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Rewrite command queue handling. Each client still has a command queue,
but there is also now a global command queue. Instead of command queues
being dispatched on demand from wherever the command happens to be
added, they are now all dispatched from the top level server
loop. Command queues may now also include callbacks as well as commands,
and items may be inserted after the current command as well as at the end.

This all makes command queues significantly more predictable and easier
to use, and avoids the complex multiple nested command queues used by
source-file, if-shell and friends.

A mass rename of struct cmdq to a better name (cmdq_item probably) is
coming.

/* $OpenBSD: server-client.c,v 1.194 2016/10/16 17:55:14 nicm Exp $ */

/*
 * Copyright (c) 2009 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 <sys/uio.h>

#include <errno.h>
#include <event.h>
#include <fcntl.h>
#include <imsg.h>
#include <paths.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "tmux.h"

static void	server_client_free(int, short, void *);
static void	server_client_check_focus(struct window_pane *);
static void	server_client_check_resize(struct window_pane *);
static key_code	server_client_check_mouse(struct client *);
static void	server_client_repeat_timer(int, short, void *);
static void	server_client_click_timer(int, short, void *);
static void	server_client_check_exit(struct client *);
static void	server_client_check_redraw(struct client *);
static void	server_client_set_title(struct client *);
static void	server_client_reset_state(struct client *);
static int	server_client_assume_paste(struct session *);

static void	server_client_dispatch(struct imsg *, void *);
static void	server_client_dispatch_command(struct client *, struct imsg *);
static void	server_client_dispatch_identify(struct client *, struct imsg *);
static void	server_client_dispatch_shell(struct client *);

/* Check if this client is inside this server. */
int
server_client_check_nested(struct client *c)
{
	struct environ_entry	*envent;
	struct window_pane	*wp;

	if (c->tty.path == NULL)
		return (0);

	envent = environ_find(c->environ, "TMUX");
	if (envent == NULL || *envent->value == '\0')
		return (0);

	RB_FOREACH(wp, window_pane_tree, &all_window_panes) {
		if (strcmp(wp->tty, c->tty.path) == 0)
			return (1);
	}
	return (0);
}

/* Set client key table. */
void
server_client_set_key_table(struct client *c, const char *name)
{
	if (name == NULL)
		name = server_client_get_key_table(c);

	key_bindings_unref_table(c->keytable);
	c->keytable = key_bindings_get_table(name, 1);
	c->keytable->references++;
}

/* Get default key table. */
const char *
server_client_get_key_table(struct client *c)
{
	struct session	*s = c->session;
	const char	*name;

	if (s == NULL)
		return ("root");

	name = options_get_string(s->options, "key-table");
	if (*name == '\0')
		return ("root");
	return (name);
}

/* Is this client using the default key table? */
int
server_client_is_default_key_table(struct client *c)
{
	return (strcmp(c->keytable->name, server_client_get_key_table(c)) == 0);
}

/* Create a new client. */
void
server_client_create(int fd)
{
	struct client	*c;

	setblocking(fd, 0);

	c = xcalloc(1, sizeof *c);
	c->references = 1;
	c->peer = proc_add_peer(server_proc, fd, server_client_dispatch, c);

	if (gettimeofday(&c->creation_time, NULL) != 0)
		fatal("gettimeofday failed");
	memcpy(&c->activity_time, &c->creation_time, sizeof c->activity_time);

	c->environ = environ_create();

	c->fd = -1;
	c->cwd = NULL;

	TAILQ_INIT(&c->queue);

	c->stdin_data = evbuffer_new();
	c->stdout_data = evbuffer_new();
	c->stderr_data = evbuffer_new();

	c->tty.fd = -1;
	c->title = NULL;

	c->session = NULL;
	c->last_session = NULL;
	c->tty.sx = 80;
	c->tty.sy = 24;

	screen_init(&c->status, c->tty.sx, 1, 0);

	c->message_string = NULL;
	TAILQ_INIT(&c->message_log);

	c->prompt_string = NULL;
	c->prompt_buffer = NULL;
	c->prompt_index = 0;

	c->flags |= CLIENT_FOCUSED;

	c->keytable = key_bindings_get_table("root", 1);
	c->keytable->references++;

	evtimer_set(&c->repeat_timer, server_client_repeat_timer, c);
	evtimer_set(&c->click_timer, server_client_click_timer, c);

	TAILQ_INSERT_TAIL(&clients, c, entry);
	log_debug("new client %p", c);
}

/* Open client terminal if needed. */
int
server_client_open(struct client *c, char **cause)
{
	if (c->flags & CLIENT_CONTROL)
		return (0);

	if (strcmp(c->ttyname, "/dev/tty") == 0) {
		*cause = xstrdup("can't use /dev/tty");
		return (-1);
	}

	if (!(c->flags & CLIENT_TERMINAL)) {
		*cause = xstrdup("not a terminal");
		return (-1);
	}

	if (tty_open(&c->tty, cause) != 0)
		return (-1);

	return (0);
}

/* Lost a client. */
void
server_client_lost(struct client *c)
{
	struct message_entry	*msg, *msg1;

	c->flags |= CLIENT_DEAD;

	server_clear_identify(c, NULL);
	status_prompt_clear(c);
	status_message_clear(c);

	if (c->stdin_callback != NULL)
		c->stdin_callback(c, 1, c->stdin_callback_data);

	TAILQ_REMOVE(&clients, c, entry);
	log_debug("lost client %p", c);

	/*
	 * If CLIENT_TERMINAL hasn't been set, then tty_init hasn't been called
	 * and tty_free might close an unrelated fd.
	 */
	if (c->flags & CLIENT_TERMINAL)
		tty_free(&c->tty);
	free(c->ttyname);
	free(c->term);

	evbuffer_free(c->stdin_data);
	evbuffer_free(c->stdout_data);
	if (c->stderr_data != c->stdout_data)
		evbuffer_free(c->stderr_data);

	if (event_initialized(&c->status_timer))
		evtimer_del(&c->status_timer);
	screen_free(&c->status);

	free(c->title);
	free((void *)c->cwd);

	evtimer_del(&c->repeat_timer);
	evtimer_del(&c->click_timer);

	key_bindings_unref_table(c->keytable);

	if (event_initialized(&c->identify_timer))
		evtimer_del(&c->identify_timer);

	free(c->message_string);
	if (event_initialized(&c->message_timer))
		evtimer_del(&c->message_timer);
	TAILQ_FOREACH_SAFE(msg, &c->message_log, entry, msg1) {
		free(msg->msg);
		TAILQ_REMOVE(&c->message_log, msg, entry);
		free(msg);
	}

	free(c->prompt_string);
	free(c->prompt_buffer);

	environ_free(c->environ);

	proc_remove_peer(c->peer);
	c->peer = NULL;

	server_client_unref(c);

	server_add_accept(0); /* may be more file descriptors now */

	recalculate_sizes();
	server_check_unattached();
	server_update_socket();
}

/* Remove reference from a client. */
void
server_client_unref(struct client *c)
{
	log_debug("unref client %p (%d references)", c, c->references);

	c->references--;
	if (c->references == 0)
		event_once(-1, EV_TIMEOUT, server_client_free, c, NULL);
}

/* Free dead client. */
static void
server_client_free(__unused int fd, __unused short events, void *arg)
{
	struct client	*c = arg;

	log_debug("free client %p (%d references)", c, c->references);

	if (!TAILQ_EMPTY(&c->queue))
		fatalx("queue not empty");

	if (c->references == 0)
		free(c);
}

/* Detach a client. */
void
server_client_detach(struct client *c, enum msgtype msgtype)
{
	struct session	*s = c->session;

	if (s == NULL)
		return;

	hooks_run(c->session->hooks, c, NULL, "client-detached");
	proc_send_s(c->peer, msgtype, s->name);
}

/* Check for mouse keys. */
static key_code
server_client_check_mouse(struct client *c)
{
	struct session		*s = c->session;
	struct mouse_event	*m = &c->tty.mouse;
	struct window		*w;
	struct window_pane	*wp;
	u_int			 x, y, b;
	int			 flag;
	key_code		 key;
	struct timeval		 tv;
	enum { NOTYPE, DOWN, UP, DRAG, WHEEL, DOUBLE, TRIPLE } type = NOTYPE;
	enum { NOWHERE, PANE, STATUS, BORDER } where = NOWHERE;

	log_debug("mouse %02x at %u,%u (last %u,%u) (%d)", m->b, m->x, m->y,
	    m->lx, m->ly, c->tty.mouse_drag_flag);

	/* What type of event is this? */
	if (MOUSE_DRAG(m->b)) {
		type = DRAG;
		if (c->tty.mouse_drag_flag) {
			x = m->x, y = m->y, b = m->b;
			log_debug("drag update at %u,%u", x, y);
		} else {
			x = m->lx, y = m->ly, b = m->lb;
			log_debug("drag start at %u,%u", x, y);
		}
	} else if (MOUSE_WHEEL(m->b)) {
		type = WHEEL;
		x = m->x, y = m->y, b = m->b;
		log_debug("wheel at %u,%u", x, y);
	} else if (MOUSE_BUTTONS(m->b) == 3) {
		type = UP;
		x = m->x, y = m->y, b = m->lb;
		log_debug("up at %u,%u", x, y);
	} else {
		if (c->flags & CLIENT_DOUBLECLICK) {
			evtimer_del(&c->click_timer);
			c->flags &= ~CLIENT_DOUBLECLICK;
			if (m->b == c->click_button) {
				type = DOUBLE;
				x = m->x, y = m->y, b = m->b;
				log_debug("double-click at %u,%u", x, y);
				flag = CLIENT_TRIPLECLICK;
				goto add_timer;
			}
		} else if (c->flags & CLIENT_TRIPLECLICK) {
			evtimer_del(&c->click_timer);
			c->flags &= ~CLIENT_TRIPLECLICK;
			if (m->b == c->click_button) {
				type = TRIPLE;
				x = m->x, y = m->y, b = m->b;
				log_debug("triple-click at %u,%u", x, y);
				goto have_event;
			}
		}

		type = DOWN;
		x = m->x, y = m->y, b = m->b;
		log_debug("down at %u,%u", x, y);
		flag = CLIENT_DOUBLECLICK;

	add_timer:
		if (KEYC_CLICK_TIMEOUT != 0) {
			c->flags |= flag;
			c->click_button = m->b;

			tv.tv_sec = KEYC_CLICK_TIMEOUT / 1000;
			tv.tv_usec = (KEYC_CLICK_TIMEOUT % 1000) * 1000L;
			evtimer_del(&c->click_timer);
			evtimer_add(&c->click_timer, &tv);
		}
	}

have_event:
	if (type == NOTYPE)
		return (KEYC_UNKNOWN);

	/* Always save the session. */
	m->s = s->id;

	/* Is this on the status line? */
	m->statusat = status_at_line(c);
	if (m->statusat != -1 && y == (u_int)m->statusat) {
		w = status_get_window_at(c, x);
		if (w == NULL)
			return (KEYC_UNKNOWN);
		m->w = w->id;
		where = STATUS;
	} else
		m->w = -1;

	/* Not on status line. Adjust position and check for border or pane. */
	if (where == NOWHERE) {
		if (m->statusat == 0 && y > 0)
			y--;
		else if (m->statusat > 0 && y >= (u_int)m->statusat)
			y = m->statusat - 1;

		TAILQ_FOREACH(wp, &s->curw->window->panes, entry) {
			if ((wp->xoff + wp->sx == x &&
			    wp->yoff <= 1 + y &&
			    wp->yoff + wp->sy >= y) ||
			    (wp->yoff + wp->sy == y &&
			    wp->xoff <= 1 + x &&
			    wp->xoff + wp->sx >= x))
				break;
		}
		if (wp != NULL)
			where = BORDER;
		else {
			wp = window_get_active_at(s->curw->window, x, y);
			if (wp != NULL) {
				where = PANE;
				log_debug("mouse at %u,%u is on pane %%%u",
				    x, y, wp->id);
			}
		}
		if (where == NOWHERE)
			return (KEYC_UNKNOWN);
		m->wp = wp->id;
		m->w = wp->window->id;
	} else
		m->wp = -1;

	/* Stop dragging if needed. */
	if (type != DRAG && c->tty.mouse_drag_flag) {
		if (c->tty.mouse_drag_release != NULL)
			c->tty.mouse_drag_release(c, m);

		c->tty.mouse_drag_update = NULL;
		c->tty.mouse_drag_release = NULL;

		/*
		 * End a mouse drag by passing a MouseDragEnd key corresponding
		 * to the button that started the drag.
		 */
		switch (c->tty.mouse_drag_flag) {
		case 1:
			if (where == PANE)
				key = KEYC_MOUSEDRAGEND1_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEDRAGEND1_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEDRAGEND1_BORDER;
			break;
		case 2:
			if (where == PANE)
				key = KEYC_MOUSEDRAGEND2_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEDRAGEND2_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEDRAGEND2_BORDER;
			break;
		case 3:
			if (where == PANE)
				key = KEYC_MOUSEDRAGEND3_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEDRAGEND3_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEDRAGEND3_BORDER;
			break;
		default:
			key = KEYC_MOUSE;
			break;
		}
		c->tty.mouse_drag_flag = 0;

		return (key);
	}

	/* Convert to a key binding. */
	key = KEYC_UNKNOWN;
	switch (type) {
	case NOTYPE:
		break;
	case DRAG:
		if (c->tty.mouse_drag_update != NULL)
			c->tty.mouse_drag_update(c, m);
		else {
			switch (MOUSE_BUTTONS(b)) {
			case 0:
				if (where == PANE)
					key = KEYC_MOUSEDRAG1_PANE;
				if (where == STATUS)
					key = KEYC_MOUSEDRAG1_STATUS;
				if (where == BORDER)
					key = KEYC_MOUSEDRAG1_BORDER;
				break;
			case 1:
				if (where == PANE)
					key = KEYC_MOUSEDRAG2_PANE;
				if (where == STATUS)
					key = KEYC_MOUSEDRAG2_STATUS;
				if (where == BORDER)
					key = KEYC_MOUSEDRAG2_BORDER;
				break;
			case 2:
				if (where == PANE)
					key = KEYC_MOUSEDRAG3_PANE;
				if (where == STATUS)
					key = KEYC_MOUSEDRAG3_STATUS;
				if (where == BORDER)
					key = KEYC_MOUSEDRAG3_BORDER;
				break;
			}
		}

		/*
		 * Begin a drag by setting the flag to a non-zero value that
		 * corresponds to the mouse button in use.
		 */
		c->tty.mouse_drag_flag = MOUSE_BUTTONS(b) + 1;
		break;
	case WHEEL:
		if (MOUSE_BUTTONS(b) == MOUSE_WHEEL_UP) {
			if (where == PANE)
				key = KEYC_WHEELUP_PANE;
			if (where == STATUS)
				key = KEYC_WHEELUP_STATUS;
			if (where == BORDER)
				key = KEYC_WHEELUP_BORDER;
		} else {
			if (where == PANE)
				key = KEYC_WHEELDOWN_PANE;
			if (where == STATUS)
				key = KEYC_WHEELDOWN_STATUS;
			if (where == BORDER)
				key = KEYC_WHEELDOWN_BORDER;
		}
		break;
	case UP:
		switch (MOUSE_BUTTONS(b)) {
		case 0:
			if (where == PANE)
				key = KEYC_MOUSEUP1_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEUP1_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEUP1_BORDER;
			break;
		case 1:
			if (where == PANE)
				key = KEYC_MOUSEUP2_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEUP2_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEUP2_BORDER;
			break;
		case 2:
			if (where == PANE)
				key = KEYC_MOUSEUP3_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEUP3_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEUP3_BORDER;
			break;
		}
		break;
	case DOWN:
		switch (MOUSE_BUTTONS(b)) {
		case 0:
			if (where == PANE)
				key = KEYC_MOUSEDOWN1_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEDOWN1_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEDOWN1_BORDER;
			break;
		case 1:
			if (where == PANE)
				key = KEYC_MOUSEDOWN2_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEDOWN2_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEDOWN2_BORDER;
			break;
		case 2:
			if (where == PANE)
				key = KEYC_MOUSEDOWN3_PANE;
			if (where == STATUS)
				key = KEYC_MOUSEDOWN3_STATUS;
			if (where == BORDER)
				key = KEYC_MOUSEDOWN3_BORDER;
			break;
		}
		break;
	case DOUBLE:
		switch (MOUSE_BUTTONS(b)) {
		case 0:
			if (where == PANE)
				key = KEYC_DOUBLECLICK1_PANE;
			if (where == STATUS)
				key = KEYC_DOUBLECLICK1_STATUS;
			if (where == BORDER)
				key = KEYC_DOUBLECLICK1_BORDER;
			break;
		case 1:
			if (where == PANE)
				key = KEYC_DOUBLECLICK2_PANE;
			if (where == STATUS)
				key = KEYC_DOUBLECLICK2_STATUS;
			if (where == BORDER)
				key = KEYC_DOUBLECLICK2_BORDER;
			break;
		case 2:
			if (where == PANE)
				key = KEYC_DOUBLECLICK3_PANE;
			if (where == STATUS)
				key = KEYC_DOUBLECLICK3_STATUS;
			if (where == BORDER)
				key = KEYC_DOUBLECLICK3_BORDER;
			break;
		}
		break;
	case TRIPLE:
		switch (MOUSE_BUTTONS(b)) {
		case 0:
			if (where == PANE)
				key = KEYC_TRIPLECLICK1_PANE;
			if (where == STATUS)
				key = KEYC_TRIPLECLICK1_STATUS;
			if (where == BORDER)
				key = KEYC_TRIPLECLICK1_BORDER;
			break;
		case 1:
			if (where == PANE)
				key = KEYC_TRIPLECLICK2_PANE;
			if (where == STATUS)
				key = KEYC_TRIPLECLICK2_STATUS;
			if (where == BORDER)
				key = KEYC_TRIPLECLICK2_BORDER;
			break;
		case 2:
			if (where == PANE)
				key = KEYC_TRIPLECLICK3_PANE;
			if (where == STATUS)
				key = KEYC_TRIPLECLICK3_STATUS;
			if (where == BORDER)
				key = KEYC_TRIPLECLICK3_BORDER;
			break;
		}
		break;
	}
	if (key == KEYC_UNKNOWN)
		return (KEYC_UNKNOWN);

	/* Apply modifiers if any. */
	if (b & MOUSE_MASK_META)
		key |= KEYC_ESCAPE;
	if (b & MOUSE_MASK_CTRL)
		key |= KEYC_CTRL;
	if (b & MOUSE_MASK_SHIFT)
		key |= KEYC_SHIFT;

	return (key);
}

/* Is this fast enough to probably be a paste? */
static int
server_client_assume_paste(struct session *s)
{
	struct timeval	tv;
	int		t;

	if ((t = options_get_number(s->options, "assume-paste-time")) == 0)
		return (0);

	timersub(&s->activity_time, &s->last_activity_time, &tv);
	if (tv.tv_sec == 0 && tv.tv_usec < t * 1000) {
		log_debug("session %s pasting (flag %d)", s->name,
		    !!(s->flags & SESSION_PASTING));
		if (s->flags & SESSION_PASTING)
			return (1);
		s->flags |= SESSION_PASTING;
		return (0);
	}
	log_debug("session %s not pasting", s->name);
	s->flags &= ~SESSION_PASTING;
	return (0);
}

/* Handle data key input from client. */
void
server_client_handle_key(struct client *c, key_code key)
{
	struct mouse_event	*m = &c->tty.mouse;
	struct session		*s = c->session;
	struct window		*w;
	struct window_pane	*wp;
	struct timeval		 tv;
	const char		*name;
	struct key_table	*table;
	struct key_binding	 bd_find, *bd;
	int			 xtimeout;

	/* Check the client is good to accept input. */
	if (s == NULL || (c->flags & (CLIENT_DEAD|CLIENT_SUSPENDED)) != 0)
		return;
	w = s->curw->window;
	if (KEYC_IS_MOUSE(key))
		wp = cmd_mouse_pane(m, NULL, NULL);
	else
		wp = w->active;

	/* Update the activity timer. */
	if (gettimeofday(&c->activity_time, NULL) != 0)
		fatal("gettimeofday failed");
	session_update_activity(s, &c->activity_time);

	/* Number keys jump to pane in identify mode. */
	if (c->flags & CLIENT_IDENTIFY && key >= '0' && key <= '9') {
		if (c->flags & CLIENT_READONLY)
			return;
		window_unzoom(w);
		wp = window_pane_at_index(w, key - '0');
		if (wp != NULL && !window_pane_visible(wp))
			wp = NULL;
		server_clear_identify(c, wp);
		return;
	}

	/* Handle status line. */
	if (!(c->flags & CLIENT_READONLY)) {
		status_message_clear(c);
		server_clear_identify(c, NULL);
	}
	if (c->prompt_string != NULL) {
		if (c->flags & CLIENT_READONLY)
			return;
		if (status_prompt_key(c, key) == 0)
			return;
	}

	/* Check for mouse keys. */
	if (key == KEYC_MOUSE) {
		if (c->flags & CLIENT_READONLY)
			return;
		key = server_client_check_mouse(c);
		if (key == KEYC_UNKNOWN)
			return;

		m->valid = 1;
		m->key = key;

		if (!options_get_number(s->options, "mouse"))
			goto forward;
	} else
		m->valid = 0;

	/* Treat everything as a regular key when pasting is detected. */
	if (!KEYC_IS_MOUSE(key) && server_client_assume_paste(s))
		goto forward;

retry:
	/*
	 * Work out the current key table. If the pane is in a mode, use
	 * the mode table instead of the default key table.
	 */
	name = NULL;
	if (wp != NULL && wp->mode != NULL && wp->mode->key_table != NULL)
		name = wp->mode->key_table(wp);
	if (name == NULL || !server_client_is_default_key_table(c))
		table = c->keytable;
	else
		table = key_bindings_get_table(name, 1);

	/* Try to see if there is a key binding in the current table. */
	bd_find.key = key;
	bd = RB_FIND(key_bindings, &table->key_bindings, &bd_find);
	if (bd != NULL) {
		/*
		 * Key was matched in this table. If currently repeating but a
		 * non-repeating binding was found, stop repeating and try
		 * again in the root table.
		 */
		if ((c->flags & CLIENT_REPEAT) && !bd->can_repeat) {
			server_client_set_key_table(c, NULL);
			c->flags &= ~CLIENT_REPEAT;
			server_status_client(c);
			goto retry;
		}

		/*
		 * Take a reference to this table to make sure the key binding
		 * doesn't disappear.
		 */
		table->references++;

		/*
		 * If this is a repeating key, start the timer. Otherwise reset
		 * the client back to the root table.
		 */
		xtimeout = options_get_number(s->options, "repeat-time");
		if (xtimeout != 0 && bd->can_repeat) {
			c->flags |= CLIENT_REPEAT;

			tv.tv_sec = xtimeout / 1000;
			tv.tv_usec = (xtimeout % 1000) * 1000L;
			evtimer_del(&c->repeat_timer);
			evtimer_add(&c->repeat_timer, &tv);
		} else {
			c->flags &= ~CLIENT_REPEAT;
			server_client_set_key_table(c, NULL);
		}
		server_status_client(c);

		/* Dispatch the key binding. */
		key_bindings_dispatch(bd, c, m);
		key_bindings_unref_table(table);
		return;
	}

	/*
	 * No match in this table. If repeating, switch the client back to the
	 * root table and try again.
	 */
	if (c->flags & CLIENT_REPEAT) {
		server_client_set_key_table(c, NULL);
		c->flags &= ~CLIENT_REPEAT;
		server_status_client(c);
		goto retry;
	}

	/* If no match and we're not in the root table, that's it. */
	if (name == NULL && !server_client_is_default_key_table(c)) {
		server_client_set_key_table(c, NULL);
		server_status_client(c);
		return;
	}

	/*
	 * No match, but in the root table. Prefix switches to the prefix table
	 * and everything else is passed through.
	 */
	if (key == (key_code)options_get_number(s->options, "prefix") ||
	    key == (key_code)options_get_number(s->options, "prefix2")) {
		server_client_set_key_table(c, "prefix");
		server_status_client(c);
		return;
	}

forward:
	if (c->flags & CLIENT_READONLY)
		return;
	if (wp != NULL)
		window_pane_key(wp, c, s, key, m);
}

/* Client functions that need to happen every loop. */
void
server_client_loop(void)
{
	struct client		*c;
	struct window		*w;
	struct window_pane	*wp;

	TAILQ_FOREACH(c, &clients, entry) {
		server_client_check_exit(c);
		if (c->session != NULL) {
			server_client_check_redraw(c);
			server_client_reset_state(c);
		}
	}

	/*
	 * Any windows will have been redrawn as part of clients, so clear
	 * their flags now. Also check pane focus and resize.
	 */
	RB_FOREACH(w, windows, &windows) {
		w->flags &= ~WINDOW_REDRAW;
		TAILQ_FOREACH(wp, &w->panes, entry) {
			if (wp->fd != -1) {
				server_client_check_focus(wp);
				server_client_check_resize(wp);
			}
			wp->flags &= ~PANE_REDRAW;
		}
		check_window_name(w);
	}
}

static void
server_client_resize_event(__unused int fd, __unused short events, void *data)
{
	struct window_pane	*wp = data;
	struct winsize		 ws;

	evtimer_del(&wp->resize_timer);

	if (!(wp->flags & PANE_RESIZE))
		return;

	memset(&ws, 0, sizeof ws);
	ws.ws_col = wp->sx;
	ws.ws_row = wp->sy;

	if (ioctl(wp->fd, TIOCSWINSZ, &ws) == -1)
		fatal("ioctl failed");

	wp->flags &= ~PANE_RESIZE;
}

/* Check if pane should be resized. */
static void
server_client_check_resize(struct window_pane *wp)
{
	struct timeval	 tv = { .tv_usec = 250000 };

	if (!(wp->flags & PANE_RESIZE))
		return;

	if (!event_initialized(&wp->resize_timer))
		evtimer_set(&wp->resize_timer, server_client_resize_event, wp);

	/*
	 * The first resize should happen immediately, so if the timer is not
	 * running, do it now.
	 */
	if (!evtimer_pending(&wp->resize_timer, NULL))
		server_client_resize_event(-1, 0, wp);

	/*
	 * If the pane is in the alternate screen, let the timer expire and
	 * resize to give the application a chance to redraw. If not, keep
	 * pushing the timer back.
	 */
	if (wp->saved_grid != NULL && evtimer_pending(&wp->resize_timer, NULL))
		return;
	evtimer_del(&wp->resize_timer);
	evtimer_add(&wp->resize_timer, &tv);
}

/* Check whether pane should be focused. */
static void
server_client_check_focus(struct window_pane *wp)
{
	struct client	*c;
	int		 push;

	/* Are focus events off? */
	if (!options_get_number(global_options, "focus-events"))
		return;

	/* Do we need to push the focus state? */
	push = wp->flags & PANE_FOCUSPUSH;
	wp->flags &= ~PANE_FOCUSPUSH;

	/* If we don't care about focus, forget it. */
	if (!(wp->base.mode & MODE_FOCUSON))
		return;

	/* If we're not the active pane in our window, we're not focused. */
	if (wp->window->active != wp)
		goto not_focused;

	/* If we're in a mode, we're not focused. */
	if (wp->screen != &wp->base)
		goto not_focused;

	/*
	 * If our window is the current window in any focused clients with an
	 * attached session, we're focused.
	 */
	TAILQ_FOREACH(c, &clients, entry) {
		if (c->session == NULL || !(c->flags & CLIENT_FOCUSED))
			continue;
		if (c->session->flags & SESSION_UNATTACHED)
			continue;

		if (c->session->curw->window == wp->window)
			goto focused;
	}

not_focused:
	if (push || (wp->flags & PANE_FOCUSED))
		bufferevent_write(wp->event, "\033[O", 3);
	wp->flags &= ~PANE_FOCUSED;
	return;

focused:
	if (push || !(wp->flags & PANE_FOCUSED))
		bufferevent_write(wp->event, "\033[I", 3);
	wp->flags |= PANE_FOCUSED;
}

/*
 * Update cursor position and mode settings. The scroll region and attributes
 * are cleared when idle (waiting for an event) as this is the most likely time
 * a user may interrupt tmux, for example with ~^Z in ssh(1). This is a
 * compromise between excessive resets and likelihood of an interrupt.
 *
 * tty_region/tty_reset/tty_update_mode already take care of not resetting
 * things that are already in their default state.
 */
static void
server_client_reset_state(struct client *c)
{
	struct window		*w = c->session->curw->window;
	struct window_pane	*wp = w->active;
	struct screen		*s = wp->screen;
	struct options		*oo = c->session->options;
	int			 status, mode, o;

	if (c->flags & (CLIENT_CONTROL|CLIENT_SUSPENDED))
		return;

	tty_region(&c->tty, 0, c->tty.sy - 1);

	status = options_get_number(oo, "status");
	if (!window_pane_visible(wp) || wp->yoff + s->cy >= c->tty.sy - status)
		tty_cursor(&c->tty, 0, 0);
	else {
		o = status && options_get_number(oo, "status-position") == 0;
		tty_cursor(&c->tty, wp->xoff + s->cx, o + wp->yoff + s->cy);
	}

	/*
	 * Set mouse mode if requested. To support dragging, always use button
	 * mode.
	 */
	mode = s->mode;
	if (options_get_number(oo, "mouse"))
		mode = (mode & ~ALL_MOUSE_MODES) | MODE_MOUSE_BUTTON;

	/* Set the terminal mode and reset attributes. */
	tty_update_mode(&c->tty, mode, s);
	tty_reset(&c->tty);
}

/* Repeat time callback. */
static void
server_client_repeat_timer(__unused int fd, __unused short events, void *data)
{
	struct client	*c = data;

	if (c->flags & CLIENT_REPEAT) {
		server_client_set_key_table(c, NULL);
		c->flags &= ~CLIENT_REPEAT;
		server_status_client(c);
	}
}

/* Double-click callback. */
static void
server_client_click_timer(__unused int fd, __unused short events, void *data)
{
	struct client	*c = data;

	c->flags &= ~(CLIENT_DOUBLECLICK|CLIENT_TRIPLECLICK);
}

/* Check if client should be exited. */
static void
server_client_check_exit(struct client *c)
{
	if (!(c->flags & CLIENT_EXIT))
		return;

	if (EVBUFFER_LENGTH(c->stdin_data) != 0)
		return;
	if (EVBUFFER_LENGTH(c->stdout_data) != 0)
		return;
	if (EVBUFFER_LENGTH(c->stderr_data) != 0)
		return;

	proc_send(c->peer, MSG_EXIT, -1, &c->retval, sizeof c->retval);
	c->flags &= ~CLIENT_EXIT;
}

/* Check for client redraws. */
static void
server_client_check_redraw(struct client *c)
{
	struct session		*s = c->session;
	struct tty		*tty = &c->tty;
	struct window_pane	*wp;
	int		 	 flags, masked;

	if (c->flags & (CLIENT_CONTROL|CLIENT_SUSPENDED))
		return;

	if (c->flags & (CLIENT_REDRAW|CLIENT_STATUS)) {
		if (options_get_number(s->options, "set-titles"))
			server_client_set_title(c);
		screen_redraw_update(c); /* will adjust flags */
	}

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

	if (c->flags & CLIENT_REDRAW) {
		tty_update_mode(tty, tty->mode, NULL);
		screen_redraw_screen(c, 1, 1, 1);
		c->flags &= ~(CLIENT_STATUS|CLIENT_BORDERS);
	} else if (c->flags & CLIENT_REDRAWWINDOW) {
		tty_update_mode(tty, tty->mode, NULL);
		TAILQ_FOREACH(wp, &c->session->curw->window->panes, entry)
			screen_redraw_pane(c, wp);
		c->flags &= ~CLIENT_REDRAWWINDOW;
	} else {
		TAILQ_FOREACH(wp, &c->session->curw->window->panes, entry) {
			if (wp->flags & PANE_REDRAW) {
				tty_update_mode(tty, tty->mode, NULL);
				screen_redraw_pane(c, wp);
			}
		}
	}

	masked = c->flags & (CLIENT_BORDERS|CLIENT_STATUS);
	if (masked != 0)
		tty_update_mode(tty, tty->mode, NULL);
	if (masked == CLIENT_BORDERS)
		screen_redraw_screen(c, 0, 0, 1);
	else if (masked == CLIENT_STATUS)
		screen_redraw_screen(c, 0, 1, 0);
	else if (masked != 0)
		screen_redraw_screen(c, 0, 1, 1);

	tty->flags = (tty->flags & ~(TTY_FREEZE|TTY_NOCURSOR)) | flags;
	tty_update_mode(tty, tty->mode, NULL);

	c->flags &= ~(CLIENT_REDRAW|CLIENT_BORDERS|CLIENT_STATUS|
	    CLIENT_STATUSFORCE);
}

/* Set client title. */
static void
server_client_set_title(struct client *c)
{
	struct session		*s = c->session;
	const char		*template;
	char			*title;
	struct format_tree	*ft;

	template = options_get_string(s->options, "set-titles-string");

	ft = format_create(NULL, 0);
	format_defaults(ft, c, NULL, NULL, NULL);

	title = format_expand_time(ft, template, time(NULL));
	if (c->title == NULL || strcmp(title, c->title) != 0) {
		free(c->title);
		c->title = xstrdup(title);
		tty_set_title(&c->tty, c->title);
	}
	free(title);

	format_free(ft);
}

/* Dispatch message from client. */
static void
server_client_dispatch(struct imsg *imsg, void *arg)
{
	struct client		*c = arg;
	struct msg_stdin_data	 stdindata;
	const char		*data;
	ssize_t			 datalen;
	struct session		*s;

	if (c->flags & CLIENT_DEAD)
		return;

	if (imsg == NULL) {
		server_client_lost(c);
		return;
	}

	data = imsg->data;
	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;

	switch (imsg->hdr.type) {
	case MSG_IDENTIFY_FLAGS:
	case MSG_IDENTIFY_TERM:
	case MSG_IDENTIFY_TTYNAME:
	case MSG_IDENTIFY_CWD:
	case MSG_IDENTIFY_STDIN:
	case MSG_IDENTIFY_ENVIRON:
	case MSG_IDENTIFY_CLIENTPID:
	case MSG_IDENTIFY_DONE:
		server_client_dispatch_identify(c, imsg);
		break;
	case MSG_COMMAND:
		server_client_dispatch_command(c, imsg);
		break;
	case MSG_STDIN:
		if (datalen != sizeof stdindata)
			fatalx("bad MSG_STDIN size");
		memcpy(&stdindata, data, sizeof stdindata);

		if (c->stdin_callback == NULL)
			break;
		if (stdindata.size <= 0)
			c->stdin_closed = 1;
		else {
			evbuffer_add(c->stdin_data, stdindata.data,
			    stdindata.size);
		}
		c->stdin_callback(c, c->stdin_closed,
		    c->stdin_callback_data);
		break;
	case MSG_RESIZE:
		if (datalen != 0)
			fatalx("bad MSG_RESIZE size");

		if (c->flags & CLIENT_CONTROL)
			break;
		if (tty_resize(&c->tty)) {
			recalculate_sizes();
			server_redraw_client(c);
		}
		if (c->session != NULL)
			hooks_run(c->session->hooks, c, NULL, "client-resized");
		break;
	case MSG_EXITING:
		if (datalen != 0)
			fatalx("bad MSG_EXITING size");

		c->session = NULL;
		tty_close(&c->tty);
		proc_send(c->peer, MSG_EXITED, -1, NULL, 0);
		break;
	case MSG_WAKEUP:
	case MSG_UNLOCK:
		if (datalen != 0)
			fatalx("bad MSG_WAKEUP size");

		if (!(c->flags & CLIENT_SUSPENDED))
			break;
		c->flags &= ~CLIENT_SUSPENDED;

		if (c->tty.fd == -1) /* exited in the meantime */
			break;
		s = c->session;

		if (gettimeofday(&c->activity_time, NULL) != 0)
			fatal("gettimeofday failed");

		tty_start_tty(&c->tty);
		server_redraw_client(c);
		recalculate_sizes();

		if (s != NULL)
			session_update_activity(s, &c->activity_time);
		break;
	case MSG_SHELL:
		if (datalen != 0)
			fatalx("bad MSG_SHELL size");

		server_client_dispatch_shell(c);
		break;
	}
}

/* Callback when command is done. */
static enum cmd_retval
server_client_command_done(struct cmd_q *cmdq, __unused void *data)
{
	struct client	*c = cmdq->client;

	if (~c->flags & CLIENT_ATTACHED)
		c->flags |= CLIENT_EXIT;
	return (CMD_RETURN_NORMAL);
}

/* Show an error message. */
static enum cmd_retval
server_client_command_error(struct cmd_q *cmdq, void *data)
{
	char	*error = data;

	cmdq_error(cmdq, "%s", error);
	free(error);

	return (CMD_RETURN_NORMAL);
}

/* Handle command message. */
static void
server_client_dispatch_command(struct client *c, struct imsg *imsg)
{
	struct msg_command_data	  data;
	char			 *buf;
	size_t			  len;
	struct cmd_list		 *cmdlist = NULL;
	int			  argc;
	char			**argv, *cause;

	if (imsg->hdr.len - IMSG_HEADER_SIZE < sizeof data)
		fatalx("bad MSG_COMMAND size");
	memcpy(&data, imsg->data, sizeof data);

	buf = (char *)imsg->data + sizeof data;
	len = imsg->hdr.len  - IMSG_HEADER_SIZE - sizeof data;
	if (len > 0 && buf[len - 1] != '\0')
		fatalx("bad MSG_COMMAND string");

	argc = data.argc;
	if (cmd_unpack_argv(buf, len, argc, &argv) != 0) {
		cause = xstrdup("command too long");
		goto error;
	}

	if (argc == 0) {
		argc = 1;
		argv = xcalloc(1, sizeof *argv);
		*argv = xstrdup("new-session");
	}

	if ((cmdlist = cmd_list_parse(argc, argv, NULL, 0, &cause)) == NULL) {
		cmd_free_argv(argc, argv);
		goto error;
	}
	cmd_free_argv(argc, argv);

	cmdq_append(c, cmdq_get_command(cmdlist, NULL, NULL, 0));
	cmdq_append(c, cmdq_get_callback(server_client_command_done, NULL));
	cmd_list_free(cmdlist);
	return;

error:
	cmdq_append(c, cmdq_get_callback(server_client_command_error, cause));

	if (cmdlist != NULL)
		cmd_list_free(cmdlist);

	c->flags |= CLIENT_EXIT;
}

/* Handle identify message. */
static void
server_client_dispatch_identify(struct client *c, struct imsg *imsg)
{
	const char	*data, *home;
	size_t	 	 datalen;
	int		 flags;

	if (c->flags & CLIENT_IDENTIFIED)
		fatalx("out-of-order identify message");

	data = imsg->data;
	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;

	switch (imsg->hdr.type)	{
	case MSG_IDENTIFY_FLAGS:
		if (datalen != sizeof flags)
			fatalx("bad MSG_IDENTIFY_FLAGS size");
		memcpy(&flags, data, sizeof flags);
		c->flags |= flags;
		log_debug("client %p IDENTIFY_FLAGS %#x", c, flags);
		break;
	case MSG_IDENTIFY_TERM:
		if (datalen == 0 || data[datalen - 1] != '\0')
			fatalx("bad MSG_IDENTIFY_TERM string");
		c->term = xstrdup(data);
		log_debug("client %p IDENTIFY_TERM %s", c, data);
		break;
	case MSG_IDENTIFY_TTYNAME:
		if (datalen == 0 || data[datalen - 1] != '\0')
			fatalx("bad MSG_IDENTIFY_TTYNAME string");
		c->ttyname = xstrdup(data);
		log_debug("client %p IDENTIFY_TTYNAME %s", c, data);
		break;
	case MSG_IDENTIFY_CWD:
		if (datalen == 0 || data[datalen - 1] != '\0')
			fatalx("bad MSG_IDENTIFY_CWD string");
		if (access(data, X_OK) == 0)
			c->cwd = xstrdup(data);
		else if ((home = find_home()) != NULL)
			c->cwd = xstrdup(home);
		else
			c->cwd = xstrdup("/");
		log_debug("client %p IDENTIFY_CWD %s", c, data);
		break;
	case MSG_IDENTIFY_STDIN:
		if (datalen != 0)
			fatalx("bad MSG_IDENTIFY_STDIN size");
		c->fd = imsg->fd;
		log_debug("client %p IDENTIFY_STDIN %d", c, imsg->fd);
		break;
	case MSG_IDENTIFY_ENVIRON:
		if (datalen == 0 || data[datalen - 1] != '\0')
			fatalx("bad MSG_IDENTIFY_ENVIRON string");
		if (strchr(data, '=') != NULL)
			environ_put(c->environ, data);
		log_debug("client %p IDENTIFY_ENVIRON %s", c, data);
		break;
	case MSG_IDENTIFY_CLIENTPID:
		if (datalen != sizeof c->pid)
			fatalx("bad MSG_IDENTIFY_CLIENTPID size");
		memcpy(&c->pid, data, sizeof c->pid);
		log_debug("client %p IDENTIFY_CLIENTPID %ld", c, (long)c->pid);
		break;
	default:
		break;
	}

	if (imsg->hdr.type != MSG_IDENTIFY_DONE)
		return;
	c->flags |= CLIENT_IDENTIFIED;

	if (c->flags & CLIENT_CONTROL) {
		c->stdin_callback = control_callback;

		evbuffer_free(c->stderr_data);
		c->stderr_data = c->stdout_data;

		if (c->flags & CLIENT_CONTROLCONTROL)
			evbuffer_add_printf(c->stdout_data, "\033P1000p");
		proc_send(c->peer, MSG_STDIN, -1, NULL, 0);

		c->tty.fd = -1;

		close(c->fd);
		c->fd = -1;

		return;
	}

	if (c->fd == -1)
		return;
	if (tty_init(&c->tty, c, c->fd, c->term) != 0) {
		close(c->fd);
		c->fd = -1;
		return;
	}
	if (c->flags & CLIENT_UTF8)
		c->tty.flags |= TTY_UTF8;
	if (c->flags & CLIENT_256COLOURS)
		c->tty.term_flags |= TERM_256COLOURS;

	tty_resize(&c->tty);

	if (!(c->flags & CLIENT_CONTROL))
		c->flags |= CLIENT_TERMINAL;
}

/* Handle shell message. */
static void
server_client_dispatch_shell(struct client *c)
{
	const char	*shell;

	shell = options_get_string(global_s_options, "default-shell");
	if (*shell == '\0' || areshell(shell))
		shell = _PATH_BSHELL;
	proc_send_s(c->peer, MSG_SHELL, shell);

	proc_kill_peer(c->peer);
}

/* Event callback to push more stdout data if any left. */
static void
server_client_stdout_cb(__unused int fd, __unused short events, void *arg)
{
	struct client	*c = arg;

	if (~c->flags & CLIENT_DEAD)
		server_client_push_stdout(c);
	server_client_unref(c);
}

/* Push stdout to client if possible. */
void
server_client_push_stdout(struct client *c)
{
	struct msg_stdout_data data;
	size_t                 sent, left;

	left = EVBUFFER_LENGTH(c->stdout_data);
	while (left != 0) {
		sent = left;
		if (sent > sizeof data.data)
			sent = sizeof data.data;
		memcpy(data.data, EVBUFFER_DATA(c->stdout_data), sent);
		data.size = sent;

		if (proc_send(c->peer, MSG_STDOUT, -1, &data, sizeof data) != 0)
			break;
		evbuffer_drain(c->stdout_data, sent);

		left = EVBUFFER_LENGTH(c->stdout_data);
		log_debug("%s: client %p, sent %zu, left %zu", __func__, c,
		    sent, left);
	}
	if (left != 0) {
		c->references++;
		event_once(-1, EV_TIMEOUT, server_client_stdout_cb, c, NULL);
		log_debug("%s: client %p, queued", __func__, c);
	}
}

/* Event callback to push more stderr data if any left. */
static void
server_client_stderr_cb(__unused int fd, __unused short events, void *arg)
{
	struct client	*c = arg;

	if (~c->flags & CLIENT_DEAD)
		server_client_push_stderr(c);
	server_client_unref(c);
}

/* Push stderr to client if possible. */
void
server_client_push_stderr(struct client *c)
{
	struct msg_stderr_data data;
	size_t                 sent, left;

	if (c->stderr_data == c->stdout_data) {
		server_client_push_stdout(c);
		return;
	}

	left = EVBUFFER_LENGTH(c->stderr_data);
	while (left != 0) {
		sent = left;
		if (sent > sizeof data.data)
			sent = sizeof data.data;
		memcpy(data.data, EVBUFFER_DATA(c->stderr_data), sent);
		data.size = sent;

		if (proc_send(c->peer, MSG_STDERR, -1, &data, sizeof data) != 0)
			break;
		evbuffer_drain(c->stderr_data, sent);

		left = EVBUFFER_LENGTH(c->stderr_data);
		log_debug("%s: client %p, sent %zu, left %zu", __func__, c,
		    sent, left);
	}
	if (left != 0) {
		c->references++;
		event_once(-1, EV_TIMEOUT, server_client_stderr_cb, c, NULL);
		log_debug("%s: client %p, queued", __func__, c);
	}
}