Check for the right return value from sscanf.

[tmux-openbsd.git] / server-client.c

/* $OpenBSD$ */

/*
 * 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 <event.h>
#include <fcntl.h>
#include <string.h>
#include <time.h>
#include <paths.h>
#include <unistd.h>

#include "tmux.h"

void    server_client_check_mouse(struct client *c,
            struct window_pane *wp, struct mouse_event *mouse);
void    server_client_handle_key(int, struct mouse_event *, void *);
void    server_client_repeat_timer(int, short, void *);
void    server_client_check_exit(struct client *);
void    server_client_check_backoff(struct client *);
void    server_client_check_redraw(struct client *);
void    server_client_set_title(struct client *);
void    server_client_reset_state(struct client *);
void    server_client_in_callback(struct bufferevent *, short, void *);
void    server_client_out_callback(struct bufferevent *, short, void *);
void    server_client_err_callback(struct bufferevent *, short, void *);

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

void printflike2 server_client_msg_error(struct cmd_ctx *, const char *, ...);
void printflike2 server_client_msg_print(struct cmd_ctx *, const char *, ...);
void printflike2 server_client_msg_info(struct cmd_ctx *, const char *, ...);

/* 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);

        c->stdin_event = NULL;
        c->stdout_event = NULL;
        c->stderr_event = NULL;

        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->last_mouse.b = MOUSE_UP;
        c->last_mouse.x = c->last_mouse.y = -1;

        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);
}

/* 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);

        if (c->stdin_event != NULL)
                bufferevent_free(c->stdin_event);
        if (c->stdin_fd != -1) {
                setblocking(c->stdin_fd, 1);
                close(c->stdin_fd);
        }
        if (c->stdout_event != NULL)
                bufferevent_free(c->stdout_event);
        if (c->stdout_fd != -1) {
                setblocking(c->stdout_fd, 1);
                close(c->stdout_fd);
        }
        if (c->stderr_event != NULL)
                bufferevent_free(c->stderr_event);
        if (c->stderr_fd != -1) {
                setblocking(c->stderr_fd, 1);
                close(c->stderr_fd);
        }

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

        if (c->title != NULL)
                xfree(c->title);

        evtimer_del(&c->repeat_timer);

        evtimer_del(&c->identify_timer);

        if (c->message_string != NULL)
                xfree(c->message_string);
        evtimer_del(&c->message_timer);
        for (i = 0; i < ARRAY_LENGTH(&c->message_log); i++) {
                msg = &ARRAY_ITEM(&c->message_log, i);
                xfree(msg->msg);
        }
        ARRAY_FREE(&c->message_log);

        if (c->prompt_string != NULL)
                xfree(c->prompt_string);
        if (c->prompt_buffer != NULL)
                xfree(c->prompt_buffer);

        if (c->cwd != NULL)
                xfree(c->cwd);

        environ_free(&c->environ);

        close(c->ibuf.fd);
        imsg_clear(&c->ibuf);
        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;

        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_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 mouse_event *mouse)
{
        struct session  *s = c->session;
        struct options  *oo = &s->options;
        int              statusat;

        statusat = status_at_line(c);

        /* Is this a window selection click on the status line? */
        if (statusat != -1 && mouse->y == (u_int)statusat &&
            options_get_number(oo, "mouse-select-window")) {
                if (mouse->b == MOUSE_UP && c->last_mouse.b != MOUSE_UP) {
                        status_set_window_at(c, mouse->x);
                        return;
                }
                if (mouse->b & MOUSE_45) {
                        if ((mouse->b & MOUSE_BUTTON) == MOUSE_1) {
                                session_previous(c->session, 0);
                                server_redraw_session(s);
                        }
                        if ((mouse->b & MOUSE_BUTTON) == MOUSE_2) {
                                session_next(c->session, 0);
                                server_redraw_session(s);
                        }
                        return;
                }
                memcpy(&c->last_mouse, mouse, sizeof c->last_mouse);
                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 &&mouse->y > 0)
                mouse->y--;
        else if (statusat > 0 && mouse->y >= (u_int)statusat)
                mouse->y = statusat - 1;

        /* Is this a pane selection? Allow down only in copy mode. */
        if (options_get_number(oo, "mouse-select-pane") &&
            ((!(mouse->b & MOUSE_DRAG) && mouse->b != MOUSE_UP) ||
            wp->mode != &window_copy_mode)) {
                window_set_active_at(wp->window, mouse->x, mouse->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, mouse);

        /* Update last and pass through to client. */
        memcpy(&c->last_mouse, mouse, sizeof c->last_mouse);
        window_pane_mouse(wp, c->session, mouse);
}

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

        /* 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->activity_time, &c->activity_time, sizeof s->activity_time);

        w = c->session->curw->window;
        wp = w->active;
        oo = &c->session->options;

        /* 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;
                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, mouse);
                return;
        }

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

        /* No previous prefix key. */
        if (!(c->flags & CLIENT_PREFIX)) {
                if (isprefix)
                        c->flags |= CLIENT_PREFIX;
                else {
                        /* Try as a non-prefix key binding. */
                        if ((bd = key_bindings_lookup(key)) == NULL) {
                                if (!(c->flags & CLIENT_READONLY))
                                        window_pane_key(wp, c->session, key);
                        } else
                                key_bindings_dispatch(bd, c);
                }
                return;
        }

        /* Prefix key already pressed. Reset prefix and lookup key. */
        c->flags &= ~CLIENT_PREFIX;
        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, c->session, 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, c->session, key);
                return;
        }

        /* If this key can repeat, reset the repeat flags and timer. */
        xtimeout = options_get_number(&c->session->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.
         */
        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)
                        wp->flags &= ~PANE_REDRAW;
        }
}

/*
 * 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;

        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->last_mouse.b & 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. */
/* ARGSUSED */
void
server_client_repeat_timer(unused int fd, unused short events, void *data)
{
        struct client   *c = data;

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

/* Check if client should be exited. */
void
server_client_check_exit(struct client *c)
{
        struct msg_exit_data    exitdata;

        if (!(c->flags & CLIENT_EXIT))
                return;

        if (c->stdout_fd != -1 && c->stdout_event != NULL &&
            EVBUFFER_LENGTH(c->stdout_event->output) != 0)
                return;
        if (c->stderr_fd != -1 && c->stderr_event != NULL &&
            EVBUFFER_LENGTH(c->stderr_event->output) != 0)
                return;

        exitdata.retcode = c->retcode;
        server_write_client(c, MSG_EXIT, &exitdata, sizeof exitdata);

        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;

        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) {
                if (c->title != NULL)
                        xfree(c->title);
                c->title = xstrdup(title);
                tty_set_title(&c->tty, c->title);
        }
        xfree(title);
}

/*
 * Error callback for client stdin. Caller must increase reference count when
 * enabling event!
 */
void
server_client_in_callback(
    unused struct bufferevent *bufev, unused short what, void *data)
{
        struct client   *c = data;

        c->references--;
        if (c->flags & CLIENT_DEAD)
                return;

        bufferevent_disable(c->stdin_event, EV_READ|EV_WRITE);
        setblocking(c->stdin_fd, 1);
        close(c->stdin_fd);
        c->stdin_fd = -1;

        if (c->stdin_callback != NULL)
                c->stdin_callback(c, c->stdin_data);
}

/* Error callback for client stdout. */
void
server_client_out_callback(
    unused struct bufferevent *bufev, unused short what, unused void *data)
{
        struct client   *c = data;

        bufferevent_disable(c->stdout_event, EV_READ|EV_WRITE);
        setblocking(c->stdout_fd, 1);
        close(c->stdout_fd);
        c->stdout_fd = -1;
}

/* Error callback for client stderr. */
void
server_client_err_callback(
    unused struct bufferevent *bufev, unused short what, unused void *data)
{
        struct client   *c = data;

        bufferevent_disable(c->stderr_event, EV_READ|EV_WRITE);
        setblocking(c->stderr_fd, 1);
        close(c->stderr_fd);
        c->stderr_fd = -1;
}

/* Dispatch message from client. */
int
server_client_msg_dispatch(struct client *c)
{
        struct imsg              imsg;
        struct msg_command_data  commanddata;
        struct msg_identify_data identifydata;
        struct msg_environ_data  environdata;
        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);
                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_COMMAND:
                        if (datalen != sizeof commanddata)
                                fatalx("bad MSG_COMMAND size");
                        memcpy(&commanddata, imsg.data, sizeof commanddata);

                        server_client_msg_command(c, &commanddata);
                        break;
                case MSG_IDENTIFY:
                        if (datalen != sizeof identifydata)
                                fatalx("bad MSG_IDENTIFY size");
                        if (imsg.fd == -1)
                                fatalx("MSG_IDENTIFY missing fd");
                        memcpy(&identifydata, imsg.data, sizeof identifydata);

                        c->stdin_fd = imsg.fd;
                        c->stdin_event = bufferevent_new(c->stdin_fd,
                            NULL, NULL, server_client_in_callback, c);
                        if (c->stdin_event == NULL)
                                fatalx("failed to create stdin event");
                        setblocking(c->stdin_fd, 0);

                        server_client_msg_identify(c, &identifydata, imsg.fd);
                        break;
                case MSG_STDOUT:
                        if (datalen != 0)
                                fatalx("bad MSG_STDOUT size");
                        if (imsg.fd == -1)
                                fatalx("MSG_STDOUT missing fd");

                        c->stdout_fd = imsg.fd;
                        c->stdout_event = bufferevent_new(c->stdout_fd,
                            NULL, NULL, server_client_out_callback, c);
                        if (c->stdout_event == NULL)
                                fatalx("failed to create stdout event");
                        setblocking(c->stdout_fd, 0);

                        break;
                case MSG_STDERR:
                        if (datalen != 0)
                                fatalx("bad MSG_STDERR size");
                        if (imsg.fd == -1)
                                fatalx("MSG_STDERR missing fd");

                        c->stderr_fd = imsg.fd;
                        c->stderr_event = bufferevent_new(c->stderr_fd,
                            NULL, NULL, server_client_err_callback, c);
                        if (c->stderr_event == NULL)
                                fatalx("failed to create stderr event");
                        setblocking(c->stderr_fd, 0);

                        break;
                case MSG_RESIZE:
                        if (datalen != 0)
                                fatalx("bad MSG_RESIZE size");

                        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_ENVIRON:
                        if (datalen != sizeof environdata)
                                fatalx("bad MSG_ENVIRON size");
                        memcpy(&environdata, imsg.data, sizeof environdata);

                        environdata.var[(sizeof environdata.var) - 1] = '\0';
                        if (strchr(environdata.var, '=') != NULL)
                                environ_put(&c->environ, environdata.var);
                        break;
                case MSG_SHELL:
                        if (datalen != 0)
                                fatalx("bad MSG_SHELL size");

                        server_client_msg_shell(c);
                        break;
                default:
                        fatalx("unexpected message");
                }

                imsg_free(&imsg);
        }
}

/* Callback to send error message to client. */
void printflike2
server_client_msg_error(struct cmd_ctx *ctx, const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        evbuffer_add_vprintf(ctx->cmdclient->stderr_event->output, fmt, ap);
        va_end(ap);

        bufferevent_write(ctx->cmdclient->stderr_event, "\n", 1);
        ctx->cmdclient->retcode = 1;
}

/* Callback to send print message to client. */
void printflike2
server_client_msg_print(struct cmd_ctx *ctx, const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        evbuffer_add_vprintf(ctx->cmdclient->stdout_event->output, fmt, ap);
        va_end(ap);

        bufferevent_write(ctx->cmdclient->stdout_event, "\n", 1);
}

/* Callback to send print message to client, if not quiet. */
void printflike2
server_client_msg_info(struct cmd_ctx *ctx, const char *fmt, ...)
{
        va_list ap;

        if (options_get_number(&global_options, "quiet"))
                return;

        va_start(ap, fmt);
        evbuffer_add_vprintf(ctx->cmdclient->stdout_event->output, fmt, ap);
        va_end(ap);

        bufferevent_write(ctx->cmdclient->stdout_event, "\n", 1);
}

/* Handle command message. */
void
server_client_msg_command(struct client *c, struct msg_command_data *data)
{
        struct cmd_ctx   ctx;
        struct cmd_list *cmdlist = NULL;
        int              argc;
        char           **argv, *cause;

        ctx.error = server_client_msg_error;
        ctx.print = server_client_msg_print;
        ctx.info = server_client_msg_info;

        ctx.msgdata = data;
        ctx.curclient = NULL;

        ctx.cmdclient = c;

        argc = data->argc;
        data->argv[(sizeof data->argv) - 1] = '\0';
        if (cmd_unpack_argv(data->argv, sizeof data->argv, argc, &argv) != 0) {
                server_client_msg_error(&ctx, "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, &cause)) == NULL) {
                server_client_msg_error(&ctx, "%s", cause);
                cmd_free_argv(argc, argv);
                goto error;
        }
        cmd_free_argv(argc, argv);

        if (cmd_list_exec(cmdlist, &ctx) != 1)
                c->flags |= CLIENT_EXIT;
        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 msg_identify_data *data, int fd)
{
        int     tty_fd;

        c->cwd = NULL;
        data->cwd[(sizeof data->cwd) - 1] = '\0';
        if (*data->cwd != '\0')
                c->cwd = xstrdup(data->cwd);

        if (!isatty(fd))
            return;
        if ((tty_fd = dup(fd)) == -1)
                fatal("dup failed");
        data->term[(sizeof data->term) - 1] = '\0';
        tty_init(&c->tty, tty_fd, data->term);
        if (data->flags & IDENTIFY_UTF8)
                c->tty.flags |= TTY_UTF8;
        if (data->flags & IDENTIFY_256COLOURS)
                c->tty.term_flags |= TERM_256COLOURS;
        else if (data->flags & IDENTIFY_88COLOURS)
                c->tty.term_flags |= TERM_88COLOURS;
        c->tty.key_callback = server_client_handle_key;
        c->tty.key_data = c;

        tty_resize(&c->tty);

        c->flags |= CLIENT_TERMINAL;
}

/* Handle shell message. */
void
server_client_msg_shell(struct client *c)
{
        struct msg_shell_data    data;
        const char              *shell;

        shell = options_get_string(&global_s_options, "default-shell");

        if (*shell == '\0' || areshell(shell))
                shell = _PATH_BSHELL;
        if (strlcpy(data.shell, shell, sizeof data.shell) >= sizeof data.shell)
                strlcpy(data.shell, _PATH_BSHELL, sizeof data.shell);

        server_write_client(c, MSG_SHELL, &data, sizeof data);
        c->flags |= CLIENT_BAD; /* it will die after exec */
}