int n)
{
        if (tty_term_has(tty->term, code))
                tty_putcode_i(tty, code, n);
        else {
                while (n-- > 0)
                        tty_putcode(tty, code1);
        }
}

void
tty_repeat_space(struct tty *tty, u_int n)
{
        static char s[500];

        if (*s != ' ')
                memset(s, ' ', sizeof s);

        while (n > sizeof s) {
                tty_putn(tty, s, sizeof s, sizeof s);
                n -= sizeof s;
        }
        if (n != 0)
                tty_putn(tty, s, n, n);
}

/* Is this window bigger than the terminal? */
int
tty_window_bigger(struct tty *tty)
{
        struct client   *c = tty->client;
        struct window   *w = c->session->curw->window;

        return (tty->sx < w->sx || tty->sy - status_line_size(c) < w->sy);
}

/* What offset should this window be drawn at? */
int
tty_window_offset(struct tty *tty, u_int *ox, u_int *oy, u_int *sx, u_int *sy)
{
        *ox = tty->oox;
        *oy = tty->ooy;
        *sx = tty->osx;
        *sy = tty->osy;

        return (tty->oflag);
}

/* What offset should this window be drawn at? */
static int
tty_window_offset1(struct tty *tty, u_int *ox, u_int *oy, u_int *sx, u_int *sy)
{
        struct client           *c = tty->client;
        struct window           *w = c->session->curw->window;
        struct window_pane      *wp = server_client_get_pane(c);
        u_int                    cx, cy, lines;

        lines = status_line_size(c);

        if (tty->sx >= w->sx && tty->sy - lines >= w->sy) {
                *ox = 0;
                *oy = 0;
                *sx = w->sx;
                *sy = w->sy;

                c->pan_window = NULL;
                return (0);
        }

        *sx = tty->sx;
        *sy = tty->sy - lines;

        if (c->pan_window == w) {
                if (*sx >= w->sx)
                        c->pan_ox = 0;
                else if (c->pan_ox + *sx > w->sx)
                        c->pan_ox = w->sx - *sx;
                *ox = c->pan_ox;
                if (*sy >= w->sy)
                        c->pan_oy = 0;
                else if (c->pan_oy + *sy > w->sy)
                        c->pan_oy = w->sy - *sy;
                *oy = c->pan_oy;
                return (1);
        }

        if (~wp->screen->mode & MODE_CURSOR) {
                *ox = 0;
                *oy = 0;
        } else {
                cx = wp->xoff + wp->screen->cx;
                cy = wp->yoff + wp->screen->cy;

                if (cx < *sx)
                        *ox = 0;
                else if (cx > w->sx - *sx)
                        *ox = w->sx - *sx;
                else
                        *ox = cx - *sx / 2;

                if (cy < *sy)
                        *oy = 0;
                else if (cy > w->sy - *sy)
                        *oy = w->sy - *sy;
                else
                        *oy = cy - *sy / 2;
        }

        c->pan_window = NULL;
        return (1);
}

/* Update stored offsets for a window and redraw if necessary. */
void
tty_update_window_offset(struct window *w)
{
        struct client   *c;

        TAILQ_FOREACH(c, &clients, entry) {
                if (c->session != NULL &&
                    c->session->curw != NULL &&
                    c->session->curw->window == w)
                        tty_update_client_offset(c);
        }
}

/* Update stored offsets for a client and redraw if necessary. */
void
tty_update_client_offset(struct client *c)
{
        u_int   ox, oy, sx, sy;

        if (~c->flags & CLIENT_TERMINAL)
                return;

        c->tty.oflag = tty_window_offset1(&c->tty, &ox, &oy, &sx, &sy);
        if (ox == c->tty.oox &&
            oy == c->tty.ooy &&
            sx == c->tty.osx &&
            sy == c->tty.osy)
                return;

        log_debug ("%s: %s offset has changed (%u,%u %ux%u -> %u,%u %ux%u)",
            __func__, c->name, c->tty.oox, c->tty.ooy, c->tty.osx, c->tty.osy,
            ox, oy, sx, sy);

        c->tty.oox = ox;
        c->tty.ooy = oy;
        c->tty.osx = sx;
        c->tty.osy = sy;

        c->flags |= (CLIENT_REDRAWWINDOW|CLIENT_REDRAWSTATUS);
}

/*
 * Is the region large enough to be worth redrawing once later rather than
 * probably several times now? Currently yes if it is more than 50% of the
 * pane.
 */
static int
tty_large_region(__unused struct tty *tty, const struct tty_ctx *ctx)
{
        return (ctx->orlower - ctx->orupper >= ctx->sy / 2);
}

/*
 * Return if BCE is needed but the terminal doesn't have it - it'll need to be
 * emulated.
 */
int
tty_fake_bce(const struct tty *tty, const struct grid_cell *gc, u_int bg)
{
        if (tty_term_flag(tty->term, TTYC_BCE))
                return (0);
        if (!COLOUR_DEFAULT(bg) || !COLOUR_DEFAULT(gc->bg))
                return (1);
        return (0);
}

/*
 * Redraw scroll region using data from screen (already updated). Used when
 * CSR not supported, or window is a pane that doesn't take up the full
 * width of the terminal.
 */
static void
tty_redraw_region(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client           *c = tty->client;
        u_int                    i;

        /*
         * If region is large, schedule a redraw. In most cases this is likely
         * to be followed by some more scrolling.
         */
        if (tty_large_region(tty, ctx)) {
                log_debug("%s: %s large redraw", __func__, c->name);
                ctx->redraw_cb(ctx);
                return;
        }

        for (i = ctx->orupper; i <= ctx->orlower; i++)
                tty_draw_pane(tty, ctx, i);
}

/* Is this position visible in the pane? */
static int
tty_is_visible(__unused struct tty *tty, const struct tty_ctx *ctx, u_int px,
    u_int py, u_int nx, u_int ny)
{
        u_int   xoff = ctx->rxoff + px, yoff = ctx->ryoff + py;

        if (!ctx->bigger)
                return (1);

        if (xoff + nx <= ctx->wox || xoff >= ctx->wox + ctx->wsx ||
            yoff + ny <= ctx->woy || yoff >= ctx->woy + ctx->wsy)
                return (0);
        return (1);
}

/* Clamp line position to visible part of pane. */
static int
tty_clamp_line(struct tty *tty, const struct tty_ctx *ctx, u_int px, u_int py,
    u_int nx, u_int *i, u_int *x, u_int *rx, u_int *ry)
{
        u_int   xoff = ctx->rxoff + px;

        if (!tty_is_visible(tty, ctx, px, py, nx, 1))
                return (0);
        *ry = ctx->yoff + py - ctx->woy;

        if (xoff >= ctx->wox && xoff + nx <= ctx->wox + ctx->wsx) {
                /* All visible. */
                *i = 0;
                *x = ctx->xoff + px - ctx->wox;
                *rx = nx;
        } else if (xoff < ctx->wox && xoff + nx > ctx->wox + ctx->wsx) {
                /* Both left and right not visible. */
                *i = ctx->wox;
                *x = 0;
                *rx = ctx->wsx;
        } else if (xoff < ctx->wox) {
                /* Left not visible. */
                *i = ctx->wox - (ctx->xoff + px);
                *x = 0;
                *rx = nx - *i;
        } else {
                /* Right not visible. */
                *i = 0;
                *x = (ctx->xoff + px) - ctx->wox;
                *rx = ctx->wsx - *x;
        }
        if (*rx > nx)
                fatalx("%s: x too big, %u > %u", __func__, *rx, nx);

        return (1);
}

/* Clear a line. */
static void
tty_clear_line(struct tty *tty, const struct grid_cell *defaults, u_int py,
    u_int px, u_int nx, u_int bg)
{
        struct client           *c = tty->client;
        struct visible_ranges   *r;
        struct visible_range    *rr;
        u_int                    i;

        log_debug("%s: %s, %u at %u,%u", __func__, c->name, nx, px, py);

        /* Nothing to clear. */
        if (nx == 0)
                return;

        /* If genuine BCE is available, can try escape sequences. */
        if (c->overlay_check == NULL && !tty_fake_bce(tty, defaults, bg)) {
                /* Off the end of the line, use EL if available. */
                if (px + nx >= tty->sx && tty_term_has(tty->term, TTYC_EL)) {
                        tty_cursor(tty, px, py);
                        tty_putcode(tty, TTYC_EL);
                        return;
                }

                /* At the start of the line. Use EL1. */
                if (px == 0 && tty_term_has(tty->term, TTYC_EL1)) {
                        tty_cursor(tty, px + nx - 1, py);
                        tty_putcode(tty, TTYC_EL1);
                        return;
                }

                /* Section of line. Use ECH if possible. */
                if (tty_term_has(tty->term, TTYC_ECH)) {
                        tty_cursor(tty, px, py);
                        tty_putcode_i(tty, TTYC_ECH, nx);
                        return;
                }
        }

        /*
         * Couldn't use an escape sequence, use spaces. Clear only the visible
         * bit if there is an overlay.
         */
        r = tty_check_overlay_range(tty, px, py, nx);
        for (i = 0; i < r->used; i++) {
                rr = &r->ranges[i];
                if (rr->nx != 0) {
                        tty_cursor(tty, rr->px, py);
                        tty_repeat_space(tty, rr->nx);
                }
        }
}

/* Clear a line, adjusting to visible part of pane. */
static void
tty_clear_pane_line(struct tty *tty, const struct tty_ctx *ctx, u_int py,
    u_int px, u_int nx, u_int bg)
{
        struct client   *c = tty->client;
        u_int            i, x, rx, ry;

        log_debug("%s: %s, %u at %u,%u", __func__, c->name, nx, px, py);

        if (tty_clamp_line(tty, ctx, px, py, nx, &i, &x, &rx, &ry))
                tty_clear_line(tty, &ctx->defaults, ry, x, rx, bg);
}

/* Clamp area position to visible part of pane. */
static int
tty_clamp_area(struct tty *tty, const struct tty_ctx *ctx, u_int px, u_int py,
    u_int nx, u_int ny, u_int *i, u_int *j, u_int *x, u_int *y, u_int *rx,
    u_int *ry)
{
        u_int   xoff = ctx->rxoff + px, yoff = ctx->ryoff + py;

        if (!tty_is_visible(tty, ctx, px, py, nx, ny))
                return (0);

        if (xoff >= ctx->wox && xoff + nx <= ctx->wox + ctx->wsx) {
                /* All visible. */
                *i = 0;
                *x = ctx->xoff + px - ctx->wox;
                *rx = nx;
        } else if (xoff < ctx->wox && xoff + nx > ctx->wox + ctx->wsx) {
                /* Both left and right not visible. */
                *i = ctx->wox;
                *x = 0;
                *rx = ctx->wsx;
        } else if (xoff < ctx->wox) {
                /* Left not visible. */
                *i = ctx->wox - (ctx->xoff + px);
                *x = 0;
                *rx = nx - *i;
        } else {
                /* Right not visible. */
                *i = 0;
                *x = (ctx->xoff + px) - ctx->wox;
                *rx = ctx->wsx - *x;
        }
        if (*rx > nx)
                fatalx("%s: x too big, %u > %u", __func__, *rx, nx);

        if (yoff >= ctx->woy && yoff + ny <= ctx->woy + ctx->wsy) {
                /* All visible. */
                *j = 0;
                *y = ctx->yoff + py - ctx->woy;
                *ry = ny;
        } else if (yoff < ctx->woy && yoff + ny > ctx->woy + ctx->wsy) {
                /* Both top and bottom not visible. */
                *j = ctx->woy;
                *y = 0;
                *ry = ctx->wsy;
        } else if (yoff < ctx->woy) {
                /* Top not visible. */
                *j = ctx->woy - (ctx->yoff + py);
                *y = 0;
                *ry = ny - *j;
        } else {
                /* Bottom not visible. */
                *j = 0;
                *y = (ctx->yoff + py) - ctx->woy;
                *ry = ctx->wsy - *y;
        }
        if (*ry > ny)
                fatalx("%s: y too big, %u > %u", __func__, *ry, ny);

        return (1);
}

/* Clear an area, adjusting to visible part of pane. */
static void
tty_clear_area(struct tty *tty, const struct grid_cell *defaults, u_int py,
    u_int ny, u_int px, u_int nx, u_int bg)
{
        struct client   *c = tty->client;
        u_int            yy;
        char             tmp[64];

        log_debug("%s: %s, %u,%u at %u,%u", __func__, c->name, nx, ny, px, py);

        /* Nothing to clear. */
        if (nx == 0 || ny == 0)
                return;

        /* If genuine BCE is available, can try escape sequences. */
        if (c->overlay_check == NULL && !tty_fake_bce(tty, defaults, bg)) {
                /* Use ED if clearing off the bottom of the terminal. */
                if (px == 0 &&
                    px + nx >= tty->sx &&
                    py + ny >= tty->sy &&
                    tty_term_has(tty->term, TTYC_ED)) {
                        tty_cursor(tty, 0, py);
                        tty_putcode(tty, TTYC_ED);
                        return;
                }

                /*
                 * On VT420 compatible terminals we can use DECFRA if the
                 * background colour isn't default (because it doesn't work
                 * after SGR 0).
                 */
                if ((tty->term->flags & TERM_DECFRA) && !COLOUR_DEFAULT(bg)) {
                        xsnprintf(tmp, sizeof tmp, "\033[32;%u;%u;%u;%u$x",
                            py + 1, px + 1, py + ny, px + nx);
                        tty_puts(tty, tmp);
                        return;
                }

                /* Full lines can be scrolled away to clear them. */
                if (px == 0 &&
                    px + nx >= tty->sx &&
                    ny > 2 &&
                    tty_term_has(tty->term, TTYC_CSR) &&
                    tty_term_has(tty->term, TTYC_INDN)) {
                        tty_region(tty, py, py + ny - 1);
                        tty_margin_off(tty);
                        tty_putcode_i(tty, TTYC_INDN, ny);
                        return;
                }

                /*
                 * If margins are supported, can just scroll the area off to
                 * clear it.
                 */
                if (nx > 2 &&
                    ny > 2 &&
                    tty_term_has(tty->term, TTYC_CSR) &&
                    tty_use_margin(tty) &&
                    tty_term_has(tty->term, TTYC_INDN)) {
                        tty_region(tty, py, py + ny - 1);
                        tty_margin(tty, px, px + nx - 1);
                        tty_putcode_i(tty, TTYC_INDN, ny);
                        return;
                }
        }

        /* Couldn't use an escape sequence, loop over the lines. */
        for (yy = py; yy < py + ny; yy++)
                tty_clear_line(tty, defaults, yy, px, nx, bg);
}

/* Clear an area in a pane. */
static void
tty_clear_pane_area(struct tty *tty, const struct tty_ctx *ctx, u_int py,
    u_int ny, u_int px, u_int nx, u_int bg)
{
        u_int   i, j, x, y, rx, ry;

        if (tty_clamp_area(tty, ctx, px, py, nx, ny, &i, &j, &x, &y, &rx, &ry))
                tty_clear_area(tty, &ctx->defaults, y, ry, x, rx, bg);
}

static void
tty_draw_pane(struct tty *tty, const struct tty_ctx *ctx, u_int py)
{
        struct screen   *s = ctx->s;
        u_int            nx = ctx->sx, i, x, rx, ry, j;
        struct visible_ranges   *r;
        struct visible_range    *rr;

        log_debug("%s: %s %u %d", __func__, tty->client->name, py, ctx->bigger);

        if (!ctx->bigger) {
                r = tty_check_overlay_range(tty, ctx->xoff, ctx->yoff + py, nx);
                for (j = 0; j < r->used; j++) {
                        rr = &r->ranges[j];
                        if (rr->nx != 0) {
                                tty_draw_line(tty, s, rr->px - ctx->xoff, py,
                                    rr->nx, rr->px, ctx->yoff + py,
                                    &ctx->defaults, ctx->palette);
                        }
                }
                return;
        }
        if (tty_clamp_line(tty, ctx, 0, py, nx, &i, &x, &rx, &ry)) {
                r = tty_check_overlay_range(tty, x, ry, rx);
                for (j = 0; j < r->used; j++) {
                        rr = &r->ranges[j];
                        if (rr->nx != 0) {
                                tty_draw_line(tty, s, i + (rr->px - x), py,
                                    rr->nx, rr->px, ry, &ctx->defaults,
                                    ctx->palette);
                        }
                }
        }
}

const struct grid_cell *
tty_check_codeset(struct tty *tty, const struct grid_cell *gc)
{
        static struct grid_cell new;
        int                     c;

        /* Characters less than 0x7f are always fine, no matter what. */
        if (gc->data.size == 1 && *gc->data.data < 0x7f)
                return (gc);
        if (gc->flags & GRID_FLAG_TAB)
                return (gc);

        /* UTF-8 terminal and a UTF-8 character - fine. */
        if (tty->client->flags & CLIENT_UTF8)
                return (gc);
        memcpy(&new, gc, sizeof new);

        /* See if this can be mapped to an ACS character. */
        c = tty_acs_reverse_get(tty, gc->data.data, gc->data.size);
        if (c != -1) {
                utf8_set(&new.data, c);
                new.attr |= GRID_ATTR_CHARSET;
                return (&new);
        }

        /* Replace by the right number of underscores. */
        new.data.size = gc->data.width;
        if (new.data.size > UTF8_SIZE)
                new.data.size = UTF8_SIZE;
        memset(new.data.data, '_', new.data.size);
        return (&new);
}

/* Check if a single character is covered by the overlay. */
static int
tty_check_overlay(struct tty *tty, u_int px, u_int py)
{
        struct visible_ranges   *r;

        /*
         * With a single character, if there is anything visible (that is, the
         * range is not empty), it must be that character.
         */
        r = tty_check_overlay_range(tty, px, py, 1);
        return (!server_client_ranges_is_empty(r));
}

/* Return parts of the input range which are visible. */
struct visible_ranges *
tty_check_overlay_range(struct tty *tty, u_int px, u_int py, u_int nx)
{
        struct client   *c = tty->client;

        if (c->overlay_check == NULL) {
                server_client_ensure_ranges(&tty->r, 1);
                tty->r.ranges[0].px = px;
                tty->r.ranges[0].nx = nx;
                tty->r.used = 1;
                return (&tty->r);
        }
        return (c->overlay_check(c, c->overlay_data, px, py, nx));
}

void
tty_sync_start(struct tty *tty)
{
        if (tty->flags & TTY_BLOCK)
                return;
        if (tty->flags & TTY_SYNCING)
                return;
        tty->flags |= TTY_SYNCING;

        if (tty_term_has(tty->term, TTYC_SYNC)) {
                log_debug("%s sync start", tty->client->name);
                tty_putcode_i(tty, TTYC_SYNC, 1);
        }
}

void
tty_sync_end(struct tty *tty)
{
        if (tty->flags & TTY_BLOCK)
                return;
        if (~tty->flags & TTY_SYNCING)
                return;
        tty->flags &= ~TTY_SYNCING;

        if (tty_term_has(tty->term, TTYC_SYNC)) {
                log_debug("%s sync end", tty->client->name);
                tty_putcode_i(tty, TTYC_SYNC, 2);
        }
}

static int
tty_client_ready(const struct tty_ctx *ctx, struct client *c)
{
        if (c->session == NULL || c->tty.term == NULL)
                return (0);
        if (c->flags & CLIENT_SUSPENDED)
                return (0);

        /*
         * If invisible panes are allowed (used for passthrough), don't care if
         * redrawing or frozen.
         */
        if (ctx->allow_invisible_panes)
                return (1);

        if (c->flags & CLIENT_REDRAWWINDOW)
                return (0);
        if (c->tty.flags & TTY_FREEZE)
                return (0);
        return (1);
}

void
tty_write(void (*cmdfn)(struct tty *, const struct tty_ctx *),
    struct tty_ctx *ctx)
{
        struct client   *c;
        int              state;

        if (ctx->set_client_cb == NULL)
                return;
        TAILQ_FOREACH(c, &clients, entry) {
                if (tty_client_ready(ctx, c)) {
                        state = ctx->set_client_cb(ctx, c);
                        if (state == -1)
                                break;
                        if (state == 0)
                                continue;
                        cmdfn(&c->tty, ctx);
                }
        }
}

void
tty_cmd_insertcharacter(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client   *c = tty->client;

        if (ctx->bigger ||
            !tty_full_width(tty, ctx) ||
            tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
            (!tty_term_has(tty->term, TTYC_ICH) &&
            !tty_term_has(tty->term, TTYC_ICH1)) ||
            c->overlay_check != NULL) {
                tty_draw_pane(tty, ctx, ctx->ocy);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);

        tty_emulate_repeat(tty, TTYC_ICH, TTYC_ICH1, ctx->num);
}

void
tty_cmd_deletecharacter(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client   *c = tty->client;

        if (ctx->bigger ||
            !tty_full_width(tty, ctx) ||
            tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
            (!tty_term_has(tty->term, TTYC_DCH) &&
            !tty_term_has(tty->term, TTYC_DCH1)) ||
            c->overlay_check != NULL) {
                tty_draw_pane(tty, ctx, ctx->ocy);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);

        tty_emulate_repeat(tty, TTYC_DCH, TTYC_DCH1, ctx->num);
}

void
tty_cmd_clearcharacter(struct tty *tty, const struct tty_ctx *ctx)
{
        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_clear_pane_line(tty, ctx, ctx->ocy, ctx->ocx, ctx->num, ctx->bg);
}

void
tty_cmd_insertline(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client   *c = tty->client;

        if (ctx->bigger ||
            !tty_full_width(tty, ctx) ||
            tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
            !tty_term_has(tty->term, TTYC_CSR) ||
            !tty_term_has(tty->term, TTYC_IL1) ||
            ctx->sx == 1 ||
            ctx->sy == 1 ||
            c->overlay_check != NULL) {
                tty_redraw_region(tty, ctx);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
        tty_margin_off(tty);
        tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);

        tty_emulate_repeat(tty, TTYC_IL, TTYC_IL1, ctx->num);
        tty->cx = tty->cy = UINT_MAX;
}

void
tty_cmd_deleteline(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client   *c = tty->client;

        if (ctx->bigger ||
            !tty_full_width(tty, ctx) ||
            tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
            !tty_term_has(tty->term, TTYC_CSR) ||
            !tty_term_has(tty->term, TTYC_DL1) ||
            ctx->sx == 1 ||
            ctx->sy == 1 ||
            c->overlay_check != NULL) {
                tty_redraw_region(tty, ctx);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
        tty_margin_off(tty);
        tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);

        tty_emulate_repeat(tty, TTYC_DL, TTYC_DL1, ctx->num);
        tty->cx = tty->cy = UINT_MAX;
}

void
tty_cmd_clearline(struct tty *tty, const struct tty_ctx *ctx)
{
        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_clear_pane_line(tty, ctx, ctx->ocy, 0, ctx->sx, ctx->bg);
}

void
tty_cmd_clearendofline(struct tty *tty, const struct tty_ctx *ctx)
{
        u_int   nx = ctx->sx - ctx->ocx;

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_clear_pane_line(tty, ctx, ctx->ocy, ctx->ocx, nx, ctx->bg);
}

void
tty_cmd_clearstartofline(struct tty *tty, const struct tty_ctx *ctx)
{
        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_clear_pane_line(tty, ctx, ctx->ocy, 0, ctx->ocx + 1, ctx->bg);
}

void
tty_cmd_reverseindex(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client   *c = tty->client;

        if (ctx->ocy != ctx->orupper)
                return;

        if (ctx->bigger ||
            (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
            tty_fake_bce(tty, &ctx->defaults, 8) ||
            !tty_term_has(tty->term, TTYC_CSR) ||
            (!tty_term_has(tty->term, TTYC_RI) &&
            !tty_term_has(tty->term, TTYC_RIN)) ||
            ctx->sx == 1 ||
            ctx->sy == 1 ||
            c->overlay_check != NULL) {
                tty_redraw_region(tty, ctx);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
        tty_margin_pane(tty, ctx);
        tty_cursor_pane(tty, ctx, ctx->ocx, ctx->orupper);

        if (tty_term_has(tty->term, TTYC_RI))
                tty_putcode(tty, TTYC_RI);
        else
                tty_putcode_i(tty, TTYC_RIN, 1);
}

void
tty_cmd_linefeed(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client   *c = tty->client;

        if (ctx->ocy != ctx->orlower)
                return;

        if (ctx->bigger ||
            (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
            tty_fake_bce(tty, &ctx->defaults, 8) ||
            !tty_term_has(tty->term, TTYC_CSR) ||
            ctx->sx == 1 ||
            ctx->sy == 1 ||
            c->overlay_check != NULL) {
                tty_redraw_region(tty, ctx);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
        tty_margin_pane(tty, ctx);

        /*
         * If we want to wrap a pane while using margins, the cursor needs to
         * be exactly on the right of the region. If the cursor is entirely off
         * the edge - move it back to the right. Some terminals are funny about
         * this and insert extra spaces, so only use the right if margins are
         * enabled.
         */
        if (ctx->xoff + ctx->ocx > tty->rright) {
                if (!tty_use_margin(tty))
                        tty_cursor(tty, 0, ctx->yoff + ctx->ocy);
                else
                        tty_cursor(tty, tty->rright, ctx->yoff + ctx->ocy);
        } else
                tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);

        tty_putc(tty, '\n');
}

void
tty_cmd_scrollup(struct tty *tty, const struct tty_ctx *ctx)
{
        struct client   *c = tty->client;
        u_int            i;

        if (ctx->bigger ||
            (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
            tty_fake_bce(tty, &ctx->defaults, 8) ||
            !tty_term_has(tty->term, TTYC_CSR) ||
            ctx->sx == 1 ||
            ctx->sy == 1 ||
            c->overlay_check != NULL) {
                tty_redraw_region(tty, ctx);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
        tty_margin_pane(tty, ctx);

        if (ctx->num == 1 || !tty_term_has(tty->term, TTYC_INDN)) {
                if (!tty_use_margin(tty))
                        tty_cursor(tty, 0, tty->rlower);
                else
                        tty_cursor(tty, tty->rright, tty->rlower);
                for (i = 0; i < ctx->num; i++)
                        tty_putc(tty, '\n');
        } else {
                if (tty->cy == UINT_MAX)
                        tty_cursor(tty, 0, 0);
                else
                        tty_cursor(tty, 0, tty->cy);
                tty_putcode_i(tty, TTYC_INDN, ctx->num);
        }
}

void
tty_cmd_scrolldown(struct tty *tty, const struct tty_ctx *ctx)
{
        u_int            i;
        struct client   *c = tty->client;

        if (ctx->bigger ||
            (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
            tty_fake_bce(tty, &ctx->defaults, 8) ||
            !tty_term_has(tty->term, TTYC_CSR) ||
            (!tty_term_has(tty->term, TTYC_RI) &&
            !tty_term_has(tty->term, TTYC_RIN)) ||
            ctx->sx == 1 ||
            ctx->sy == 1 ||
            c->overlay_check != NULL) {
                tty_redraw_region(tty, ctx);
                return;
        }

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
        tty_margin_pane(tty, ctx);
        tty_cursor_pane(tty, ctx, ctx->ocx, ctx->orupper);

        if (tty_term_has(tty->term, TTYC_RIN))
                tty_putcode_i(tty, TTYC_RIN, ctx->num);
        else {
                for (i = 0; i < ctx->num; i++)
                        tty_putcode(tty, TTYC_RI);
        }
}

void
tty_cmd_clearendofscreen(struct tty *tty, const struct tty_ctx *ctx)
{
        u_int   px, py, nx, ny;

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, 0, ctx->sy - 1);
        tty_margin_off(tty);

        px = 0;
        nx = ctx->sx;
        py = ctx->ocy + 1;
        ny = ctx->sy - ctx->ocy - 1;

        tty_clear_pane_area(tty, ctx, py, ny, px, nx, ctx->bg);

        px = ctx->ocx;
        nx = ctx->sx - ctx->ocx;
        py = ctx->ocy;

        tty_clear_pane_line(tty, ctx, py, px, nx, ctx->bg);
}

void
tty_cmd_clearstartofscreen(struct tty *tty, const struct tty_ctx *ctx)
{
        u_int   px, py, nx, ny;

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, 0, ctx->sy - 1);
        tty_margin_off(tty);

        px = 0;
        nx = ctx->sx;
        py = 0;
        ny = ctx->ocy;

        tty_clear_pane_area(tty, ctx, py, ny, px, nx, ctx->bg);

        px = 0;
        nx = ctx->ocx + 1;
        py = ctx->ocy;

        tty_clear_pane_line(tty, ctx, py, px, nx, ctx->bg);
}

void
tty_cmd_clearscreen(struct tty *tty, const struct tty_ctx *ctx)
{
        u_int   px, py, nx, ny;

        tty_default_attributes(tty, &ctx->defaults, ctx->palette, ctx->bg,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, 0, ctx->sy - 1);
        tty_margin_off(tty);

        px = 0;
        nx = ctx->sx;
        py = 0;
        ny = ctx->sy;

        tty_clear_pane_area(tty, ctx, py, ny, px, nx, ctx->bg);
}

void
tty_cmd_alignmenttest(struct tty *tty, const struct tty_ctx *ctx)
{
        u_int   i, j;

        if (ctx->bigger) {
                ctx->redraw_cb(ctx);
                return;
        }

        tty_attributes(tty, &grid_default_cell, &ctx->defaults, ctx->palette,
            ctx->s->hyperlinks);

        tty_region_pane(tty, ctx, 0, ctx->sy - 1);
        tty_margin_off(tty);

        for (j = 0; j < ctx->sy; j++) {
                tty_cursor_pane(tty, ctx, 0, j);
                for (i = 0; i < ctx->sx; i++)
                        tty_putc(tty, 'E');
        }
}

void
tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
{
        const struct grid_cell  *gcp = ctx->cell;
        struct screen           *s = ctx->s;
        struct visible_ranges   *r;
        u_int                    px, py, i, vis = 0;

        px = ctx->xoff + ctx->ocx - ctx->wox;
        py = ctx->yoff + ctx->ocy - ctx->woy;
        if (!tty_is_visible(tty, ctx, ctx->ocx, ctx->ocy, 1, 1) ||
            (gcp->data.width == 1 && !tty_check_overlay(tty, px, py)))
                return;

        if (ctx->num == 2) {
                tty_draw_line(tty, s, 0, s->cy, screen_size_x(s),
                    ctx->xoff - ctx->wox, py, &ctx->defaults, ctx->palette);
                return;
        }

        /* Handle partially obstructed wide characters. */
        if (gcp->data.width > 1) {
                r = tty_check_overlay_range(tty, px, py, gcp->data.width);
                for (i = 0; i < r->used; i++)
                        vis += r->ranges[i].nx;
                if (vis < gcp->data.width) {
                        tty_draw_line(tty, s, s->cx, s->cy, gcp->data.width,
                            px, py, &ctx->defaults, ctx->palette);
                        return;
                }
        }

        if (ctx->xoff + ctx->ocx - ctx->wox > tty->sx - 1 &&
            ctx->ocy == ctx->orlower &&
            tty_full_width(tty, ctx))
                tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);

        tty_margin_off(tty);
        tty_cursor_pane_unless_wrap(tty, ctx, ctx->ocx, ctx->ocy);

        tty_cell(tty, ctx->cell, &ctx->defaults, ctx->palette,
            ctx->s->hyperlinks);

        if (ctx->num == 1)
                tty_invalidate(tty);
}

void
tty_cmd_cells(struct tty *tty, const struct tty_ctx *ctx)
{
        struct visible_ranges   *r;
        struct visible_range    *rr;
        u_int                    i, px, py, cx;
        char                    *cp = ctx->ptr;

        if (!tty_is_visible(tty, ctx, ctx->ocx, ctx->ocy, ctx->num, 1))
                return;

        if (ctx->bigger &&
            (ctx->xoff + ctx->ocx < ctx->wox ||
            ctx->xoff + ctx->ocx + ctx->num > ctx->wox + ctx->wsx)) {
                if (!ctx->wrapped ||
                    !tty_full_width(tty, ctx) ||
                    (tty->term->flags & TERM_NOAM) ||
                    ctx->xoff + ctx->ocx != 0 ||
                    ctx->yoff + ctx->ocy != tty->cy + 1 ||
                    tty->cx < tty->sx ||
                    tty->cy == tty->rlower)
                        tty_draw_pane(tty, ctx, ctx->ocy);
                else
                        ctx->redraw_cb(ctx);
                return;
        }

        tty_margin_off(tty);
        tty_cursor_pane_unless_wrap(tty, ctx, ctx->ocx, ctx->ocy);
        tty_attributes(tty, ctx->cell, &ctx->defaults, ctx->palette,
            ctx->s->hyperlinks);

        /* Get tty position from pane position for overlay check. */
        px = ctx->xoff + ctx->ocx - ctx->wox;
        py = ctx->yoff + ctx->ocy - ctx->woy;

        r = tty_check_overlay_range(tty, px, py, ctx->num);
        for (i = 0; i < r->used; i++) {
                rr = &r->ranges[i];
                if (rr->nx != 0) {
                        cx = rr->px - ctx->xoff + ctx->wox;
                        tty_cursor_pane_unless_wrap(tty, ctx, cx, ctx->ocy);
                        tty_putn(tty, cp + rr->px - px, rr->nx, rr->nx);
                }
        }
}

void
tty_cmd_setselection(struct tty *tty, const struct tty_ctx *ctx)
{
        tty_set_selection(tty, ctx->ptr2, ctx->ptr, ctx->num);
}

void
tty_set_selection(struct tty *tty, const char *clip, const char *buf,
    size_t len)
{
        char    *encoded;
        size_t   size;

        if (~tty->flags & TTY_STARTED)
                return;
        if (!tty_term_has(tty->term, TTYC_MS))
                return;

        size = 4 * ((len + 2) / 3) + 1; /* storage for base64 */
        encoded = xmalloc(size);

        b64_ntop(buf, len, encoded, size);
        tty->flags |= TTY_NOBLOCK;
        tty_putcode_ss(tty, TTYC_MS, clip, encoded);

        free(encoded);
}

void
tty_cmd_rawstring(struct tty *tty, const struct tty_ctx *ctx)
{
        tty->flags |= TTY_NOBLOCK;
        tty_add(tty, ctx->ptr, ctx->num);
        tty_invalidate(tty);
}

void
tty_cmd_syncstart(struct tty *tty, const struct tty_ctx *ctx)
{
        if (ctx->num == 0x11) {
                /*
                 * This is an overlay and a command that moves the cursor so
                 * start synchronized updates.
                 */
                tty_sync_start(tty);
        } else if (~ctx->num & 0x10) {
                /*
                 * This is a pane. If there is an overlay, always start;
                 * otherwise, only if requested.
                 */
                if (ctx->num || tty->client->overlay_draw != NULL)
                        tty_sync_start(tty);
        }
}

void
tty_cell(struct tty *tty, const struct grid_cell *gc,
    const struct grid_cell *defaults, struct colour_palette *palette,
    struct hyperlinks *hl)
{
        const struct grid_cell  *gcp;

        /* Skip last character if terminal is stupid. */
        if ((tty->term->flags & TERM_NOAM) &&
            tty->cy == tty->sy - 1 &&
            tty->cx == tty->sx - 1)
                return;

        /* If this is a padding character, do nothing. */
        if (gc->flags & GRID_FLAG_PADDING)
                return;

        /* Check the output codeset and apply attributes. */
        gcp = tty_check_codeset(tty, gc);
        tty_attributes(tty, gcp, defaults, palette, hl);

        /* If it is a single character, write with putc to handle ACS. */
        if (gcp->data.size == 1) {
                if (*gcp->data.data < 0x20 || *gcp->data.data == 0x7f)
                        return;
                tty_putc(tty, *gcp->data.data);
                return;
        }

        /* Write the data. */
        tty_putn(tty, gcp->data.data, gcp->data.size, gcp->data.width);
}

void
tty_reset(struct tty *tty)
{
        struct grid_cell        *gc = &tty->cell;

        if (!grid_cells_equal(gc, &grid_default_cell)) {
                if (gc->link != 0)
                        tty_putcode_ss(tty, TTYC_HLS, "", "");
                if ((gc->attr & GRID_ATTR_CHARSET) && tty_acs_needed(tty))
                        tty_putcode(tty, TTYC_RMACS);
                tty_putcode(tty, TTYC_SGR0);
                memcpy(gc, &grid_default_cell, sizeof *gc);
        }
        memcpy(&tty->last_cell, &grid_default_cell, sizeof tty->last_cell);
}

void
tty_invalidate(struct tty *tty)
{
        memcpy(&tty->cell, &grid_default_cell, sizeof tty->cell);
        memcpy(&tty->last_cell, &grid_default_cell, sizeof tty->last_cell);

        tty->cx = tty->cy = UINT_MAX;
        tty->rupper = tty->rleft = UINT_MAX;
        tty->rlower = tty->rright = UINT_MAX;

        if (tty->flags & TTY_STARTED) {
                if (tty_use_margin(tty))
                        tty_putcode(tty, TTYC_ENMG);
                tty_putcode(tty, TTYC_SGR0);

                tty->mode = ALL_MODES;
                tty_update_mode(tty, MODE_CURSOR, NULL);

                tty_cursor(tty, 0, 0);
                tty_region_off(tty);
                tty_margin_off(tty);
        } else
                tty->mode = MODE_CURSOR;
}

/* Turn off margin. */
void
tty_region_off(struct tty *tty)
{
        tty_region(tty, 0, tty->sy - 1);
}

/* Set region inside pane. */
static void
tty_region_pane(struct tty *tty, const struct tty_ctx *ctx, u_int rupper,
    u_int rlower)
{
        tty_region(tty, ctx->yoff + rupper - ctx->woy,
            ctx->yoff + rlower - ctx->woy);
}

/* Set region at absolute position. */
static void
tty_region(struct tty *tty, u_int rupper, u_int rlower)
{
        if (tty->rlower == rlower && tty->rupper == rupper)
                return;
        if (!tty_term_has(tty->term, TTYC_CSR))
                return;

        tty->rupper = rupper;
        tty->rlower = rlower;

        /*
         * Some terminals (such as PuTTY) do not correctly reset the cursor to
         * 0,0 if it is beyond the last column (they do not reset their wrap
         * flag so further output causes a line feed). As a workaround, do an
         * explicit move to 0 first.
         */
        if (tty->cx >= tty->sx) {
                if (tty->cy == UINT_MAX)
                        tty_cursor(tty, 0, 0);
                else
                        tty_cursor(tty, 0, tty->cy);
        }

        tty_putcode_ii(tty, TTYC_CSR, tty->rupper, tty->rlower);
        tty->cx = tty->cy = UINT_MAX;
}

/* Turn off margin. */
void
tty_margin_off(struct tty *tty)
{
        tty_margin(tty, 0, tty->sx - 1);
}

/* Set margin inside pane. */
static void
tty_margin_pane(struct tty *tty, const struct tty_ctx *ctx)
{
        tty_margin(tty, ctx->xoff - ctx->wox,
            ctx->xoff + ctx->sx - 1 - ctx->wox);
}

/* Set margin at absolute position. */
static void
tty_margin(struct tty *tty, u_int rleft, u_int rright)
{
        if (!tty_use_margin(tty))
                return;
        if (tty->rleft == rleft && tty->rright == rright)
                return;

        tty_putcode_ii(tty, TTYC_CSR, tty->rupper, tty->rlower);

        tty->rleft = rleft;
        tty->rright = rright;

        if (rleft == 0 && rright == tty->sx - 1)
                tty_putcode(tty, TTYC_CLMG);
        else
                tty_putcode_ii(tty, TTYC_CMG, rleft, rright);
        tty->cx = tty->cy = UINT_MAX;
}

/*
 * Move the cursor, unless it would wrap itself when the next character is
 * printed.
 */
static void
tty_cursor_pane_unless_wrap(struct tty *tty, const struct tty_ctx *ctx,
    u_int cx, u_int cy)
{
        if (!ctx->wrapped ||
            !tty_full_width(tty, ctx) ||
            (tty->term->flags & TERM_NOAM) ||
            ctx->xoff + cx != 0 ||
            ctx->yoff + cy != tty->cy + 1 ||
            tty->cx < tty->sx ||
            tty->cy == tty->rlower)
                tty_cursor_pane(tty, ctx, cx, cy);
        else
                log_debug("%s: will wrap at %u,%u", __func__, tty->cx, tty->cy);
}

/* Move cursor inside pane. */
static void
tty_cursor_pane(struct tty *tty, const struct tty_ctx *ctx, u_int cx, u_int cy)
{
        tty_cursor(tty, ctx->xoff + cx - ctx->wox, ctx->yoff + cy - ctx->woy);
}

/* Move cursor to absolute position. */
void
tty_cursor(struct tty *tty, u_int cx, u_int cy)
{
        struct tty_term *term = tty->term;
        u_int            thisx, thisy;
        int              change;

        if (tty->flags & TTY_BLOCK)
                return;

        thisx = tty->cx;
        thisy = tty->cy;

        /*
         * If in the automargin space, and want to be there, do not move.
         * Otherwise, force the cursor to be in range (and complain).
         */
        if (cx == thisx && cy == thisy && cx == tty->sx)
                return;
        if (cx > tty->sx - 1) {
                log_debug("%s: x too big %u > %u", __func__, cx, tty->sx - 1);
                cx = tty->sx - 1;
        }

        /* No change. */
        if (cx == thisx && cy == thisy)
                return;

        /* Currently at the very end of the line - use absolute movement. */
        if (thisx > tty->sx - 1)
                goto absolute;

        /* Move to home position (0, 0). */
        if (cx == 0 && cy == 0 && tty_term_has(term, TTYC_HOME)) {
                tty_putcode(tty, TTYC_HOME);
                goto out;
        }

        /* Zero on the next line. */
        if (cx == 0 && cy == thisy + 1 && thisy != tty->rlower &&
            (!tty_use_margin(tty) || tty->rleft == 0)) {
                tty_putc(tty, '\r');
                tty_putc(tty, '\n');
                goto out;
        }

        /* Moving column or row. */
        if (cy == thisy) {
                /*
                 * Moving column only, row staying the same.
                 */

                /* To left edge. */
                if (cx == 0 && (!tty_use_margin(tty) || tty->rleft == 0)) {
                        tty_putc(tty, '\r');
                        goto out;
                }

                /* One to the left. */
                if (cx == thisx - 1 && tty_term_has(term, TTYC_CUB1)) {
                        tty_putcode(tty, TTYC_CUB1);
                        goto out;
                }

                /* One to the right. */
                if (cx == thisx + 1 && tty_term_has(term, TTYC_CUF1)) {
                        tty_putcode(tty, TTYC_CUF1);
                        goto out;
                }

                /* Calculate difference. */
                change = thisx - cx;    /* +ve left, -ve right */

                /*
                 * Use HPA if change is larger than absolute, otherwise move
                 * the cursor with CUB/CUF.
                 */
                if ((u_int) abs(change) > cx && tty_term_has(term, TTYC_HPA)) {
                        tty_putcode_i(tty, TTYC_HPA, cx);
                        goto out;
                } else if (change > 0 &&
                    tty_term_has(term, TTYC_CUB) &&
                    !tty_use_margin(tty)) {
                        if (change == 2 && tty_term_has(term, TTYC_CUB1)) {
                                tty_putcode(tty, TTYC_CUB1);
                                tty_putcode(tty, TTYC_CUB1);
                                goto out;
                        }
                        tty_putcode_i(tty, TTYC_CUB, change);
                        goto out;
                } else if (change < 0 &&
                    tty_term_has(term, TTYC_CUF) &&
                    !tty_use_margin(tty)) {
                        tty_putcode_i(tty, TTYC_CUF, -change);
                        goto out;
                }
        } else if (cx == thisx) {
                /*
                 * Moving row only, column staying the same.
                 */

                /* One above. */
                if (thisy != tty->rupper &&
                    cy == thisy - 1 && tty_term_has(term, TTYC_CUU1)) {
                        tty_putcode(tty, TTYC_CUU1);
                        goto out;
                }

                /* One below. */
                if (thisy != tty->rlower &&
                    cy == thisy + 1 && tty_term_has(term, TTYC_CUD1)) {
                        tty_putcode(tty, TTYC_CUD1);
                        goto out;
                }

                /* Calculate difference. */
                change = thisy - cy;    /* +ve up, -ve down */

                /*
                 * Try to use VPA if change is larger than absolute or if this
                 * change would cross the scroll region, otherwise use CUU/CUD.
                 */
                if ((u_int) abs(change) > cy ||
                    (change < 0 && cy - change > tty->rlower) ||
                    (change > 0 && cy - change < tty->rupper)) {
                            if (tty_term_has(term, TTYC_VPA)) {
                                    tty_putcode_i(tty, TTYC_VPA, cy);
                                    goto out;
                            }
                } else if (change > 0 && tty_term_has(term, TTYC_CUU)) {
                        tty_putcode_i(tty, TTYC_CUU, change);
                        goto out;
                } else if (change < 0 && tty_term_has(term, TTYC_CUD)) {
                        tty_putcode_i(tty, TTYC_CUD, -change);
                        goto out;
                }
        }

absolute:
        /* Absolute movement. */
        tty_putcode_ii(tty, TTYC_CUP, cy, cx);

out:
        tty->cx = cx;
        tty->cy = cy;
}

static void
tty_hyperlink(struct tty *tty, const struct grid_cell *gc,
    struct hyperlinks *hl)
{
        const char      *uri, *id;

        if (gc->link == tty->cell.link)
                return;
        tty->cell.link = gc->link;

        if (hl == NULL)
                return;

        if (gc->link == 0 || !hyperlinks_get(hl, gc->link, &uri, NULL, &id))
                tty_putcode_ss(tty, TTYC_HLS, "", "");
        else
                tty_putcode_ss(tty, TTYC_HLS, id, uri);
}

void
tty_attributes(struct tty *tty, const struct grid_cell *gc,
    const struct grid_cell *defaults, struct colour_palette *palette,
    struct hyperlinks *hl)
{
        struct grid_cell        *tc = &tty->cell, gc2;
        int                      changed;

        /* Copy cell and update default colours. */
        memcpy(&gc2, gc, sizeof gc2);
        if (~gc->flags & GRID_FLAG_NOPALETTE) {
                if (gc2.fg == 8)
                        gc2.fg = defaults->fg;
                if (gc2.bg == 8)
                        gc2.bg = defaults->bg;
        }

        /* Ignore cell if it is the same as the last one. */
        if (gc2.attr == tty->last_cell.attr &&
            gc2.fg == tty->last_cell.fg &&
            gc2.bg == tty->last_cell.bg &&
            gc2.us == tty->last_cell.us &&
                gc2.link == tty->last_cell.link)
                return;

        /*
         * If no setab, try to use the reverse attribute as a best-effort for a
         * non-default background. This is a bit of a hack but it doesn't do
         * any serious harm and makes a couple of applications happier.
         */
        if (!tty_term_has(tty->term, TTYC_SETAB)) {
                if (gc2.attr & GRID_ATTR_REVERSE) {
                        if (gc2.fg != 7 && !COLOUR_DEFAULT(gc2.fg))
                                gc2.attr &= ~GRID_ATTR_REVERSE;
                } else {
                        if (gc2.bg != 0 && !COLOUR_DEFAULT(gc2.bg))
                                gc2.attr |= GRID_ATTR_REVERSE;
                }
        }

        /* Fix up the colours if necessary. */
        tty_check_fg(tty, palette, &gc2);
        tty_check_bg(tty, palette, &gc2);
        tty_check_us(tty, palette, &gc2);

        /*
         * If any bits are being cleared or the underline colour is now default,
         * reset everything.
         */
        if ((tc->attr & ~gc2.attr) || (tc->us != gc2.us && gc2.us == 0))
                tty_reset(tty);

        /*
         * Set the colours. This may call tty_reset() (so it comes next) and
         * may add to (NOT remove) the desired attributes.
         */
        tty_colours(tty, &gc2);

        /* Filter out attribute bits already set. */
        changed = gc2.attr & ~tc->attr;
        tc->attr = gc2.attr;

        /* Set the attributes. */
        if (changed & GRID_ATTR_BRIGHT)
                tty_putcode(tty, TTYC_BOLD);
        if (changed & GRID_ATTR_DIM)
                tty_putcode(tty, TTYC_DIM);
        if (changed & GRID_ATTR_ITALICS)
                tty_set_italics(tty);
        if (changed & GRID_ATTR_ALL_UNDERSCORE) {
                if (changed & GRID_ATTR_UNDERSCORE)
                        tty_putcode(tty, TTYC_SMUL);
                else if (changed & GRID_ATTR_UNDERSCORE_2)
                        tty_putcode_i(tty, TTYC_SMULX, 2);
                else if (changed & GRID_ATTR_UNDERSCORE_3)
                        tty_putcode_i(tty, TTYC_SMULX, 3);
                else if (changed & GRID_ATTR_UNDERSCORE_4)
                        tty_putcode_i(tty, TTYC_SMULX, 4);
                else if (changed & GRID_ATTR_UNDERSCORE_5)
                        tty_putcode_i(tty, TTYC_SMULX, 5);
        }
        if (changed & GRID_ATTR_BLINK)
                tty_putcode(tty, TTYC_BLINK);
        if (changed & GRID_ATTR_REVERSE) {
                if (tty_term_has(tty->term, TTYC_REV))
                        tty_putcode(tty, TTYC_REV);
                else if (tty_term_has(tty->term, TTYC_SMSO))
                        tty_putcode(tty, TTYC_SMSO);
        }
        if (changed & GRID_ATTR_HIDDEN)
                tty_putcode(tty, TTYC_INVIS);
        if (changed & GRID_ATTR_STRIKETHROUGH)
                tty_putcode(tty, TTYC_SMXX);
        if (changed & GRID_ATTR_OVERLINE)
                tty_putcode(tty, TTYC_SMOL);
        if ((changed & GRID_ATTR_CHARSET) && tty_acs_needed(tty))
                tty_putcode(tty, TTYC_SMACS);

        /* Set hyperlink if any. */
        tty_hyperlink(tty, gc, hl);

        memcpy(&tty->last_cell, &gc2, sizeof tty->last_cell);
}

static void
tty_colours(struct tty *tty, const struct grid_cell *gc)
{
        struct grid_cell        *tc = &tty->cell;

        /* No changes? Nothing is necessary. */
        if (gc->fg == tc->fg && gc->bg == tc->bg && gc->us == tc->us)
                return;

        /*
         * Is either the default colour? This is handled specially because the
         * best solution might be to reset both colours to default, in which
         * case if only one is default need to fall onward to set the other
         * colour.
         */
        if (COLOUR_DEFAULT(gc->fg) || COLOUR_DEFAULT(gc->bg)) {
                /*
                 * If don't have AX, send sgr0. This resets both colours to default.
                 * Otherwise, try to set the default colour only as needed.
                 */
                if (!tty_term_flag(tty->term, TTYC_AX))
                        tty_reset(tty);
                else {
                        if (COLOUR_DEFAULT(gc->fg) && !COLOUR_DEFAULT(tc->fg)) {
                                tty_puts(tty, "\033[39m");
                                tc->fg = gc->fg;
                        }
                        if (COLOUR_DEFAULT(gc->bg) && !COLOUR_DEFAULT(tc->bg)) {
                                tty_puts(tty, "\033[49m");
                                tc->bg = gc->bg;
                        }
                }
        }

        /* Set the foreground colour. */
        if (!COLOUR_DEFAULT(gc->fg) && gc->fg != tc->fg)
                tty_colours_fg(tty, gc);

        /*
         * Set the background colour. This must come after the foreground as
         * tty_colours_fg() can call tty_reset().
         */
        if (!COLOUR_DEFAULT(gc->bg) && gc->bg != tc->bg)
                tty_colours_bg(tty, gc);

        /* Set the underscore colour. */
        if (gc->us != tc->us)
                tty_colours_us(tty, gc);
}

static void
tty_check_fg(struct tty *tty, struct colour_palette *palette,
    struct grid_cell *gc)
{
        u_char  r, g, b;
        u_int   colours;
        int     c;

        /*
         * Perform substitution if this pane has a palette. If the bright
         * attribute is set and Nobr is not present, use the bright entry in
         * the palette by changing to the aixterm colour
         */
        if (~gc->flags & GRID_FLAG_NOPALETTE) {
                c = gc->fg;
                if (c < 8 &&
                    gc->attr & GRID_ATTR_BRIGHT &&
                    !tty_term_has(tty->term, TTYC_NOBR))
                        c += 90;
                if ((c = colour_palette_get(palette, c)) != -1)
                        gc->fg = c;
        }

        /* Is this a 24-bit colour? */
        if (gc->fg & COLOUR_FLAG_RGB) {
                /* Not a 24-bit terminal? Translate to 256-colour palette. */
                if (tty->term->flags & TERM_RGBCOLOURS)
                        return;
                colour_split_rgb(gc->fg, &r, &g, &b);
                gc->fg = colour_find_rgb(r, g, b);
        }

        /* How many colours does this terminal have? */
        if (tty->term->flags & TERM_256COLOURS)
                colours = 256;
        else
                colours = tty_term_number(tty->term, TTYC_COLORS);

        /* Is this a 256-colour colour? */
        if (gc->fg & COLOUR_FLAG_256) {
                /* And not a 256 colour mode? */
                if (colours >= 256)
                        return;
                gc->fg = colour_256to16(gc->fg);
                if (~gc->fg & 8)
                        return;
                gc->fg &= 7;
                if (colours >= 16)
                        gc->fg += 90;
                else {
                        /*
                         * Mapping to black-on-black or white-on-white is not
                         * much use, so change the foreground.
                         */
                        if (gc->fg == 0 && gc->bg == 0)
                                gc->fg = 7;
                        else if (gc->fg == 7 && gc->bg == 7)
                                gc->fg = 0;
                }
                return;
        }

        /* Is this an aixterm colour? */
        if (gc->fg >= 90 && gc->fg <= 97 && colours < 16) {
                gc->fg -= 90;
                gc->attr |= GRID_ATTR_BRIGHT;
        }
}

static void
tty_check_bg(struct tty *tty, struct colour_palette *palette,
    struct grid_cell *gc)
{
        u_char  r, g, b;
        u_int   colours;
        int     c;

        /* Perform substitution if this pane has a palette. */
        if (~gc->flags & GRID_FLAG_NOPALETTE) {
                if ((c = colour_palette_get(palette, gc->bg)) != -1)
                        gc->bg = c;
        }

        /* Is this a 24-bit colour? */
        if (gc->bg & COLOUR_FLAG_RGB) {
                /* Not a 24-bit terminal? Translate to 256-colour palette. */
                if (tty->term->flags & TERM_RGBCOLOURS)
                        return;
                colour_split_rgb(gc->bg, &r, &g, &b);
                gc->bg = colour_find_rgb(r, g, b);
        }

        /* How many colours does this terminal have? */
        if (tty->term->flags & TERM_256COLOURS)
                colours = 256;
        else
                colours = tty_term_number(tty->term, TTYC_COLORS);

        /* Is this a 256-colour colour? */
        if (gc->bg & COLOUR_FLAG_256) {
                /*
                 * And not a 256 colour mode? Translate to 16-colour
                 * palette. Bold background doesn't exist portably, so just
                 * discard the bold bit if set.
                 */
                if (colours >= 256)
                        return;
                gc->bg = colour_256to16(gc->bg);
                if (~gc->bg & 8)
                        return;
                gc->bg &= 7;
                if (colours >= 16)
                        gc->bg += 90;
                return;
        }

        /* Is this an aixterm colour? */
        if (gc->bg >= 90 && gc->bg <= 97 && colours < 16)
                gc->bg -= 90;
}

static void
tty_check_us(__unused struct tty *tty, struct colour_palette *palette,
    struct grid_cell *gc)
{
        int     c;

        /* Perform substitution if this pane has a palette. */
        if (~gc->flags & GRID_FLAG_NOPALETTE) {
                if ((c = colour_palette_get(palette, gc->us)) != -1)
                        gc->us = c;
        }

        /* Convert underscore colour if only RGB can be supported. */
        if (!tty_term_has(tty->term, TTYC_SETULC1)) {
                    if ((c = colour_force_rgb (gc->us)) == -1)
                            gc->us = 8;
                    else
                            gc->us = c;
        }
}

static void
tty_colours_fg(struct tty *tty, const struct grid_cell *gc)
{
        struct grid_cell        *tc = &tty->cell;
        char                     s[32];

        /*
         * If the current colour is an aixterm bright colour and the new is not,
         * reset because some terminals do not clear bright correctly.
         */
        if (tty->cell.fg >= 90 &&
            tty->cell.bg <= 97 &&
            (gc->fg < 90 || gc->fg > 97))
                tty_reset(tty);

        /* Is this a 24-bit or 256-colour colour? */
        if (gc->fg & COLOUR_FLAG_RGB || gc->fg & COLOUR_FLAG_256) {
                if (tty_try_colour(tty, gc->fg, "38") == 0)
                        goto save;
                /* Should not get here, already converted in tty_check_fg. */
                return;
        }

        /* Is this an aixterm bright colour? */
        if (gc->fg >= 90 && gc->fg <= 97) {
                if (tty->term->flags & TERM_256COLOURS) {
                        xsnprintf(s, sizeof s, "\033[%dm", gc->fg);
                        tty_puts(tty, s);
                } else
                        tty_putcode_i(tty, TTYC_SETAF, gc->fg - 90 + 8);
                goto save;
        }

        /* Otherwise set the foreground colour. */
        tty_putcode_i(tty, TTYC_SETAF, gc->fg);

save:
        /* Save the new values in the terminal current cell. */
        tc->fg = gc->fg;
}

static void
tty_colours_bg(struct tty *tty, const struct grid_cell *gc)
{
        struct grid_cell        *tc = &tty->cell;
        char                     s[32];

        /* Is this a 24-bit or 256-colour colour? */
        if (gc->bg & COLOUR_FLAG_RGB || gc->bg & COLOUR_FLAG_256) {
                if (tty_try_colour(tty, gc->bg, "48") == 0)
                        goto save;
                /* Should not get here, already converted in tty_check_bg. */
                return;
        }

        /* Is this an aixterm bright colour? */
        if (gc->bg >= 90 && gc->bg <= 97) {
                if (tty->term->flags & TERM_256COLOURS) {
                        xsnprintf(s, sizeof s, "\033[%dm", gc->bg + 10);
                        tty_puts(tty, s);
                } else
                        tty_putcode_i(tty, TTYC_SETAB, gc->bg - 90 + 8);
                goto save;
        }

        /* Otherwise set the background colour. */
        tty_putcode_i(tty, TTYC_SETAB, gc->bg);

save:
        /* Save the new values in the terminal current cell. */
        tc->bg = gc->bg;
}

static void
tty_colours_us(struct tty *tty, const struct grid_cell *gc)
{
        struct grid_cell        *tc = &tty->cell;
        u_int                    c;
        u_char                   r, g, b;

        /* Clear underline colour. */
        if (COLOUR_DEFAULT(gc->us)) {
                tty_putcode(tty, TTYC_OL);
                goto save;
        }

        /*
         * If this is not an RGB colour, use Setulc1 if it exists, otherwise
         * convert.
         */
        if (~gc->us & COLOUR_FLAG_RGB) {
                c = gc->us;
                if ((~c & COLOUR_FLAG_256) && (c >= 90 && c <= 97))
                        c -= 82;
                tty_putcode_i(tty, TTYC_SETULC1, c & ~COLOUR_FLAG_256);
                return;
        }

        /*
         * Setulc and setal follows the ncurses(3) one argument "direct colour"
         * capability format. Calculate the colour value.
         */
        colour_split_rgb(gc->us, &r, &g, &b);
        c = (65536 * r) + (256 * g) + b;

        /*
         * Write the colour. Only use setal if the RGB flag is set because the
         * non-RGB version may be wrong.
         */
        if (tty_term_has(tty->term, TTYC_SETULC))
                tty_putcode_i(tty, TTYC_SETULC, c);
        else if (tty_term_has(tty->term, TTYC_SETAL) &&
            tty_term_has(tty->term, TTYC_RGB))
                tty_putcode_i(tty, TTYC_SETAL, c);

save:
        /* Save the new values in the terminal current cell. */
        tc->us = gc->us;
}

static int
tty_try_colour(struct tty *tty, int colour, const char *type)
{
        u_char  r, g, b;

        if (colour & COLOUR_FLAG_256) {
                if (*type == '3' && tty_term_has(tty->term, TTYC_SETAF))
                        tty_putcode_i(tty, TTYC_SETAF, colour & 0xff);
                else if (tty_term_has(tty->term, TTYC_SETAB))
                        tty_putcode_i(tty, TTYC_SETAB, colour & 0xff);
                return (0);
        }

        if (colour & COLOUR_FLAG_RGB) {
                colour_split_rgb(colour & 0xffffff, &r, &g, &b);
                if (*type == '3' && tty_term_has(tty->term, TTYC_SETRGBF))
                        tty_putcode_iii(tty, TTYC_SETRGBF, r, g, b);
                else if (tty_term_has(tty->term, TTYC_SETRGBB))
                        tty_putcode_iii(tty, TTYC_SETRGBB, r, g, b);
                return (0);
        }

        return (-1);
}

static void
tty_window_default_style(struct grid_cell *gc, struct window_pane *wp)
{
        memcpy(gc, &grid_default_cell, sizeof *gc);
        gc->fg = wp->palette.fg;
        gc->bg = wp->palette.bg;
}

void
tty_default_colours(struct grid_cell *gc, struct window_pane *wp)
{
        struct options          *oo = wp->options;
        struct format_tree      *ft;

        memcpy(gc, &grid_default_cell, sizeof *gc);

        if (wp->flags & PANE_STYLECHANGED) {
                log_debug("%%%u: style changed", wp->id);
                wp->flags &= ~PANE_STYLECHANGED;

                ft = format_create(NULL, NULL, FORMAT_PANE|wp->id,
                    FORMAT_NOJOBS);
                format_defaults(ft, NULL, NULL, NULL, wp);
                tty_window_default_style(&wp->cached_active_gc, wp);
                style_add(&wp->cached_active_gc, oo, "window-active-style", ft);
                tty_window_default_style(&wp->cached_gc, wp);
                style_add(&wp->cached_gc, oo, "window-style", ft);
                format_free(ft);
        }

        if (gc->fg == 8) {
                if (wp == wp->window->active && wp->cached_active_gc.fg != 8)
                        gc->fg = wp->cached_active_gc.fg;
                else
                        gc->fg = wp->cached_gc.fg;
        }

        if (gc->bg == 8) {
                if (wp == wp->window->active && wp->cached_active_gc.bg != 8)
                        gc->bg = wp->cached_active_gc.bg;
                else
                        gc->bg = wp->cached_gc.bg;
        }
}

void
tty_default_attributes(struct tty *tty, const struct grid_cell *defaults,
    struct colour_palette *palette, u_int bg, struct hyperlinks *hl)
{
        struct grid_cell        gc;

        memcpy(&gc, &grid_default_cell, sizeof gc);
        gc.bg = bg;
        tty_attributes(tty, &gc, defaults, palette, hl);
}

static void
tty_clipboard_query_callback(__unused int fd, __unused short events, void *data)
{
        struct tty      *tty = data;

        tty->flags &= ~TTY_OSC52QUERY;
}

void
tty_clipboard_query(struct tty *tty)
{
        struct timeval   tv = { .tv_sec = TTY_QUERY_TIMEOUT };

        if ((tty->flags & TTY_STARTED) && (~tty->flags & TTY_OSC52QUERY)) {
                tty_putcode_ss(tty, TTYC_MS, "", "?");
                tty->flags |= TTY_OSC52QUERY;
                evtimer_add(&tty->clipboard_timer, &tv);
        }
}