server.c - tmux - Rivoreo Source Code Repositories

 /* $OpenBSD$ */

 /*
  * Copyright (c) 2007 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 <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/un.h>
 #include <sys/wait.h>

 #include <errno.h>
 #include <fcntl.h>
 #include <paths.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <syslog.h>
 #include <termios.h>
 #include <time.h>
 #include <unistd.h>

 #include "tmux.h"

 /*
  * Main server functions.
  */

 /* Client list. */
 struct clients	 clients;
 struct clients	 dead_clients;

 /* Mapping of a pollfd to an fd independent of its position in the array. */
 struct poll_item {
 	int	 fd;
 	int	 events;

 	void	 (*fn)(int, int, void *);
 	void	*data;

 	RB_ENTRY(poll_item) entry;
 };
 RB_HEAD(poll_items, poll_item) poll_items;

 int		 server_poll_cmp(struct poll_item *, struct poll_item *);
 struct poll_item*server_poll_lookup(int);
 void		 server_poll_add(int, int, void (*)(int, int, void *), void *);
 struct pollfd	*server_poll_flatten(int *);
 void		 server_poll_dispatch(struct pollfd *, int);
 void		 server_poll_reset(void);
 RB_PROTOTYPE(poll_items, poll_item, entry, server_poll_cmp);
 RB_GENERATE(poll_items, poll_item, entry, server_poll_cmp);

 int		 server_create_socket(void);
 void		 server_callback(int, int, void *);
 int		 server_main(int);
 void		 server_shutdown(void);
 int		 server_should_shutdown(void);
 void		 server_child_signal(void);
 void		 server_fill_windows(void);
 void		 server_fill_clients(void);
 void		 server_fill_jobs(void);
 void		 server_clean_dead(void);
 void		 server_second_timers(void);
 void		 server_lock_server(void);
 void		 server_lock_sessions(void);
 int		 server_update_socket(void);

 int
 server_poll_cmp(struct poll_item *pitem1, struct poll_item *pitem2)
 {
 	return (pitem1->fd - pitem2->fd);
 }

 void
 server_poll_add(int fd, int events, void (*fn)(int, int, void *), void *data)
 {
 	struct poll_item	*pitem;

 	pitem = xmalloc(sizeof *pitem);
 	pitem->fd = fd;
 	pitem->events = events;

 	pitem->fn = fn;
 	pitem->data = data;

 	RB_INSERT(poll_items, &poll_items, pitem);
 }

 struct poll_item *
 server_poll_lookup(int fd)
 {
 	struct poll_item	pitem;

 	pitem.fd = fd;
 	return (RB_FIND(poll_items, &poll_items, &pitem));
 }

 struct pollfd *
 server_poll_flatten(int *nfds)
 {
 	struct poll_item	*pitem;
 	struct pollfd		*pfds;

 	pfds = NULL;
 	*nfds = 0;
 	RB_FOREACH(pitem, poll_items, &poll_items) {
 		pfds = xrealloc(pfds, (*nfds) + 1, sizeof *pfds);
 		pfds[*nfds].fd = pitem->fd;
 		pfds[*nfds].events = pitem->events;
 		(*nfds)++;
 	}
 	return (pfds);
 }

 void
 server_poll_dispatch(struct pollfd *pfds, int nfds)
 {
 	struct poll_item	*pitem;
 	struct pollfd		*pfd;

 	while (nfds > 0) {
 		pfd = &pfds[--nfds];
 		if (pfd->revents != 0) {
 			pitem = server_poll_lookup(pfd->fd);
 			pitem->fn(pitem->fd, pfd->revents, pitem->data);
 		}
 	}
 	xfree(pfds);
 }

 void
 server_poll_reset(void)
 {
 	struct poll_item	*pitem;

 	while (!RB_EMPTY(&poll_items)) {
 		pitem = RB_ROOT(&poll_items);
 		RB_REMOVE(poll_items, &poll_items, pitem);
 		xfree(pitem);
 	}
 }

 /* Create server socket. */
 int
 server_create_socket(void)
 {
 	struct sockaddr_un	sa;
 	size_t			size;
 	mode_t			mask;
 	int			fd, mode;

 	memset(&sa, 0, sizeof sa);
 	sa.sun_family = AF_UNIX;
 	size = strlcpy(sa.sun_path, socket_path, sizeof sa.sun_path);
 	if (size >= sizeof sa.sun_path) {
 		errno = ENAMETOOLONG;
 		fatal("socket failed");
 	}
 	unlink(sa.sun_path);

 	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
 		fatal("socket failed");

 	mask = umask(S_IXUSR|S_IRWXG|S_IRWXO);
 	if (bind(fd, (struct sockaddr *) &sa, SUN_LEN(&sa)) == -1)
 		fatal("bind failed");
 	umask(mask);

 	if (listen(fd, 16) == -1)
 		fatal("listen failed");

 	if ((mode = fcntl(fd, F_GETFL)) == -1)
 		fatal("fcntl failed");
 	if (fcntl(fd, F_SETFL, mode|O_NONBLOCK) == -1)
 		fatal("fcntl failed");
 	if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
 		fatal("fcntl failed");

 	return (fd);
 }

 /* Callback for server socket. */
 void
 server_callback(int fd, int events, unused void *data)
 {
 	struct sockaddr_storage	sa;
 	socklen_t		slen = sizeof sa;
 	int			newfd;

 	if (events & (POLLERR|POLLNVAL|POLLHUP))
 		fatalx("lost server socket");
 	if (!(events & POLLIN))
 		return;

 	newfd = accept(fd, (struct sockaddr *) &sa, &slen);
 	if (newfd == -1) {
 		if (errno == EAGAIN || errno == EINTR || errno == ECONNABORTED)
 			return;
 		fatal("accept failed");
 	}
 	if (sigterm) {
 		close(newfd);
 		return;
 	}
 	server_client_create(newfd);
 }

 /* Fork new server. */
 int
 server_start(char *path)
 {
 	struct client	*c;
 	int		 pair[2], srv_fd;
 	char		*cause;
 	char		 rpathbuf[MAXPATHLEN];

 	/* The first client is special and gets a socketpair; create it. */
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0)
 		fatal("socketpair failed");

 	switch (fork()) {
 	case -1:
 		fatal("fork failed");
 	case 0:
 		break;
 	default:
 		close(pair[1]);
 		return (pair[0]);
 	}
 	close(pair[0]);

 	/*
 	 * Must daemonise before loading configuration as the PID changes so
 	 * $TMUX would be wrong for sessions created in the config file.
 	 */
 	if (daemon(1, 0) != 0)
 		fatal("daemon failed");

 	logfile("server");
 	log_debug("server started, pid %ld", (long) getpid());

 	ARRAY_INIT(&windows);
 	ARRAY_INIT(&clients);
 	ARRAY_INIT(&dead_clients);
 	ARRAY_INIT(&sessions);
 	ARRAY_INIT(&dead_sessions);
 	TAILQ_INIT(&session_groups);
 	mode_key_init_trees();
 	key_bindings_init();
 	utf8_build();

 	start_time = time(NULL);
 	socket_path = path;

 	if (realpath(socket_path, rpathbuf) == NULL)
 		strlcpy(rpathbuf, socket_path, sizeof rpathbuf);
 	log_debug("socket path %s", socket_path);
 	setproctitle("server (%s)", rpathbuf);

 	srv_fd = server_create_socket();
 	server_client_create(pair[1]);

 	if (access(SYSTEM_CFG, R_OK) != 0) {
 		if (errno != ENOENT) {
 			xasprintf(
 			    &cause, "%s: %s", strerror(errno), SYSTEM_CFG);
 			goto error;
 		}
 	} else if (load_cfg(SYSTEM_CFG, NULL, &cause) != 0)
 		goto error;
 	if (cfg_file != NULL && load_cfg(cfg_file, NULL, &cause) != 0)
 		goto error;

 	exit(server_main(srv_fd));

 error:
 	/* Write the error and shutdown the server. */
 	c = ARRAY_FIRST(&clients);

 	server_write_error(c, cause);
 	xfree(cause);

 	sigterm = 1;
 	server_shutdown();

 	exit(server_main(srv_fd));
 }

 /* Main server loop. */
 int
 server_main(int srv_fd)
 {
 	struct pollfd	*pfds;
 	int		 nfds, xtimeout;
 	u_int		 i;
 	time_t		 now, last;

 	siginit();
 	log_debug("server socket is %d", srv_fd);

 	last = time(NULL);

 	pfds = NULL;
 	for (;;) {
 		/* If sigterm, kill all windows and clients. */
 		if (sigterm)
 			server_shutdown();

 		/* Stop if no sessions or clients left. */
 		if (server_should_shutdown())
 			break;

 		/* Handle child exit. */
 		if (sigchld) {
 			sigchld = 0;
 			server_child_signal();
 			continue;
 		}

 		/* Recreate socket on SIGUSR1. */
 		if (sigusr1) {
 			sigusr1 = 0;
 			close(srv_fd);
 			srv_fd = server_create_socket();
 			continue;
 		}

 		/* Initialise pollfd array and add server socket. */
 		server_poll_reset();
 		server_poll_add(srv_fd, POLLIN, server_callback, NULL);

 		/* Fill window and client sockets. */
 		server_fill_jobs();
 		server_fill_windows();
 		server_fill_clients();

 		/* Update socket permissions. */
 		xtimeout = INFTIM;
 		if (server_update_socket() != 0)
 			xtimeout = POLL_TIMEOUT;

 		/* Do the poll. */
 		pfds = server_poll_flatten(&nfds);
 		if (poll(pfds, nfds, xtimeout) == -1) {
 			if (errno == EAGAIN || errno == EINTR)
 				continue;
 			fatal("poll failed");
 		}
 		server_poll_dispatch(pfds, nfds);

 		/* Call second-based timers. */
 		now = time(NULL);
 		if (now != last) {
 			last = now;
 			server_second_timers();
 		}

 		/* Run once-per-loop events. */
 		server_job_loop();
 		server_window_loop();
 		server_client_loop();

 		/* Collect any unset key bindings. */
 		key_bindings_clean();

 		/* Collect dead clients and sessions. */
 		server_clean_dead();
 	}
 	server_poll_reset();

 	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
 		if (ARRAY_ITEM(&sessions, i) != NULL)
 			session_destroy(ARRAY_ITEM(&sessions, i));
 	}
 	ARRAY_FREE(&sessions);

 	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
 		if (ARRAY_ITEM(&clients, i) != NULL)
 			server_client_lost(ARRAY_ITEM(&clients, i));
 	}
 	ARRAY_FREE(&clients);

 	mode_key_free_trees();
 	key_bindings_free();

 	close(srv_fd);

 	unlink(socket_path);
 	xfree(socket_path);

 	options_free(&global_s_options);
 	options_free(&global_w_options);

 	return (0);
 }

 /* Kill all clients. */
 void
 server_shutdown(void)
 {
 	struct session	*s;
 	struct client	*c;
 	u_int		 i, j;

 	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
 		c = ARRAY_ITEM(&clients, i);
 		if (c != NULL) {
 			if (c->flags & (CLIENT_BAD|CLIENT_SUSPENDED))
 				server_client_lost(c);
 			else
 				server_write_client(c, MSG_SHUTDOWN, NULL, 0);
 		}
 	}

 	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
 		s = ARRAY_ITEM(&sessions, i);
 		for (j = 0; j < ARRAY_LENGTH(&clients); j++) {
 			c = ARRAY_ITEM(&clients, j);
 			if (c != NULL && c->session == s) {
 				s = NULL;
 				break;
 			}
 		}
 		if (s != NULL)
 			session_destroy(s);
 	}
 }

 /* Check if the server should be shutting down (no more clients or windows). */
 int
 server_should_shutdown(void)
 {
 	u_int	i;

 	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
 		if (ARRAY_ITEM(&sessions, i) != NULL)
 			return (0);
 	}
 	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
 		if (ARRAY_ITEM(&clients, i) != NULL)
 			return (0);
 	}
 	return (1);
 }

 /* Handle SIGCHLD. */
 void
 server_child_signal(void)
 {
 	struct window		*w;
 	struct window_pane	*wp;
 	struct job		*job;
 	int		 	 status;
 	pid_t		 	 pid;
 	u_int		 	 i;

 	for (;;) {
 		switch (pid = waitpid(WAIT_ANY, &status, WNOHANG|WUNTRACED)) {
 		case -1:
 			if (errno == ECHILD)
 				return;
 			fatal("waitpid failed");
 		case 0:
 			return;
 		}
 		if (!WIFSTOPPED(status)) {
 			SLIST_FOREACH(job, &all_jobs, lentry) {
 				if (pid == job->pid) {
 					job->pid = -1;
 					job->status = status;
 				}
 			}
 			continue;
 		}
 		if (WSTOPSIG(status) == SIGTTIN || WSTOPSIG(status) == SIGTTOU)
 			continue;

 		for (i = 0; i < ARRAY_LENGTH(&windows); i++) {
 			w = ARRAY_ITEM(&windows, i);
 			if (w == NULL)
 				continue;
 			TAILQ_FOREACH(wp, &w->panes, entry) {
 				if (wp->pid == pid) {
 					if (killpg(pid, SIGCONT) != 0)
 						kill(pid, SIGCONT);
 				}
 			}
 		}
 	}
 }

 /* Fill window pollfds. */
 void
 server_fill_windows(void)
 {
 	struct window		*w;
 	struct window_pane	*wp;
 	u_int		 	 i;
 	int			 events;

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

 		TAILQ_FOREACH(wp, &w->panes, entry) {
 			if (wp->fd == -1)
 				continue;
 			events = POLLIN;
 			if (BUFFER_USED(wp->out) > 0)
 				events |= POLLOUT;
 			server_poll_add(
 			    wp->fd, events, server_window_callback, wp);

 			if (wp->pipe_fd == -1)
 				continue;
 			events = 0;
 			if (BUFFER_USED(wp->pipe_buf) > 0)
 				events |= POLLOUT;
 			server_poll_add(
 			    wp->pipe_fd, events, server_window_callback, wp);
 		}
 	}
 }

 /* Fill client pollfds. */
 void
 server_fill_clients(void)
 {
 	struct client	*c;
 	u_int		 i;
 	int		 events;

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

 		if (c != NULL) {
 			events = 0;
 			if (!(c->flags & CLIENT_BAD))
 				events |= POLLIN;
 			if (c->ibuf.w.queued > 0)
 				events |= POLLOUT;
 			server_poll_add(
 			    c->ibuf.fd, events, server_client_callback, c);
 		}

 		if (c != NULL && !(c->flags & CLIENT_SUSPENDED) &&
 		    c->tty.fd != -1 && c->session != NULL) {
 			events = POLLIN;
 			if (BUFFER_USED(c->tty.out) > 0)
 				events |= POLLOUT;
 			server_poll_add(
 			    c->tty.fd, events, server_client_callback, c);
 		}
 	}
 }

 /* Fill in job fds. */
 void
 server_fill_jobs(void)
 {
 	struct job	*job;

 	SLIST_FOREACH(job, &all_jobs, lentry) {
 		if (job->fd == -1)
 			continue;
 		server_poll_add(job->fd, POLLIN, server_job_callback, job);
 	}
 }

 /* Free dead, unreferenced clients and sessions. */
 void
 server_clean_dead(void)
 {
 	struct session	*s;
 	struct client	*c;
 	u_int		 i;

 	for (i = 0; i < ARRAY_LENGTH(&dead_sessions); i++) {
 		s = ARRAY_ITEM(&dead_sessions, i);
 		if (s == NULL || s->references != 0)
 			continue;
 		ARRAY_SET(&dead_sessions, i, NULL);
 		xfree(s);
 	}

 	for (i = 0; i < ARRAY_LENGTH(&dead_clients); i++) {
 		c = ARRAY_ITEM(&dead_clients, i);
 		if (c == NULL || c->references != 0)
 			continue;
 		ARRAY_SET(&dead_clients, i, NULL);
 		xfree(c);
 	}
 }

 /* Call any once-per-second timers. */
 void
 server_second_timers(void)
 {
 	struct window		*w;
 	struct window_pane	*wp;
 	u_int		 	 i;

 	if (options_get_number(&global_s_options, "lock-server"))
 		server_lock_server();
 	else
 		server_lock_sessions();

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

 		TAILQ_FOREACH(wp, &w->panes, entry) {
 			if (wp->mode != NULL && wp->mode->timer != NULL)
 				wp->mode->timer(wp);
 		}
 	}
 }

 /* Lock the server if ALL sessions have hit the time limit. */
 void
 server_lock_server(void)
 {
 	struct session  *s;
 	u_int            i;
 	int		 timeout;
 	time_t           t;

 	t = time(NULL);
 	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
 		if ((s = ARRAY_ITEM(&sessions, i)) == NULL)
 			continue;

 		if (s->flags & SESSION_UNATTACHED) {
 			s->activity = time(NULL);
 			continue;
 		}

 		timeout = options_get_number(&s->options, "lock-after-time");
 		if (timeout <= 0 || t <= s->activity + timeout)
 			return;	/* not timed out */
 	}

 	server_lock();
 	recalculate_sizes();
 }

 /* Lock any sessions which have timed out. */
 void
 server_lock_sessions(void)
 {
         struct session  *s;
         u_int            i;
 	int		 timeout;
         time_t           t;

         t = time(NULL);
         for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
 		if ((s = ARRAY_ITEM(&sessions, i)) == NULL)
 			continue;

 		if (s->flags & SESSION_UNATTACHED) {
 			s->activity = time(NULL);
 			continue;
 		}

 		timeout = options_get_number(&s->options, "lock-after-time");
 		if (timeout > 0 && t > s->activity + timeout) {
 			server_lock_session(s);
 			recalculate_sizes();
 		}
 	}
 }

 /* Update socket execute permissions based on whether sessions are attached. */
 int
 server_update_socket(void)
 {
 	struct session	*s;
 	u_int		 i;
 	static int	 last = -1;
 	int		 n;

 	n = 0;
 	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
 		s = ARRAY_ITEM(&sessions, i);
 		if (s != NULL && !(s->flags & SESSION_UNATTACHED)) {
 			n++;
 			break;
 		}
 	}

 	if (n != last) {
 		last = n;
 		if (n != 0)
 			chmod(socket_path, S_IRWXU);
 		else
 			chmod(socket_path, S_IRUSR|S_IWUSR);
 	}

 	return (n);
 }
	/* $OpenBSD$ */

	/*
	* Copyright (c) 2007 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 <sys/socket.h>
	#include <sys/stat.h>
	#include <sys/un.h>
	#include <sys/wait.h>

	#include <errno.h>
	#include <fcntl.h>
	#include <paths.h>
	#include <signal.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <syslog.h>
	#include <termios.h>
	#include <time.h>
	#include <unistd.h>

	#include "tmux.h"

	/*
	* Main server functions.
	*/

	/* Client list. */
	struct clients clients;
	struct clients dead_clients;

	/* Mapping of a pollfd to an fd independent of its position in the array. */
	struct poll_item {
	int fd;
	int events;

	void (fn)(int, int, void );
	void *data;

	RB_ENTRY(poll_item) entry;
	};
	RB_HEAD(poll_items, poll_item) poll_items;

	int server_poll_cmp(struct poll_item , struct poll_item );
	struct poll_item*server_poll_lookup(int);
	void server_poll_add(int, int, void ()(int, int, void ), void *);
	struct pollfd server_poll_flatten(int );
	void server_poll_dispatch(struct pollfd *, int);
	void server_poll_reset(void);
	RB_PROTOTYPE(poll_items, poll_item, entry, server_poll_cmp);
	RB_GENERATE(poll_items, poll_item, entry, server_poll_cmp);

	int server_create_socket(void);
	void server_callback(int, int, void *);
	int server_main(int);
	void server_shutdown(void);
	int server_should_shutdown(void);
	void server_child_signal(void);
	void server_fill_windows(void);
	void server_fill_clients(void);
	void server_fill_jobs(void);
	void server_clean_dead(void);
	void server_second_timers(void);
	void server_lock_server(void);
	void server_lock_sessions(void);
	int server_update_socket(void);

	int
	server_poll_cmp(struct poll_item pitem1, struct poll_item pitem2)
	{
	return (pitem1->fd - pitem2->fd);
	}

	void
	server_poll_add(int fd, int events, void (fn)(int, int, void ), void *data)
	{
	struct poll_item *pitem;

	pitem = xmalloc(sizeof *pitem);
	pitem->fd = fd;
	pitem->events = events;

	pitem->fn = fn;
	pitem->data = data;

	RB_INSERT(poll_items, &poll_items, pitem);
	}

	struct poll_item *
	server_poll_lookup(int fd)
	{
	struct poll_item pitem;

	pitem.fd = fd;
	return (RB_FIND(poll_items, &poll_items, &pitem));
	}

	struct pollfd *
	server_poll_flatten(int *nfds)
	{
	struct poll_item *pitem;
	struct pollfd *pfds;

	pfds = NULL;
	*nfds = 0;
	RB_FOREACH(pitem, poll_items, &poll_items) {
	pfds = xrealloc(pfds, (nfds) + 1, sizeof pfds);
	pfds[*nfds].fd = pitem->fd;
	pfds[*nfds].events = pitem->events;
	(*nfds)++;
	}
	return (pfds);
	}

	void
	server_poll_dispatch(struct pollfd *pfds, int nfds)
	{
	struct poll_item *pitem;
	struct pollfd *pfd;

	while (nfds > 0) {
	pfd = &pfds[--nfds];
	if (pfd->revents != 0) {
	pitem = server_poll_lookup(pfd->fd);
	pitem->fn(pitem->fd, pfd->revents, pitem->data);
	}
	}
	xfree(pfds);
	}

	void
	server_poll_reset(void)
	{
	struct poll_item *pitem;

	while (!RB_EMPTY(&poll_items)) {
	pitem = RB_ROOT(&poll_items);
	RB_REMOVE(poll_items, &poll_items, pitem);
	xfree(pitem);
	}
	}

	/* Create server socket. */
	int
	server_create_socket(void)
	{
	struct sockaddr_un sa;
	size_t size;
	mode_t mask;
	int fd, mode;

	memset(&sa, 0, sizeof sa);
	sa.sun_family = AF_UNIX;
	size = strlcpy(sa.sun_path, socket_path, sizeof sa.sun_path);
	if (size >= sizeof sa.sun_path) {
	errno = ENAMETOOLONG;
	fatal("socket failed");
	}
	unlink(sa.sun_path);

	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
	fatal("socket failed");

	mask = umask(S_IXUSR\|S_IRWXG\|S_IRWXO);
	if (bind(fd, (struct sockaddr *) &sa, SUN_LEN(&sa)) == -1)
	fatal("bind failed");
	umask(mask);

	if (listen(fd, 16) == -1)
	fatal("listen failed");

	if ((mode = fcntl(fd, F_GETFL)) == -1)
	fatal("fcntl failed");
	if (fcntl(fd, F_SETFL, mode\|O_NONBLOCK) == -1)
	fatal("fcntl failed");
	if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
	fatal("fcntl failed");

	return (fd);
	}

	/* Callback for server socket. */
	void
	server_callback(int fd, int events, unused void *data)
	{
	struct sockaddr_storage sa;
	socklen_t slen = sizeof sa;
	int newfd;

	if (events & (POLLERR\|POLLNVAL\|POLLHUP))
	fatalx("lost server socket");
	if (!(events & POLLIN))
	return;

	newfd = accept(fd, (struct sockaddr *) &sa, &slen);
	if (newfd == -1) {
	if (errno == EAGAIN \|\| errno == EINTR \|\| errno == ECONNABORTED)
	return;
	fatal("accept failed");
	}
	if (sigterm) {
	close(newfd);
	return;
	}
	server_client_create(newfd);
	}

	/* Fork new server. */
	int
	server_start(char *path)
	{
	struct client *c;
	int pair[2], srv_fd;
	char *cause;
	char rpathbuf[MAXPATHLEN];

	/* The first client is special and gets a socketpair; create it. */
	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0)
	fatal("socketpair failed");

	switch (fork()) {
	case -1:
	fatal("fork failed");
	case 0:
	break;
	default:
	close(pair[1]);
	return (pair[0]);
	}
	close(pair[0]);

	/*
	* Must daemonise before loading configuration as the PID changes so
	* $TMUX would be wrong for sessions created in the config file.
	*/
	if (daemon(1, 0) != 0)
	fatal("daemon failed");

	logfile("server");
	log_debug("server started, pid %ld", (long) getpid());

	ARRAY_INIT(&windows);
	ARRAY_INIT(&clients);
	ARRAY_INIT(&dead_clients);
	ARRAY_INIT(&sessions);
	ARRAY_INIT(&dead_sessions);
	TAILQ_INIT(&session_groups);
	mode_key_init_trees();
	key_bindings_init();
	utf8_build();

	start_time = time(NULL);
	socket_path = path;

	if (realpath(socket_path, rpathbuf) == NULL)
	strlcpy(rpathbuf, socket_path, sizeof rpathbuf);
	log_debug("socket path %s", socket_path);
	setproctitle("server (%s)", rpathbuf);

	srv_fd = server_create_socket();
	server_client_create(pair[1]);

	if (access(SYSTEM_CFG, R_OK) != 0) {
	if (errno != ENOENT) {
	xasprintf(
	&cause, "%s: %s", strerror(errno), SYSTEM_CFG);
	goto error;
	}
	} else if (load_cfg(SYSTEM_CFG, NULL, &cause) != 0)
	goto error;
	if (cfg_file != NULL && load_cfg(cfg_file, NULL, &cause) != 0)
	goto error;

	exit(server_main(srv_fd));

	error:
	/* Write the error and shutdown the server. */
	c = ARRAY_FIRST(&clients);

	server_write_error(c, cause);
	xfree(cause);

	sigterm = 1;
	server_shutdown();

	exit(server_main(srv_fd));
	}

	/* Main server loop. */
	int
	server_main(int srv_fd)
	{
	struct pollfd *pfds;
	int nfds, xtimeout;
	u_int i;
	time_t now, last;

	siginit();
	log_debug("server socket is %d", srv_fd);

	last = time(NULL);

	pfds = NULL;
	for (;;) {
	/* If sigterm, kill all windows and clients. */
	if (sigterm)
	server_shutdown();

	/* Stop if no sessions or clients left. */
	if (server_should_shutdown())
	break;

	/* Handle child exit. */
	if (sigchld) {
	sigchld = 0;
	server_child_signal();
	continue;
	}

	/* Recreate socket on SIGUSR1. */
	if (sigusr1) {
	sigusr1 = 0;
	close(srv_fd);
	srv_fd = server_create_socket();
	continue;
	}

	/* Initialise pollfd array and add server socket. */
	server_poll_reset();
	server_poll_add(srv_fd, POLLIN, server_callback, NULL);

	/* Fill window and client sockets. */
	server_fill_jobs();
	server_fill_windows();
	server_fill_clients();

	/* Update socket permissions. */
	xtimeout = INFTIM;
	if (server_update_socket() != 0)
	xtimeout = POLL_TIMEOUT;

	/* Do the poll. */
	pfds = server_poll_flatten(&nfds);
	if (poll(pfds, nfds, xtimeout) == -1) {
	if (errno == EAGAIN \|\| errno == EINTR)
	continue;
	fatal("poll failed");
	}
	server_poll_dispatch(pfds, nfds);

	/* Call second-based timers. */
	now = time(NULL);
	if (now != last) {
	last = now;
	server_second_timers();
	}

	/* Run once-per-loop events. */
	server_job_loop();
	server_window_loop();
	server_client_loop();

	/* Collect any unset key bindings. */
	key_bindings_clean();

	/* Collect dead clients and sessions. */
	server_clean_dead();
	}
	server_poll_reset();

	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
	if (ARRAY_ITEM(&sessions, i) != NULL)
	session_destroy(ARRAY_ITEM(&sessions, i));
	}
	ARRAY_FREE(&sessions);

	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
	if (ARRAY_ITEM(&clients, i) != NULL)
	server_client_lost(ARRAY_ITEM(&clients, i));
	}
	ARRAY_FREE(&clients);

	mode_key_free_trees();
	key_bindings_free();

	close(srv_fd);

	unlink(socket_path);
	xfree(socket_path);

	options_free(&global_s_options);
	options_free(&global_w_options);

	return (0);
	}

	/* Kill all clients. */
	void
	server_shutdown(void)
	{
	struct session *s;
	struct client *c;
	u_int i, j;

	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
	c = ARRAY_ITEM(&clients, i);
	if (c != NULL) {
	if (c->flags & (CLIENT_BAD\|CLIENT_SUSPENDED))
	server_client_lost(c);
	else
	server_write_client(c, MSG_SHUTDOWN, NULL, 0);
	}
	}

	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
	s = ARRAY_ITEM(&sessions, i);
	for (j = 0; j < ARRAY_LENGTH(&clients); j++) {
	c = ARRAY_ITEM(&clients, j);
	if (c != NULL && c->session == s) {
	s = NULL;
	break;
	}
	}
	if (s != NULL)
	session_destroy(s);
	}
	}

	/* Check if the server should be shutting down (no more clients or windows). */
	int
	server_should_shutdown(void)
	{
	u_int i;

	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
	if (ARRAY_ITEM(&sessions, i) != NULL)
	return (0);
	}
	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
	if (ARRAY_ITEM(&clients, i) != NULL)
	return (0);
	}
	return (1);
	}

	/* Handle SIGCHLD. */
	void
	server_child_signal(void)
	{
	struct window *w;
	struct window_pane *wp;
	struct job *job;
	int status;
	pid_t pid;
	u_int i;

	for (;;) {
	switch (pid = waitpid(WAIT_ANY, &status, WNOHANG\|WUNTRACED)) {
	case -1:
	if (errno == ECHILD)
	return;
	fatal("waitpid failed");
	case 0:
	return;
	}
	if (!WIFSTOPPED(status)) {
	SLIST_FOREACH(job, &all_jobs, lentry) {
	if (pid == job->pid) {
	job->pid = -1;
	job->status = status;
	}
	}
	continue;
	}
	if (WSTOPSIG(status) == SIGTTIN \|\| WSTOPSIG(status) == SIGTTOU)
	continue;

	for (i = 0; i < ARRAY_LENGTH(&windows); i++) {
	w = ARRAY_ITEM(&windows, i);
	if (w == NULL)
	continue;
	TAILQ_FOREACH(wp, &w->panes, entry) {
	if (wp->pid == pid) {
	if (killpg(pid, SIGCONT) != 0)
	kill(pid, SIGCONT);
	}
	}
	}
	}
	}

	/* Fill window pollfds. */
	void
	server_fill_windows(void)
	{
	struct window *w;
	struct window_pane *wp;
	u_int i;
	int events;

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

	TAILQ_FOREACH(wp, &w->panes, entry) {
	if (wp->fd == -1)
	continue;
	events = POLLIN;
	if (BUFFER_USED(wp->out) > 0)
	events \|= POLLOUT;
	server_poll_add(
	wp->fd, events, server_window_callback, wp);

	if (wp->pipe_fd == -1)
	continue;
	events = 0;
	if (BUFFER_USED(wp->pipe_buf) > 0)
	events \|= POLLOUT;
	server_poll_add(
	wp->pipe_fd, events, server_window_callback, wp);
	}
	}
	}

	/* Fill client pollfds. */
	void
	server_fill_clients(void)
	{
	struct client *c;
	u_int i;
	int events;

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

	if (c != NULL) {
	events = 0;
	if (!(c->flags & CLIENT_BAD))
	events \|= POLLIN;
	if (c->ibuf.w.queued > 0)
	events \|= POLLOUT;
	server_poll_add(
	c->ibuf.fd, events, server_client_callback, c);
	}

	if (c != NULL && !(c->flags & CLIENT_SUSPENDED) &&
	c->tty.fd != -1 && c->session != NULL) {
	events = POLLIN;
	if (BUFFER_USED(c->tty.out) > 0)
	events \|= POLLOUT;
	server_poll_add(
	c->tty.fd, events, server_client_callback, c);
	}
	}
	}

	/* Fill in job fds. */
	void
	server_fill_jobs(void)
	{
	struct job *job;

	SLIST_FOREACH(job, &all_jobs, lentry) {
	if (job->fd == -1)
	continue;
	server_poll_add(job->fd, POLLIN, server_job_callback, job);
	}
	}

	/* Free dead, unreferenced clients and sessions. */
	void
	server_clean_dead(void)
	{
	struct session *s;
	struct client *c;
	u_int i;

	for (i = 0; i < ARRAY_LENGTH(&dead_sessions); i++) {
	s = ARRAY_ITEM(&dead_sessions, i);
	if (s == NULL \|\| s->references != 0)
	continue;
	ARRAY_SET(&dead_sessions, i, NULL);
	xfree(s);
	}

	for (i = 0; i < ARRAY_LENGTH(&dead_clients); i++) {
	c = ARRAY_ITEM(&dead_clients, i);
	if (c == NULL \|\| c->references != 0)
	continue;
	ARRAY_SET(&dead_clients, i, NULL);
	xfree(c);
	}
	}

	/* Call any once-per-second timers. */
	void
	server_second_timers(void)
	{
	struct window *w;
	struct window_pane *wp;
	u_int i;

	if (options_get_number(&global_s_options, "lock-server"))
	server_lock_server();
	else
	server_lock_sessions();

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

	TAILQ_FOREACH(wp, &w->panes, entry) {
	if (wp->mode != NULL && wp->mode->timer != NULL)
	wp->mode->timer(wp);
	}
	}
	}

	/* Lock the server if ALL sessions have hit the time limit. */
	void
	server_lock_server(void)
	{
	struct session *s;
	u_int i;
	int timeout;
	time_t t;

	t = time(NULL);
	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
	if ((s = ARRAY_ITEM(&sessions, i)) == NULL)
	continue;

	if (s->flags & SESSION_UNATTACHED) {
	s->activity = time(NULL);
	continue;
	}

	timeout = options_get_number(&s->options, "lock-after-time");
	if (timeout <= 0 \|\| t <= s->activity + timeout)
	return; /* not timed out */
	}

	server_lock();
	recalculate_sizes();
	}

	/* Lock any sessions which have timed out. */
	void
	server_lock_sessions(void)
	{
	struct session *s;
	u_int i;
	int timeout;
	time_t t;

	t = time(NULL);
	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
	if ((s = ARRAY_ITEM(&sessions, i)) == NULL)
	continue;

	if (s->flags & SESSION_UNATTACHED) {
	s->activity = time(NULL);
	continue;
	}

	timeout = options_get_number(&s->options, "lock-after-time");
	if (timeout > 0 && t > s->activity + timeout) {
	server_lock_session(s);
	recalculate_sizes();
	}
	}
	}

	/* Update socket execute permissions based on whether sessions are attached. */
	int
	server_update_socket(void)
	{
	struct session *s;
	u_int i;
	static int last = -1;
	int n;

	n = 0;
	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
	s = ARRAY_ITEM(&sessions, i);
	if (s != NULL && !(s->flags & SESSION_UNATTACHED)) {
	n++;
	break;
	}
	}

	if (n != last) {
	last = n;
	if (n != 0)
	chmod(socket_path, S_IRWXU);
	else
	chmod(socket_path, S_IRUSR\|S_IWUSR);
	}

	return (n);
	}