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We accidentally haven't been using $TMUX to work out the session for a
while and in fact it is less useful that using the client ttyname. So
don't bother and don't pass it from the client. If we need it in future
it is in c->environ.

/* $OpenBSD: server-client.c,v 1.111 2013/10/10 12:29:35 nicm Exp $ */

/*
 * Copyright (c) 2009 Nicholas Marriott <nicm@users.sourceforge.net>
 *
 * 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 <event.h>
#include <fcntl.h>
#include <paths.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "tmux.h"

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

int	server_client_msg_dispatch(struct client *);
void	server_client_msg_command(struct client *, struct imsg *);
void	server_client_msg_identify(struct client *, struct imsg *);
void	server_client_msg_shell(struct client *);

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

	setblocking(fd, 0);

	c = xcalloc(1, sizeof *c);
	c->references = 0;
	imsg_init(&c->ibuf, fd);
	server_update_event(c);

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

	environ_init(&c->environ);

	c->cmdq = cmdq_new(c);
	c->cmdq->client_exit = 1;

	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);
	RB_INIT(&c->status_new);
	RB_INIT(&c->status_old);

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

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

	c->tty.mouse.xb = c->tty.mouse.button = 3;
	c->tty.mouse.x = c->tty.mouse.y = -1;
	c->tty.mouse.lx = c->tty.mouse.ly = -1;
	c->tty.mouse.sx = c->tty.mouse.sy = -1;
	c->tty.mouse.event = MOUSE_EVENT_UP;
	c->tty.mouse.flags = 0;

	c->flags |= CLIENT_FOCUSED;

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

	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
		if (ARRAY_ITEM(&clients, i) == NULL) {
			ARRAY_SET(&clients, i, c);
			return;
		}
	}
	ARRAY_ADD(&clients, c);
	log_debug("new client %d", fd);
}

/* Open client terminal if needed. */
int
server_client_open(struct client *c, struct session *s, char **cause)
{
	struct options	*oo = s != NULL ? &s->options : &global_s_options;
	char		*overrides;

	if (c->flags & CLIENT_CONTROL)
		return (0);

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

	overrides = options_get_string(oo, "terminal-overrides");
	if (tty_open(&c->tty, overrides, cause) != 0)
		return (-1);

	return (0);
}

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

	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
		if (ARRAY_ITEM(&clients, i) == c)
			ARRAY_SET(&clients, i, NULL);
	}
	log_debug("lost client %d", c->ibuf.fd);

	/*
	 * 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);

	status_free_jobs(&c->status_new);
	status_free_jobs(&c->status_old);
	screen_free(&c->status);

	free(c->title);
	close(c->cwd);

	evtimer_del(&c->repeat_timer);

	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);
	for (i = 0; i < ARRAY_LENGTH(&c->message_log); i++) {
		msg = &ARRAY_ITEM(&c->message_log, i);
		free(msg->msg);
	}
	ARRAY_FREE(&c->message_log);

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

	c->cmdq->dead = 1;
	cmdq_free(c->cmdq);
	c->cmdq = NULL;

	environ_free(&c->environ);

	close(c->ibuf.fd);
	imsg_clear(&c->ibuf);
	if (event_initialized(&c->event))
		event_del(&c->event);

	for (i = 0; i < ARRAY_LENGTH(&dead_clients); i++) {
		if (ARRAY_ITEM(&dead_clients, i) == NULL) {
			ARRAY_SET(&dead_clients, i, c);
			break;
		}
	}
	if (i == ARRAY_LENGTH(&dead_clients))
		ARRAY_ADD(&dead_clients, c);
	c->flags |= CLIENT_DEAD;

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

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

/* Process a single client event. */
void
server_client_callback(int fd, short events, void *data)
{
	struct client	*c = data;

	if (c->flags & CLIENT_DEAD)
		return;

	if (fd == c->ibuf.fd) {
		if (events & EV_WRITE && msgbuf_write(&c->ibuf.w) < 0)
			goto client_lost;

		if (c->flags & CLIENT_BAD) {
			if (c->ibuf.w.queued == 0)
				goto client_lost;
			return;
		}

		if (events & EV_READ && server_client_msg_dispatch(c) != 0)
			goto client_lost;
	}

	server_push_stdout(c);
	server_push_stderr(c);

	server_update_event(c);
	return;

client_lost:
	server_client_lost(c);
}

/* Handle client status timer. */
void
server_client_status_timer(void)
{
	struct client	*c;
	struct session	*s;
	struct timeval	 tv;
	u_int		 i;
	int		 interval;
	time_t		 difference;

	if (gettimeofday(&tv, NULL) != 0)
		fatal("gettimeofday failed");

	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
		c = ARRAY_ITEM(&clients, i);
		if (c == NULL || c->session == NULL)
			continue;
		if (c->message_string != NULL || c->prompt_string != NULL) {
			/*
			 * Don't need timed redraw for messages/prompts so bail
			 * now. The status timer isn't reset when they are
			 * redrawn anyway.
			 */
			continue;
		}
		s = c->session;

		if (!options_get_number(&s->options, "status"))
			continue;
		interval = options_get_number(&s->options, "status-interval");

		difference = tv.tv_sec - c->status_timer.tv_sec;
		if (difference >= interval) {
			status_update_jobs(c);
			c->flags |= CLIENT_STATUS;
		}
	}
}

/* Check for mouse keys. */
void
server_client_check_mouse(struct client *c, struct window_pane *wp)
{
	struct session		*s = c->session;
	struct options		*oo = &s->options;
	struct mouse_event	*m = &c->tty.mouse;
	int			 statusat;

	statusat = status_at_line(c);

	/* Is this a window selection click on the status line? */
	if (statusat != -1 && m->y == (u_int)statusat &&
	    options_get_number(oo, "mouse-select-window")) {
		if (m->event & MOUSE_EVENT_CLICK) {
			status_set_window_at(c, m->x);
		} else if (m->event == MOUSE_EVENT_WHEEL) {
			if (m->wheel == MOUSE_WHEEL_UP)
				session_previous(c->session, 0);
			else if (m->wheel == MOUSE_WHEEL_DOWN)
				session_next(c->session, 0);
			server_redraw_session(s);
		}
		recalculate_sizes();
		return;
	}

	/*
	 * Not on status line - adjust mouse position if status line is at the
	 * top and limit if at the bottom. From here on a struct mouse
	 * represents the offset onto the window itself.
	 */
	if (statusat == 0 && m->y > 0)
		m->y--;
	else if (statusat > 0 && m->y >= (u_int)statusat)
		m->y = statusat - 1;

	/* Is this a pane selection? Allow down only in copy mode. */
	if (options_get_number(oo, "mouse-select-pane") &&
	    (m->event == MOUSE_EVENT_DOWN || wp->mode != &window_copy_mode)) {
		window_set_active_at(wp->window, m->x, m->y);
		server_redraw_window_borders(wp->window);
		wp = wp->window->active; /* may have changed */
	}

	/* Check if trying to resize pane. */
	if (options_get_number(oo, "mouse-resize-pane"))
		layout_resize_pane_mouse(c);

	/* Update last and pass through to client. */
	window_pane_mouse(wp, c->session, m);
}

/* Is this fast enough to probably be a paste? */
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)
		return (1);
	return (0);
}

/* Handle data key input from client. */
void
server_client_handle_key(struct client *c, int key)
{
	struct session		*s;
	struct window		*w;
	struct window_pane	*wp;
	struct timeval		 tv;
	struct key_binding	*bd;
	int		      	 xtimeout, isprefix, ispaste;

	/* Check the client is good to accept input. */
	if ((c->flags & (CLIENT_DEAD|CLIENT_SUSPENDED)) != 0)
		return;

	if (c->session == NULL)
		return;
	s = c->session;

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

	memcpy(&s->last_activity_time, &s->activity_time,
	    sizeof s->last_activity_time);
	memcpy(&s->activity_time, &c->activity_time, sizeof s->activity_time);

	w = c->session->curw->window;
	wp = w->active;

	/* Special case: 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))
			window_set_active_pane(w, wp);
		server_clear_identify(c);
		return;
	}

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

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

	/* Is this a prefix key? */
	if (key == options_get_number(&s->options, "prefix"))
		isprefix = 1;
	else if (key == options_get_number(&s->options, "prefix2"))
		isprefix = 1;
	else
		isprefix = 0;

	/* Treat prefix as a regular key when pasting is detected. */
	ispaste = server_client_assume_paste(s);
	if (ispaste)
		isprefix = 0;

	/* No previous prefix key. */
	if (!(c->flags & CLIENT_PREFIX)) {
		if (isprefix) {
			c->flags |= CLIENT_PREFIX;
			server_status_client(c);
			return;
		}

		/* Try as a non-prefix key binding. */
		if (ispaste || (bd = key_bindings_lookup(key)) == NULL) {
			if (!(c->flags & CLIENT_READONLY))
				window_pane_key(wp, s, key);
		} else
			key_bindings_dispatch(bd, c);
		return;
	}

	/* Prefix key already pressed. Reset prefix and lookup key. */
	c->flags &= ~CLIENT_PREFIX;
	server_status_client(c);
	if ((bd = key_bindings_lookup(key | KEYC_PREFIX)) == NULL) {
		/* If repeating, treat this as a key, else ignore. */
		if (c->flags & CLIENT_REPEAT) {
			c->flags &= ~CLIENT_REPEAT;
			if (isprefix)
				c->flags |= CLIENT_PREFIX;
			else if (!(c->flags & CLIENT_READONLY))
				window_pane_key(wp, s, key);
		}
		return;
	}

	/* If already repeating, but this key can't repeat, skip it. */
	if (c->flags & CLIENT_REPEAT && !bd->can_repeat) {
		c->flags &= ~CLIENT_REPEAT;
		if (isprefix)
			c->flags |= CLIENT_PREFIX;
		else if (!(c->flags & CLIENT_READONLY))
			window_pane_key(wp, s, key);
		return;
	}

	/* If this key can repeat, reset the repeat flags and timer. */
	xtimeout = options_get_number(&s->options, "repeat-time");
	if (xtimeout != 0 && bd->can_repeat) {
		c->flags |= CLIENT_PREFIX|CLIENT_REPEAT;

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

	/* Dispatch the command. */
	key_bindings_dispatch(bd, c);
}

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

	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
		c = ARRAY_ITEM(&clients, i);
		if (c == NULL)
			continue;

		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.
	 */
	for (i = 0; i < ARRAY_LENGTH(&windows); i++) {
		w = ARRAY_ITEM(&windows, i);
		if (w == NULL)
			continue;

		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 if pane should be resized. */
void
server_client_check_resize(struct window_pane *wp)
{
	struct winsize	ws;

	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 whether pane should be focused. */
void
server_client_check_focus(struct window_pane *wp)
{
	u_int		 i;
	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.
	 */
	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
		c = ARRAY_ITEM(&clients, i);
		if (c == NULL || c->session == NULL)
			continue;

		if (!(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.
 */
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;
	struct options		*wo = &w->options;
	int			 status, mode, o;

	if (c->flags & CLIENT_SUSPENDED)
		return;

	if (c->flags & CLIENT_CONTROL)
		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);
	}

	/*
	 * Resizing panes with the mouse requires at least button mode to give
	 * a smooth appearance.
	 */
	mode = s->mode;
	if ((c->tty.mouse.flags & MOUSE_RESIZE_PANE) &&
	    !(mode & (MODE_MOUSE_BUTTON|MODE_MOUSE_ANY)))
		mode |= MODE_MOUSE_BUTTON;

	/*
	 * Any mode will do for mouse-select-pane, but set standard mode if
	 * none.
	 */
	if ((mode & ALL_MOUSE_MODES) == 0) {
		if (TAILQ_NEXT(TAILQ_FIRST(&w->panes), entry) != NULL &&
		    options_get_number(oo, "mouse-select-pane"))
			mode |= MODE_MOUSE_STANDARD;
		else if (options_get_number(oo, "mouse-resize-pane"))
			mode |= MODE_MOUSE_STANDARD;
		else if (options_get_number(oo, "mouse-select-window"))
			mode |= MODE_MOUSE_STANDARD;
		else if (options_get_number(wo, "mode-mouse"))
			mode |= MODE_MOUSE_STANDARD;
	}

	/*
	 * Set UTF-8 mouse input if required. If the terminal is UTF-8, the
	 * user has set mouse-utf8 and any mouse mode is in effect, turn on
	 * UTF-8 mouse input. If the receiving terminal hasn't requested it
	 * (that is, it isn't in s->mode), then it'll be converted in
	 * input_mouse.
	 */
	if ((c->tty.flags & TTY_UTF8) &&
	    (mode & ALL_MOUSE_MODES) && options_get_number(oo, "mouse-utf8"))
		mode |= MODE_MOUSE_UTF8;
	else
		mode &= ~MODE_MOUSE_UTF8;

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

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

	if (c->flags & CLIENT_REPEAT) {
		if (c->flags & CLIENT_PREFIX)
			server_status_client(c);
		c->flags &= ~(CLIENT_PREFIX|CLIENT_REPEAT);
	}
}

/* Check if client should be exited. */
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;

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

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

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

	flags = c->tty.flags & TTY_FREEZE;
	c->tty.flags &= ~TTY_FREEZE;

	if (c->flags & (CLIENT_REDRAW|CLIENT_STATUS)) {
		if (options_get_number(&s->options, "set-titles"))
			server_client_set_title(c);

		if (c->message_string != NULL)
			redraw = status_message_redraw(c);
		else if (c->prompt_string != NULL)
			redraw = status_prompt_redraw(c);
		else
			redraw = status_redraw(c);
		if (!redraw)
			c->flags &= ~CLIENT_STATUS;
	}

	if (c->flags & CLIENT_REDRAW) {
		screen_redraw_screen(c, 0, 0);
		c->flags &= ~(CLIENT_STATUS|CLIENT_BORDERS);
	} else if (c->flags & CLIENT_REDRAWWINDOW) {
		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)
				screen_redraw_pane(c, wp);
		}
	}

	if (c->flags & CLIENT_BORDERS)
		screen_redraw_screen(c, 0, 1);

	if (c->flags & CLIENT_STATUS)
		screen_redraw_screen(c, 1, 0);

	c->tty.flags |= flags;

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

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

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

	title = status_replace(c, NULL, NULL, NULL, template, time(NULL), 1);
	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);
}

/* Dispatch message from client. */
int
server_client_msg_dispatch(struct client *c)
{
	struct imsg		 imsg;
	struct msg_stdin_data	 stdindata;
	const char		*data;
	ssize_t			 n, datalen;

	if ((n = imsg_read(&c->ibuf)) == -1 || n == 0)
		return (-1);

	for (;;) {
		if ((n = imsg_get(&c->ibuf, &imsg)) == -1)
			return (-1);
		if (n == 0)
			return (0);

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

		if (imsg.hdr.peerid != PROTOCOL_VERSION) {
			server_write_client(c, MSG_VERSION, NULL, 0);
			c->flags |= CLIENT_BAD;
			imsg_free(&imsg);
			continue;
		}

		log_debug("got %d from client %d", imsg.hdr.type, c->ibuf.fd);
		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_DONE:
			server_client_msg_identify(c, &imsg);
			break;
		case MSG_COMMAND:
			server_client_msg_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);
			}
			break;
		case MSG_EXITING:
			if (datalen != 0)
				fatalx("bad MSG_EXITING size");

			c->session = NULL;
			tty_close(&c->tty);
			server_write_client(c, MSG_EXITED, 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 (gettimeofday(&c->activity_time, NULL) != 0)
				fatal("gettimeofday");
			if (c->session != NULL)
				session_update_activity(c->session);

			tty_start_tty(&c->tty);
			server_redraw_client(c);
			recalculate_sizes();
			break;
		case MSG_SHELL:
			if (datalen != 0)
				fatalx("bad MSG_SHELL size");

			server_client_msg_shell(c);
			break;
		}

		imsg_free(&imsg);
	}
}

/* Handle command message. */
void
server_client_msg_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) {
		cmdq_error(c->cmdq, "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) {
		cmdq_error(c->cmdq, "%s", cause);
		cmd_free_argv(argc, argv);
		goto error;
	}
	cmd_free_argv(argc, argv);

	cmdq_run(c->cmdq, cmdlist);
	cmd_list_free(cmdlist);
	return;

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

	c->flags |= CLIENT_EXIT;
}

/* Handle identify message. */
void
server_client_msg_identify(struct client *c, struct imsg *imsg)
{
	const char	*data;
	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;
		break;
	case MSG_IDENTIFY_TERM:
		if (datalen == 0 || data[datalen - 1] != '\0')
			fatalx("bad MSG_IDENTIFY_TERM string");
		c->term = xstrdup(data);
		break;
	case MSG_IDENTIFY_TTYNAME:
		if (datalen == 0 || data[datalen - 1] != '\0')
			fatalx("bad MSG_IDENTIFY_TTYNAME string");
		c->ttyname = xstrdup(data);
		break;
	case MSG_IDENTIFY_CWD:
		if (datalen != 0)
			fatalx("bad MSG_IDENTIFY_CWD size");
		c->cwd = imsg->fd;
		break;
	case MSG_IDENTIFY_STDIN:
		if (datalen != 0)
			fatalx("bad MSG_IDENTIFY_STDIN size");
		c->fd = 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);
		break;
	default:
		break;
	}

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

#ifdef __CYGWIN__
	c->fd = open(c->ttyname, O_RDWR|O_NOCTTY);
	c->cwd = open(".", O_RDONLY);
#endif

	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");
		server_write_client(c, MSG_STDIN, NULL, 0);

		c->tty.fd = -1;
		c->tty.log_fd = -1;

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

		return;
	}

	if (c->fd == -1)
		return;
	if (!isatty(c->fd)) {
		close(c->fd);
		c->fd = -1;
		return;
	}
	tty_init(&c->tty, c, c->fd, c->term);
	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. */
void
server_client_msg_shell(struct client *c)
{
	const char	*shell;

	shell = options_get_string(&global_s_options, "default-shell");
	if (*shell == '\0' || areshell(shell))
		shell = _PATH_BSHELL;
	server_write_client(c, MSG_SHELL, shell, strlen(shell) + 1);

	c->flags |= CLIENT_BAD;	/* it will die after exec */
}