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Revision 1.266, Wed Apr 19 06:52:27 2017 UTC (7 years, 1 month ago) by nicm
Branch: MAIN
Changes since 1.265: +65 -3 lines

When the data we have buffered to write to a terminal grows beyond a
reasonable amount (currently width * height * 8 bytes), discard all
output to the terminal and start trying to redraw periodically
instead. Continue with this until the amount of data we are trying to
write falls to a low level again.

This helps to prevent tmux sitting on a huge buffer of data when there
are processes with fast output running inside tmux but the outside
terminal is slow.

A new client_discarded format holds the amount of data that has been
discarded due to this mechanism.

The three variables (when to start this, when to stop, and how often to
redraw) are basically "works for me" at the moment, this is going in to
see how it goes and if it causes problems for anyone else.

/* $OpenBSD: tty.c,v 1.266 2017/04/19 06:52:27 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 int	tty_client_ready(struct client *, struct window_pane *);

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 *, const char *);
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 *, const struct window_pane *,
		    struct grid_cell *);
static void	tty_check_bg(struct tty *, const struct window_pane *,
		    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_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 window_pane *,
		    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_cell(struct tty *, const struct grid_cell *,
		    const struct window_pane *);
static void	tty_default_colours(struct grid_cell *,
		    const struct window_pane *);
static void	tty_default_attributes(struct tty *, const struct window_pane *,
		    u_int);

#define tty_use_acs(tty) \
	(tty_term_has((tty)->term, TTYC_ACSC) && !((tty)->flags & TTY_UTF8))
#define tty_use_margin(tty) \
	((tty)->term_type == TTY_VT420)

#define tty_pane_full_width(tty, ctx) \
	((ctx)->xoff == 0 && screen_size_x((ctx)->wp->screen) >= (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)

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, int fd, char *term)
{
	if (!isatty(fd))
		return (-1);

	memset(tty, 0, sizeof *tty);

	if (term == NULL || *term == '\0')
		tty->term_name = xstrdup("unknown");
	else
		tty->term_name = xstrdup(term);

	tty->fd = fd;
	tty->client = c;

	tty->cstyle = 0;
	tty->ccolour = xstrdup("");

	tty->flags = 0;

	tty->term_flags = 0;
	tty->term_type = TTY_UNKNOWN;

	return (0);
}

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

	if (ioctl(tty->fd, TIOCGWINSZ, &ws) != -1) {
		sx = ws.ws_col;
		if (sx == 0)
			sx = 80;
		sy = ws.ws_row;
		if (sy == 0)
			sy = 24;
	} else {
		sx = 80;
		sy = 24;
	}
	log_debug("%s: %s now %ux%u", __func__, c->name, sx, sy);

	if (!tty_set_size(tty, sx, sy))
		return (0);
	tty_invalidate(tty);
	return (1);
}

int
tty_set_size(struct tty *tty, u_int sx, u_int sy)
{
	if (sx == tty->sx && sy == tty->sy)
		return (0);
	tty->sx = sx;
	tty->sy = sy;
	return (1);
}

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

	nread = evbuffer_read(tty->in, tty->fd, -1);
	if (nread == -1)
		return;
	log_debug("%s: read %d bytes (already %zu)", c->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_REDRAW;
	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 < 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, tty->fd);
	if (nwrite == -1)
		return;
	log_debug("%s: wrote %d bytes (of %zu)", c->name, nwrite, size);

	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)
{
	tty->term = tty_term_find(tty->term_name, tty->fd, 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, tty->fd, EV_PERSIST|EV_READ,
	    tty_read_callback, tty);
	tty->in = evbuffer_new();

	event_set(&tty->event_out, tty->fd, EV_WRITE, tty_write_callback, tty);
	tty->out = evbuffer_new();

	evtimer_set(&tty->timer, tty_timer_callback, tty);

	tty_start_tty(tty);

	tty_keys_build(tty);

	return (0);
}

void
tty_start_tty(struct tty *tty)
{
	struct termios	tio;

	if (tty->fd != -1 && tcgetattr(tty->fd, &tty->tio) == 0) {
		setblocking(tty->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(tty->fd, TCSANOW, &tio) == 0)
			tcflush(tty->fd, TCIOFLUSH);
	}

	tty_putcode(tty, TTYC_SMCUP);

	tty_putcode(tty, TTYC_SMKX);
	if (tty_use_acs(tty))
		tty_putcode(tty, TTYC_ENACS);
	tty_putcode(tty, TTYC_CLEAR);

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

	if (tty_term_flag(tty->term, TTYC_XT)) {
		if (options_get_number(global_options, "focus-events")) {
			tty->flags |= TTY_FOCUS;
			tty_puts(tty, "\033[?1004h");
		}
		tty_puts(tty, "\033[c");
	}

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

	tty_force_cursor_colour(tty, "");

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

void
tty_stop_tty(struct tty *tty)
{
	struct winsize	ws;

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

	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(tty->fd, TIOCGWINSZ, &ws) == -1)
		return;
	if (tcsetattr(tty->fd, TCSANOW, &tty->tio) == -1)
		return;

	tty_raw(tty, tty_term_string2(tty->term, TTYC_CSR, 0, ws.ws_row - 1));
	if (tty_use_acs(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_term_has(tty->term, TTYC_SS) && tty->cstyle != 0) {
		if (tty_term_has(tty->term, TTYC_SE))
			tty_raw(tty, tty_term_string(tty->term, TTYC_SE));
		else
			tty_raw(tty, tty_term_string1(tty->term, TTYC_SS, 0));
	}
	if (tty->mode & MODE_BRACKETPASTE)
		tty_raw(tty, "\033[?2004l");
	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[?1006l\033[?1005l");

	if (tty_term_flag(tty->term, TTYC_XT)) {
		if (tty->flags & TTY_FOCUS) {
			tty->flags &= ~TTY_FOCUS;
			tty_raw(tty, "\033[?1004l");
		}
	}

	if (tty_use_margin(tty))
		tty_raw(tty, "\033[?69l"); /* DECLRMM */
	tty_raw(tty, tty_term_string(tty->term, TTYC_RMCUP));

	setblocking(tty->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;
	}

	if (tty->fd != -1) {
		close(tty->fd);
		tty->fd = -1;
	}
}

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

	free(tty->ccolour);
	free(tty->term_name);
}

void
tty_set_type(struct tty *tty, int type)
{
	tty->term_type = type;

	if (tty_use_margin(tty))
		tty_puts(tty, "\033[?69h"); /* DECLRMM */
}

void
tty_raw(struct tty *tty, const char *s)
{
	ssize_t	n, slen;
	u_int	i;

	slen = strlen(s);
	for (i = 0; i < 5; i++) {
		n = write(tty->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_putcode1(struct tty *tty, enum tty_code_code code, int a)
{
	if (a < 0)
		return;
	tty_puts(tty, tty_term_string1(tty->term, code, a));
}

void
tty_putcode2(struct tty *tty, enum tty_code_code code, int a, int b)
{
	if (a < 0 || b < 0)
		return;
	tty_puts(tty, tty_term_string2(tty->term, code, a, b));
}

void
tty_putcode_ptr1(struct tty *tty, enum tty_code_code code, const void *a)
{
	if (a != NULL)
		tty_puts(tty, tty_term_ptr1(tty->term, code, a));
}

void
tty_putcode_ptr2(struct tty *tty, enum tty_code_code code, const void *a,
    const void *b)
{
	if (a != NULL && b != NULL)
		tty_puts(tty, tty_term_ptr2(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, (const char *)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->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 !xenl 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_EARLYWRAP)
				tty_putcode2(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)
{
	tty_add(tty, buf, len);
	if (tty->cx + width > tty->sx)
		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);
}

static void
tty_force_cursor_colour(struct tty *tty, const char *ccolour)
{
	if (*ccolour == '\0')
		tty_putcode(tty, TTYC_CR);
	else
		tty_putcode_ptr1(tty, TTYC_CS, ccolour);
	free(tty->ccolour);
	tty->ccolour = xstrdup(ccolour);
}

void
tty_update_mode(struct tty *tty, int mode, struct screen *s)
{
	int	changed;

	if (s != NULL && strcmp(s->ccolour, tty->ccolour) != 0)
		tty_force_cursor_colour(tty, s->ccolour);

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

	changed = mode ^ tty->mode;
	if (changed & MODE_BLINKING) {
		if (tty_term_has(tty->term, TTYC_CVVIS))
			tty_putcode(tty, TTYC_CVVIS);
		else
			tty_putcode(tty, TTYC_CNORM);
		changed |= MODE_CURSOR;
	}
	if (changed & MODE_CURSOR) {
		if (mode & MODE_CURSOR)
			tty_putcode(tty, TTYC_CNORM);
		else
			tty_putcode(tty, TTYC_CIVIS);
	}
	if (s != NULL && tty->cstyle != s->cstyle) {
		if (tty_term_has(tty->term, TTYC_SS)) {
			if (s->cstyle == 0 &&
			    tty_term_has(tty->term, TTYC_SE))
				tty_putcode(tty, TTYC_SE);
			else
				tty_putcode1(tty, TTYC_SS, s->cstyle);
		}
		tty->cstyle = s->cstyle;
	}
	if (changed & ALL_MOUSE_MODES) {
		if (mode & ALL_MOUSE_MODES) {
			/*
			 * Enable the SGR (1006) extension unconditionally, as
			 * it is safe from misinterpretation.
			 */
			tty_puts(tty, "\033[?1006h");
			if (mode & MODE_MOUSE_ALL)
				tty_puts(tty, "\033[?1003h");
			else if (mode & MODE_MOUSE_BUTTON)
				tty_puts(tty, "\033[?1002h");
			else if (mode & MODE_MOUSE_STANDARD)
				tty_puts(tty, "\033[?1000h");
		} else {
			if (tty->mode & MODE_MOUSE_ALL)
				tty_puts(tty, "\033[?1003l");
			else if (tty->mode & MODE_MOUSE_BUTTON)
				tty_puts(tty, "\033[?1002l");
			else if (tty->mode & MODE_MOUSE_STANDARD)
				tty_puts(tty, "\033[?1000l");
			tty_puts(tty, "\033[?1006l");
		}
	}
	if (changed & MODE_BRACKETPASTE) {
		if (mode & MODE_BRACKETPASTE)
			tty_puts(tty, "\033[?2004h");
		else
			tty_puts(tty, "\033[?2004l");
	}
	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_putcode1(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 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)
{
	struct window_pane	*wp = ctx->wp;

	return (ctx->orlower - ctx->orupper >= screen_size_y(wp->screen) / 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 window_pane *wp, u_int bg)
{
	struct grid_cell	gc;

	if (tty_term_flag(tty->term, TTYC_BCE))
		return (0);

	memcpy(&gc, &grid_default_cell, sizeof gc);
	if (wp != NULL)
		tty_default_colours(&gc, wp);

	if (bg != 8 || gc.bg != 8)
		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 window_pane	*wp = ctx->wp;
	struct screen		*s = wp->screen;
	u_int			 i;

	/*
	 * If region is large, schedule a window redraw. In most cases this is
	 * likely to be followed by some more scrolling.
	 */
	if (tty_large_region(tty, ctx)) {
		wp->flags |= PANE_REDRAW;
		return;
	}

	if (ctx->ocy < ctx->orupper || ctx->ocy > ctx->orlower) {
		for (i = ctx->ocy; i < screen_size_y(s); i++)
			tty_draw_pane(tty, wp, i, ctx->xoff, ctx->yoff);
	} else {
		for (i = ctx->orupper; i <= ctx->orlower; i++)
			tty_draw_pane(tty, wp, i, ctx->xoff, ctx->yoff);
	}
}

void
tty_draw_pane(struct tty *tty, const struct window_pane *wp, u_int py, u_int ox,
    u_int oy)
{
	tty_draw_line(tty, wp, wp->screen, py, ox, oy);
}

void
tty_draw_line(struct tty *tty, const struct window_pane *wp,
    struct screen *s, u_int py, u_int ox, u_int oy)
{
	struct grid_cell	 gc, last;
	u_int			 i, j, sx, width;
	int			 flags, cleared = 0;
	char			 buf[512];
	size_t			 len;

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

	tty_region_off(tty);
	tty_margin_off(tty);

	sx = screen_size_x(s);
	if (sx > s->grid->linedata[s->grid->hsize + py].cellused)
		sx = s->grid->linedata[s->grid->hsize + py].cellused;
	if (sx > tty->sx)
		sx = tty->sx;

	if (screen_size_x(s) < tty->sx &&
	    ox == 0 &&
	    sx != screen_size_x(s) &&
	    tty_term_has(tty->term, TTYC_EL1) &&
	    !tty_fake_bce(tty, wp, 8)) {
		tty_default_attributes(tty, wp, 8);
		tty_cursor(tty, screen_size_x(s) - 1, oy + py);
		tty_putcode(tty, TTYC_EL1);
		cleared = 1;
	}
	if (sx != 0)
		tty_cursor(tty, ox, oy + py);

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

	for (i = 0; i < sx; i++) {
		grid_view_get_cell(s->grid, i, py, &gc);
		if (len != 0 &&
		    (((~tty->flags & TTY_UTF8) &&
		    (gc.data.size != 1 ||
		    *gc.data.data >= 0x7f ||
		    gc.data.width != 1)) ||
		    (gc.attr & GRID_ATTR_CHARSET) ||
		    gc.flags != last.flags ||
		    gc.attr != last.attr ||
		    gc.fg != last.fg ||
		    gc.bg != last.bg ||
		    (sizeof buf) - len < gc.data.size)) {
			tty_attributes(tty, &last, wp);
			tty_putn(tty, buf, len, width);

			len = 0;
			width = 0;
		}

		if (gc.flags & GRID_FLAG_SELECTED)
			screen_select_cell(s, &last, &gc);
		else
			memcpy(&last, &gc, sizeof last);
		if (((~tty->flags & TTY_UTF8) &&
		    (gc.data.size != 1 ||
		    *gc.data.data >= 0x7f ||
		    gc.data.width != 1)) ||
		    (gc.attr & GRID_ATTR_CHARSET)) {
			tty_attributes(tty, &last, wp);
			if (~tty->flags & TTY_UTF8) {
				for (j = 0; j < gc.data.width; j++)
					tty_putc(tty, '_');
			} else {
				for (j = 0; j < gc.data.size; j++)
					tty_putc(tty, gc.data.data[j]);
			}
		} else {
			memcpy(buf + len, gc.data.data, gc.data.size);
			len += gc.data.size;
			width += gc.data.width;
		}
	}
	if (len != 0) {
		tty_attributes(tty, &last, wp);
		tty_putn(tty, buf, len, width);
	}

	if (!cleared && sx < tty->sx) {
		tty_default_attributes(tty, wp, 8);
		tty_cursor(tty, ox + sx, oy + py);
		if (sx != screen_size_x(s) &&
		    ox + screen_size_x(s) >= tty->sx &&
		    tty_term_has(tty->term, TTYC_EL) &&
		    !tty_fake_bce(tty, wp, 8))
			tty_putcode(tty, TTYC_EL);
		else
			tty_repeat_space(tty, screen_size_x(s) - sx);
	}

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

static int
tty_client_ready(struct client *c, struct window_pane *wp)
{
	if (c->session == NULL || c->tty.term == NULL)
		return (0);
	if (c->flags & (CLIENT_REDRAW|CLIENT_SUSPENDED))
		return (0);
	if (c->tty.flags & TTY_FREEZE)
		return (0);
	if (c->session->curw->window != wp->window)
		return (0);
	return (1);
}

void
tty_write(void (*cmdfn)(struct tty *, const struct tty_ctx *),
    struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;
	struct client		*c;

	/* wp can be NULL if updating the screen but not the terminal. */
	if (wp == NULL)
		return;

	if ((wp->flags & (PANE_REDRAW|PANE_DROP)) || !window_pane_visible(wp))
		return;

	TAILQ_FOREACH(c, &clients, entry) {
		if (!tty_client_ready(c, wp))
			continue;

		ctx->xoff = wp->xoff;
		ctx->yoff = wp->yoff;
		if (status_at_line(c) == 0)
			ctx->yoff++;

		cmdfn(&c->tty, ctx);
	}
}

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

	if (!tty_pane_full_width(tty, ctx) ||
	    tty_fake_bce(tty, wp, ctx->bg) ||
	    (!tty_term_has(tty->term, TTYC_ICH) &&
	    !tty_term_has(tty->term, TTYC_ICH1))) {
		tty_draw_pane(tty, wp, ctx->ocy, ctx->xoff, ctx->yoff);
		return;
	}

	tty_default_attributes(tty, wp, ctx->bg);

	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 window_pane	*wp = ctx->wp;

	if (!tty_pane_full_width(tty, ctx) ||
	    tty_fake_bce(tty, wp, ctx->bg) ||
	    (!tty_term_has(tty->term, TTYC_DCH) &&
	    !tty_term_has(tty->term, TTYC_DCH1))) {
		tty_draw_pane(tty, wp, ctx->ocy, ctx->xoff, ctx->yoff);
		return;
	}

	tty_default_attributes(tty, wp, ctx->bg);

	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_attributes(tty, &grid_default_cell, ctx->wp);

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

	if (tty_term_has(tty->term, TTYC_ECH) &&
	    !tty_fake_bce(tty, ctx->wp, 8))
		tty_putcode1(tty, TTYC_ECH, ctx->num);
	else
		tty_repeat_space(tty, ctx->num);
}

void
tty_cmd_insertline(struct tty *tty, const struct tty_ctx *ctx)
{
	if (!tty_pane_full_width(tty, ctx) ||
	    tty_fake_bce(tty, ctx->wp, ctx->bg) ||
	    !tty_term_has(tty->term, TTYC_CSR) ||
	    !tty_term_has(tty->term, TTYC_IL1)) {
		tty_redraw_region(tty, ctx);
		return;
	}

	tty_default_attributes(tty, ctx->wp, ctx->bg);

	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);
}

void
tty_cmd_deleteline(struct tty *tty, const struct tty_ctx *ctx)
{
	if (!tty_pane_full_width(tty, ctx) ||
	    tty_fake_bce(tty, ctx->wp, ctx->bg) ||
	    !tty_term_has(tty->term, TTYC_CSR) ||
	    !tty_term_has(tty->term, TTYC_DL1)) {
		tty_redraw_region(tty, ctx);
		return;
	}

	tty_default_attributes(tty, ctx->wp, ctx->bg);

	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);
}

void
tty_cmd_clearline(struct tty *tty, const struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;
	struct screen		*s = wp->screen;
	u_int			 sx = screen_size_x(s);

	tty_default_attributes(tty, wp, ctx->bg);

	tty_cursor_pane(tty, ctx, 0, ctx->ocy);

	if (tty_pane_full_width(tty, ctx) &&
	    !tty_fake_bce(tty, wp, ctx->bg) &&
	    tty_term_has(tty->term, TTYC_EL))
		tty_putcode(tty, TTYC_EL);
	else
		tty_repeat_space(tty, sx);
}

void
tty_cmd_clearendofline(struct tty *tty, const struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;
	struct screen		*s = wp->screen;
	u_int			 sx = screen_size_x(s);

	tty_default_attributes(tty, wp, ctx->bg);

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

	if (tty_pane_full_width(tty, ctx) &&
	    tty_term_has(tty->term, TTYC_EL) &&
	    !tty_fake_bce(tty, wp, ctx->bg))
		tty_putcode(tty, TTYC_EL);
	else
		tty_repeat_space(tty, sx - ctx->ocx);
}

void
tty_cmd_clearstartofline(struct tty *tty, const struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;

	tty_default_attributes(tty, wp, ctx->bg);

	if (ctx->xoff == 0 &&
	    tty_term_has(tty->term, TTYC_EL1) &&
	    !tty_fake_bce(tty, ctx->wp, ctx->bg)) {
		tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);
		tty_putcode(tty, TTYC_EL1);
	} else {
		tty_cursor_pane(tty, ctx, 0, ctx->ocy);
		tty_repeat_space(tty, ctx->ocx + 1);
	}
}

void
tty_cmd_reverseindex(struct tty *tty, const struct tty_ctx *ctx)
{
	if (ctx->ocy != ctx->orupper)
		return;

	if (!tty_pane_full_width(tty, ctx) ||
	    tty_fake_bce(tty, ctx->wp, 8) ||
	    !tty_term_has(tty->term, TTYC_CSR) ||
	    !tty_term_has(tty->term, TTYC_RI)) {
		tty_redraw_region(tty, ctx);
		return;
	}

	tty_attributes(tty, &grid_default_cell, ctx->wp);

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

	tty_putcode(tty, TTYC_RI);
}

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

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

	if ((!tty_pane_full_width(tty, ctx) && !tty_use_margin(tty)) ||
	    tty_fake_bce(tty, wp, 8) ||
	    !tty_term_has(tty->term, TTYC_CSR)) {
		tty_redraw_region(tty, ctx);
		return;
	}

	tty_attributes(tty, &grid_default_cell, wp);

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

	/*
	 * If we want to wrap a pane, the cursor needs to be exactly on the
	 * right of the region. But if the pane isn't on the right, it may be
	 * off the edge - if so, move the cursor back to the right.
	 */
	if (ctx->xoff + ctx->ocx > tty->rright)
		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 window_pane	*wp = ctx->wp;
	u_int			 i;

	if ((!tty_pane_full_width(tty, ctx) && !tty_use_margin(tty)) ||
	    tty_fake_bce(tty, wp, 8) ||
	    !tty_term_has(tty->term, TTYC_CSR)) {
		tty_redraw_region(tty, ctx);
		return;
	}

	tty_attributes(tty, &grid_default_cell, wp);

	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)) {
		tty_cursor(tty, tty->rright, tty->rlower);
		for (i = 0; i < ctx->num; i++)
			tty_putc(tty, '\n');
	} else
		tty_putcode1(tty, TTYC_INDN, ctx->num);
}

void
tty_cmd_clearendofscreen(struct tty *tty, const struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;
	struct screen		*s = wp->screen;
	u_int			 i, j;
	u_int			 sx = screen_size_x(s), sy = screen_size_y(s);

	tty_default_attributes(tty, wp, ctx->bg);

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

	if (tty_pane_full_width(tty, ctx) &&
	    ctx->yoff + wp->sy >= tty->sy - 1 &&
	    status_at_line(tty->client) <= 0 &&
	    tty_term_has(tty->term, TTYC_ED)) {
		tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);
		tty_putcode(tty, TTYC_ED);
	} else if (tty_pane_full_width(tty, ctx) &&
	    tty_term_has(tty->term, TTYC_EL) &&
	    !tty_fake_bce(tty, wp, ctx->bg)) {
		tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);
		tty_putcode(tty, TTYC_EL);
		if (ctx->ocy != sy - 1) {
			tty_cursor_pane(tty, ctx, 0, ctx->ocy + 1);
			for (i = ctx->ocy + 1; i < sy; i++) {
				tty_putcode(tty, TTYC_EL);
				if (i == sy - 1)
					continue;
				tty_emulate_repeat(tty, TTYC_CUD, TTYC_CUD1, 1);
				tty->cy++;
			}
		}
	} else {
		tty_cursor_pane(tty, ctx, ctx->ocx, ctx->ocy);
		tty_repeat_space(tty, sx - ctx->ocx);
		for (j = ctx->ocy + 1; j < sy; j++) {
			tty_cursor_pane(tty, ctx, 0, j);
			tty_repeat_space(tty, sx);
		}
	}
}

void
tty_cmd_clearstartofscreen(struct tty *tty, const struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;
	struct screen		*s = wp->screen;
	u_int			 i, j;
	u_int			 sx = screen_size_x(s), sy = screen_size_y(s);

	tty_default_attributes(tty, wp, ctx->bg);

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

	if (tty_pane_full_width(tty, ctx) &&
	    tty_term_has(tty->term, TTYC_EL) &&
	    !tty_fake_bce(tty, wp, ctx->bg)) {
		tty_cursor_pane(tty, ctx, 0, 0);
		for (i = 0; i < ctx->ocy; i++) {
			tty_putcode(tty, TTYC_EL);
			tty_emulate_repeat(tty, TTYC_CUD, TTYC_CUD1, 1);
			tty->cy++;
		}
	} else {
		tty_cursor_pane(tty, ctx, 0, 0);
		for (j = 0; j < ctx->ocy; j++) {
			tty_cursor_pane(tty, ctx, 0, j);
			tty_repeat_space(tty, sx);
		}
	}
	tty_cursor_pane(tty, ctx, 0, ctx->ocy);
	tty_repeat_space(tty, ctx->ocx + 1);
}

void
tty_cmd_clearscreen(struct tty *tty, const struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;
	struct screen		*s = wp->screen;
	u_int			 i, j;
	u_int			 sx = screen_size_x(s), sy = screen_size_y(s);

	tty_default_attributes(tty, wp, ctx->bg);

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

	if (tty_pane_full_width(tty, ctx) &&
	    status_at_line(tty->client) <= 0 &&
	    tty_term_has(tty->term, TTYC_ED)) {
		tty_cursor_pane(tty, ctx, 0, 0);
		tty_putcode(tty, TTYC_ED);
	} else if (tty_pane_full_width(tty, ctx) &&
	    tty_term_has(tty->term, TTYC_EL) &&
	    !tty_fake_bce(tty, wp, ctx->bg)) {
		tty_cursor_pane(tty, ctx, 0, 0);
		for (i = 0; i < sy; i++) {
			tty_putcode(tty, TTYC_EL);
			if (i != sy - 1) {
				tty_emulate_repeat(tty, TTYC_CUD, TTYC_CUD1, 1);
				tty->cy++;
			}
		}
	} else {
		tty_cursor_pane(tty, ctx, 0, 0);
		for (j = 0; j < sy; j++) {
			tty_cursor_pane(tty, ctx, 0, j);
			tty_repeat_space(tty, sx);
		}
	}
}

void
tty_cmd_alignmenttest(struct tty *tty, const struct tty_ctx *ctx)
{
	struct window_pane	*wp = ctx->wp;
	struct screen		*s = wp->screen;
	u_int			 i, j;

	tty_attributes(tty, &grid_default_cell, wp);

	tty_region_pane(tty, ctx, 0, screen_size_y(s) - 1);
	tty_margin_off(tty);

	for (j = 0; j < screen_size_y(s); j++) {
		tty_cursor_pane(tty, ctx, 0, j);
		for (i = 0; i < screen_size_x(s); i++)
			tty_putc(tty, 'E');
	}
}

void
tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
{
	if (ctx->xoff + ctx->ocx > tty->sx - 1 && ctx->ocy == ctx->orlower) {
		if (tty_pane_full_width(tty, ctx))
			tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
		else
			tty_margin_off(tty);
	}

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

	tty_cell(tty, ctx->cell, ctx->wp);
}

void
tty_cmd_cells(struct tty *tty, const struct tty_ctx *ctx)
{
	tty_cursor_pane_unless_wrap(tty, ctx, ctx->ocx, ctx->ocy);

	tty_attributes(tty, ctx->cell, ctx->wp);
	tty_putn(tty, ctx->ptr, ctx->num, ctx->num);
}

void
tty_cmd_setselection(struct tty *tty, const struct tty_ctx *ctx)
{
	char	*buf;
	size_t	 off;

	if (!tty_term_has(tty->term, TTYC_MS))
		return;

	off = 4 * ((ctx->num + 2) / 3) + 1; /* storage for base64 */
	buf = xmalloc(off);

	b64_ntop(ctx->ptr, ctx->num, buf, off);
	tty_putcode_ptr2(tty, TTYC_MS, "", buf);

	free(buf);
}

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

static void
tty_cell(struct tty *tty, const struct grid_cell *gc,
    const struct window_pane *wp)
{
	u_int	i;

	/* Skip last character if terminal is stupid. */
	if ((tty->term->flags & TERM_EARLYWRAP) &&
	    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;

	/* Set the attributes. */
	tty_attributes(tty, gc, wp);

	/* Get the cell and if ASCII write with putc to do ACS translation. */
	if (gc->data.size == 1) {
		if (*gc->data.data < 0x20 || *gc->data.data == 0x7f)
			return;
		tty_putc(tty, *gc->data.data);
		return;
	}

	/* If not UTF-8, write _. */
	if (!(tty->flags & TTY_UTF8)) {
		for (i = 0; i < gc->data.width; i++)
			tty_putc(tty, '_');
		return;
	}

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

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

	if (!grid_cells_equal(gc, &grid_default_cell)) {
		if ((gc->attr & GRID_ATTR_CHARSET) && tty_use_acs(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);
	tty->last_wp = -1;
}

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->last_wp = -1;

	tty->cx = tty->cy = UINT_MAX;

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

	if (tty->flags & TTY_STARTED) {
		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->yoff + rlower);
}

/* 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)
		tty_cursor(tty, 0, tty->cy);

	tty_putcode2(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->xoff + ctx->wp->sx - 1);
}

/* Set margin at absolute position. */
static void
tty_margin(struct tty *tty, u_int rleft, u_int rright)
{
	char s[64];

	if (!tty_use_margin(tty))
		return;
	if (tty->rleft == rleft && tty->rright == rright)
		return;

	tty_putcode2(tty, TTYC_CSR, tty->rupper, tty->rlower);

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

	if (rleft == 0 && rright == tty->sx - 1)
		snprintf(s, sizeof s, "\033[s");
	else
		snprintf(s, sizeof s, "\033[%u;%us", rleft + 1, rright + 1);
	tty_puts(tty, s);
	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 (!tty_pane_full_width(tty, ctx) ||
	    (tty->term->flags & TERM_EARLYWRAP) ||
	    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->yoff + cy);
}

/* 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 (cx > tty->sx - 1)
		cx = tty->sx - 1;

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

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

	/* Very end of the line, just 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_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_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_putcode1(tty, TTYC_HPA, cx);
			goto out;
		} else if (change > 0 && tty_term_has(term, TTYC_CUB)) {
			if (change == 2 && tty_term_has(term, TTYC_CUB1)) {
				tty_putcode(tty, TTYC_CUB1);
				tty_putcode(tty, TTYC_CUB1);
				goto out;
			}
			tty_putcode1(tty, TTYC_CUB, change);
			goto out;
		} else if (change < 0 && tty_term_has(term, TTYC_CUF)) {
			tty_putcode1(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_putcode1(tty, TTYC_VPA, cy);
				    goto out;
			    }
		} else if (change > 0 && tty_term_has(term, TTYC_CUU)) {
			tty_putcode1(tty, TTYC_CUU, change);
			goto out;
		} else if (change < 0 && tty_term_has(term, TTYC_CUD)) {
			tty_putcode1(tty, TTYC_CUD, -change);
			goto out;
		}
	}

absolute:
	/* Absolute movement. */
	tty_putcode2(tty, TTYC_CUP, cy, cx);

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

void
tty_attributes(struct tty *tty, const struct grid_cell *gc,
    const struct window_pane *wp)
{
	struct grid_cell	*tc = &tty->cell, gc2;
	int			 changed;

	/* Ignore cell if it is the same as the last one. */
	if (wp != NULL &&
	    (int)wp->id == tty->last_wp &&
	    ~(wp->window->flags & WINDOW_STYLECHANGED) &&
	    gc->attr == tty->last_cell.attr &&
	    gc->fg == tty->last_cell.fg &&
	    gc->bg == tty->last_cell.bg)
		return;
	tty->last_wp = (wp != NULL ? (int)wp->id : -1);
	memcpy(&tty->last_cell, gc, sizeof tty->last_cell);

	/* Copy cell and update default colours. */
	memcpy(&gc2, gc, sizeof gc2);
	if (wp != NULL)
		tty_default_colours(&gc2, wp);

	/*
	 * 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 && gc2.fg != 8)
				gc2.attr &= ~GRID_ATTR_REVERSE;
		} else {
			if (gc2.bg != 0 && gc2.bg != 8)
				gc2.attr |= GRID_ATTR_REVERSE;
		}
	}

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

	/* If any bits are being cleared, reset everything. */
	if (tc->attr & ~gc2.attr)
		tty_reset(tty);

	/*
	 * Set the colours. This may call tty_reset() (so it comes next) and
	 * may add to (NOT remove) the desired attributes by changing new_attr.
	 */
	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_UNDERSCORE)
		tty_putcode(tty, TTYC_SMUL);
	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_CHARSET) && tty_use_acs(tty))
		tty_putcode(tty, TTYC_SMACS);
}

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)
		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 (gc->fg == 8 || gc->bg == 8) {
		/*
		 * 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 (gc->fg == 8 && tc->fg != 8) {
				if (have_ax)
					tty_puts(tty, "\033[39m");
				else if (tc->fg != 7)
					tty_putcode1(tty, TTYC_SETAF, 7);
				tc->fg = 8;
			}
			if (gc->bg == 8 && tc->bg != 8) {
				if (have_ax)
					tty_puts(tty, "\033[49m");
				else if (tc->bg != 0)
					tty_putcode1(tty, TTYC_SETAB, 0);
				tc->bg = 8;
			}
		}
	}

	/* Set the foreground colour. */
	if (gc->fg != 8 && 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 (gc->bg != 8 && gc->bg != tc->bg)
		tty_colours_bg(tty, gc);
}

static void
tty_check_fg(struct tty *tty, const struct window_pane *wp,
    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) &&
	    (c = window_pane_get_palette(wp, gc->fg)) != -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_flag(tty->term, TTYC_TC)) {
			colour_split_rgb(gc->fg, &r, &g, &b);
			gc->fg = colour_find_rgb(r, g, b);
		} else
			return;
	}

	/* How many colours does this terminal have? */
	if ((tty->term->flags|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;
				else
					gc->attr |= GRID_ATTR_BRIGHT;
			} else
				gc->attr &= ~GRID_ATTR_BRIGHT;
		}
		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, const struct window_pane *wp,
    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) &&
	    (c = window_pane_get_palette(wp, 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_flag(tty->term, TTYC_TC)) {
			colour_split_rgb(gc->bg, &r, &g, &b);
			gc->bg = colour_find_rgb(r, g, b);
		} else
			return;
	}

	/* How many colours does this terminal have? */
	if ((tty->term->flags|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->fg += 90;
			}
		}
		return;
	}

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

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_fg;
		/* Should not get here, already converted in tty_check_fg. */
		return;
	}

	/* Is this an aixterm bright colour? */
	if (gc->fg >= 90 && gc->fg <= 97) {
		xsnprintf(s, sizeof s, "\033[%dm", gc->fg);
		tty_puts(tty, s);
		goto save_fg;
	}

	/* Otherwise set the foreground colour. */
	tty_putcode1(tty, TTYC_SETAF, gc->fg);

save_fg:
	/* 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_bg;
		/* Should not get here, already converted in tty_check_bg. */
		return;
	}

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

	/* Otherwise set the background colour. */
	tty_putcode1(tty, TTYC_SETAB, gc->bg);

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

static int
tty_try_colour(struct tty *tty, int colour, const char *type)
{
	u_char	r, g, b;
	char	s[32];

	if (colour & COLOUR_FLAG_256) {
		/*
		 * If the user has specified -2 to the client, setaf and setab
		 * may not work (or they may not want to use them), so send the
		 * usual sequence.
		 */
		if (tty->term_flags & TERM_256COLOURS)
			goto fallback_256;

		/*
		 * If the terminfo entry has 256 colours and setaf and setab
		 * exist, assume that they work correctly.
		 */
		if (tty->term->flags & TERM_256COLOURS) {
			if (*type == '3') {
				if (!tty_term_has(tty->term, TTYC_SETAF))
					goto fallback_256;
				tty_putcode1(tty, TTYC_SETAF, colour & 0xff);
			} else {
				if (!tty_term_has(tty->term, TTYC_SETAB))
					goto fallback_256;
				tty_putcode1(tty, TTYC_SETAB, colour & 0xff);
			}
			return (0);
		}
		goto fallback_256;
	}

	if (colour & COLOUR_FLAG_RGB) {
		if (!tty_term_flag(tty->term, TTYC_TC))
			return (-1);

		colour_split_rgb(colour & 0xffffff, &r, &g, &b);
		xsnprintf(s, sizeof s, "\033[%s;2;%hhu;%hhu;%hhum", type,
		    r, g, b);
		tty_puts(tty, s);
		return (0);
	}

	return (-1);

fallback_256:
	xsnprintf(s, sizeof s, "\033[%s;5;%dm", type, colour & 0xff);
	tty_puts(tty, s);
	return (0);
}

static void
tty_default_colours(struct grid_cell *gc, const struct window_pane *wp)
{
	struct window		*w = wp->window;
	struct options		*oo = w->options;
	const struct grid_cell	*agc, *pgc, *wgc;
	int			 c;

	if (w->flags & WINDOW_STYLECHANGED) {
		w->flags &= ~WINDOW_STYLECHANGED;
		agc = options_get_style(oo, "window-active-style");
		memcpy(&w->active_style, agc, sizeof w->active_style);
		wgc = options_get_style(oo, "window-style");
		memcpy(&w->style, wgc, sizeof w->style);
	} else {
		agc = &w->active_style;
		wgc = &w->style;
	}
	pgc = &wp->colgc;

	if (gc->fg == 8) {
		if (pgc->fg != 8)
			gc->fg = pgc->fg;
		else if (wp == w->active && agc->fg != 8)
			gc->fg = agc->fg;
		else
			gc->fg = wgc->fg;

		if (gc->fg != 8 &&
		    (c = window_pane_get_palette(wp, gc->fg)) != -1)
			gc->fg = c;
	}

	if (gc->bg == 8) {
		if (pgc->bg != 8)
			gc->bg = pgc->bg;
		else if (wp == w->active && agc->bg != 8)
			gc->bg = agc->bg;
		else
			gc->bg = wgc->bg;

		if (gc->bg != 8 &&
		    (c = window_pane_get_palette(wp, gc->bg)) != -1)
			gc->bg = c;
	}
}

static void
tty_default_attributes(struct tty *tty, const struct window_pane *wp, u_int bg)
{
	static struct grid_cell gc;

	memcpy(&gc, &grid_default_cell, sizeof gc);
	gc.bg = bg;
	tty_attributes(tty, &gc, wp);
}