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Give each client a name. This defaults to the tty name as before but
falls back to an alternative if the tty name is not available. This is
clearer than overloading the client ttyname member and allows us to
remove the path stored in the tty struct, it should always be the same
as the client.

/* $OpenBSD: cmd-find.c,v 1.43 2017/04/05 10:49:46 nicm Exp $ */

/*
 * Copyright (c) 2015 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <fnmatch.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <paths.h>
#include <unistd.h>

#include "tmux.h"

static struct session *cmd_find_try_TMUX(struct client *, struct window *);
static int	cmd_find_client_better(struct client *, struct client *);
static struct client *cmd_find_best_client(struct client **, u_int);
static int	cmd_find_session_better(struct session *, struct session *,
		    int);
static struct session *cmd_find_best_session(struct session **, u_int, int);
static int	cmd_find_best_session_with_window(struct cmd_find_state *);
static int	cmd_find_best_winlink_with_window(struct cmd_find_state *);

static int	cmd_find_current_session_with_client(struct cmd_find_state *);
static int	cmd_find_current_session(struct cmd_find_state *);
static struct client *cmd_find_current_client(struct cmdq_item *);

static const char *cmd_find_map_table(const char *[][2], const char *);

static int	cmd_find_get_session(struct cmd_find_state *, const char *);
static int	cmd_find_get_window(struct cmd_find_state *, const char *);
static int	cmd_find_get_window_with_session(struct cmd_find_state *,
		    const char *);
static int	cmd_find_get_pane(struct cmd_find_state *, const char *);
static int	cmd_find_get_pane_with_session(struct cmd_find_state *,
		    const char *);
static int	cmd_find_get_pane_with_window(struct cmd_find_state *,
		    const char *);

static const char *cmd_find_session_table[][2] = {
	{ NULL, NULL }
};
static const char *cmd_find_window_table[][2] = {
	{ "{start}", "^" },
	{ "{last}", "!" },
	{ "{end}", "$" },
	{ "{next}", "+" },
	{ "{previous}", "-" },
	{ NULL, NULL }
};
static const char *cmd_find_pane_table[][2] = {
	{ "{last}", "!" },
	{ "{next}", "+" },
	{ "{previous}", "-" },
	{ "{top}", "top" },
	{ "{bottom}", "bottom" },
	{ "{left}", "left" },
	{ "{right}", "right" },
	{ "{top-left}", "top-left" },
	{ "{top-right}", "top-right" },
	{ "{bottom-left}", "bottom-left" },
	{ "{bottom-right}", "bottom-right" },
	{ "{up-of}", "{up-of}" },
	{ "{down-of}", "{down-of}" },
	{ "{left-of}", "{left-of}" },
	{ "{right-of}", "{right-of}" },
	{ NULL, NULL }
};

/* Get session from TMUX if present. */
static struct session *
cmd_find_try_TMUX(struct client *c, struct window *w)
{
	struct environ_entry	*envent;
	char			 tmp[256];
	long long		 pid;
	u_int			 session;
	struct session		*s;

	envent = environ_find(c->environ, "TMUX");
	if (envent == NULL)
		return (NULL);

	if (sscanf(envent->value, "%255[^,],%lld,%d", tmp, &pid, &session) != 3)
		return (NULL);
	if (pid != getpid())
		return (NULL);
	log_debug("client %p TMUX is %s (session @%u)", c, envent->value,
	    session);

	s = session_find_by_id(session);
	if (s == NULL || (w != NULL && !session_has(s, w)))
		return (NULL);
	return (s);
}

/* Is this client better? */
static int
cmd_find_client_better(struct client *c, struct client *than)
{
	if (than == NULL)
		return (1);
	return (timercmp(&c->activity_time, &than->activity_time, >));
}

/* Find best client from a list, or all if list is NULL. */
static struct client *
cmd_find_best_client(struct client **clist, u_int csize)
{
	struct client	*c_loop, *c;
	u_int		 i;

	c = NULL;
	if (clist != NULL) {
		for (i = 0; i < csize; i++) {
			if (clist[i]->session == NULL)
				continue;
			if (cmd_find_client_better(clist[i], c))
				c = clist[i];
		}
	} else {
		TAILQ_FOREACH(c_loop, &clients, entry) {
			if (c_loop->session == NULL)
				continue;
			if (cmd_find_client_better(c_loop, c))
				c = c_loop;
		}
	}
	return (c);
}

/* Is this session better? */
static int
cmd_find_session_better(struct session *s, struct session *than, int flags)
{
	int	attached;

	if (than == NULL)
		return (1);
	if (flags & CMD_FIND_PREFER_UNATTACHED) {
		attached = (~than->flags & SESSION_UNATTACHED);
		if (attached && (s->flags & SESSION_UNATTACHED))
			return (1);
		else if (!attached && (~s->flags & SESSION_UNATTACHED))
			return (0);
	}
	return (timercmp(&s->activity_time, &than->activity_time, >));
}

/* Find best session from a list, or all if list is NULL. */
static struct session *
cmd_find_best_session(struct session **slist, u_int ssize, int flags)
{
	struct session	 *s_loop, *s;
	u_int		  i;

	s = NULL;
	if (slist != NULL) {
		for (i = 0; i < ssize; i++) {
			if (cmd_find_session_better(slist[i], s, flags))
				s = slist[i];
		}
	} else {
		RB_FOREACH(s_loop, sessions, &sessions) {
			if (cmd_find_session_better(s_loop, s, flags))
				s = s_loop;
		}
	}
	return (s);
}

/* Find best session and winlink for window. */
static int
cmd_find_best_session_with_window(struct cmd_find_state *fs)
{
	struct session	**slist = NULL;
	u_int		  ssize;
	struct session	 *s;

	if (fs->item != NULL && fs->item->client != NULL) {
		fs->s = cmd_find_try_TMUX(fs->item->client, fs->w);
		if (fs->s != NULL)
			return (cmd_find_best_winlink_with_window(fs));
	}

	ssize = 0;
	RB_FOREACH(s, sessions, &sessions) {
		if (!session_has(s, fs->w))
			continue;
		slist = xreallocarray(slist, ssize + 1, sizeof *slist);
		slist[ssize++] = s;
	}
	if (ssize == 0)
		goto fail;
	fs->s = cmd_find_best_session(slist, ssize, fs->flags);
	if (fs->s == NULL)
		goto fail;
	free(slist);
	return (cmd_find_best_winlink_with_window(fs));

fail:
	free(slist);
	return (-1);
}

/*
 * Find the best winlink for a window (the current if it contains the pane,
 * otherwise the first).
 */
static int
cmd_find_best_winlink_with_window(struct cmd_find_state *fs)
{
	struct winlink	 *wl, *wl_loop;

	wl = NULL;
	if (fs->s->curw != NULL && fs->s->curw->window == fs->w)
		wl = fs->s->curw;
	else {
		RB_FOREACH(wl_loop, winlinks, &fs->s->windows) {
			if (wl_loop->window == fs->w) {
				wl = wl_loop;
				break;
			}
		}
	}
	if (wl == NULL)
		return (-1);
	fs->wl = wl;
	fs->idx = fs->wl->idx;
	return (0);
}

/* Find current session when we have an unattached client. */
static int
cmd_find_current_session_with_client(struct cmd_find_state *fs)
{
	struct window_pane	*wp;

	/*
	 * If this is running in a pane, we can use that to limit the list of
	 * sessions to those containing that pane (we still use the current
	 * window in the best session).
	 */
	if (fs->item != NULL) {
		RB_FOREACH(wp, window_pane_tree, &all_window_panes) {
			if (strcmp(wp->tty, fs->item->client->ttyname) == 0)
				break;
		}
	} else
		wp = NULL;

	/* Not running in a pane. We know nothing. Find the best session. */
	if (wp == NULL)
		goto unknown_pane;

	/* Find the best session and winlink containing this pane. */
	fs->w = wp->window;
	if (cmd_find_best_session_with_window(fs) != 0) {
		if (wp != NULL) {
			/*
			 * The window may have been destroyed but the pane
			 * still on all_window_panes due to something else
			 * holding a reference.
			 */
			goto unknown_pane;
		}
		return (-1);
	}

	/* Use the current window and pane from this session. */
	fs->wl = fs->s->curw;
	fs->idx = fs->wl->idx;
	fs->w = fs->wl->window;
	fs->wp = fs->w->active;

	return (0);

unknown_pane:
	fs->s = NULL;
	if (fs->item != NULL)
		fs->s = cmd_find_try_TMUX(fs->item->client, NULL);
	if (fs->s == NULL)
		fs->s = cmd_find_best_session(NULL, 0, fs->flags);
	if (fs->s == NULL)
		return (-1);
	fs->wl = fs->s->curw;
	fs->idx = fs->wl->idx;
	fs->w = fs->wl->window;
	fs->wp = fs->w->active;

	return (0);
}

/*
 * Work out the best current state. If this function succeeds, the state is
 * guaranteed to be completely filled in.
 */
static int
cmd_find_current_session(struct cmd_find_state *fs)
{
	/* If we know the current client, use it. */
	if (fs->item != NULL && fs->item->client != NULL) {
		log_debug("%s: have client %p%s", __func__, fs->item->client,
		    fs->item->client->session == NULL ? "" : " (with session)");
		if (fs->item->client->session == NULL)
			return (cmd_find_current_session_with_client(fs));
		fs->s = fs->item->client->session;
		fs->wl = fs->s->curw;
		fs->idx = fs->wl->idx;
		fs->w = fs->wl->window;
		fs->wp = fs->w->active;
		return (0);
	}

	/* We know nothing, find the best session and client. */
	fs->s = cmd_find_best_session(NULL, 0, fs->flags);
	if (fs->s == NULL)
		return (-1);
	fs->wl = fs->s->curw;
	fs->idx = fs->wl->idx;
	fs->w = fs->wl->window;
	fs->wp = fs->w->active;

	return (0);
}

/* Work out the best current client. */
static struct client *
cmd_find_current_client(struct cmdq_item *item)
{
	struct cmd_find_state	 current;
	struct session		*s;
	struct client		*c, **clist = NULL;
	u_int		 	 csize;

	/* If the queue client has a session, use it. */
	if (item->client != NULL && item->client->session != NULL) {
		log_debug("%s: using item %p client %p", __func__, item,
		    item->client);
		return (item->client);
	}

	/* Otherwise find the current session. */
	cmd_find_clear_state(&current, item, 0);
	if (cmd_find_current_session(&current) != 0)
		return (NULL);

	/* If it is attached, find the best of it's clients. */
	s = current.s;
	log_debug("%s: current session $%u %s", __func__, s->id, s->name);
	if (~s->flags & SESSION_UNATTACHED) {
		csize = 0;
		TAILQ_FOREACH(c, &clients, entry) {
			if (c->session != s)
				continue;
			clist = xreallocarray(clist, csize + 1, sizeof *clist);
			clist[csize++] = c;
		}
		if (csize != 0) {
			c = cmd_find_best_client(clist, csize);
			if (c != NULL) {
				free(clist);
				return (c);
			}
		}
		free(clist);
	}

	/* Otherwise pick best of all clients. */
	return (cmd_find_best_client(NULL, 0));
}

/* Maps string in table. */
static const char *
cmd_find_map_table(const char *table[][2], const char *s)
{
	u_int	i;

	for (i = 0; table[i][0] != NULL; i++) {
		if (strcmp(s, table[i][0]) == 0)
			return (table[i][1]);
	}
	return (s);
}

/* Find session from string. Fills in s. */
static int
cmd_find_get_session(struct cmd_find_state *fs, const char *session)
{
	struct session	*s, *s_loop;
	struct client	*c;

	log_debug("%s: %s", __func__, session);

	/* Check for session ids starting with $. */
	if (*session == '$') {
		fs->s = session_find_by_id_str(session);
		if (fs->s == NULL)
			return (-1);
		return (0);
	}

	/* Look for exactly this session. */
	fs->s = session_find(session);
	if (fs->s != NULL)
		return (0);

	/* Look for as a client. */
	c = cmd_find_client(NULL, session, 1);
	if (c != NULL && c->session != NULL) {
		fs->s = c->session;
		return (0);
	}

	/* Stop now if exact only. */
	if (fs->flags & CMD_FIND_EXACT_SESSION)
		return (-1);

	/* Otherwise look for prefix. */
	s = NULL;
	RB_FOREACH(s_loop, sessions, &sessions) {
		if (strncmp(session, s_loop->name, strlen(session)) == 0) {
			if (s != NULL)
				return (-1);
			s = s_loop;
		}
	}
	if (s != NULL) {
		fs->s = s;
		return (0);
	}

	/* Then as a pattern. */
	s = NULL;
	RB_FOREACH(s_loop, sessions, &sessions) {
		if (fnmatch(session, s_loop->name, 0) == 0) {
			if (s != NULL)
				return (-1);
			s = s_loop;
		}
	}
	if (s != NULL) {
		fs->s = s;
		return (0);
	}

	return (-1);
}

/* Find window from string. Fills in s, wl, w. */
static int
cmd_find_get_window(struct cmd_find_state *fs, const char *window)
{
	log_debug("%s: %s", __func__, window);

	/* Check for window ids starting with @. */
	if (*window == '@') {
		fs->w = window_find_by_id_str(window);
		if (fs->w == NULL)
			return (-1);
		return (cmd_find_best_session_with_window(fs));
	}

	/* Not a window id, so use the current session. */
	fs->s = fs->current->s;

	/* We now only need to find the winlink in this session. */
	if (cmd_find_get_window_with_session(fs, window) == 0)
		return (0);

	/* Otherwise try as a session itself. */
	if (cmd_find_get_session(fs, window) == 0) {
		fs->wl = fs->s->curw;
		fs->w = fs->wl->window;
		if (~fs->flags & CMD_FIND_WINDOW_INDEX)
			fs->idx = fs->wl->idx;
		return (0);
	}

	return (-1);
}

/*
 * Find window from string, assuming it is in given session. Needs s, fills in
 * wl and w.
 */
static int
cmd_find_get_window_with_session(struct cmd_find_state *fs, const char *window)
{
	struct winlink	*wl;
	const char	*errstr;
	int		 idx, n, exact;
	struct session	*s;

	log_debug("%s: %s", __func__, window);
	exact = (fs->flags & CMD_FIND_EXACT_WINDOW);

	/*
	 * Start with the current window as the default. So if only an index is
	 * found, the window will be the current.
	 */
	fs->wl = fs->s->curw;
	fs->w = fs->wl->window;

	/* Check for window ids starting with @. */
	if (*window == '@') {
		fs->w = window_find_by_id_str(window);
		if (fs->w == NULL || !session_has(fs->s, fs->w))
			return (-1);
		return (cmd_find_best_winlink_with_window(fs));
	}

	/* Try as an offset. */
	if (!exact && (window[0] == '+' || window[0] == '-')) {
		if (window[1] != '\0')
			n = strtonum(window + 1, 1, INT_MAX, NULL);
		else
			n = 1;
		s = fs->s;
		if (fs->flags & CMD_FIND_WINDOW_INDEX) {
			if (window[0] == '+') {
				if (INT_MAX - s->curw->idx < n)
					return (-1);
				fs->idx = s->curw->idx + n;
			} else {
				if (n < s->curw->idx)
					return (-1);
				fs->idx = s->curw->idx - n;
			}
			return (0);
		}
		if (window[0] == '+')
			fs->wl = winlink_next_by_number(s->curw, s, n);
		else
			fs->wl = winlink_previous_by_number(s->curw, s, n);
		if (fs->wl != NULL) {
			fs->idx = fs->wl->idx;
			fs->w = fs->wl->window;
			return (0);
		}
	}

	/* Try special characters. */
	if (!exact) {
		if (strcmp(window, "!") == 0) {
			fs->wl = TAILQ_FIRST(&fs->s->lastw);
			if (fs->wl == NULL)
				return (-1);
			fs->idx = fs->wl->idx;
			fs->w = fs->wl->window;
			return (0);
		} else if (strcmp(window, "^") == 0) {
			fs->wl = RB_MIN(winlinks, &fs->s->windows);
			if (fs->wl == NULL)
				return (-1);
			fs->idx = fs->wl->idx;
			fs->w = fs->wl->window;
			return (0);
		} else if (strcmp(window, "$") == 0) {
			fs->wl = RB_MAX(winlinks, &fs->s->windows);
			if (fs->wl == NULL)
				return (-1);
			fs->idx = fs->wl->idx;
			fs->w = fs->wl->window;
			return (0);
		}
	}

	/* First see if this is a valid window index in this session. */
	if (window[0] != '+' && window[0] != '-') {
		idx = strtonum(window, 0, INT_MAX, &errstr);
		if (errstr == NULL) {
			if (fs->flags & CMD_FIND_WINDOW_INDEX) {
				fs->idx = idx;
				return (0);
			}
			fs->wl = winlink_find_by_index(&fs->s->windows, idx);
			if (fs->wl != NULL) {
				fs->w = fs->wl->window;
				return (0);
			}
		}
	}

	/* Look for exact matches, error if more than one. */
	fs->wl = NULL;
	RB_FOREACH(wl, winlinks, &fs->s->windows) {
		if (strcmp(window, wl->window->name) == 0) {
			if (fs->wl != NULL)
				return (-1);
			fs->wl = wl;
		}
	}
	if (fs->wl != NULL) {
		fs->idx = fs->wl->idx;
		fs->w = fs->wl->window;
		return (0);
	}

	/* Stop now if exact only. */
	if (exact)
		return (-1);

	/* Try as the start of a window name, error if multiple. */
	fs->wl = NULL;
	RB_FOREACH(wl, winlinks, &fs->s->windows) {
		if (strncmp(window, wl->window->name, strlen(window)) == 0) {
			if (fs->wl != NULL)
				return (-1);
			fs->wl = wl;
		}
	}
	if (fs->wl != NULL) {
		fs->idx = fs->wl->idx;
		fs->w = fs->wl->window;
		return (0);
	}

	/* Now look for pattern matches, again error if multiple. */
	fs->wl = NULL;
	RB_FOREACH(wl, winlinks, &fs->s->windows) {
		if (fnmatch(window, wl->window->name, 0) == 0) {
			if (fs->wl != NULL)
				return (-1);
			fs->wl = wl;
		}
	}
	if (fs->wl != NULL) {
		fs->idx = fs->wl->idx;
		fs->w = fs->wl->window;
		return (0);
	}

	return (-1);
}

/* Find pane from string. Fills in s, wl, w, wp. */
static int
cmd_find_get_pane(struct cmd_find_state *fs, const char *pane)
{
	log_debug("%s: %s", __func__, pane);

	/* Check for pane ids starting with %. */
	if (*pane == '%') {
		fs->wp = window_pane_find_by_id_str(pane);
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		fs->w = fs->wp->window;
		return (cmd_find_best_session_with_window(fs));
	}

	/* Not a pane id, so try the current session and window. */
	fs->s = fs->current->s;
	fs->wl = fs->current->wl;
	fs->idx = fs->current->idx;
	fs->w = fs->current->w;

	/* We now only need to find the pane in this window. */
	if (cmd_find_get_pane_with_window(fs, pane) == 0)
		return (0);

	/* Otherwise try as a window itself (this will also try as session). */
	if (cmd_find_get_window(fs, pane) == 0) {
		fs->wp = fs->w->active;
		return (0);
	}

	return (-1);
}

/*
 * Find pane from string, assuming it is in given session. Needs s, fills in wl
 * and w and wp.
 */
static int
cmd_find_get_pane_with_session(struct cmd_find_state *fs, const char *pane)
{
	log_debug("%s: %s", __func__, pane);

	/* Check for pane ids starting with %. */
	if (*pane == '%') {
		fs->wp = window_pane_find_by_id_str(pane);
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		fs->w = fs->wp->window;
		return (cmd_find_best_winlink_with_window(fs));
	}

	/* Otherwise use the current window. */
	fs->wl = fs->s->curw;
	fs->idx = fs->wl->idx;
	fs->w = fs->wl->window;

	/* Now we just need to look up the pane. */
	return (cmd_find_get_pane_with_window(fs, pane));
}

/*
 * Find pane from string, assuming it is in the given window. Needs w, fills in
 * wp.
 */
static int
cmd_find_get_pane_with_window(struct cmd_find_state *fs, const char *pane)
{
	const char		*errstr;
	int			 idx;
	struct window_pane	*wp;
	u_int			 n;

	log_debug("%s: %s", __func__, pane);

	/* Check for pane ids starting with %. */
	if (*pane == '%') {
		fs->wp = window_pane_find_by_id_str(pane);
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		if (fs->wp->window != fs->w)
			return (-1);
		return (0);
	}

	/* Try special characters. */
	if (strcmp(pane, "!") == 0) {
		if (fs->w->last == NULL)
			return (-1);
		fs->wp = fs->w->last;
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		return (0);
	} else if (strcmp(pane, "{up-of}") == 0) {
		fs->wp = window_pane_find_up(fs->w->active);
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		return (0);
	} else if (strcmp(pane, "{down-of}") == 0) {
		fs->wp = window_pane_find_down(fs->w->active);
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		return (0);
	} else if (strcmp(pane, "{left-of}") == 0) {
		fs->wp = window_pane_find_left(fs->w->active);
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		return (0);
	} else if (strcmp(pane, "{right-of}") == 0) {
		fs->wp = window_pane_find_right(fs->w->active);
		if (fs->wp == NULL || window_pane_outside(fs->wp))
			return (-1);
		return (0);
	}

	/* Try as an offset. */
	if (pane[0] == '+' || pane[0] == '-') {
		if (pane[1] != '\0')
			n = strtonum(pane + 1, 1, INT_MAX, NULL);
		else
			n = 1;
		wp = fs->w->active;
		if (pane[0] == '+')
			fs->wp = window_pane_next_by_number(fs->w, wp, n);
		else
			fs->wp = window_pane_previous_by_number(fs->w, wp, n);
		if (fs->wp != NULL && !window_pane_outside(fs->wp))
			return (0);
	}

	/* Get pane by index. */
	idx = strtonum(pane, 0, INT_MAX, &errstr);
	if (errstr == NULL) {
		fs->wp = window_pane_at_index(fs->w, idx);
		if (fs->wp != NULL && !window_pane_outside(fs->wp))
			return (0);
	}

	/* Try as a description. */
	fs->wp = window_find_string(fs->w, pane);
	if (fs->wp != NULL && !window_pane_outside(fs->wp))
		return (0);

	return (-1);
}

/* Clear state. */
void
cmd_find_clear_state(struct cmd_find_state *fs, struct cmdq_item *item,
    int flags)
{
	memset(fs, 0, sizeof *fs);

	fs->item = item;
	fs->flags = flags;

	fs->idx = -1;
}

/* Check if state is empty/ */
int
cmd_find_empty_state(struct cmd_find_state *fs)
{
	if (fs->s == NULL && fs->wl == NULL && fs->w == NULL && fs->wp == NULL)
		return (1);
	return (0);
}

/* Check if a state if valid. */
int
cmd_find_valid_state(struct cmd_find_state *fs)
{
	struct winlink	*wl;

	if (fs->s == NULL || fs->wl == NULL || fs->w == NULL || fs->wp == NULL)
		return (0);

	if (!session_alive(fs->s))
		return (0);

	RB_FOREACH(wl, winlinks, &fs->s->windows) {
		if (wl->window == fs->w && wl == fs->wl)
			break;
	}
	if (wl == NULL)
		return (0);

	if (fs->w != fs->wl->window)
		return (0);

	if (!window_has_pane(fs->w, fs->wp))
		return (0);
	return (!window_pane_outside(fs->wp));
}

/* Copy a state. */
void
cmd_find_copy_state(struct cmd_find_state *dst, struct cmd_find_state *src)
{
	dst->s = src->s;
	dst->wl = src->wl;
	dst->idx = src->idx;
	dst->w = src->w;
	dst->wp = src->wp;
}

/* Log the result. */
void
cmd_find_log_state(const char *prefix, struct cmd_find_state *fs)
{
	if (fs->s != NULL)
		log_debug("%s: s=$%u", prefix, fs->s->id);
	else
		log_debug("%s: s=none", prefix);
	if (fs->wl != NULL) {
		log_debug("%s: wl=%u %d w=@%u %s", prefix, fs->wl->idx,
		    fs->wl->window == fs->w, fs->w->id, fs->w->name);
	} else
		log_debug("%s: wl=none", prefix);
	if (fs->wp != NULL)
		log_debug("%s: wp=%%%u", prefix, fs->wp->id);
	else
		log_debug("%s: wp=none", prefix);
	if (fs->idx != -1)
		log_debug("%s: idx=%d", prefix, fs->idx);
	else
		log_debug("%s: idx=none", prefix);
}

/* Find state from a session. */
int
cmd_find_from_session(struct cmd_find_state *fs, struct session *s)
{
	cmd_find_clear_state(fs, NULL, 0);

	fs->s = s;
	fs->wl = fs->s->curw;
	fs->w = fs->wl->window;
	fs->wp = fs->w->active;

	cmd_find_log_state(__func__, fs);
	return (0);
}

/* Find state from a winlink. */
int
cmd_find_from_winlink(struct cmd_find_state *fs, struct session *s,
    struct winlink *wl)
{
	cmd_find_clear_state(fs, NULL, 0);

	fs->s = s;
	fs->wl = wl;
	fs->w = wl->window;
	fs->wp = wl->window->active;

	cmd_find_log_state(__func__, fs);
	return (0);
}

/* Find state from a session and window. */
int
cmd_find_from_session_window(struct cmd_find_state *fs, struct session *s,
    struct window *w)
{
	cmd_find_clear_state(fs, NULL, 0);

	fs->s = s;
	fs->w = w;
	if (cmd_find_best_winlink_with_window(fs) != 0)
		return (-1);
	fs->wp = fs->w->active;

	cmd_find_log_state(__func__, fs);
	return (0);
}

/* Find state from a window. */
int
cmd_find_from_window(struct cmd_find_state *fs, struct window *w)
{
	cmd_find_clear_state(fs, NULL, 0);

	fs->w = w;
	if (cmd_find_best_session_with_window(fs) != 0)
		return (-1);
	if (cmd_find_best_winlink_with_window(fs) != 0)
		return (-1);
	fs->wp = fs->w->active;

	cmd_find_log_state(__func__, fs);
	return (0);
}

/* Find state from a pane. */
int
cmd_find_from_pane(struct cmd_find_state *fs, struct window_pane *wp)
{
	if (cmd_find_from_window(fs, wp->window) != 0)
		return (-1);
	if (window_pane_outside(wp))
		return (-1);
	fs->wp = wp;

	cmd_find_log_state(__func__, fs);
	return (0);
}

/* Find current state. */
int
cmd_find_current(struct cmd_find_state *fs, struct cmdq_item *item, int flags)
{
	cmd_find_clear_state(fs, item, flags);
	if (cmd_find_current_session(fs) != 0) {
		if (~flags & CMD_FIND_QUIET)
			cmdq_error(item, "no current session");
		return (-1);
	}
	return (0);
}

/*
 * Split target into pieces and resolve for the given type. Fills in the given
 * state. Returns 0 on success or -1 on error.
 */
int
cmd_find_target(struct cmd_find_state *fs, struct cmd_find_state *current,
    struct cmdq_item *item, const char *target, enum cmd_find_type type,
    int flags)
{
	struct mouse_event	*m;
	char			*colon, *period, *copy = NULL;
	const char		*session, *window, *pane;

	/* Log the arguments. */
	if (target == NULL)
		log_debug("%s: target none, type %d", __func__, type);
	else
		log_debug("%s: target %s, type %d", __func__, target, type);
	log_debug("%s: item %p, flags %#x", __func__, item, flags);

	/* Clear new state. */
	cmd_find_clear_state(fs, item, flags);

	/* Find current state. */
	if (server_check_marked() && (flags & CMD_FIND_DEFAULT_MARKED)) {
		fs->current = &marked_pane;
		log_debug("%s: current is marked pane", __func__);
	} else if (cmd_find_valid_state(&item->current)) {
		fs->current = &item->current;
		log_debug("%s: current is from queue", __func__);
	} else {
		fs->current = current;
		log_debug("%s: current is from argument", __func__);
	}
	if (!cmd_find_empty_state(fs->current) &&
	    !cmd_find_valid_state(fs->current))
		fatalx("invalid current find state");

	/* An empty or NULL target is the current. */
	if (target == NULL || *target == '\0')
		goto current;

	/* Mouse target is a plain = or {mouse}. */
	if (strcmp(target, "=") == 0 || strcmp(target, "{mouse}") == 0) {
		m = &item->mouse;
		switch (type) {
		case CMD_FIND_PANE:
			fs->wp = cmd_mouse_pane(m, &fs->s, &fs->wl);
			if (fs->wp != NULL && !window_pane_outside(fs->wp))
				fs->w = fs->wl->window;
			break;
		case CMD_FIND_WINDOW:
		case CMD_FIND_SESSION:
			fs->wl = cmd_mouse_window(m, &fs->s);
			if (fs->wl != NULL) {
				fs->w = fs->wl->window;
				fs->wp = fs->w->active;
			}
			break;
		}
		if (fs->wp == NULL) {
			if (~flags & CMD_FIND_QUIET)
				cmdq_error(item, "no mouse target");
			goto error;
		}
		goto found;
	}

	/* Marked target is a plain ~ or {marked}. */
	if (strcmp(target, "~") == 0 || strcmp(target, "{marked}") == 0) {
		if (!server_check_marked()) {
			if (~flags & CMD_FIND_QUIET)
				cmdq_error(item, "no marked target");
			goto error;
		}
		cmd_find_copy_state(fs, &marked_pane);
		goto found;
	}

	/* Find separators if they exist. */
	copy = xstrdup(target);
	colon = strchr(copy, ':');
	if (colon != NULL)
		*colon++ = '\0';
	if (colon == NULL)
		period = strchr(copy, '.');
	else
		period = strchr(colon, '.');
	if (period != NULL)
		*period++ = '\0';

	/* Set session, window and pane parts. */
	session = window = pane = NULL;
	if (colon != NULL && period != NULL) {
		session = copy;
		window = colon;
		pane = period;
	} else if (colon != NULL && period == NULL) {
		session = copy;
		window = colon;
	} else if (colon == NULL && period != NULL) {
		window = copy;
		pane = period;
	} else {
		if (*copy == '$')
			session = copy;
		else if (*copy == '@')
			window = copy;
		else if (*copy == '%')
			pane = copy;
		else {
			switch (type) {
			case CMD_FIND_SESSION:
				session = copy;
				break;
			case CMD_FIND_WINDOW:
				window = copy;
				break;
			case CMD_FIND_PANE:
				pane = copy;
				break;
			}
		}
	}

	/* Set exact match flags. */
	if (session != NULL && *session == '=') {
		session++;
		fs->flags |= CMD_FIND_EXACT_SESSION;
	}
	if (window != NULL && *window == '=') {
		window++;
		fs->flags |= CMD_FIND_EXACT_WINDOW;
	}

	/* Empty is the same as NULL. */
	if (session != NULL && *session == '\0')
		session = NULL;
	if (window != NULL && *window == '\0')
		window = NULL;
	if (pane != NULL && *pane == '\0')
		pane = NULL;

	/* Map though conversion table. */
	if (session != NULL)
		session = cmd_find_map_table(cmd_find_session_table, session);
	if (window != NULL)
		window = cmd_find_map_table(cmd_find_window_table, window);
	if (pane != NULL)
		pane = cmd_find_map_table(cmd_find_pane_table, pane);

	log_debug("target %s (flags %#x): session=%s, window=%s, pane=%s",
	    target, flags, session == NULL ? "none" : session,
	    window == NULL ? "none" : window, pane == NULL ? "none" : pane);

	/* No pane is allowed if want an index. */
	if (pane != NULL && (flags & CMD_FIND_WINDOW_INDEX)) {
		if (~flags & CMD_FIND_QUIET)
			cmdq_error(item, "can't specify pane here");
		goto error;
	}

	/* If the session isn't NULL, look it up. */
	if (session != NULL) {
		/* This will fill in session. */
		if (cmd_find_get_session(fs, session) != 0)
			goto no_session;

		/* If window and pane are NULL, use that session's current. */
		if (window == NULL && pane == NULL) {
			fs->wl = fs->s->curw;
			fs->idx = -1;
			fs->w = fs->wl->window;
			fs->wp = fs->w->active;
			goto found;
		}

		/* If window is present but pane not, find window in session. */
		if (window != NULL && pane == NULL) {
			/* This will fill in winlink and window. */
			if (cmd_find_get_window_with_session(fs, window) != 0)
				goto no_window;
			fs->wp = fs->wl->window->active;
			goto found;
		}

		/* If pane is present but window not, find pane. */
		if (window == NULL && pane != NULL) {
			/* This will fill in winlink and window and pane. */
			if (cmd_find_get_pane_with_session(fs, pane) != 0)
				goto no_pane;
			goto found;
		}

		/*
		 * If window and pane are present, find both in session. This
		 * will fill in winlink and window.
		 */
		if (cmd_find_get_window_with_session(fs, window) != 0)
			goto no_window;
		/* This will fill in pane. */
		if (cmd_find_get_pane_with_window(fs, pane) != 0)
			goto no_pane;
		goto found;
	}

	/* No session. If window and pane, try them. */
	if (window != NULL && pane != NULL) {
		/* This will fill in session, winlink and window. */
		if (cmd_find_get_window(fs, window) != 0)
			goto no_window;
		/* This will fill in pane. */
		if (cmd_find_get_pane_with_window(fs, pane) != 0)
			goto no_pane;
		goto found;
	}

	/* If just window is present, try it. */
	if (window != NULL && pane == NULL) {
		/* This will fill in session, winlink and window. */
		if (cmd_find_get_window(fs, window) != 0)
			goto no_window;
		fs->wp = fs->wl->window->active;
		goto found;
	}

	/* If just pane is present, try it. */
	if (window == NULL && pane != NULL) {
		/* This will fill in session, winlink, window and pane. */
		if (cmd_find_get_pane(fs, pane) != 0)
			goto no_pane;
		goto found;
	}

current:
	/* Use the current session. */
	cmd_find_copy_state(fs, fs->current);
	if (flags & CMD_FIND_WINDOW_INDEX)
		fs->idx = -1;
	goto found;

error:
	fs->current = NULL;
	log_debug("%s: error", __func__);

	free(copy);
	return (-1);

found:
	fs->current = NULL;
	cmd_find_log_state(__func__, fs);

	free(copy);
	return (0);

no_session:
	if (~flags & CMD_FIND_QUIET)
		cmdq_error(item, "can't find session %s", session);
	goto error;

no_window:
	if (~flags & CMD_FIND_QUIET)
		cmdq_error(item, "can't find window %s", window);
	goto error;

no_pane:
	if (~flags & CMD_FIND_QUIET)
		cmdq_error(item, "can't find pane %s", pane);
	goto error;
}

/* Find the target client or report an error and return NULL. */
struct client *
cmd_find_client(struct cmdq_item *item, const char *target, int quiet)
{
	struct client	*c;
	char		*copy;
	size_t		 size;

	/* A NULL argument means the current client. */
	if (item != NULL && target == NULL) {
		c = cmd_find_current_client(item);
		if (c == NULL && !quiet)
			cmdq_error(item, "no current client");
		log_debug("%s: no target, return %p", __func__, c);
		return (c);
	}
	copy = xstrdup(target);

	/* Trim a single trailing colon if any. */
	size = strlen(copy);
	if (size != 0 && copy[size - 1] == ':')
		copy[size - 1] = '\0';

	/* Check name and path of each client. */
	TAILQ_FOREACH(c, &clients, entry) {
		if (c->session == NULL)
			continue;
		if (strcmp(copy, c->name) == 0)
			break;

		if (*c->ttyname == '\0')
			continue;
		if (strcmp(copy, c->ttyname) == 0)
			break;
		if (strncmp(c->ttyname, _PATH_DEV, (sizeof _PATH_DEV) - 1) != 0)
			continue;
		if (strcmp(copy, c->ttyname + (sizeof _PATH_DEV) - 1) == 0)
			break;
	}

	/* If no client found, report an error. */
	if (c == NULL && !quiet)
		cmdq_error(item, "can't find client %s", copy);

	free(copy);
	log_debug("%s: target %s, return %p", __func__, target, c);
	return (c);
}