session.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/time.h>

 #include <paths.h>
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <time.h>

 #include "tmux.h"

 /* Global session list. */
 struct sessions	sessions;
 struct sessions dead_sessions;
 u_int		next_session_id;
 struct session_groups session_groups;

 struct winlink *session_next_alert(struct winlink *);
 struct winlink *session_previous_alert(struct winlink *);

 RB_GENERATE(sessions, session, entry, session_cmp);

 int
 session_cmp(struct session *s1, struct session *s2)
 {
 	return (strcmp(s1->name, s2->name));
 }

 /*
  * Find if session is still alive. This is true if it is still on the global
  * sessions list.
  */
 int
 session_alive(struct session *s)
 {
 	struct session *s_loop;

 	RB_FOREACH(s_loop, sessions, &sessions) {
 		if (s_loop == s)
 			return (1);
 	}
 	return (0);
 }

 /* Find session by name. */
 struct session *
 session_find(const char *name)
 {
 	struct session	s;

 	s.name = (char *) name;
 	return (RB_FIND(sessions, &sessions, &s));
 }

 /* Find session by id. */
 struct session *
 session_find_by_id(u_int id)
 {
 	struct session	*s;

 	RB_FOREACH(s, sessions, &sessions) {
 		if (s->id == id)
 			return (s);
 	}
 	return (NULL);
 }

 /* Create a new session. */
 struct session *
 session_create(const char *name, const char *cmd, const char *cwd,
     struct environ *env, struct termios *tio, int idx, u_int sx, u_int sy,
     char **cause)
 {
 	struct session	*s;

 	s = xmalloc(sizeof *s);
 	s->references = 0;
 	s->flags = 0;

 	if (gettimeofday(&s->creation_time, NULL) != 0)
 		fatal("gettimeofday failed");
 	session_update_activity(s);

 	s->cwd = xstrdup(cwd);

 	s->curw = NULL;
 	TAILQ_INIT(&s->lastw);
 	RB_INIT(&s->windows);

 	options_init(&s->options, &global_s_options);
 	environ_init(&s->environ);
 	if (env != NULL)
 		environ_copy(env, &s->environ);

 	s->tio = NULL;
 	if (tio != NULL) {
 		s->tio = xmalloc(sizeof *s->tio);
 		memcpy(s->tio, tio, sizeof *s->tio);
 	}

 	s->sx = sx;
 	s->sy = sy;

 	if (name != NULL) {
 		s->name = xstrdup(name);
 		s->id = next_session_id++;
 	} else {
 		s->name = NULL;
 		do {
 			s->id = next_session_id++;
 			free (s->name);
 			xasprintf(&s->name, "%u", s->id);
 		} while (RB_FIND(sessions, &sessions, s) != NULL);
 	}
 	RB_INSERT(sessions, &sessions, s);

 	if (cmd != NULL) {
 		if (session_new(s, NULL, cmd, cwd, idx, cause) == NULL) {
 			session_destroy(s);
 			return (NULL);
 		}
 		session_select(s, RB_ROOT(&s->windows)->idx);
 	}

 	log_debug("session %s created", s->name);
 	notify_session_created(s);

 	return (s);
 }

 /* Destroy a session. */
 void
 session_destroy(struct session *s)
 {
 	struct winlink	*wl;

 	log_debug("session %s destroyed", s->name);

 	RB_REMOVE(sessions, &sessions, s);
 	notify_session_closed(s);

 	free(s->tio);

 	session_group_remove(s);
 	environ_free(&s->environ);
 	options_free(&s->options);

 	while (!TAILQ_EMPTY(&s->lastw))
 		winlink_stack_remove(&s->lastw, TAILQ_FIRST(&s->lastw));
 	while (!RB_EMPTY(&s->windows)) {
 		wl = RB_ROOT(&s->windows);
 		notify_window_unlinked(s, wl->window);
 		winlink_remove(&s->windows, wl);
 	}

 	free(s->cwd);

 	RB_INSERT(sessions, &dead_sessions, s);
 }

 /* Check a session name is valid: not empty and no colons. */
 int
 session_check_name(const char *name)
 {
 	return (*name != '\0' && strchr(name, ':') == NULL);
 }

 /* Update session active time. */
 void
 session_update_activity(struct session *s)
 {
 	if (gettimeofday(&s->activity_time, NULL) != 0)
 		fatal("gettimeofday");
 }

 /* Find the next usable session. */
 struct session *
 session_next_session(struct session *s)
 {
 	struct session *s2;

 	if (RB_EMPTY(&sessions) || !session_alive(s))
 		return (NULL);

 	s2 = RB_NEXT(sessions, &sessions, s);
 	if (s2 == NULL)
 		s2 = RB_MIN(sessions, &sessions);
 	if (s2 == s)
 		return (NULL);
 	return (s2);
 }

 /* Find the previous usable session. */
 struct session *
 session_previous_session(struct session *s)
 {
 	struct session *s2;

 	if (RB_EMPTY(&sessions) || !session_alive(s))
 		return (NULL);

 	s2 = RB_PREV(sessions, &sessions, s);
 	if (s2 == NULL)
 		s2 = RB_MAX(sessions, &sessions);
 	if (s2 == s)
 		return (NULL);
 	return (s2);
 }

 /* Create a new window on a session. */
 struct winlink *
 session_new(struct session *s,
     const char *name, const char *cmd, const char *cwd, int idx, char **cause)
 {
 	struct window	*w;
 	struct winlink	*wl;
 	struct environ	 env;
 	const char	*shell;
 	u_int		 hlimit;

 	if ((wl = winlink_add(&s->windows, idx)) == NULL) {
 		xasprintf(cause, "index in use: %d", idx);
 		return (NULL);
 	}

 	environ_init(&env);
 	environ_copy(&global_environ, &env);
 	environ_copy(&s->environ, &env);
 	server_fill_environ(s, &env);

 	shell = options_get_string(&s->options, "default-shell");
 	if (*shell == '\0' || areshell(shell))
 		shell = _PATH_BSHELL;

 	hlimit = options_get_number(&s->options, "history-limit");
 	w = window_create(
 	    name, cmd, shell, cwd, &env, s->tio, s->sx, s->sy, hlimit, cause);
 	if (w == NULL) {
 		winlink_remove(&s->windows, wl);
 		environ_free(&env);
 		return (NULL);
 	}
 	winlink_set_window(wl, w);
 	notify_window_linked(s, w);
 	environ_free(&env);

 	if (options_get_number(&s->options, "set-remain-on-exit"))
 		options_set_number(&w->options, "remain-on-exit", 1);

 	session_group_synchronize_from(s);
 	return (wl);
 }

 /* Attach a window to a session. */
 struct winlink *
 session_attach(struct session *s, struct window *w, int idx, char **cause)
 {
 	struct winlink	*wl;

 	if ((wl = winlink_add(&s->windows, idx)) == NULL) {
 		xasprintf(cause, "index in use: %d", idx);
 		return (NULL);
 	}
 	winlink_set_window(wl, w);
 	notify_window_linked(s, w);

 	session_group_synchronize_from(s);
 	return (wl);
 }

 /* Detach a window from a session. */
 int
 session_detach(struct session *s, struct winlink *wl)
 {
 	if (s->curw == wl &&
 	    session_last(s) != 0 && session_previous(s, 0) != 0)
 		session_next(s, 0);

 	wl->flags &= ~WINLINK_ALERTFLAGS;
 	notify_window_unlinked(s, wl->window);
 	winlink_stack_remove(&s->lastw, wl);
 	winlink_remove(&s->windows, wl);
 	session_group_synchronize_from(s);
 	if (RB_EMPTY(&s->windows)) {
 		session_destroy(s);
 		return (1);
 	}
 	return (0);
 }

 /* Return if session has window. */
 struct winlink *
 session_has(struct session *s, struct window *w)
 {
 	struct winlink	*wl;

 	RB_FOREACH(wl, winlinks, &s->windows) {
 		if (wl->window == w)
 			return (wl);
 	}
 	return (NULL);
 }

 struct winlink *
 session_next_alert(struct winlink *wl)
 {
 	while (wl != NULL) {
 		if (wl->flags & WINLINK_ALERTFLAGS)
 			break;
 		wl = winlink_next(wl);
 	}
 	return (wl);
 }

 /* Move session to next window. */
 int
 session_next(struct session *s, int alert)
 {
 	struct winlink	*wl;

 	if (s->curw == NULL)
 		return (-1);

 	wl = winlink_next(s->curw);
 	if (alert)
 		wl = session_next_alert(wl);
 	if (wl == NULL) {
 		wl = RB_MIN(winlinks, &s->windows);
 		if (alert && ((wl = session_next_alert(wl)) == NULL))
 			return (-1);
 	}
 	return (session_set_current(s, wl));
 }

 struct winlink *
 session_previous_alert(struct winlink *wl)
 {
 	while (wl != NULL) {
 		if (wl->flags & WINLINK_ALERTFLAGS)
 			break;
 		wl = winlink_previous(wl);
 	}
 	return (wl);
 }

 /* Move session to previous window. */
 int
 session_previous(struct session *s, int alert)
 {
 	struct winlink	*wl;

 	if (s->curw == NULL)
 		return (-1);

 	wl = winlink_previous(s->curw);
 	if (alert)
 		wl = session_previous_alert(wl);
 	if (wl == NULL) {
 		wl = RB_MAX(winlinks, &s->windows);
 		if (alert && (wl = session_previous_alert(wl)) == NULL)
 			return (-1);
 	}
 	return (session_set_current(s, wl));
 }

 /* Move session to specific window. */
 int
 session_select(struct session *s, int idx)
 {
 	struct winlink	*wl;

 	wl = winlink_find_by_index(&s->windows, idx);
 	return (session_set_current(s, wl));
 }

 /* Move session to last used window. */
 int
 session_last(struct session *s)
 {
 	struct winlink	*wl;

 	wl = TAILQ_FIRST(&s->lastw);
 	if (wl == NULL)
 		return (-1);
 	if (wl == s->curw)
 		return (1);

 	return (session_set_current(s, wl));
 }

 /* Set current winlink to wl .*/
 int
 session_set_current(struct session *s, struct winlink *wl)
 {
 	if (wl == NULL)
 		return (-1);
 	if (wl == s->curw)
 		return (1);

 	winlink_stack_remove(&s->lastw, wl);
 	winlink_stack_push(&s->lastw, s->curw);
 	s->curw = wl;
 	winlink_clear_flags(wl);
 	return (0);
 }

 /* Find the session group containing a session. */
 struct session_group *
 session_group_find(struct session *target)
 {
 	struct session_group	*sg;
 	struct session		*s;

 	TAILQ_FOREACH(sg, &session_groups, entry) {
 		TAILQ_FOREACH(s, &sg->sessions, gentry) {
 			if (s == target)
 				return (sg);
 		}
 	}
 	return (NULL);
 }

 /* Find session group index. */
 u_int
 session_group_index(struct session_group *sg)
 {
 	struct session_group   *sg2;
 	u_int			i;

 	i = 0;
 	TAILQ_FOREACH(sg2, &session_groups, entry) {
 		if (sg == sg2)
 			return (i);
 		i++;
 	}

 	fatalx("session group not found");
 }

 /*
  * Add a session to the session group containing target, creating it if
  * necessary.
  */
 void
 session_group_add(struct session *target, struct session *s)
 {
 	struct session_group	*sg;

 	if ((sg = session_group_find(target)) == NULL) {
 		sg = xmalloc(sizeof *sg);
 		TAILQ_INSERT_TAIL(&session_groups, sg, entry);
 		TAILQ_INIT(&sg->sessions);
 		TAILQ_INSERT_TAIL(&sg->sessions, target, gentry);
 	}
 	TAILQ_INSERT_TAIL(&sg->sessions, s, gentry);
 }

 /* Remove a session from its group and destroy the group if empty. */
 void
 session_group_remove(struct session *s)
 {
 	struct session_group	*sg;

 	if ((sg = session_group_find(s)) == NULL)
 		return;
 	TAILQ_REMOVE(&sg->sessions, s, gentry);
 	if (TAILQ_NEXT(TAILQ_FIRST(&sg->sessions), gentry) == NULL)
 		TAILQ_REMOVE(&sg->sessions, TAILQ_FIRST(&sg->sessions), gentry);
 	if (TAILQ_EMPTY(&sg->sessions)) {
 		TAILQ_REMOVE(&session_groups, sg, entry);
 		free(sg);
 	}
 }

 /* Synchronize a session to its session group. */
 void
 session_group_synchronize_to(struct session *s)
 {
 	struct session_group	*sg;
 	struct session		*target;

 	if ((sg = session_group_find(s)) == NULL)
 		return;

 	target = NULL;
 	TAILQ_FOREACH(target, &sg->sessions, gentry) {
 		if (target != s)
 			break;
 	}
 	session_group_synchronize1(target, s);
 }

 /* Synchronize a session group to a session. */
 void
 session_group_synchronize_from(struct session *target)
 {
 	struct session_group	*sg;
 	struct session		*s;

 	if ((sg = session_group_find(target)) == NULL)
 		return;

 	TAILQ_FOREACH(s, &sg->sessions, gentry) {
 		if (s != target)
 			session_group_synchronize1(target, s);
 	}
 }

 /*
  * Synchronize a session with a target session. This means destroying all
  * winlinks then recreating them, then updating the current window, last window
  * stack and alerts.
  */
 void
 session_group_synchronize1(struct session *target, struct session *s)
 {
 	struct winlinks		 old_windows, *ww;
 	struct winlink_stack	 old_lastw;
 	struct winlink		*wl, *wl2;

 	/* Don't do anything if the session is empty (it'll be destroyed). */
 	ww = &target->windows;
 	if (RB_EMPTY(ww))
 		return;

 	/* If the current window has vanished, move to the next now. */
 	if (s->curw != NULL &&
 	    winlink_find_by_index(ww, s->curw->idx) == NULL &&
 	    session_last(s) != 0 && session_previous(s, 0) != 0)
 		session_next(s, 0);

 	/* Save the old pointer and reset it. */
 	memcpy(&old_windows, &s->windows, sizeof old_windows);
 	RB_INIT(&s->windows);

 	/* Link all the windows from the target. */
 	RB_FOREACH(wl, winlinks, ww) {
 		wl2 = winlink_add(&s->windows, wl->idx);
 		winlink_set_window(wl2, wl->window);
 		notify_window_linked(s, wl2->window);
 		wl2->flags |= wl->flags & WINLINK_ALERTFLAGS;
 	}

 	/* Fix up the current window. */
 	if (s->curw != NULL)
 		s->curw = winlink_find_by_index(&s->windows, s->curw->idx);
 	else
 		s->curw = winlink_find_by_index(&s->windows, target->curw->idx);

 	/* Fix up the last window stack. */
 	memcpy(&old_lastw, &s->lastw, sizeof old_lastw);
 	TAILQ_INIT(&s->lastw);
 	TAILQ_FOREACH(wl, &old_lastw, sentry) {
 		wl2 = winlink_find_by_index(&s->windows, wl->idx);
 		if (wl2 != NULL)
 			TAILQ_INSERT_TAIL(&s->lastw, wl2, sentry);
 	}

 	/* Then free the old winlinks list. */
 	while (!RB_EMPTY(&old_windows)) {
 		wl = RB_ROOT(&old_windows);
 		if (winlink_find_by_window_id(&s->windows, wl->window->id) == NULL)
 		    notify_window_unlinked(s, wl->window);
 		winlink_remove(&old_windows, wl);
 	}
 }

 /* Renumber the windows across winlinks attached to a specific session. */
 void
 session_renumber_windows(struct session *s)
 {
 	struct winlink		*wl, *wl1, *wl_new;
 	struct winlinks		 old_wins;
 	struct winlink_stack	 old_lastw;
 	int			 new_idx, new_curw_idx;

 	/* Save and replace old window list. */
 	memcpy(&old_wins, &s->windows, sizeof old_wins);
 	RB_INIT(&s->windows);

 	/* Start renumbering from the base-index if it's set. */
 	new_idx = options_get_number(&s->options, "base-index");
 	new_curw_idx = 0;

 	/* Go through the winlinks and assign new indexes. */
 	RB_FOREACH(wl, winlinks, &old_wins) {
 		wl_new = winlink_add(&s->windows, new_idx);
 		winlink_set_window(wl_new, wl->window);
 		wl_new->flags |= wl->flags & WINLINK_ALERTFLAGS;

 		if (wl == s->curw)
 			new_curw_idx = wl_new->idx;

 		new_idx++;
 	}

 	/* Fix the stack of last windows now. */
 	memcpy(&old_lastw, &s->lastw, sizeof old_lastw);
 	TAILQ_INIT(&s->lastw);
 	TAILQ_FOREACH(wl, &old_lastw, sentry) {
 		wl_new = winlink_find_by_window(&s->windows, wl->window);
 		if (wl_new != NULL)
 			TAILQ_INSERT_TAIL(&s->lastw, wl_new, sentry);
 	}

 	/* Set the current window. */
 	s->curw = winlink_find_by_index(&s->windows, new_curw_idx);

 	/* Free the old winlinks (reducing window references too). */
 	RB_FOREACH_SAFE(wl, winlinks, &old_wins, wl1)
 		winlink_remove(&old_wins, wl);
 }
	/* $OpenBSD$ */

	/*
	* 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/time.h>

	#include <paths.h>
	#include <string.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <time.h>

	#include "tmux.h"

	/* Global session list. */
	struct sessions sessions;
	struct sessions dead_sessions;
	u_int next_session_id;
	struct session_groups session_groups;

	struct winlink session_next_alert(struct winlink );
	struct winlink session_previous_alert(struct winlink );

	RB_GENERATE(sessions, session, entry, session_cmp);

	int
	session_cmp(struct session s1, struct session s2)
	{
	return (strcmp(s1->name, s2->name));
	}

	/*
	* Find if session is still alive. This is true if it is still on the global
	* sessions list.
	*/
	int
	session_alive(struct session *s)
	{
	struct session *s_loop;

	RB_FOREACH(s_loop, sessions, &sessions) {
	if (s_loop == s)
	return (1);
	}
	return (0);
	}

	/* Find session by name. */
	struct session *
	session_find(const char *name)
	{
	struct session s;

	s.name = (char *) name;
	return (RB_FIND(sessions, &sessions, &s));
	}

	/* Find session by id. */
	struct session *
	session_find_by_id(u_int id)
	{
	struct session *s;

	RB_FOREACH(s, sessions, &sessions) {
	if (s->id == id)
	return (s);
	}
	return (NULL);
	}

	/* Create a new session. */
	struct session *
	session_create(const char name, const char cmd, const char *cwd,
	struct environ env, struct termios tio, int idx, u_int sx, u_int sy,
	char **cause)
	{
	struct session *s;

	s = xmalloc(sizeof *s);
	s->references = 0;
	s->flags = 0;

	if (gettimeofday(&s->creation_time, NULL) != 0)
	fatal("gettimeofday failed");
	session_update_activity(s);

	s->cwd = xstrdup(cwd);

	s->curw = NULL;
	TAILQ_INIT(&s->lastw);
	RB_INIT(&s->windows);

	options_init(&s->options, &global_s_options);
	environ_init(&s->environ);
	if (env != NULL)
	environ_copy(env, &s->environ);

	s->tio = NULL;
	if (tio != NULL) {
	s->tio = xmalloc(sizeof *s->tio);
	memcpy(s->tio, tio, sizeof *s->tio);
	}

	s->sx = sx;
	s->sy = sy;

	if (name != NULL) {
	s->name = xstrdup(name);
	s->id = next_session_id++;
	} else {
	s->name = NULL;
	do {
	s->id = next_session_id++;
	free (s->name);
	xasprintf(&s->name, "%u", s->id);
	} while (RB_FIND(sessions, &sessions, s) != NULL);
	}
	RB_INSERT(sessions, &sessions, s);

	if (cmd != NULL) {
	if (session_new(s, NULL, cmd, cwd, idx, cause) == NULL) {
	session_destroy(s);
	return (NULL);
	}
	session_select(s, RB_ROOT(&s->windows)->idx);
	}

	log_debug("session %s created", s->name);
	notify_session_created(s);

	return (s);
	}

	/* Destroy a session. */
	void
	session_destroy(struct session *s)
	{
	struct winlink *wl;

	log_debug("session %s destroyed", s->name);

	RB_REMOVE(sessions, &sessions, s);
	notify_session_closed(s);

	free(s->tio);

	session_group_remove(s);
	environ_free(&s->environ);
	options_free(&s->options);

	while (!TAILQ_EMPTY(&s->lastw))
	winlink_stack_remove(&s->lastw, TAILQ_FIRST(&s->lastw));
	while (!RB_EMPTY(&s->windows)) {
	wl = RB_ROOT(&s->windows);
	notify_window_unlinked(s, wl->window);
	winlink_remove(&s->windows, wl);
	}

	free(s->cwd);

	RB_INSERT(sessions, &dead_sessions, s);
	}

	/* Check a session name is valid: not empty and no colons. */
	int
	session_check_name(const char *name)
	{
	return (*name != '\0' && strchr(name, ':') == NULL);
	}

	/* Update session active time. */
	void
	session_update_activity(struct session *s)
	{
	if (gettimeofday(&s->activity_time, NULL) != 0)
	fatal("gettimeofday");
	}

	/* Find the next usable session. */
	struct session *
	session_next_session(struct session *s)
	{
	struct session *s2;

	if (RB_EMPTY(&sessions) \|\| !session_alive(s))
	return (NULL);

	s2 = RB_NEXT(sessions, &sessions, s);
	if (s2 == NULL)
	s2 = RB_MIN(sessions, &sessions);
	if (s2 == s)
	return (NULL);
	return (s2);
	}

	/* Find the previous usable session. */
	struct session *
	session_previous_session(struct session *s)
	{
	struct session *s2;

	if (RB_EMPTY(&sessions) \|\| !session_alive(s))
	return (NULL);

	s2 = RB_PREV(sessions, &sessions, s);
	if (s2 == NULL)
	s2 = RB_MAX(sessions, &sessions);
	if (s2 == s)
	return (NULL);
	return (s2);
	}

	/* Create a new window on a session. */
	struct winlink *
	session_new(struct session *s,
	const char name, const char cmd, const char cwd, int idx, char *cause)
	{
	struct window *w;
	struct winlink *wl;
	struct environ env;
	const char *shell;
	u_int hlimit;

	if ((wl = winlink_add(&s->windows, idx)) == NULL) {
	xasprintf(cause, "index in use: %d", idx);
	return (NULL);
	}

	environ_init(&env);
	environ_copy(&global_environ, &env);
	environ_copy(&s->environ, &env);
	server_fill_environ(s, &env);

	shell = options_get_string(&s->options, "default-shell");
	if (*shell == '\0' \|\| areshell(shell))
	shell = _PATH_BSHELL;

	hlimit = options_get_number(&s->options, "history-limit");
	w = window_create(
	name, cmd, shell, cwd, &env, s->tio, s->sx, s->sy, hlimit, cause);
	if (w == NULL) {
	winlink_remove(&s->windows, wl);
	environ_free(&env);
	return (NULL);
	}
	winlink_set_window(wl, w);
	notify_window_linked(s, w);
	environ_free(&env);

	if (options_get_number(&s->options, "set-remain-on-exit"))
	options_set_number(&w->options, "remain-on-exit", 1);

	session_group_synchronize_from(s);
	return (wl);
	}

	/* Attach a window to a session. */
	struct winlink *
	session_attach(struct session s, struct window w, int idx, char **cause)
	{
	struct winlink *wl;

	if ((wl = winlink_add(&s->windows, idx)) == NULL) {
	xasprintf(cause, "index in use: %d", idx);
	return (NULL);
	}
	winlink_set_window(wl, w);
	notify_window_linked(s, w);

	session_group_synchronize_from(s);
	return (wl);
	}

	/* Detach a window from a session. */
	int
	session_detach(struct session s, struct winlink wl)
	{
	if (s->curw == wl &&
	session_last(s) != 0 && session_previous(s, 0) != 0)
	session_next(s, 0);

	wl->flags &= ~WINLINK_ALERTFLAGS;
	notify_window_unlinked(s, wl->window);
	winlink_stack_remove(&s->lastw, wl);
	winlink_remove(&s->windows, wl);
	session_group_synchronize_from(s);
	if (RB_EMPTY(&s->windows)) {
	session_destroy(s);
	return (1);
	}
	return (0);
	}

	/* Return if session has window. */
	struct winlink *
	session_has(struct session s, struct window w)
	{
	struct winlink *wl;

	RB_FOREACH(wl, winlinks, &s->windows) {
	if (wl->window == w)
	return (wl);
	}
	return (NULL);
	}

	struct winlink *
	session_next_alert(struct winlink *wl)
	{
	while (wl != NULL) {
	if (wl->flags & WINLINK_ALERTFLAGS)
	break;
	wl = winlink_next(wl);
	}
	return (wl);
	}

	/* Move session to next window. */
	int
	session_next(struct session *s, int alert)
	{
	struct winlink *wl;

	if (s->curw == NULL)
	return (-1);

	wl = winlink_next(s->curw);
	if (alert)
	wl = session_next_alert(wl);
	if (wl == NULL) {
	wl = RB_MIN(winlinks, &s->windows);
	if (alert && ((wl = session_next_alert(wl)) == NULL))
	return (-1);
	}
	return (session_set_current(s, wl));
	}

	struct winlink *
	session_previous_alert(struct winlink *wl)
	{
	while (wl != NULL) {
	if (wl->flags & WINLINK_ALERTFLAGS)
	break;
	wl = winlink_previous(wl);
	}
	return (wl);
	}

	/* Move session to previous window. */
	int
	session_previous(struct session *s, int alert)
	{
	struct winlink *wl;

	if (s->curw == NULL)
	return (-1);

	wl = winlink_previous(s->curw);
	if (alert)
	wl = session_previous_alert(wl);
	if (wl == NULL) {
	wl = RB_MAX(winlinks, &s->windows);
	if (alert && (wl = session_previous_alert(wl)) == NULL)
	return (-1);
	}
	return (session_set_current(s, wl));
	}

	/* Move session to specific window. */
	int
	session_select(struct session *s, int idx)
	{
	struct winlink *wl;

	wl = winlink_find_by_index(&s->windows, idx);
	return (session_set_current(s, wl));
	}

	/* Move session to last used window. */
	int
	session_last(struct session *s)
	{
	struct winlink *wl;

	wl = TAILQ_FIRST(&s->lastw);
	if (wl == NULL)
	return (-1);
	if (wl == s->curw)
	return (1);

	return (session_set_current(s, wl));
	}

	/* Set current winlink to wl .*/
	int
	session_set_current(struct session s, struct winlink wl)
	{
	if (wl == NULL)
	return (-1);
	if (wl == s->curw)
	return (1);

	winlink_stack_remove(&s->lastw, wl);
	winlink_stack_push(&s->lastw, s->curw);
	s->curw = wl;
	winlink_clear_flags(wl);
	return (0);
	}

	/* Find the session group containing a session. */
	struct session_group *
	session_group_find(struct session *target)
	{
	struct session_group *sg;
	struct session *s;

	TAILQ_FOREACH(sg, &session_groups, entry) {
	TAILQ_FOREACH(s, &sg->sessions, gentry) {
	if (s == target)
	return (sg);
	}
	}
	return (NULL);
	}

	/* Find session group index. */
	u_int
	session_group_index(struct session_group *sg)
	{
	struct session_group *sg2;
	u_int i;

	i = 0;
	TAILQ_FOREACH(sg2, &session_groups, entry) {
	if (sg == sg2)
	return (i);
	i++;
	}

	fatalx("session group not found");
	}

	/*
	* Add a session to the session group containing target, creating it if
	* necessary.
	*/
	void
	session_group_add(struct session target, struct session s)
	{
	struct session_group *sg;

	if ((sg = session_group_find(target)) == NULL) {
	sg = xmalloc(sizeof *sg);
	TAILQ_INSERT_TAIL(&session_groups, sg, entry);
	TAILQ_INIT(&sg->sessions);
	TAILQ_INSERT_TAIL(&sg->sessions, target, gentry);
	}
	TAILQ_INSERT_TAIL(&sg->sessions, s, gentry);
	}

	/* Remove a session from its group and destroy the group if empty. */
	void
	session_group_remove(struct session *s)
	{
	struct session_group *sg;

	if ((sg = session_group_find(s)) == NULL)
	return;
	TAILQ_REMOVE(&sg->sessions, s, gentry);
	if (TAILQ_NEXT(TAILQ_FIRST(&sg->sessions), gentry) == NULL)
	TAILQ_REMOVE(&sg->sessions, TAILQ_FIRST(&sg->sessions), gentry);
	if (TAILQ_EMPTY(&sg->sessions)) {
	TAILQ_REMOVE(&session_groups, sg, entry);
	free(sg);
	}
	}

	/* Synchronize a session to its session group. */
	void
	session_group_synchronize_to(struct session *s)
	{
	struct session_group *sg;
	struct session *target;

	if ((sg = session_group_find(s)) == NULL)
	return;

	target = NULL;
	TAILQ_FOREACH(target, &sg->sessions, gentry) {
	if (target != s)
	break;
	}
	session_group_synchronize1(target, s);
	}

	/* Synchronize a session group to a session. */
	void
	session_group_synchronize_from(struct session *target)
	{
	struct session_group *sg;
	struct session *s;

	if ((sg = session_group_find(target)) == NULL)
	return;

	TAILQ_FOREACH(s, &sg->sessions, gentry) {
	if (s != target)
	session_group_synchronize1(target, s);
	}
	}

	/*
	* Synchronize a session with a target session. This means destroying all
	* winlinks then recreating them, then updating the current window, last window
	* stack and alerts.
	*/
	void
	session_group_synchronize1(struct session target, struct session s)
	{
	struct winlinks old_windows, *ww;
	struct winlink_stack old_lastw;
	struct winlink wl, wl2;

	/* Don't do anything if the session is empty (it'll be destroyed). */
	ww = &target->windows;
	if (RB_EMPTY(ww))
	return;

	/* If the current window has vanished, move to the next now. */
	if (s->curw != NULL &&
	winlink_find_by_index(ww, s->curw->idx) == NULL &&
	session_last(s) != 0 && session_previous(s, 0) != 0)
	session_next(s, 0);

	/* Save the old pointer and reset it. */
	memcpy(&old_windows, &s->windows, sizeof old_windows);
	RB_INIT(&s->windows);

	/* Link all the windows from the target. */
	RB_FOREACH(wl, winlinks, ww) {
	wl2 = winlink_add(&s->windows, wl->idx);
	winlink_set_window(wl2, wl->window);
	notify_window_linked(s, wl2->window);
	wl2->flags \|= wl->flags & WINLINK_ALERTFLAGS;
	}

	/* Fix up the current window. */
	if (s->curw != NULL)
	s->curw = winlink_find_by_index(&s->windows, s->curw->idx);
	else
	s->curw = winlink_find_by_index(&s->windows, target->curw->idx);

	/* Fix up the last window stack. */
	memcpy(&old_lastw, &s->lastw, sizeof old_lastw);
	TAILQ_INIT(&s->lastw);
	TAILQ_FOREACH(wl, &old_lastw, sentry) {
	wl2 = winlink_find_by_index(&s->windows, wl->idx);
	if (wl2 != NULL)
	TAILQ_INSERT_TAIL(&s->lastw, wl2, sentry);
	}

	/* Then free the old winlinks list. */
	while (!RB_EMPTY(&old_windows)) {
	wl = RB_ROOT(&old_windows);
	if (winlink_find_by_window_id(&s->windows, wl->window->id) == NULL)
	notify_window_unlinked(s, wl->window);
	winlink_remove(&old_windows, wl);
	}
	}

	/* Renumber the windows across winlinks attached to a specific session. */
	void
	session_renumber_windows(struct session *s)
	{
	struct winlink wl, wl1, *wl_new;
	struct winlinks old_wins;
	struct winlink_stack old_lastw;
	int new_idx, new_curw_idx;

	/* Save and replace old window list. */
	memcpy(&old_wins, &s->windows, sizeof old_wins);
	RB_INIT(&s->windows);

	/* Start renumbering from the base-index if it's set. */
	new_idx = options_get_number(&s->options, "base-index");
	new_curw_idx = 0;

	/* Go through the winlinks and assign new indexes. */
	RB_FOREACH(wl, winlinks, &old_wins) {
	wl_new = winlink_add(&s->windows, new_idx);
	winlink_set_window(wl_new, wl->window);
	wl_new->flags \|= wl->flags & WINLINK_ALERTFLAGS;

	if (wl == s->curw)
	new_curw_idx = wl_new->idx;

	new_idx++;
	}

	/* Fix the stack of last windows now. */
	memcpy(&old_lastw, &s->lastw, sizeof old_lastw);
	TAILQ_INIT(&s->lastw);
	TAILQ_FOREACH(wl, &old_lastw, sentry) {
	wl_new = winlink_find_by_window(&s->windows, wl->window);
	if (wl_new != NULL)
	TAILQ_INSERT_TAIL(&s->lastw, wl_new, sentry);
	}

	/* Set the current window. */
	s->curw = winlink_find_by_index(&s->windows, new_curw_idx);

	/* Free the old winlinks (reducing window references too). */
	RB_FOREACH_SAFE(wl, winlinks, &old_wins, wl1)
	winlink_remove(&old_wins, wl);
	}