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File: [local] / src / usr.bin / tmux / tty.c (download)

Revision 1.435, Fri Sep 15 15:49:05 2023 UTC (8 months ago) by nicm
Branch: MAIN
CVS Tags: OPENBSD_7_5_BASE, OPENBSD_7_5, OPENBSD_7_4_BASE, OPENBSD_7_4
Changes since 1.434: +4 -1 lines

Change UTF-8 combining to inspect the previous character at the cursor
position rather than keeping the last character from the input stream,
this is how most terminals work and fixes problems with displaying these
characters in vim. GitHub issue 3600.

/* $OpenBSD: tty.c,v 1.435 2023/09/15 15:49:05 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 <unistd.h>

#include "tmux.h"

static int	tty_log_fd = -1;

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_invalidate(struct tty *);
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 int	tty_fake_bce(const struct tty *, const struct grid_cell *,
		    u_int);
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_repeat_space(struct tty *, u_int);
static void	tty_draw_pane(struct tty *, const struct tty_ctx *, u_int);
static void	tty_default_attributes(struct tty *, const struct grid_cell *,
		    struct colour_palette *, u_int, struct hyperlinks *);
static int	tty_check_overlay(struct tty *, u_int, u_int);
static void	tty_check_overlay_range(struct tty *, u_int, u_int, u_int,
		    struct overlay_ranges *);

#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;
	} 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->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;
}

void
tty_start_tty(struct tty *tty)
{
	struct client	*c = tty->client;
	struct termios	 tio;
	struct timeval	 tv = { .tv_sec = TTY_QUERY_TIMEOUT };

	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);

	evtimer_set(&tty->start_timer, tty_start_timer_callback, tty);
	evtimer_add(&tty->start_timer, &tv);

	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->term->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\\");
		tty_puts(tty, "\033]11;?\033\\");
	} else
		tty->flags |= TTY_ALL_REQUEST_FLAGS;
	tty->last_requests = time (NULL);
}

void
tty_repeat_requests(struct tty *tty)
{
	time_t	t = time (NULL);

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

	if (t - tty->last_requests <= TTY_REQUEST_LIMIT)
		return;
	tty->last_requests = t;

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

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);

	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));

	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);
}

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_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);
	}
}

static 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.
 */
static 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 overlay_ranges	 r;
	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.
	 */
	tty_check_overlay_range(tty, px, py, nx, &r);
	for (i = 0; i < OVERLAY_MAX_RANGES; i++) {
		if (r.nx[i] == 0)
			continue;
		tty_cursor(tty, r.px[i], py);
		tty_repeat_space(tty, r.nx[i]);
	}
}

/* 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;

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

	if (!ctx->bigger) {
		tty_draw_line(tty, s, 0, py, nx, ctx->xoff, ctx->yoff + py,
		    &ctx->defaults, ctx->palette);
		return;
	}
	if (tty_clamp_line(tty, ctx, 0, py, nx, &i, &x, &rx, &ry)) {
		tty_draw_line(tty, s, i, py, rx, x, ry, &ctx->defaults,
		    ctx->palette);
	}
}

static 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);

	/* 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 obstructed by the overlay and return a
 * boolean.
 */
static int
tty_check_overlay(struct tty *tty, u_int px, u_int py)
{
	struct overlay_ranges	r;

	/*
	 * A unit width range will always return nx[2] == 0 from a check, even
	 * with multiple overlays, so it's sufficient to check just the first
	 * two entries.
	 */
	tty_check_overlay_range(tty, px, py, 1, &r);
	if (r.nx[0] + r.nx[1] == 0)
		return (0);
	return (1);
}

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

	if (c->overlay_check == NULL) {
		r->px[0] = px;
		r->nx[0] = nx;
		r->px[1] = 0;
		r->nx[1] = 0;
		r->px[2] = 0;
		r->nx[2] = 0;
		return;
	}

	c->overlay_check(c, c->overlay_data, px, py, nx, r);
}

void
tty_draw_line(struct tty *tty, struct screen *s, u_int px, u_int py, u_int nx,
    u_int atx, u_int aty, const struct grid_cell *defaults,
    struct colour_palette *palette)
{
	struct grid		*gd = s->grid;
	struct grid_cell	 gc, last;
	const struct grid_cell	*gcp;
	struct grid_line	*gl;
	struct client		*c = tty->client;
	struct overlay_ranges	 r;
	u_int			 i, j, ux, sx, width, hidden, eux, nxx;
	u_int			 cellsize;
	int			 flags, cleared = 0, wrapped = 0;
	char			 buf[512];
	size_t			 len;

	log_debug("%s: px=%u py=%u nx=%u atx=%u aty=%u", __func__,
	    px, py, nx, atx, aty);
	log_debug("%s: defaults: fg=%d, bg=%d", __func__, defaults->fg,
	    defaults->bg);

	/*
	 * py is the line in the screen to draw.
	 * px is the start x and nx is the width to draw.
	 * atx,aty is the line on the terminal to draw it.
	 */

	flags = (tty->flags & TTY_NOCURSOR);
	tty->flags |= TTY_NOCURSOR;
	tty_update_mode(tty, tty->mode, s);

	tty_region_off(tty);
	tty_margin_off(tty);

	/*
	 * Clamp the width to cellsize - note this is not cellused, because
	 * there may be empty background cells after it (from BCE).
	 */
	sx = screen_size_x(s);
	if (nx > sx)
		nx = sx;
	cellsize = grid_get_line(gd, gd->hsize + py)->cellsize;
	if (sx > cellsize)
		sx = cellsize;
	if (sx > tty->sx)
		sx = tty->sx;
	if (sx > nx)
		sx = nx;
	ux = 0;

	if (py == 0)
		gl = NULL;
	else
		gl = grid_get_line(gd, gd->hsize + py - 1);
	if (gl == NULL ||
	    (~gl->flags & GRID_LINE_WRAPPED) ||
	    atx != 0 ||
	    tty->cx < tty->sx ||
	    nx < tty->sx) {
		if (nx < tty->sx &&
		    atx == 0 &&
		    px + sx != nx &&
		    tty_term_has(tty->term, TTYC_EL1) &&
		    !tty_fake_bce(tty, defaults, 8) &&
		    c->overlay_check == NULL) {
			tty_default_attributes(tty, defaults, palette, 8,
			    s->hyperlinks);
			tty_cursor(tty, nx - 1, aty);
			tty_putcode(tty, TTYC_EL1);
			cleared = 1;
		}
	} else {
		log_debug("%s: wrapped line %u", __func__, aty);
		wrapped = 1;
	}

	memcpy(&last, &grid_default_cell, sizeof last);
	len = 0;
	width = 0;

	for (i = 0; i < sx; i++) {
		grid_view_get_cell(gd, px + i, py, &gc);
		gcp = tty_check_codeset(tty, &gc);
		if (len != 0 &&
		    (!tty_check_overlay(tty, atx + ux + width, aty) ||
		    (gcp->attr & GRID_ATTR_CHARSET) ||
		    gcp->flags != last.flags ||
		    gcp->attr != last.attr ||
		    gcp->fg != last.fg ||
		    gcp->bg != last.bg ||
		    gcp->us != last.us ||
		    gcp->link != last.link ||
		    ux + width + gcp->data.width > nx ||
		    (sizeof buf) - len < gcp->data.size)) {
			tty_attributes(tty, &last, defaults, palette,
			    s->hyperlinks);
			if (last.flags & GRID_FLAG_CLEARED) {
				log_debug("%s: %zu cleared", __func__, len);
				tty_clear_line(tty, defaults, aty, atx + ux,
				    width, last.bg);
			} else {
				if (!wrapped || atx != 0 || ux != 0)
					tty_cursor(tty, atx + ux, aty);
				tty_putn(tty, buf, len, width);
			}
			ux += width;

			len = 0;
			width = 0;
			wrapped = 0;
		}

		if (gcp->flags & GRID_FLAG_SELECTED)
			screen_select_cell(s, &last, gcp);
		else
			memcpy(&last, gcp, sizeof last);

		tty_check_overlay_range(tty, atx + ux, aty, gcp->data.width,
		    &r);
		hidden = 0;
		for (j = 0; j < OVERLAY_MAX_RANGES; j++)
			hidden += r.nx[j];
		hidden = gcp->data.width - hidden;
		if (hidden != 0 && hidden == gcp->data.width) {
			if (~gcp->flags & GRID_FLAG_PADDING)
				ux += gcp->data.width;
		} else if (hidden != 0 || ux + gcp->data.width > nx) {
			if (~gcp->flags & GRID_FLAG_PADDING) {
				tty_attributes(tty, &last, defaults, palette,
				    s->hyperlinks);
				for (j = 0; j < OVERLAY_MAX_RANGES; j++) {
					if (r.nx[j] == 0)
						continue;
					/* Effective width drawn so far. */
					eux = r.px[j] - atx;
					if (eux < nx) {
						tty_cursor(tty, r.px[j], aty);
						nxx = nx - eux;
						if (r.nx[j] > nxx)
							r.nx[j] = nxx;
						tty_repeat_space(tty, r.nx[j]);
						ux = eux + r.nx[j];
					}
				}
			}
		} else if (gcp->attr & GRID_ATTR_CHARSET) {
			tty_attributes(tty, &last, defaults, palette,
			    s->hyperlinks);
			tty_cursor(tty, atx + ux, aty);
			for (j = 0; j < gcp->data.size; j++)
				tty_putc(tty, gcp->data.data[j]);
			ux += gcp->data.width;
		} else if (~gcp->flags & GRID_FLAG_PADDING) {
			memcpy(buf + len, gcp->data.data, gcp->data.size);
			len += gcp->data.size;
			width += gcp->data.width;
		}
	}
	if (len != 0 && ((~last.flags & GRID_FLAG_CLEARED) || last.bg != 8)) {
		tty_attributes(tty, &last, defaults, palette, s->hyperlinks);
		if (last.flags & GRID_FLAG_CLEARED) {
			log_debug("%s: %zu cleared (end)", __func__, len);
			tty_clear_line(tty, defaults, aty, atx + ux, width,
			    last.bg);
		} else {
			if (!wrapped || atx != 0 || ux != 0)
				tty_cursor(tty, atx + ux, aty);
			tty_putn(tty, buf, len, width);
		}
		ux += width;
	}

	if (!cleared && ux < nx) {
		log_debug("%s: %u to end of line (%zu cleared)", __func__,
		    nx - ux, len);
		tty_default_attributes(tty, defaults, palette, 8,
		    s->hyperlinks);
		tty_clear_line(tty, defaults, aty, atx + ux, nx - ux, 8);
	}

	tty->flags = (tty->flags & ~TTY_NOCURSOR) | flags;
	tty_update_mode(tty, tty->mode, s);
}

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 overlay_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;

	/* Handle partially obstructed wide characters. */
	if (gcp->data.width > 1) {
		tty_check_overlay_range(tty, px, py, gcp->data.width, &r);
		for (i = 0; i < OVERLAY_MAX_RANGES; i++)
			vis += r.nx[i];
		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 overlay_ranges	 r;
	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;

	tty_check_overlay_range(tty, px, py, ctx->num, &r);
	for (i = 0; i < OVERLAY_MAX_RANGES; i++) {
		if (r.nx[i] == 0)
			continue;
		/* Convert back to pane position for printing. */
		cx = r.px[i] - ctx->xoff + ctx->wox;
		tty_cursor_pane_unless_wrap(tty, ctx, cx, ctx->ocy);
		tty_putn(tty, cp + r.px[i] - px, r.nx[i], r.nx[i]);
	}
}

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 *flags, 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, flags, 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) {
		tty_attributes(tty, gcp, defaults, palette, hl);
		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);
}

static 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_term_has(tty->term, TTYC_SMULX))
			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;
	int			 have_ax;

	/* 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 but do have op, send sgr0 (op can't
		 * actually be used because it is sometimes the same as sgr0
		 * and sometimes isn't). This resets both colours to default.
		 *
		 * Otherwise, try to set the default colour only as needed.
		 */
		have_ax = tty_term_flag(tty->term, TTYC_AX);
		if (!have_ax && tty_term_has(tty->term, TTYC_OP))
			tty_reset(tty);
		else {
			if (COLOUR_DEFAULT(gc->fg) && !COLOUR_DEFAULT(tc->fg)) {
				if (have_ax)
					tty_puts(tty, "\033[39m");
				else if (tc->fg != 7)
					tty_putcode_i(tty, TTYC_SETAF, 7);
				tc->fg = gc->fg;
			}
			if (COLOUR_DEFAULT(gc->bg) && !COLOUR_DEFAULT(tc->bg)) {
				if (have_ax)
					tty_puts(tty, "\033[49m");
				else if (tc->bg != 0)
					tty_putcode_i(tty, TTYC_SETAB, 0);
				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_colour_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) {
			gc->fg = colour_256to16(gc->fg);
			if (gc->fg & 8) {
				gc->fg &= 7;
				if (colours >= 16)
					gc->fg += 90;
			}
		}
		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) {
			gc->bg = colour_256to16(gc->bg);
			if (gc->bg & 8) {
				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];

	/* 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;
	}
}

static 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;
	struct client	*c = tty->client;

	c->flags &= ~CLIENT_CLIPBOARDBUFFER;
	free(c->clipboard_panes);
	c->clipboard_panes = NULL;
	c->clipboard_npanes = 0;

	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))
		return;
	tty_putcode_ss(tty, TTYC_MS, "", "?");

	tty->flags |= TTY_OSC52QUERY;
	evtimer_set(&tty->clipboard_timer, tty_clipboard_query_callback, tty);
	evtimer_add(&tty->clipboard_timer, &tv);
}