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Support for windows larger than visible on the attached client. This has
been a limitation for a long time.

There are two new options, window-size and default-size, and a new
command, resize-window. The force-width and force-height options and the
session_width and session_height formats have been removed.

The new window-size option tells tmux how to work out the size of
windows: largest means it picks the size of the largest session,
smallest the smallest session (similar to the old behaviour) and manual
means that it does not automatically resize windows. The default is
currently largest but this may change. aggressive-resize modifies the
choice of session for largest and smallest as it did before.

If a window is in a session attached to a client that is too small, only
part of the window is shown. tmux attempts to keep the cursor visible,
so the part of the window displayed is changed as the cursor moves (with
a small delay, to try and avoid excess redrawing when applications
redraw status lines or similar that are not currently visible). The
offset of the visible portion of the window is shown in status-right.

Drawing windows which are larger than the client is not as efficient as
those which fit, particularly when the cursor moves, so it is
recommended to avoid using this on slow machines or networks (set
window-size to smallest or manual).

The resize-window command can be used to resize a window manually. If it
is used, the window-size option is automatically set to manual for the
window (undo this with "setw -u window-size"). resize-window works in a
similar way to resize-pane (-U -D -L -R -x -y flags) but also has -a and
-A flags. -a sets the window to the size of the smallest client (what it
would be if window-size was smallest) and -A the largest.

For the same behaviour as force-width or force-height, use resize-window
-x or -y, and "setw -u window-size" to revert to automatic sizing..

If the global window-size option is set to manual, the default-size
option is used for new windows. If -x or -y is used with new-session,
that sets the default-size option for the new session.

The maximum size of a window is 10000x10000. But expect applications to
complain and much higher memory use if making a window excessively
big. The minimum size is the size required for the current layout
including borders.

The refresh-client command can be used to pan around a window, -U -D -L
-R moves up, down, left or right and -c returns to automatic cursor
tracking. The position is reset when the current window is changed.

/* $OpenBSD: format.c,v 1.164 2018/10/18 08:38:01 nicm Exp $ */

/*
 * Copyright (c) 2011 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 <sys/wait.h>

#include <ctype.h>
#include <errno.h>
#include <fnmatch.h>
#include <libgen.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "tmux.h"

/*
 * Build a list of key-value pairs and use them to expand #{key} entries in a
 * string.
 */

struct format_entry;
typedef void (*format_cb)(struct format_tree *, struct format_entry *);

static char	*format_job_get(struct format_tree *, const char *);
static void	 format_job_timer(int, short, void *);

static char	*format_find(struct format_tree *, const char *, int);
static void	 format_add_cb(struct format_tree *, const char *, format_cb);
static void	 format_add_tv(struct format_tree *, const char *,
		     struct timeval *);
static int	 format_replace(struct format_tree *, const char *, size_t,
		     char **, size_t *, size_t *);

static void	 format_defaults_session(struct format_tree *,
		     struct session *);
static void	 format_defaults_client(struct format_tree *, struct client *);
static void	 format_defaults_winlink(struct format_tree *, struct winlink *);

/* Entry in format job tree. */
struct format_job {
	struct client		*client;
	u_int			 tag;
	const char		*cmd;
	const char		*expanded;

	time_t			 last;
	char			*out;
	int			 updated;

	struct job		*job;
	int			 status;

	RB_ENTRY(format_job)	 entry;
};

/* Format job tree. */
static struct event format_job_event;
static int format_job_cmp(struct format_job *, struct format_job *);
static RB_HEAD(format_job_tree, format_job) format_jobs = RB_INITIALIZER();
RB_GENERATE_STATIC(format_job_tree, format_job, entry, format_job_cmp);

/* Format job tree comparison function. */
static int
format_job_cmp(struct format_job *fj1, struct format_job *fj2)
{
	if (fj1->tag < fj2->tag)
		return (-1);
	if (fj1->tag > fj2->tag)
		return (1);
	return (strcmp(fj1->cmd, fj2->cmd));
}

/* Format modifiers. */
#define FORMAT_TIMESTRING 0x1
#define FORMAT_BASENAME 0x2
#define FORMAT_DIRNAME 0x4
#define FORMAT_SUBSTITUTE 0x8
#define FORMAT_QUOTE 0x10

/* Entry in format tree. */
struct format_entry {
	char			*key;
	char			*value;
	time_t			 t;
	format_cb		 cb;
	RB_ENTRY(format_entry)	 entry;
};

/* Format entry tree. */
struct format_tree {
	struct client		*c;
	struct session		*s;
	struct winlink		*wl;
	struct window		*w;
	struct window_pane	*wp;

	struct client		*client;
	u_int			 tag;
	int			 flags;

	RB_HEAD(format_entry_tree, format_entry) tree;
};
static int format_entry_cmp(struct format_entry *, struct format_entry *);
RB_GENERATE_STATIC(format_entry_tree, format_entry, entry, format_entry_cmp);

/* Format entry tree comparison function. */
static int
format_entry_cmp(struct format_entry *fe1, struct format_entry *fe2)
{
	return (strcmp(fe1->key, fe2->key));
}

/* Single-character uppercase aliases. */
static const char *format_upper[] = {
	NULL,		/* A */
	NULL,		/* B */
	NULL,		/* C */
	"pane_id",	/* D */
	NULL,		/* E */
	"window_flags",	/* F */
	NULL,		/* G */
	"host",		/* H */
	"window_index",	/* I */
	NULL,		/* J */
	NULL,		/* K */
	NULL,		/* L */
	NULL,		/* M */
	NULL,		/* N */
	NULL,		/* O */
	"pane_index",	/* P */
	NULL,		/* Q */
	NULL,		/* R */
	"session_name",	/* S */
	"pane_title",	/* T */
	NULL,		/* U */
	NULL,		/* V */
	"window_name",	/* W */
	NULL,		/* X */
	NULL,		/* Y */
	NULL 		/* Z */
};

/* Single-character lowercase aliases. */
static const char *format_lower[] = {
	NULL,		/* a */
	NULL,		/* b */
	NULL,		/* c */
	NULL,		/* d */
	NULL,		/* e */
	NULL,		/* f */
	NULL,		/* g */
	"host_short",	/* h */
	NULL,		/* i */
	NULL,		/* j */
	NULL,		/* k */
	NULL,		/* l */
	NULL,		/* m */
	NULL,		/* n */
	NULL,		/* o */
	NULL,		/* p */
	NULL,		/* q */
	NULL,		/* r */
	NULL,		/* s */
	NULL,		/* t */
	NULL,		/* u */
	NULL,		/* v */
	NULL,		/* w */
	NULL,		/* x */
	NULL,		/* y */
	NULL		/* z */
};

/* Format job update callback. */
static void
format_job_update(struct job *job)
{
	struct format_job	*fj = job_get_data(job);
	struct evbuffer		*evb = job_get_event(job)->input;
	char			*line = NULL, *next;
	time_t			 t;

	while ((next = evbuffer_readline(evb)) != NULL) {
		free(line);
		line = next;
	}
	if (line == NULL)
		return;
	fj->updated = 1;

	free(fj->out);
	fj->out = line;

	log_debug("%s: %p %s: %s", __func__, fj, fj->cmd, fj->out);

	t = time(NULL);
	if (fj->status && fj->last != t) {
		if (fj->client != NULL)
			server_status_client(fj->client);
		fj->last = t;
	}
}

/* Format job complete callback. */
static void
format_job_complete(struct job *job)
{
	struct format_job	*fj = job_get_data(job);
	struct evbuffer		*evb = job_get_event(job)->input;
	char			*line, *buf;
	size_t			 len;

	fj->job = NULL;

	buf = NULL;
	if ((line = evbuffer_readline(evb)) == NULL) {
		len = EVBUFFER_LENGTH(evb);
		buf = xmalloc(len + 1);
		if (len != 0)
			memcpy(buf, EVBUFFER_DATA(evb), len);
		buf[len] = '\0';
	} else
		buf = line;

	log_debug("%s: %p %s: %s", __func__, fj, fj->cmd, buf);

	if (*buf != '\0' || !fj->updated) {
		free(fj->out);
		fj->out = buf;
	} else
		free(buf);

	if (fj->status) {
		if (fj->client != NULL)
			server_status_client(fj->client);
		fj->status = 0;
	}
}

/* Find a job. */
static char *
format_job_get(struct format_tree *ft, const char *cmd)
{
	struct format_job_tree	*jobs;
	struct format_job	 fj0, *fj;
	time_t			 t;
	char			*expanded;
	int			 force;

	if (ft->client == NULL)
		jobs = &format_jobs;
	else if (ft->client->jobs != NULL)
		jobs = ft->client->jobs;
	else {
		jobs = ft->client->jobs = xmalloc(sizeof *ft->client->jobs);
		RB_INIT(jobs);
	}

	fj0.tag = ft->tag;
	fj0.cmd = cmd;
	if ((fj = RB_FIND(format_job_tree, jobs, &fj0)) == NULL) {
		fj = xcalloc(1, sizeof *fj);
		fj->client = ft->client;
		fj->tag = ft->tag;
		fj->cmd = xstrdup(cmd);
		fj->expanded = NULL;

		xasprintf(&fj->out, "<'%s' not ready>", fj->cmd);

		RB_INSERT(format_job_tree, jobs, fj);
	}

	expanded = format_expand(ft, cmd);
	if (fj->expanded == NULL || strcmp(expanded, fj->expanded) != 0) {
		free((void *)fj->expanded);
		fj->expanded = xstrdup(expanded);
		force = 1;
	} else
		force = (ft->flags & FORMAT_FORCE);

	t = time(NULL);
	if (fj->job == NULL && (force || fj->last != t)) {
		fj->job = job_run(expanded, NULL,
		    server_client_get_cwd(ft->client, NULL), format_job_update,
		    format_job_complete, NULL, fj, JOB_NOWAIT);
		if (fj->job == NULL) {
			free(fj->out);
			xasprintf(&fj->out, "<'%s' didn't start>", fj->cmd);
		}
		fj->last = t;
		fj->updated = 0;
	}

	if (ft->flags & FORMAT_STATUS)
		fj->status = 1;

	free(expanded);
	return (format_expand(ft, fj->out));
}

/* Remove old jobs. */
static void
format_job_tidy(struct format_job_tree *jobs, int force)
{
	struct format_job	*fj, *fj1;
	time_t			 now;

	now = time(NULL);
	RB_FOREACH_SAFE(fj, format_job_tree, jobs, fj1) {
		if (!force && (fj->last > now || now - fj->last < 3600))
			continue;
		RB_REMOVE(format_job_tree, jobs, fj);

		log_debug("%s: %s", __func__, fj->cmd);

		if (fj->job != NULL)
			job_free(fj->job);

		free((void *)fj->expanded);
		free((void *)fj->cmd);
		free(fj->out);

		free(fj);
	}
}

/* Remove old jobs for client. */
void
format_lost_client(struct client *c)
{
	if (c->jobs != NULL)
		format_job_tidy(c->jobs, 1);
	free(c->jobs);
}

/* Remove old jobs periodically. */
static void
format_job_timer(__unused int fd, __unused short events, __unused void *arg)
{
	struct client	*c;
	struct timeval	 tv = { .tv_sec = 60 };

	format_job_tidy(&format_jobs, 0);
	TAILQ_FOREACH(c, &clients, entry) {
		if (c->jobs != NULL)
			format_job_tidy(c->jobs, 0);
	}

	evtimer_del(&format_job_event);
	evtimer_add(&format_job_event, &tv);
}

/* Callback for host. */
static void
format_cb_host(__unused struct format_tree *ft, struct format_entry *fe)
{
	char host[HOST_NAME_MAX + 1];

	if (gethostname(host, sizeof host) != 0)
		fe->value = xstrdup("");
	else
		fe->value = xstrdup(host);
}

/* Callback for host_short. */
static void
format_cb_host_short(__unused struct format_tree *ft, struct format_entry *fe)
{
	char host[HOST_NAME_MAX + 1], *cp;

	if (gethostname(host, sizeof host) != 0)
		fe->value = xstrdup("");
	else {
		if ((cp = strchr(host, '.')) != NULL)
			*cp = '\0';
		fe->value = xstrdup(host);
	}
}

/* Callback for pid. */
static void
format_cb_pid(__unused struct format_tree *ft, struct format_entry *fe)
{
	xasprintf(&fe->value, "%ld", (long)getpid());
}

/* Callback for session_alerts. */
static void
format_cb_session_alerts(struct format_tree *ft, struct format_entry *fe)
{
	struct session	*s = ft->s;
	struct winlink	*wl;
	char		 alerts[1024], tmp[16];

	if (s == NULL)
		return;

	*alerts = '\0';
	RB_FOREACH(wl, winlinks, &s->windows) {
		if ((wl->flags & WINLINK_ALERTFLAGS) == 0)
			continue;
		xsnprintf(tmp, sizeof tmp, "%u", wl->idx);

		if (*alerts != '\0')
			strlcat(alerts, ",", sizeof alerts);
		strlcat(alerts, tmp, sizeof alerts);
		if (wl->flags & WINLINK_ACTIVITY)
			strlcat(alerts, "#", sizeof alerts);
		if (wl->flags & WINLINK_BELL)
			strlcat(alerts, "!", sizeof alerts);
		if (wl->flags & WINLINK_SILENCE)
			strlcat(alerts, "~", sizeof alerts);
	}
	fe->value = xstrdup(alerts);
}

/* Callback for session_stack. */
static void
format_cb_session_stack(struct format_tree *ft, struct format_entry *fe)
{
	struct session	*s = ft->s;
	struct winlink	*wl;
	char		 result[1024], tmp[16];

	if (s == NULL)
		return;

	xsnprintf(result, sizeof result, "%u", s->curw->idx);
	TAILQ_FOREACH(wl, &s->lastw, sentry) {
		xsnprintf(tmp, sizeof tmp, "%u", wl->idx);

		if (*result != '\0')
			strlcat(result, ",", sizeof result);
		strlcat(result, tmp, sizeof result);
	}
	fe->value = xstrdup(result);
}

/* Callback for window_stack_index. */
static void
format_cb_window_stack_index(struct format_tree *ft, struct format_entry *fe)
{
	struct session	*s = ft->wl->session;
	struct winlink	*wl;
	u_int		 idx;

	idx = 0;
	TAILQ_FOREACH(wl, &s->lastw, sentry) {
		idx++;
		if (wl == ft->wl)
			break;
	}
	if (wl != NULL)
		xasprintf(&fe->value, "%u", idx);
	else
		fe->value = xstrdup("0");
}

/* Callback for window_layout. */
static void
format_cb_window_layout(struct format_tree *ft, struct format_entry *fe)
{
	struct window	*w = ft->w;

	if (w == NULL)
		return;

	if (w->saved_layout_root != NULL)
		fe->value = layout_dump(w->saved_layout_root);
	else
		fe->value = layout_dump(w->layout_root);
}

/* Callback for window_visible_layout. */
static void
format_cb_window_visible_layout(struct format_tree *ft, struct format_entry *fe)
{
	struct window	*w = ft->w;

	if (w == NULL)
		return;

	fe->value = layout_dump(w->layout_root);
}

/* Callback for pane_start_command. */
static void
format_cb_start_command(struct format_tree *ft, struct format_entry *fe)
{
	struct window_pane	*wp = ft->wp;

	if (wp == NULL)
		return;

	fe->value = cmd_stringify_argv(wp->argc, wp->argv);
}

/* Callback for pane_current_command. */
static void
format_cb_current_command(struct format_tree *ft, struct format_entry *fe)
{
	struct window_pane	*wp = ft->wp;
	char			*cmd;

	if (wp == NULL)
		return;

	cmd = get_proc_name(wp->fd, wp->tty);
	if (cmd == NULL || *cmd == '\0') {
		free(cmd);
		cmd = cmd_stringify_argv(wp->argc, wp->argv);
		if (cmd == NULL || *cmd == '\0') {
			free(cmd);
			cmd = xstrdup(wp->shell);
		}
	}
	fe->value = parse_window_name(cmd);
	free(cmd);
}

/* Callback for history_bytes. */
static void
format_cb_history_bytes(struct format_tree *ft, struct format_entry *fe)
{
	struct window_pane	*wp = ft->wp;
	struct grid		*gd;
	struct grid_line	*gl;
	unsigned long long	 size;
	u_int			 i;

	if (wp == NULL)
		return;
	gd = wp->base.grid;

	size = 0;
	for (i = 0; i < gd->hsize; i++) {
		gl = grid_get_line(gd, i);
		size += gl->cellsize * sizeof *gl->celldata;
		size += gl->extdsize * sizeof *gl->extddata;
	}
	size += gd->hsize * sizeof *gl;

	xasprintf(&fe->value, "%llu", size);
}

/* Callback for pane_tabs. */
static void
format_cb_pane_tabs(struct format_tree *ft, struct format_entry *fe)
{
	struct window_pane	*wp = ft->wp;
	struct evbuffer		*buffer;
	u_int			 i;
	int			 size;

	if (wp == NULL)
		return;

	buffer = evbuffer_new();
	for (i = 0; i < wp->base.grid->sx; i++) {
		if (!bit_test(wp->base.tabs, i))
			continue;

		if (EVBUFFER_LENGTH(buffer) > 0)
			evbuffer_add(buffer, ",", 1);
		evbuffer_add_printf(buffer, "%u", i);
	}
	if ((size = EVBUFFER_LENGTH(buffer)) != 0)
		xasprintf(&fe->value, "%.*s", size, EVBUFFER_DATA(buffer));
	evbuffer_free(buffer);
}

/* Callback for session_group_list. */
static void
format_cb_session_group_list(struct format_tree *ft, struct format_entry *fe)
{
	struct session		*s = ft->s;
	struct session_group	*sg;
	struct session		*loop;
	struct evbuffer		*buffer;
	int			 size;

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

	buffer = evbuffer_new();
	TAILQ_FOREACH(loop, &sg->sessions, gentry) {
		if (EVBUFFER_LENGTH(buffer) > 0)
			evbuffer_add(buffer, ",", 1);
		evbuffer_add_printf(buffer, "%s", loop->name);
	}
	if ((size = EVBUFFER_LENGTH(buffer)) != 0)
		xasprintf(&fe->value, "%.*s", size, EVBUFFER_DATA(buffer));
	evbuffer_free(buffer);
}

/* Merge a format tree. */
static void
format_merge(struct format_tree *ft, struct format_tree *from)
{
	struct format_entry	*fe;

	RB_FOREACH(fe, format_entry_tree, &from->tree) {
		if (fe->value != NULL)
			format_add(ft, fe->key, "%s", fe->value);
	}
}

/* Create a new tree. */
struct format_tree *
format_create(struct client *c, struct cmdq_item *item, int tag, int flags)
{
	struct format_tree	*ft;

	if (!event_initialized(&format_job_event)) {
		evtimer_set(&format_job_event, format_job_timer, NULL);
		format_job_timer(-1, 0, NULL);
	}

	ft = xcalloc(1, sizeof *ft);
	RB_INIT(&ft->tree);

	if (c != NULL) {
		ft->client = c;
		ft->client->references++;
	}

	ft->tag = tag;
	ft->flags = flags;

	format_add_cb(ft, "host", format_cb_host);
	format_add_cb(ft, "host_short", format_cb_host_short);
	format_add_cb(ft, "pid", format_cb_pid);
	format_add(ft, "socket_path", "%s", socket_path);
	format_add_tv(ft, "start_time", &start_time);

	if (item != NULL) {
		if (item->cmd != NULL)
			format_add(ft, "command", "%s", item->cmd->entry->name);
		if (item->shared != NULL && item->shared->formats != NULL)
			format_merge(ft, item->shared->formats);
	}

	return (ft);
}

/* Free a tree. */
void
format_free(struct format_tree *ft)
{
	struct format_entry	*fe, *fe1;

	RB_FOREACH_SAFE(fe, format_entry_tree, &ft->tree, fe1) {
		RB_REMOVE(format_entry_tree, &ft->tree, fe);
		free(fe->value);
		free(fe->key);
		free(fe);
	}

	if (ft->client != NULL)
		server_client_unref(ft->client);
	free(ft);
}

/* Add a key-value pair. */
void
format_add(struct format_tree *ft, const char *key, const char *fmt, ...)
{
	struct format_entry	*fe;
	struct format_entry	*fe_now;
	va_list			 ap;

	fe = xmalloc(sizeof *fe);
	fe->key = xstrdup(key);

	fe_now = RB_INSERT(format_entry_tree, &ft->tree, fe);
	if (fe_now != NULL) {
		free(fe->key);
		free(fe);
		free(fe_now->value);
		fe = fe_now;
	}

	fe->cb = NULL;
	fe->t = 0;

	va_start(ap, fmt);
	xvasprintf(&fe->value, fmt, ap);
	va_end(ap);
}

/* Add a key and time. */
static void
format_add_tv(struct format_tree *ft, const char *key, struct timeval *tv)
{
	struct format_entry	*fe;
	struct format_entry	*fe_now;

	fe = xmalloc(sizeof *fe);
	fe->key = xstrdup(key);

	fe_now = RB_INSERT(format_entry_tree, &ft->tree, fe);
	if (fe_now != NULL) {
		free(fe->key);
		free(fe);
		free(fe_now->value);
		fe = fe_now;
	}

	fe->cb = NULL;
	fe->t = tv->tv_sec;

	fe->value = NULL;
}

/* Add a key and function. */
static void
format_add_cb(struct format_tree *ft, const char *key, format_cb cb)
{
	struct format_entry	*fe;
	struct format_entry	*fe_now;

	fe = xmalloc(sizeof *fe);
	fe->key = xstrdup(key);

	fe_now = RB_INSERT(format_entry_tree, &ft->tree, fe);
	if (fe_now != NULL) {
		free(fe->key);
		free(fe);
		free(fe_now->value);
		fe = fe_now;
	}

	fe->cb = cb;
	fe->t = 0;

	fe->value = NULL;
}

/* Quote special characters in string. */
static char *
format_quote(const char *s)
{
	const char	*cp;
	char		*out, *at;

	at = out = xmalloc(strlen(s) * 2 + 1);
	for (cp = s; *cp != '\0'; cp++) {
		if (strchr("|&;<>()$`\\\"'*?[# =%", *cp) != NULL)
			*at++ = '\\';
		*at++ = *cp;
	}
	*at = '\0';
	return (out);
}

/* Find a format entry. */
static char *
format_find(struct format_tree *ft, const char *key, int modifiers)
{
	struct format_entry	*fe, fe_find;
	struct environ_entry	*envent;
	static char		 s[64];
	struct options_entry	*o;
	const char		*found;
	int			 idx;
	char			*copy, *saved;

	if (~modifiers & FORMAT_TIMESTRING) {
		o = options_parse_get(global_options, key, &idx, 0);
		if (o == NULL && ft->w != NULL)
			o = options_parse_get(ft->w->options, key, &idx, 0);
		if (o == NULL)
			o = options_parse_get(global_w_options, key, &idx, 0);
		if (o == NULL && ft->s != NULL)
			o = options_parse_get(ft->s->options, key, &idx, 0);
		if (o == NULL)
			o = options_parse_get(global_s_options, key, &idx, 0);
		if (o != NULL) {
			found = options_tostring(o, idx, 1);
			goto found;
		}
	}
	found = NULL;

	fe_find.key = (char *) key;
	fe = RB_FIND(format_entry_tree, &ft->tree, &fe_find);
	if (fe != NULL) {
		if (modifiers & FORMAT_TIMESTRING) {
			if (fe->t == 0)
				return (NULL);
			ctime_r(&fe->t, s);
			s[strcspn(s, "\n")] = '\0';
			found = s;
			goto found;
		}
		if (fe->t != 0) {
			xsnprintf(s, sizeof s, "%lld", (long long)fe->t);
			found = s;
			goto found;
		}
		if (fe->value == NULL && fe->cb != NULL) {
			fe->cb(ft, fe);
			if (fe->value == NULL)
				fe->value = xstrdup("");
		}
		found = fe->value;
		goto found;
	}

	if (~modifiers & FORMAT_TIMESTRING) {
		envent = NULL;
		if (ft->s != NULL)
			envent = environ_find(ft->s->environ, key);
		if (envent == NULL)
			envent = environ_find(global_environ, key);
		if (envent != NULL) {
			found = envent->value;
			goto found;
		}
	}

	return (NULL);

found:
	if (found == NULL)
		return (NULL);
	copy = xstrdup(found);
	if (modifiers & FORMAT_BASENAME) {
		saved = copy;
		copy = xstrdup(basename(saved));
		free(saved);
	}
	if (modifiers & FORMAT_DIRNAME) {
		saved = copy;
		copy = xstrdup(dirname(saved));
		free(saved);
	}
	if (modifiers & FORMAT_QUOTE) {
		saved = copy;
		copy = xstrdup(format_quote(saved));
		free(saved);
	}
	return (copy);
}

/* Skip until end. */
static const char *
format_skip(const char *s, char end)
{
	int	brackets = 0;

	for (; *s != '\0'; s++) {
		if (*s == '#' && s[1] == '{')
			brackets++;
		if (*s == '#' && strchr(",#{}", s[1]) != NULL) {
			s++;
			continue;
		}
		if (*s == '}')
			brackets--;
		if (*s == end && brackets == 0)
			break;
	}
	if (*s == '\0')
		return (NULL);
	return (s);
}

/* Return left and right alternatives separated by commas. */
static int
format_choose(char *s, char **left, char **right)
{
	char	*cp;

	cp = (char *)format_skip(s, ',');
	if (cp == NULL)
		return (-1);
	*cp = '\0';

	*left = s;
	*right = cp + 1;
	return (0);
}

/* Is this true? */
int
format_true(const char *s)
{
	if (s != NULL && *s != '\0' && (s[0] != '0' || s[1] != '\0'))
		return (1);
	return (0);
}

/* Replace a key. */
static int
format_replace(struct format_tree *ft, const char *key, size_t keylen,
    char **buf, size_t *len, size_t *off)
{
	struct window_pane	*wp = ft->wp;
	char			*copy, *copy0, *endptr, *ptr, *found, *new, sep;
	char			*value, *from = NULL, *to = NULL, *left, *right;
	size_t			 valuelen, newlen, fromlen, tolen, used;
	long			 limit = 0;
	int			 modifiers = 0, compare = 0, search = 0;
	int			 literal = 0;

	/* Make a copy of the key. */
	copy0 = copy = xmalloc(keylen + 1);
	memcpy(copy, key, keylen);
	copy[keylen] = '\0';

	/* Is there a length limit or whatnot? */
	switch (copy[0]) {
	case 'l':
		if (copy[1] != ':')
			break;
		literal = 1;
		copy += 2;
		break;
	case 'm':
		if (copy[1] != ':')
			break;
		compare = -2;
		copy += 2;
		break;
	case 'C':
		if (copy[1] != ':')
			break;
		search = 1;
		copy += 2;
		break;
	case '|':
		if (copy[1] != '|' || copy[2] != ':')
			break;
		compare = -3;
		copy += 3;
		break;
	case '&':
		if (copy[1] != '&' || copy[2] != ':')
			break;
		compare = -4;
		copy += 3;
		break;
	case '!':
		if (copy[1] == '=' && copy[2] == ':') {
			compare = -1;
			copy += 3;
			break;
		}
		break;
	case '=':
		if (copy[1] == '=' && copy[2] == ':') {
			compare = 1;
			copy += 3;
			break;
		}
		errno = 0;
		limit = strtol(copy + 1, &endptr, 10);
		if (errno == ERANGE && (limit == LONG_MIN || limit == LONG_MAX))
			break;
		if (*endptr != ':')
			break;
		copy = endptr + 1;
		break;
	case 'b':
		if (copy[1] != ':')
			break;
		modifiers |= FORMAT_BASENAME;
		copy += 2;
		break;
	case 'd':
		if (copy[1] != ':')
			break;
		modifiers |= FORMAT_DIRNAME;
		copy += 2;
		break;
	case 't':
		if (copy[1] != ':')
			break;
		modifiers |= FORMAT_TIMESTRING;
		copy += 2;
		break;
	case 'q':
		if (copy[1] != ':')
			break;
		modifiers |= FORMAT_QUOTE;
		copy += 2;
		break;
	case 's':
		sep = copy[1];
		if (sep == ':' || !ispunct((u_char)sep))
			break;
		from = copy + 2;
		for (copy = from; *copy != '\0' && *copy != sep; copy++)
			/* nothing */;
		if (copy[0] != sep || copy == from) {
			copy = copy0;
			break;
		}
		copy[0] = '\0';
		to = copy + 1;
		for (copy = to; *copy != '\0' && *copy != sep; copy++)
			/* nothing */;
		if (copy[0] != sep || copy[1] != ':') {
			copy = copy0;
			break;
		}
		copy[0] = '\0';

		modifiers |= FORMAT_SUBSTITUTE;
		copy += 2;
		break;
	}

	/* Is this a literal string? */
	if (literal) {
		value = xstrdup(copy);
		goto done;
	}

	/* Is this a comparison or a conditional? */
	if (search) {
		/* Search in pane. */
		if (wp == NULL)
			value = xstrdup("0");
		else
			xasprintf(&value, "%u", window_pane_search(wp, copy));
	} else if (compare != 0) {
		/* Comparison: compare comma-separated left and right. */
		if (format_choose(copy, &left, &right) != 0)
			goto fail;
		left = format_expand(ft, left);
		right = format_expand(ft, right);
		if (compare == -3 &&
		    (format_true(left) || format_true(right)))
			value = xstrdup("1");
		else if (compare == -4 &&
		    (format_true(left) && format_true(right)))
			value = xstrdup("1");
		else if (compare == 1 && strcmp(left, right) == 0)
			value = xstrdup("1");
		else if (compare == -1 && strcmp(left, right) != 0)
			value = xstrdup("1");
		else if (compare == -2 && fnmatch(left, right, 0) == 0)
			value = xstrdup("1");
		else
			value = xstrdup("0");
		free(right);
		free(left);
	} else if (*copy == '?') {
		/* Conditional: check first and choose second or third. */
		ptr = (char *)format_skip(copy, ',');
		if (ptr == NULL)
			goto fail;
		*ptr = '\0';

		found = format_find(ft, copy + 1, modifiers);
		if (found == NULL) {
			/*
			 * If the conditional not found, try to expand it. If
			 * the expansion doesn't have any effect, then assume
			 * false.
			 */
			found = format_expand(ft, copy + 1);
			if (strcmp(found, copy + 1) == 0) {
				free(found);
				found = xstrdup("");
			}
		}
		if (format_choose(ptr + 1, &left, &right) != 0) {
			free(found);
			goto fail;
		}

		if (format_true(found))
			value = format_expand(ft, left);
		else
			value = format_expand(ft, right);
		free(found);
	} else {
		/* Neither: look up directly. */
		value = format_find(ft, copy, modifiers);
		if (value == NULL)
			value = xstrdup("");
	}

	/* Perform substitution if any. */
	if (modifiers & FORMAT_SUBSTITUTE) {
		fromlen = strlen(from);
		tolen = strlen(to);

		newlen = strlen(value) + 1;
		copy = new = xmalloc(newlen);
		for (ptr = value; *ptr != '\0'; /* nothing */) {
			if (strncmp(ptr, from, fromlen) != 0) {
				*new++ = *ptr++;
				continue;
			}
			used = new - copy;

			newlen += tolen;
			copy = xrealloc(copy, newlen);

			new = copy + used;
			memcpy(new, to, tolen);

			new += tolen;
			ptr += fromlen;
		}
		*new = '\0';
		free(value);
		value = copy;
	}

	/* Truncate the value if needed. */
	if (limit > 0) {
		new = utf8_trimcstr(value, limit);
		free(value);
		value = new;
	} else if (limit < 0) {
		new = utf8_rtrimcstr(value, -limit);
		free(value);
		value = new;
	}

done:
	/* Expand the buffer and copy in the value. */
	valuelen = strlen(value);
	while (*len - *off < valuelen + 1) {
		*buf = xreallocarray(*buf, 2, *len);
		*len *= 2;
	}
	memcpy(*buf + *off, value, valuelen);
	*off += valuelen;

	free(value);
	free(copy0);
	return (0);

fail:
	free(copy0);
	return (-1);
}

/* Expand keys in a template, passing through strftime first. */
char *
format_expand_time(struct format_tree *ft, const char *fmt, time_t t)
{
	struct tm	*tm;
	char		 s[2048];

	if (fmt == NULL || *fmt == '\0')
		return (xstrdup(""));

	tm = localtime(&t);

	if (strftime(s, sizeof s, fmt, tm) == 0)
		return (xstrdup(""));

	return (format_expand(ft, s));
}

/* Expand keys in a template. */
char *
format_expand(struct format_tree *ft, const char *fmt)
{
	char		*buf, *out, *name;
	const char	*ptr, *s, *saved = fmt;
	size_t		 off, len, n, outlen;
	int     	 ch, brackets;

	if (fmt == NULL)
		return (xstrdup(""));

	len = 64;
	buf = xmalloc(len);
	off = 0;

	while (*fmt != '\0') {
		if (*fmt != '#') {
			while (len - off < 2) {
				buf = xreallocarray(buf, 2, len);
				len *= 2;
			}
			buf[off++] = *fmt++;
			continue;
		}
		fmt++;

		ch = (u_char) *fmt++;
		switch (ch) {
		case '(':
			brackets = 1;
			for (ptr = fmt; *ptr != '\0'; ptr++) {
				if (*ptr == '(')
					brackets++;
				if (*ptr == ')' && --brackets == 0)
					break;
			}
			if (*ptr != ')' || brackets != 0)
				break;
			n = ptr - fmt;

			if (ft->flags & FORMAT_NOJOBS)
				out = xstrdup("");
			else {
				name = xstrndup(fmt, n);
				out = format_job_get(ft, name);
				free(name);
			}
			outlen = strlen(out);

			while (len - off < outlen + 1) {
				buf = xreallocarray(buf, 2, len);
				len *= 2;
			}
			memcpy(buf + off, out, outlen);
			off += outlen;

			free(out);

			fmt += n + 1;
			continue;
		case '{':
			ptr = format_skip(fmt - 2, '}');
			if (ptr == NULL)
				break;
			n = ptr - fmt;

			if (format_replace(ft, fmt, n, &buf, &len, &off) != 0)
				break;
			fmt += n + 1;
			continue;
		case '}':
		case '#':
		case ',':
			while (len - off < 2) {
				buf = xreallocarray(buf, 2, len);
				len *= 2;
			}
			buf[off++] = ch;
			continue;
		default:
			s = NULL;
			if (ch >= 'A' && ch <= 'Z')
				s = format_upper[ch - 'A'];
			else if (ch >= 'a' && ch <= 'z')
				s = format_lower[ch - 'a'];
			if (s == NULL) {
				while (len - off < 3) {
					buf = xreallocarray(buf, 2, len);
					len *= 2;
				}
				buf[off++] = '#';
				buf[off++] = ch;
				continue;
			}
			n = strlen(s);
			if (format_replace(ft, s, n, &buf, &len, &off) != 0)
				break;
			continue;
		}

		break;
	}
	buf[off] = '\0';

	log_debug("format '%s' -> '%s'", saved, buf);
	return (buf);
}

/* Expand a single string. */
char *
format_single(struct cmdq_item *item, const char *fmt, struct client *c,
    struct session *s, struct winlink *wl, struct window_pane *wp)
{
	struct format_tree	*ft;
	char			*expanded;

	if (item != NULL)
		ft = format_create(item->client, item, FORMAT_NONE, 0);
	else
		ft = format_create(NULL, item, FORMAT_NONE, 0);
	format_defaults(ft, c, s, wl, wp);

	expanded = format_expand(ft, fmt);
	format_free(ft);
	return (expanded);
}

/* Set defaults for any of arguments that are not NULL. */
void
format_defaults(struct format_tree *ft, struct client *c, struct session *s,
    struct winlink *wl, struct window_pane *wp)
{
	if (c != NULL && s != NULL && c->session != s)
		log_debug("%s: session does not match", __func__);

	format_add(ft, "session_format", "%d", s != NULL);
	format_add(ft, "window_format", "%d", wl != NULL);
	format_add(ft, "pane_format", "%d", wp != NULL);

	if (s == NULL && c != NULL)
		s = c->session;
	if (wl == NULL && s != NULL)
		wl = s->curw;
	if (wp == NULL && wl != NULL)
		wp = wl->window->active;

	if (c != NULL)
		format_defaults_client(ft, c);
	if (s != NULL)
		format_defaults_session(ft, s);
	if (wl != NULL)
		format_defaults_winlink(ft, wl);
	if (wp != NULL)
		format_defaults_pane(ft, wp);
}

/* Set default format keys for a session. */
static void
format_defaults_session(struct format_tree *ft, struct session *s)
{
	struct session_group	*sg;

	ft->s = s;

	format_add(ft, "session_name", "%s", s->name);
	format_add(ft, "session_windows", "%u", winlink_count(&s->windows));
	format_add(ft, "session_id", "$%u", s->id);

	sg = session_group_contains(s);
	format_add(ft, "session_grouped", "%d", sg != NULL);
	if (sg != NULL) {
		format_add(ft, "session_group", "%s", sg->name);
		format_add(ft, "session_group_size", "%u",
		    session_group_count (sg));
		format_add_cb(ft, "session_group_list",
		    format_cb_session_group_list);
	}

	format_add_tv(ft, "session_created", &s->creation_time);
	format_add_tv(ft, "session_last_attached", &s->last_attached_time);
	format_add_tv(ft, "session_activity", &s->activity_time);

	format_add(ft, "session_attached", "%u", s->attached);
	format_add(ft, "session_many_attached", "%d", s->attached > 1);

	format_add_cb(ft, "session_alerts", format_cb_session_alerts);
	format_add_cb(ft, "session_stack", format_cb_session_stack);
}

/* Set default format keys for a client. */
static void
format_defaults_client(struct format_tree *ft, struct client *c)
{
	struct session	*s;
	const char	*name;
	struct tty	*tty = &c->tty;
	const char	*types[] = TTY_TYPES;

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

	format_add(ft, "client_name", "%s", c->name);
	format_add(ft, "client_pid", "%ld", (long) c->pid);
	format_add(ft, "client_height", "%u", tty->sy);
	format_add(ft, "client_width", "%u", tty->sx);
	format_add(ft, "client_tty", "%s", c->ttyname);
	format_add(ft, "client_control_mode", "%d",
		!!(c->flags & CLIENT_CONTROL));

	if (tty->term_name != NULL)
		format_add(ft, "client_termname", "%s", tty->term_name);
	if (tty->term_name != NULL)
		format_add(ft, "client_termtype", "%s", types[tty->term_type]);

	format_add_tv(ft, "client_created", &c->creation_time);
	format_add_tv(ft, "client_activity", &c->activity_time);

	format_add(ft, "client_written", "%zu", c->written);
	format_add(ft, "client_discarded", "%zu", c->discarded);

	name = server_client_get_key_table(c);
	if (strcmp(c->keytable->name, name) == 0)
		format_add(ft, "client_prefix", "%d", 0);
	else
		format_add(ft, "client_prefix", "%d", 1);
	format_add(ft, "client_key_table", "%s", c->keytable->name);

	if (tty->flags & TTY_UTF8)
		format_add(ft, "client_utf8", "%d", 1);
	else
		format_add(ft, "client_utf8", "%d", 0);

	if (c->flags & CLIENT_READONLY)
		format_add(ft, "client_readonly", "%d", 1);
	else
		format_add(ft, "client_readonly", "%d", 0);

	s = c->session;
	if (s != NULL)
		format_add(ft, "client_session", "%s", s->name);
	s = c->last_session;
	if (s != NULL && session_alive(s))
		format_add(ft, "client_last_session", "%s", s->name);
}

/* Set default format keys for a window. */
void
format_defaults_window(struct format_tree *ft, struct window *w)
{
	ft->w = w;

	format_add_tv(ft, "window_activity", &w->activity_time);
	format_add(ft, "window_id", "@%u", w->id);
	format_add(ft, "window_name", "%s", w->name);
	format_add(ft, "window_width", "%u", w->sx);
	format_add(ft, "window_height", "%u", w->sy);
	format_add_cb(ft, "window_layout", format_cb_window_layout);
	format_add_cb(ft, "window_visible_layout",
	    format_cb_window_visible_layout);
	format_add(ft, "window_panes", "%u", window_count_panes(w));
	format_add(ft, "window_zoomed_flag", "%d",
	    !!(w->flags & WINDOW_ZOOMED));
}

/* Set default format keys for a winlink. */
static void
format_defaults_winlink(struct format_tree *ft, struct winlink *wl)
{
	struct client	*c = ft->c;
	struct session	*s = wl->session;
	struct window	*w = wl->window;
	int		 flag;
	u_int		 ox, oy, sx, sy;

	if (ft->w == NULL)
		ft->w = wl->window;
	ft->wl = wl;

	format_defaults_window(ft, w);

	if (c != NULL) {
		flag = tty_window_offset(&c->tty, &ox, &oy, &sx, &sy);
		format_add(ft, "window_bigger", "%d", flag);
		if (flag) {
			format_add(ft, "window_offset_x", "%u", ox);
			format_add(ft, "window_offset_y", "%u", oy);
		}
	}

	format_add(ft, "window_index", "%d", wl->idx);
	format_add_cb(ft, "window_stack_index", format_cb_window_stack_index);
	format_add(ft, "window_flags", "%s", window_printable_flags(wl));
	format_add(ft, "window_active", "%d", wl == s->curw);

	format_add(ft, "window_bell_flag", "%d",
	    !!(wl->flags & WINLINK_BELL));
	format_add(ft, "window_activity_flag", "%d",
	    !!(wl->flags & WINLINK_ACTIVITY));
	format_add(ft, "window_silence_flag", "%d",
	    !!(wl->flags & WINLINK_SILENCE));
	format_add(ft, "window_last_flag", "%d",
	    !!(wl == TAILQ_FIRST(&s->lastw)));
	format_add(ft, "window_linked", "%d", session_is_linked(s, wl->window));
}

/* Set default format keys for a window pane. */
void
format_defaults_pane(struct format_tree *ft, struct window_pane *wp)
{
	struct window	*w = wp->window;
	struct grid	*gd = wp->base.grid;
	int  		 status = wp->status;
	u_int		 idx;

	if (ft->w == NULL)
		ft->w = w;
	ft->wp = wp;

	format_add(ft, "history_size", "%u", gd->hsize);
	format_add(ft, "history_limit", "%u", gd->hlimit);
	format_add_cb(ft, "history_bytes", format_cb_history_bytes);

	if (window_pane_index(wp, &idx) != 0)
		fatalx("index not found");
	format_add(ft, "pane_index", "%u", idx);

	format_add(ft, "pane_width", "%u", wp->sx);
	format_add(ft, "pane_height", "%u", wp->sy);
	format_add(ft, "pane_title", "%s", wp->base.title);
	format_add(ft, "pane_id", "%%%u", wp->id);
	format_add(ft, "pane_active", "%d", wp == w->active);
	format_add(ft, "pane_input_off", "%d", !!(wp->flags & PANE_INPUTOFF));
	format_add(ft, "pane_pipe", "%d", wp->pipe_fd != -1);

	if ((wp->flags & PANE_STATUSREADY) && WIFEXITED(status))
		format_add(ft, "pane_dead_status", "%d", WEXITSTATUS(status));
	format_add(ft, "pane_dead", "%d", wp->fd == -1);

	format_add(ft, "pane_left", "%u", wp->xoff);
	format_add(ft, "pane_top", "%u", wp->yoff);
	format_add(ft, "pane_right", "%u", wp->xoff + wp->sx - 1);
	format_add(ft, "pane_bottom", "%u", wp->yoff + wp->sy - 1);
	format_add(ft, "pane_at_left", "%d", wp->xoff == 0);
	format_add(ft, "pane_at_top", "%d", wp->yoff == 0);
	format_add(ft, "pane_at_right", "%d", wp->xoff + wp->sx == w->sx);
	format_add(ft, "pane_at_bottom", "%d", wp->yoff + wp->sy == w->sy);

	format_add(ft, "pane_in_mode", "%d", wp->screen != &wp->base);
	if (wp->mode != NULL)
		format_add(ft, "pane_mode", "%s", wp->mode->name);

	format_add(ft, "pane_synchronized", "%d",
	    !!options_get_number(w->options, "synchronize-panes"));
	if (wp->searchstr != NULL)
		format_add(ft, "pane_search_string", "%s", wp->searchstr);

	format_add(ft, "pane_tty", "%s", wp->tty);
	format_add(ft, "pane_pid", "%ld", (long) wp->pid);
	format_add_cb(ft, "pane_start_command", format_cb_start_command);
	format_add_cb(ft, "pane_current_command", format_cb_current_command);

	format_add(ft, "cursor_x", "%u", wp->base.cx);
	format_add(ft, "cursor_y", "%u", wp->base.cy);
	format_add(ft, "scroll_region_upper", "%u", wp->base.rupper);
	format_add(ft, "scroll_region_lower", "%u", wp->base.rlower);

	window_copy_add_formats(wp, ft);

	format_add(ft, "alternate_on", "%d", wp->saved_grid ? 1 : 0);
	format_add(ft, "alternate_saved_x", "%u", wp->saved_cx);
	format_add(ft, "alternate_saved_y", "%u", wp->saved_cy);

	format_add(ft, "cursor_flag", "%d",
	    !!(wp->base.mode & MODE_CURSOR));
	format_add(ft, "insert_flag", "%d",
	    !!(wp->base.mode & MODE_INSERT));
	format_add(ft, "keypad_cursor_flag", "%d",
	    !!(wp->base.mode & MODE_KCURSOR));
	format_add(ft, "keypad_flag", "%d",
	    !!(wp->base.mode & MODE_KKEYPAD));
	format_add(ft, "wrap_flag", "%d",
	    !!(wp->base.mode & MODE_WRAP));

	format_add(ft, "mouse_any_flag", "%d",
	    !!(wp->base.mode & ALL_MOUSE_MODES));
	format_add(ft, "mouse_standard_flag", "%d",
	    !!(wp->base.mode & MODE_MOUSE_STANDARD));
	format_add(ft, "mouse_button_flag", "%d",
	    !!(wp->base.mode & MODE_MOUSE_BUTTON));
	format_add(ft, "mouse_all_flag", "%d",
	    !!(wp->base.mode & MODE_MOUSE_ALL));

	format_add_cb(ft, "pane_tabs", format_cb_pane_tabs);
}

/* Set default format keys for paste buffer. */
void
format_defaults_paste_buffer(struct format_tree *ft, struct paste_buffer *pb)
{
	struct timeval	 tv;
	size_t		 size;
	char		*s;

	timerclear(&tv);
	tv.tv_sec = paste_buffer_created(pb);
	paste_buffer_data(pb, &size);

	format_add(ft, "buffer_size", "%zu", size);
	format_add(ft, "buffer_name", "%s", paste_buffer_name(pb));
	format_add_tv(ft, "buffer_created", &tv);

	s = paste_make_sample(pb);
	format_add(ft, "buffer_sample", "%s", s);
	free(s);
}