/src/tmux/format.c

Source
/* $OpenBSD: format.c,v 1.410 2026/07/29 20:43:20 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 <math.h>
#include <pwd.h>
#include <regex.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_expand_state;

static char *format_job_get(struct format_expand_state *, const char *);
static char *format_quote_shell_single(const char *);
static char *format_expand1(struct format_expand_state *, const char *);
static int   format_replace(struct format_expand_state *, 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 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));
}

/* Maximum pad and trim width. */
#define FORMAT_MAX_WIDTH 10000

/* Maximum repeat size. */
#define FORMAT_MAX_REPEAT 10000

/* Maximum precision. */
#define FORMAT_MAX_PRECISION 100

/* Format modifiers. */
#define FORMAT_TIMESTRING 0x1
#define FORMAT_BASENAME 0x2
#define FORMAT_DIRNAME 0x4
#define FORMAT_QUOTE_SHELL 0x8
#define FORMAT_LITERAL 0x10
#define FORMAT_EXPAND 0x20
#define FORMAT_EXPANDTIME 0x40
#define FORMAT_SESSIONS 0x80
#define FORMAT_WINDOWS 0x100
#define FORMAT_PANES 0x200
#define FORMAT_PRETTY 0x400
#define FORMAT_LENGTH 0x800
#define FORMAT_WIDTH 0x1000
#define FORMAT_QUOTE_STYLE 0x2000
#define FORMAT_WINDOW_NAME 0x4000
#define FORMAT_SESSION_NAME 0x8000
#define FORMAT_CHARACTER 0x10000
#define FORMAT_COLOUR 0x20000
#define FORMAT_CLIENTS 0x40000
#define FORMAT_NOT 0x80000
#define FORMAT_NOT_NOT 0x100000
#define FORMAT_REPEAT 0x200000
#define FORMAT_QUOTE_ARGUMENTS 0x400000
#define FORMAT_RELATIVE 0x800000
#define FORMAT_CLIENT_TERMCAP 0x1000000
#define FORMAT_CLIENT_TERMFEAT 0x2000000
#define FORMAT_CLIENT_ENVIRON 0x4000000
#define FORMAT_COLOUR_ESC_FG 0x8000000
#define FORMAT_COLOUR_ESC_BG 0x10000000
#define FORMAT_QUOTE_SHELL_SQ 0x20000000
#define FORMAT_OPTIONS 0x40000000
#define FORMAT_ENVIRON 0x80000000ULL
#define FORMAT_DIFFERENCE 0x100000000ULL
#define FORMAT_CYCLE 0x200000000ULL

/* Limit on recursion. */
#define FORMAT_LOOP_LIMIT 100

/* Limit on time taken (milliseconds). */
#define FORMAT_TIME_LIMIT 100

/* How often to check the time in long loops. */
#define FORMAT_TIME_LOOP_CHECK 10000

/* Fixed animation period (ms): redraw interval and shortest frame step. */
#define FORMAT_CYCLE_PERIOD 100

/* Format expand flags. */
#define FORMAT_EXPAND_TIME 0x1
#define FORMAT_EXPAND_NOJOBS 0x2
#define FORMAT_EXPAND_NOCYCLE 0x4

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

/* Format type. */
enum format_type {
  FORMAT_TYPE_UNKNOWN,
  FORMAT_TYPE_SESSION,
  FORMAT_TYPE_WINDOW,
  FORMAT_TYPE_PANE
};

static struct sort_criteria sort_crit;

struct format_tree {
  enum format_type   type;

  struct client   *c;
  struct session    *s;
  struct winlink    *wl;
  struct window   *w;
  struct window_pane  *wp;
  struct paste_buffer *pb;

  struct cmdq_item  *item;
  struct client   *client;
  int      flags;
  u_int      tag;

  struct mouse_event   m;

  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 expand state. */
struct format_expand_state {
  struct format_tree  *ft;
  u_int      loop;
  uint64_t     start_time;
  int      flags;

  time_t       time;
  struct tm    tm;
};

/* Format modifier. */
struct format_modifier {
  char    modifier[3];
  u_int   size;

  char  **argv;
  int   argc;
};

/* 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 */
};

/* Is logging enabled? */
static inline int
format_logging(struct format_tree *ft)
{
  return (log_get_level() != 0 || (ft->flags & FORMAT_VERBOSE));
}

/* Log a message if verbose. */
static void printflike(3, 4)
format_log1(struct format_expand_state *es, const char *from, const char *fmt,
    ...)
{
  struct format_tree  *ft = es->ft;
  va_list      ap;
  char      *s;
  static const char  spaces[] = "          ";

  if (!format_logging(ft))
    return;

  va_start(ap, fmt);
  xvasprintf(&s, fmt, ap);
  va_end(ap);

  log_debug("%s: %s", from, s);
  if (ft->item != NULL && (ft->flags & FORMAT_VERBOSE))
    cmdq_print(ft->item, "#%.*s%s", es->loop, spaces, s);

  free(s);
}
#define format_log(es, fmt, ...) format_log1(es, __func__, fmt, ##__VA_ARGS__)

/* Copy expand state. */
static void
format_copy_state(struct format_expand_state *to,
    struct format_expand_state *from, int flags)
{
  to->ft = from->ft;
  to->loop = from->loop;
  to->time = from->time;
  memcpy(&to->tm, &from->tm, sizeof to->tm);
  to->flags = from->flags|flags;
  to->start_time = from->start_time;
}

/* 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_expand_state *es, const char *cmd)
{
  struct format_tree    *ft = es->ft;
  struct format_job_tree    *jobs;
  struct format_job    fj0, *fj;
  time_t         t;
  char        *expanded;
  int        force;
  struct format_expand_state   next;

  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);

    RB_INSERT(format_job_tree, jobs, fj);
  }

  format_copy_state(&next, es, FORMAT_EXPAND_NOJOBS|
      FORMAT_EXPAND_NOCYCLE);
  next.flags &= ~FORMAT_EXPAND_TIME;

  expanded = format_expand1(&next, 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 (force && fj->job != NULL)
         job_free(fj->job);
  if (force || (fj->job == NULL && fj->last != t)) {
    fj->job = job_run(expanded, 0, NULL, NULL, NULL,
        server_client_get_cwd(ft->client, NULL), format_job_update,
        format_job_complete, NULL, fj, JOB_NOWAIT, -1, -1);
    if (fj->job == NULL) {
      free(fj->out);
      xasprintf(&fj->out, "<'%s' didn't start>", fj->cmd);
    }
    fj->last = t;
    fj->updated = 0;
  } else if (fj->job != NULL && (t - fj->last) > 1 && fj->out == NULL)
    xasprintf(&fj->out, "<'%s' not ready>", fj->cmd);
  free(expanded);

  if (ft->flags & FORMAT_STATUS)
    fj->status = 1;
  if (fj->out == NULL)
    return (xstrdup(""));
  return (format_expand1(&next, 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);
  }
}

/* Work around needless -Wformat-nonliteral gcc warning. */
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-nonliteral"
#endif
static size_t
format_strftime(char *s, size_t max, const char *fmt, const struct tm *tm)
{
  return (strftime(s, max, fmt, tm));
}
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif

/* Tidy old jobs for all clients. */
void
format_tidy_jobs(void)
{
  struct client *c;

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

/* 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);
}

/* Wrapper for asprintf. */
static char * printflike(1, 2)
format_printf(const char *fmt, ...)
{
  va_list  ap;
  char  *s;

  va_start(ap, fmt);
  xvasprintf(&s, fmt, ap);
  va_end(ap);
  return (s);
}

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

  if (gethostname(host, sizeof host) != 0)
    return (xstrdup(""));
  return (xstrdup(host));
}

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

  if (gethostname(host, sizeof host) != 0)
    return (xstrdup(""));
  if ((cp = strchr(host, '.')) != NULL)
    *cp = '\0';
  return (xstrdup(host));
}

/* Callback for pid. */
static void *
format_cb_pid(__unused struct format_tree *ft)
{
  char  *value;

  xasprintf(&value, "%ld", (long)getpid());
  return (value);
}

/* Callback for session_attached_list. */
static void *
format_cb_session_attached_list(struct format_tree *ft)
{
  struct session  *s = ft->s;
  struct client *loop;
  struct evbuffer *buffer;
  int    size;
  char    *value = NULL;

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

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  TAILQ_FOREACH(loop, &clients, entry) {
    if (loop->session == s) {
      if (EVBUFFER_LENGTH(buffer) > 0)
        evbuffer_add(buffer, ",", 1);
      evbuffer_add_printf(buffer, "%s", loop->name);
    }
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  evbuffer_free(buffer);
  return (value);
}

/* Callback for session_alert. */
static void *
format_cb_session_alert(struct format_tree *ft)
{
  struct session  *s = ft->s;
  struct winlink  *wl;
  char     alerts[1024];
  int    alerted = 0;

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

  *alerts = '\0';
  RB_FOREACH(wl, winlinks, &s->windows) {
    if ((wl->flags & WINLINK_ALERTFLAGS) == 0)
      continue;
    if (~alerted & wl->flags & WINLINK_ACTIVITY) {
      strlcat(alerts, "#", sizeof alerts);
      alerted |= WINLINK_ACTIVITY;
    }
    if (~alerted & wl->flags & WINLINK_BELL) {
      strlcat(alerts, "!", sizeof alerts);
      alerted |= WINLINK_BELL;
    }
    if (~alerted & wl->flags & WINLINK_SILENCE) {
      strlcat(alerts, "~", sizeof alerts);
      alerted |= WINLINK_SILENCE;
    }
  }
  return (xstrdup(alerts));
}

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

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

  *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);
  }
  return (xstrdup(alerts));
}

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

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

  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);
  }
  return (xstrdup(result));
}

/* Callback for window_stack_index. */
static void *
format_cb_window_stack_index(struct format_tree *ft)
{
  struct session  *s;
  struct winlink  *wl;
  u_int    idx;
  char    *value = NULL;

  if (ft->wl == NULL)
    return (NULL);
  s = ft->wl->session;

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

/* Callback for window_linked_sessions_list. */
static void *
format_cb_window_linked_sessions_list(struct format_tree *ft)
{
  struct window *w;
  struct winlink  *wl;
  struct evbuffer *buffer;
  int    size;
  char    *value = NULL;

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

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  TAILQ_FOREACH(wl, &w->winlinks, wentry) {
    if (EVBUFFER_LENGTH(buffer) > 0)
      evbuffer_add(buffer, ",", 1);
    evbuffer_add_printf(buffer, "%s", wl->session->name);
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  evbuffer_free(buffer);
  return (value);
}

/* Callback for window_active_sessions. */
static void *
format_cb_window_active_sessions(struct format_tree *ft)
{
  struct window *w;
  struct winlink  *wl;
  u_int    n = 0;
  char    *value;

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

  TAILQ_FOREACH(wl, &w->winlinks, wentry) {
    if (wl->session->curw == wl)
      n++;
  }

  xasprintf(&value, "%u", n);
  return (value);
}

/* Callback for window_active_sessions_list. */
static void *
format_cb_window_active_sessions_list(struct format_tree *ft)
{
  struct window *w;
  struct winlink  *wl;
  struct evbuffer *buffer;
  int    size;
  char    *value = NULL;

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

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  TAILQ_FOREACH(wl, &w->winlinks, wentry) {
    if (wl->session->curw == wl) {
      if (EVBUFFER_LENGTH(buffer) > 0)
        evbuffer_add(buffer, ",", 1);
      evbuffer_add_printf(buffer, "%s", wl->session->name);
    }
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  evbuffer_free(buffer);
  return (value);
}

/* Callback for window_active_clients. */
static void *
format_cb_window_active_clients(struct format_tree *ft)
{
  struct window *w;
  struct client *loop;
  struct session  *client_session;
  u_int    n = 0;
  char    *value;

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

  TAILQ_FOREACH(loop, &clients, entry) {
    client_session = loop->session;
    if (client_session == NULL)
      continue;

    if (w == client_session->curw->window)
      n++;
  }

  xasprintf(&value, "%u", n);
  return (value);
}

/* Callback for window_active_clients_list. */
static void *
format_cb_window_active_clients_list(struct format_tree *ft)
{
  struct window *w;
  struct client *loop;
  struct session  *client_session;
  struct evbuffer *buffer;
  int    size;
  char    *value = NULL;

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

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  TAILQ_FOREACH(loop, &clients, entry) {
    client_session = loop->session;
    if (client_session == NULL)
      continue;

    if (w == client_session->curw->window) {
      if (EVBUFFER_LENGTH(buffer) > 0)
        evbuffer_add(buffer, ",", 1);
      evbuffer_add_printf(buffer, "%s", loop->name);
    }
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  evbuffer_free(buffer);
  return (value);
}

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

  if (w == NULL)
    return (NULL);

  if (w->saved_layout_root != NULL)
    return (layout_dump(w, w->saved_layout_root));
  return (layout_dump(w, w->layout_root));
}

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

  if (w == NULL)
    return (NULL);

  return (layout_dump(w, w->layout_root));
}

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

  if (wp == NULL)
    return (NULL);

  return (cmd_stringify_argv(wp->argc, wp->argv));
}

/* Callback for pane_start_command_list. */
static void *
format_cb_start_command_list(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  char      *buf = NULL, *s;
  size_t       len = 0;
  int      i;

  if (wp == NULL)
    return (NULL);
  if (wp->argc == 0)
    return (xstrdup(""));

  for (i = 0; i < wp->argc; i++) {
    s = format_quote_shell_single(wp->argv[i]);

    len += strlen(s) + 1;
    buf = xrealloc(buf, len);

    if (i == 0)
      *buf = '\0';
    else
      strlcat(buf, " ", len);
    strlcat(buf, s, len);

    free(s);
  }
  return (buf);
}

/* Callback for pane_start_path. */
static void *
format_cb_start_path(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp == NULL)
    return (NULL);

  if (wp->cwd == NULL)
    return (xstrdup(""));
  return (xstrdup(wp->cwd));
}

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

  if (wp == NULL || wp->shell == NULL)
    return (NULL);

  cmd = osdep_get_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);
    }
  }
  value = parse_window_name(cmd);
  free(cmd);
  return (value);
}

/* Callback for pane_current_path. */
static void *
format_cb_current_path(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  char      *cwd;

  if (wp == NULL)
    return (NULL);

  cwd = osdep_get_cwd(wp->fd);
  if (cwd == NULL)
    return (NULL);
  return (xstrdup(cwd));
}

/* Callback for history_bytes. */
static void *
format_cb_history_bytes(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct grid   *gd;
  struct grid_line  *gl;
  size_t       size = 0;
  u_int      i;
  char      *value;

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

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

  xasprintf(&value, "%zu", size);
  return (value);
}

/* Callback for history_all_bytes. */
static void *
format_cb_history_all_bytes(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct grid   *gd;
  struct grid_line  *gl;
  u_int      i, lines, cells = 0, extended_cells = 0;
  char      *value;

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

  lines = gd->hsize + gd->sy;
  for (i = 0; i < lines; i++) {
    gl = grid_get_line(gd, i);
    cells += gl->cellsize;
    extended_cells += gl->extdsize;
  }

  xasprintf(&value, "%u,%zu,%u,%zu,%u,%zu", lines,
      lines * sizeof *gl, cells, cells * sizeof *gl->celldata,
      extended_cells, extended_cells * sizeof *gl->extddata);
  return (value);
}

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

  if (wp == NULL)
    return (NULL);

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");
  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)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  evbuffer_free(buffer);
  return (value);
}

/* Callback for pane_fg. */
static void *
format_cb_pane_fg(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct grid_cell   gc;

  if (wp == NULL)
    return (NULL);

  tty_default_colours(&gc, wp, NULL);
  return (xstrdup(colour_tostring(gc.fg)));
}

/* Callback for pane_flags. */
static void *
format_cb_pane_flags(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (xstrdup(window_pane_printable_flags(ft->wp)));
  return (NULL);
}

/* Callback for pane_floating_flag. */
static void *
format_cb_pane_floating_flag(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL) {
    if (window_pane_is_floating(wp))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_modal_flag. */
static void *
format_cb_pane_modal_flag(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL) {
    if (wp == wp->window->modal)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_bg. */
static void *
format_cb_pane_bg(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct grid_cell   gc;

  if (wp == NULL)
    return (NULL);

  tty_default_colours(&gc, wp, NULL);
  return (xstrdup(colour_tostring(gc.bg)));
}

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

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

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  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)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  evbuffer_free(buffer);
  return (value);
}

/* Callback for session_group_attached_list. */
static void *
format_cb_session_group_attached_list(struct format_tree *ft)
{
  struct session    *s = ft->s, *client_session, *session_loop;
  struct session_group  *sg;
  struct client   *loop;
  struct evbuffer   *buffer;
  int      size;
  char      *value = NULL;

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

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  TAILQ_FOREACH(loop, &clients, entry) {
    client_session = loop->session;
    if (client_session == NULL)
      continue;
    TAILQ_FOREACH(session_loop, &sg->sessions, gentry) {
      if (session_loop == client_session){
        if (EVBUFFER_LENGTH(buffer) > 0)
          evbuffer_add(buffer, ",", 1);
        evbuffer_add_printf(buffer, "%s", loop->name);
      }
    }
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  evbuffer_free(buffer);
  return (value);
}

/* Callback for pane_in_mode. */
static void *
format_cb_pane_in_mode(struct format_tree *ft)
{
  struct window_pane    *wp = ft->wp;
  u_int        n = 0;
  struct window_mode_entry  *wme;
  char        *value;

  if (wp == NULL)
    return (NULL);

  TAILQ_FOREACH(wme, &wp->modes, entry)
    n++;
  xasprintf(&value, "%u", n);
  return (value);
}

/* Callback for pane_at_top. */
static void *
format_cb_pane_at_top(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  int      status, flag;
  char      *value;

  if (wp == NULL)
    return (NULL);

  status = window_pane_get_pane_status(wp);
  if (status == PANE_STATUS_TOP)
    flag = (wp->yoff == 1);
  else
    flag = (wp->yoff == 0);
  xasprintf(&value, "%d", flag);
  return (value);
}

/* Callback for pane_at_bottom. */
static void *
format_cb_pane_at_bottom(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct window   *w;
  int      status, flag;
  char      *value;

  if (wp == NULL)
    return (NULL);
  w = wp->window;

  status = window_pane_get_pane_status(wp);
  if (status == PANE_STATUS_BOTTOM)
    flag = (wp->yoff + (int)wp->sy == (int)w->sy - 1);
  else
    flag = (wp->yoff + (int)wp->sy == (int)w->sy);
  xasprintf(&value, "%d", flag);
  return (value);
}

/* Callback for cursor_character. */
static void *
format_cb_cursor_character(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct grid_cell   gc;
  char      *value = NULL;

  if (wp == NULL)
    return (NULL);

  grid_view_get_cell(wp->base.grid, wp->base.cx, wp->base.cy, &gc);
  if (~gc.flags & GRID_FLAG_PADDING)
    xasprintf(&value, "%.*s", (int)gc.data.size, gc.data.data);
  return (value);
}

/* Callback for cursor_colour. */
static void *
format_cb_cursor_colour(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp == NULL || wp->screen == NULL)
    return (NULL);

  if (wp->screen->ccolour != -1)
    return (xstrdup(colour_tostring(wp->screen->ccolour)));
  return (xstrdup(colour_tostring(wp->screen->default_ccolour)));
}

/* Callback for mouse_word. */
static void *
format_cb_mouse_word(struct format_tree *ft)
{
  struct window_pane  *wp;
  struct grid   *gd;
  u_int      x, y;

  if (!ft->m.valid)
    return (NULL);
  wp = cmd_mouse_pane(&ft->m, NULL, NULL);
  if (wp == NULL)
    return (NULL);
  if (cmd_mouse_at(wp, &ft->m, &x, &y, 0) != 0)
    return (NULL);

  if (!TAILQ_EMPTY(&wp->modes)) {
    if (window_pane_mode(wp) != WINDOW_PANE_NO_MODE)
      return (window_copy_get_word(wp, x, y));
    return (NULL);
  }
  gd = wp->base.grid;
  return (format_grid_word(gd, x, gd->hsize + y));
}

/* Callback for mouse_hyperlink. */
static void *
format_cb_mouse_hyperlink(struct format_tree *ft)
{
  struct window_pane  *wp;
  struct grid   *gd;
  u_int      x, y;

  if (!ft->m.valid)
    return (NULL);
  wp = cmd_mouse_pane(&ft->m, NULL, NULL);
  if (wp == NULL)
    return (NULL);
  if (cmd_mouse_at(wp, &ft->m, &x, &y, 0) != 0)
    return (NULL);

  if (!TAILQ_EMPTY(&wp->modes)) {
    if (window_pane_mode(wp) != WINDOW_PANE_NO_MODE)
      return (window_copy_get_hyperlink(wp, x, y));
    return (NULL);
  }
  gd = wp->base.grid;
  return (format_grid_hyperlink(gd, x, gd->hsize + y, wp->screen));
}

/* Callback for mouse_line. */
static void *
format_cb_mouse_line(struct format_tree *ft)
{
  struct window_pane  *wp;
  struct grid   *gd;
  u_int      x, y;

  if (!ft->m.valid)
    return (NULL);
  wp = cmd_mouse_pane(&ft->m, NULL, NULL);
  if (wp == NULL)
    return (NULL);
  if (cmd_mouse_at(wp, &ft->m, &x, &y, 0) != 0)
    return (NULL);

  if (!TAILQ_EMPTY(&wp->modes)) {
    if (window_pane_mode(wp) != WINDOW_PANE_NO_MODE)
      return (window_copy_get_line(wp, y));
    return (NULL);
  }
  gd = wp->base.grid;
  return (format_grid_line(gd, gd->hsize + y));
}

/* Callback for mouse_status_line. */
static void *
format_cb_mouse_status_line(struct format_tree *ft)
{
  char  *value;
  u_int  y;

  if (!ft->m.valid)
    return (NULL);
  if (ft->c == NULL || (~ft->c->tty.flags & TTY_STARTED))
    return (NULL);

  if (ft->m.statusat == 0 && ft->m.y < ft->m.statuslines) {
    y = ft->m.y;
  } else if (ft->m.statusat > 0 && ft->m.y >= (u_int)ft->m.statusat) {
    y = ft->m.y - ft->m.statusat;
  } else
    return (NULL);
  xasprintf(&value, "%u", y);
  return (value);

}

/* Callback for mouse_status_range. */
static void *
format_cb_mouse_status_range(struct format_tree *ft)
{
  struct style_range  *sr;
  u_int      x, y;

  if (!ft->m.valid)
    return (NULL);
  if (ft->c == NULL || (~ft->c->tty.flags & TTY_STARTED))
    return (NULL);

  if (ft->m.statusat == 0 && ft->m.y < ft->m.statuslines) {
    x = ft->m.x;
    y = ft->m.y;
  } else if (ft->m.statusat > 0 && ft->m.y >= (u_int)ft->m.statusat) {
    x = ft->m.x;
    y = ft->m.y - ft->m.statusat;
  } else
    return (NULL);

  sr = status_get_range(ft->c, x, y);
  if (sr == NULL)
    return (NULL);
  switch (sr->type) {
  case STYLE_RANGE_NONE:
    return (NULL);
  case STYLE_RANGE_LEFT:
    return (xstrdup("left"));
  case STYLE_RANGE_RIGHT:
    return (xstrdup("right"));
  case STYLE_RANGE_PANE:
    return (xstrdup("pane"));
  case STYLE_RANGE_WINDOW:
    return (xstrdup("window"));
  case STYLE_RANGE_SESSION:
    return (xstrdup("session"));
  case STYLE_RANGE_USER:
    return (xstrdup(sr->string));
  case STYLE_RANGE_CONTROL:
    return (xstrdup("control"));
  }
  return (NULL);
}

/* Callback for alternate_on. */
static void *
format_cb_alternate_on(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.saved_grid != NULL)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for alternate_saved_x. */
static void *
format_cb_alternate_saved_x(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.saved_cx));
  return (NULL);
}

/* Callback for alternate_saved_y. */
static void *
format_cb_alternate_saved_y(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.saved_cy));
  return (NULL);
}

/* Callback for bracket_paste_flag. */
static void *
format_cb_bracket_paste_flag(struct format_tree *ft)
{
  if (ft->wp != NULL && ft->wp->screen != NULL) {
    if (ft->wp->screen->mode & MODE_BRACKETPASTE)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for buffer_name. */
static void *
format_cb_buffer_name(struct format_tree *ft)
{
  if (ft->pb != NULL)
    return (xstrdup(paste_buffer_name(ft->pb)));
  return (NULL);
}

/* Callback for buffer_sample. */
static void *
format_cb_buffer_sample(struct format_tree *ft)
{
  if (ft->pb != NULL)
    return (paste_make_sample(ft->pb));
  return (NULL);
}

/* Callback for buffer_full. */
static void *
format_cb_buffer_full(struct format_tree *ft)
{
  size_t     size;
  const char  *s;

  if (ft->pb != NULL) {
    s = paste_buffer_data(ft->pb, &size);
    if (s != NULL)
      return (xstrndup(s, size));
  }
  return (NULL);
}

/* Callback for buffer_size. */
static void *
format_cb_buffer_size(struct format_tree *ft)
{
  size_t  size;

  if (ft->pb != NULL) {
    paste_buffer_data(ft->pb, &size);
    return (format_printf("%zu", size));
  }
  return (NULL);
}

/* Callback for client_cell_height. */
static void *
format_cb_client_cell_height(struct format_tree *ft)
{
  if (ft->c != NULL && (ft->c->tty.flags & TTY_STARTED))
    return (format_printf("%u", ft->c->tty.ypixel));
  return (NULL);
}

/* Callback for client_cell_width. */
static void *
format_cb_client_cell_width(struct format_tree *ft)
{
  if (ft->c != NULL && (ft->c->tty.flags & TTY_STARTED))
    return (format_printf("%u", ft->c->tty.xpixel));
  return (NULL);
}

/* Callback for client_colours. */
static void *
format_cb_client_colours(struct format_tree *ft)
{
  struct tty_term *term;
  u_int    colours;

  if (ft->c == NULL || (~ft->c->tty.flags & TTY_STARTED))
    return (NULL);
  term = ft->c->tty.term;

  if (term->flags & TERM_RGBCOLOURS)
    colours = 16777216;
  else if (term->flags & TERM_256COLOURS)
    colours = 256;
  else {
    colours = tty_term_number(term, TTYC_COLORS);
    if (colours < 8)
      colours = 2;
    else if (colours < 16)
      colours = 8;
    else
      colours = 16;
  }
  return (format_printf("%u", colours));
}

/* Callback for client_control_mode. */
static void *
format_cb_client_control_mode(struct format_tree *ft)
{
  if (ft->c != NULL) {
    if (ft->c->flags & CLIENT_CONTROL)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for client_discarded. */
static void *
format_cb_client_discarded(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (format_printf("%zu", ft->c->discarded));
  return (NULL);
}

/* Callback for client_flags. */
static void *
format_cb_client_flags(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (xstrdup(server_client_get_flags(ft->c)));
  return (NULL);
}

/* Callback for client_height. */
static void *
format_cb_client_height(struct format_tree *ft)
{
  if (ft->c != NULL && (ft->c->tty.flags & TTY_STARTED))
    return (format_printf("%u", ft->c->tty.sy));
  return (NULL);
}

/* Callback for client_key_table. */
static void *
format_cb_client_key_table(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (xstrdup(ft->c->keytable->name));
  return (NULL);
}

/* Callback for client_last_session. */
static void *
format_cb_client_last_session(struct format_tree *ft)
{
  if (ft->c != NULL &&
      ft->c->last_session != NULL &&
      session_alive(ft->c->last_session))
    return (xstrdup(ft->c->last_session->name));
  return (NULL);
}

/* Callback for client_name. */
static void *
format_cb_client_name(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (xstrdup(ft->c->name));
  return (NULL);
}

/* Callback for client_pid. */
static void *
format_cb_client_pid(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (format_printf("%ld", (long)ft->c->pid));
  return (NULL);
}

/* Callback for client_prefix. */
static void *
format_cb_client_prefix(struct format_tree *ft)
{
  const char  *name;

  if (ft->c != NULL) {
    name = server_client_get_key_table(ft->c);
    if (strcmp(ft->c->keytable->name, name) == 0)
      return (xstrdup("0"));
    return (xstrdup("1"));
  }
  return (NULL);
}

/* Callback for client_readonly. */
static void *
format_cb_client_readonly(struct format_tree *ft)
{
  if (ft->c != NULL) {
    if (ft->c->flags & CLIENT_READONLY)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for client_session. */
static void *
format_cb_client_session(struct format_tree *ft)
{
  if (ft->c != NULL && ft->c->session != NULL)
    return (xstrdup(ft->c->session->name));
  return (NULL);
}

/* Callback for client_termfeatures. */
static void *
format_cb_client_termfeatures(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (xstrdup(tty_get_features(ft->c->term_features)));
  return (NULL);
}

/* Callback for client_termname. */
static void *
format_cb_client_termname(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (xstrdup(ft->c->term_name));
  return (NULL);
}

/* Callback for client_termtype. */
static void *
format_cb_client_termtype(struct format_tree *ft)
{
  if (ft->c != NULL) {
    if (ft->c->term_type == NULL)
      return (xstrdup(""));
    return (xstrdup(ft->c->term_type));
  }
  return (NULL);
}

/* Callback for client_tty. */
static void *
format_cb_client_tty(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (xstrdup(ft->c->ttyname));
  return (NULL);
}

/* Callback for client_uid. */
static void *
format_cb_client_uid(struct format_tree *ft)
{
  uid_t uid;

  if (ft->c != NULL) {
    uid = proc_get_peer_uid(ft->c->peer);
    if (uid != (uid_t)-1)
      return (format_printf("%ld", (long)uid));
  }
  return (NULL);
}

/* Callback for client_user. */
static void *
format_cb_client_user(struct format_tree *ft)
{
  uid_t    uid;
  struct passwd *pw;

  if (ft->c != NULL) {
    if (ft->c->user != NULL)
      return (xstrdup(ft->c->user));
    uid = proc_get_peer_uid(ft->c->peer);
    if (uid != (uid_t)-1 && (pw = getpwuid(uid)) != NULL) {
      ft->c->user = xstrdup(pw->pw_name);
      return (xstrdup(ft->c->user));
    }
  }
  return (NULL);
}

/* Callback for client_utf8. */
static void *
format_cb_client_utf8(struct format_tree *ft)
{
  if (ft->c != NULL) {
    if (ft->c->flags & CLIENT_UTF8)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for client_width. */
static void *
format_cb_client_width(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (format_printf("%u", ft->c->tty.sx));
  return (NULL);
}

/* Callback for client_written. */
static void *
format_cb_client_written(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (format_printf("%zu", ft->c->written));
  return (NULL);
}

/* Callback for client_theme. */
static void *
format_cb_client_theme(struct format_tree *ft)
{
  if (ft->c != NULL) {
    switch (ft->c->theme) {
    case THEME_DARK:
      return (xstrdup("dark"));
    case THEME_LIGHT:
      return (xstrdup("light"));
    case THEME_UNKNOWN:
      return (NULL);
    }
  }
  return (NULL);
}

/* Callback for config_files. */
static void *
format_cb_config_files(__unused struct format_tree *ft)
{
  char  *s = NULL;
  size_t   slen = 0;
  u_int  i;
  size_t   n;

  for (i = 0; i < cfg_nfiles; i++) {
    n = strlen(cfg_files[i]) + 1;
    s = xrealloc(s, slen + n + 1);
    slen += xsnprintf(s + slen, n + 1, "%s,", cfg_files[i]);
  }
  if (s == NULL)
    return (xstrdup(""));
  s[slen - 1] = '\0';
  return (s);
}

/* Callback for cursor_flag. */
static void *
format_cb_cursor_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_CURSOR)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for cursor_shape. */
static void *
format_cb_cursor_shape(struct format_tree *ft)
{
  if (ft->wp != NULL && ft->wp->screen != NULL) {
    switch (ft->wp->screen->cstyle) {
    case SCREEN_CURSOR_BLOCK:
      return (xstrdup("block"));
    case SCREEN_CURSOR_UNDERLINE:
      return (xstrdup("underline"));
    case SCREEN_CURSOR_BAR:
      return (xstrdup("bar"));
    default:
      return (xstrdup("default"));
    }
  }
  return (NULL);
}

/* Callback for cursor_very_visible. */
static void *
format_cb_cursor_very_visible(struct format_tree *ft)
{
  if (ft->wp != NULL && ft->wp->screen != NULL) {
    if (ft->wp->screen->mode & MODE_CURSOR_VERY_VISIBLE)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for cursor_x. */
static void *
format_cb_cursor_x(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.cx));
  return (NULL);
}

/* Callback for cursor_y. */
static void *
format_cb_cursor_y(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.cy));
  return (NULL);
}

/* Callback for cursor_blinking. */
static void *
format_cb_cursor_blinking(struct format_tree *ft)
{
  if (ft->wp != NULL && ft->wp->screen != NULL) {
    if (ft->wp->screen->mode & MODE_CURSOR_BLINKING)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for history_limit. */
static void *
format_cb_history_limit(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.grid->hlimit));
  return (NULL);
}

/* Callback for history_size. */
static void *
format_cb_history_size(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.grid->hsize));
  return (NULL);
}

/* Callback for insert_flag. */
static void *
format_cb_insert_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_INSERT)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for keypad_cursor_flag. */
static void *
format_cb_keypad_cursor_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_KCURSOR)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for keypad_flag. */
static void *
format_cb_keypad_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_KKEYPAD)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for mouse_all_flag. */
static void *
format_cb_mouse_all_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_MOUSE_ALL)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for mouse_any_flag. */
static void *
format_cb_mouse_any_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & ALL_MOUSE_MODES)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for mouse_button_flag. */
static void *
format_cb_mouse_button_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_MOUSE_BUTTON)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for mouse_pane. */
static void *
format_cb_mouse_pane(struct format_tree *ft)
{
  struct window_pane  *wp;

  if (ft->m.valid) {
    wp = cmd_mouse_pane(&ft->m, NULL, NULL);
    if (wp != NULL)
      return (format_printf("%%%u", wp->id));
    return (NULL);
  }
  return (NULL);
}

/* Callback for mouse_sgr_flag. */
static void *
format_cb_mouse_sgr_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_MOUSE_SGR)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for mouse_standard_flag. */
static void *
format_cb_mouse_standard_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_MOUSE_STANDARD)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for mouse_utf8_flag. */
static void *
format_cb_mouse_utf8_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_MOUSE_UTF8)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for mouse_x. */
static void *
format_cb_mouse_x(struct format_tree *ft)
{
  struct window_pane  *wp;
  u_int      x, y;

  if (!ft->m.valid)
    return (NULL);
  wp = cmd_mouse_pane(&ft->m, NULL, NULL);
  if (wp != NULL && cmd_mouse_at(wp, &ft->m, &x, &y, 0) == 0)
    return (format_printf("%u", x));
  if (ft->c != NULL && (ft->c->tty.flags & TTY_STARTED)) {
    if (ft->m.statusat == 0 && ft->m.y < ft->m.statuslines)
      return (format_printf("%u", ft->m.x));
    if (ft->m.statusat > 0 && ft->m.y >= (u_int)ft->m.statusat)
      return (format_printf("%u", ft->m.x));
  }
  return (NULL);
}

/* Callback for mouse_y. */
static void *
format_cb_mouse_y(struct format_tree *ft)
{
  struct window_pane  *wp;
  u_int      x, y;

  if (!ft->m.valid)
    return (NULL);
  wp = cmd_mouse_pane(&ft->m, NULL, NULL);
  if (wp != NULL && cmd_mouse_at(wp, &ft->m, &x, &y, 0) == 0)
    return (format_printf("%u", y));
  if (ft->c != NULL && (ft->c->tty.flags & TTY_STARTED)) {
    if (ft->m.statusat == 0 && ft->m.y < ft->m.statuslines)
      return (format_printf("%u", ft->m.y));
    if (ft->m.statusat > 0 && ft->m.y >= (u_int)ft->m.statusat)
      return (format_printf("%u", ft->m.y - ft->m.statusat));
  }
  return (NULL);
}

/* Callback for next_session_id. */
static void *
format_cb_next_session_id(__unused struct format_tree *ft)
{
  return (format_printf("$%u", next_session_id));
}

/* Callback for origin_flag. */
static void *
format_cb_origin_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_ORIGIN)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for synchronized_output_flag. */
static void *
format_cb_synchronized_output_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_SYNC)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_active. */
static void *
format_cb_pane_active(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp == ft->wp->window->active)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_at_left. */
static void *
format_cb_pane_at_left(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->xoff == 0)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_at_right. */
static void *
format_cb_pane_at_right(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->xoff + (int)ft->wp->sx == (int)ft->wp->window->sx)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_bottom. */
static void *
format_cb_pane_bottom(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL)
    return (format_printf("%d", wp->yoff + (int)wp->sy - 1));
  return (NULL);
}

/* Callback for pane_dead. */
static void *
format_cb_pane_dead(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL) {
    if (wp->fd == -1 && (wp->flags & PANE_STATUSREADY))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_dead_signal. */
static void *
format_cb_pane_dead_signal(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  const char    *name;

  if (wp != NULL) {
    if ((wp->flags & PANE_STATUSREADY) && WIFSIGNALED(wp->status)) {
      name = sig2name(WTERMSIG(wp->status));
      return (format_printf("%s", name));
    }
    return (NULL);
  }
  return (NULL);
}

/* Callback for pane_dead_status. */
static void *
format_cb_pane_dead_status(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL) {
    if ((wp->flags & PANE_STATUSREADY) && WIFEXITED(wp->status))
      return (format_printf("%d", WEXITSTATUS(wp->status)));
    return (NULL);
  }
  return (NULL);
}

/* Callback for pane_dead_time. */
static void *
format_cb_pane_dead_time(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL) {
    if (wp->flags & PANE_STATUSDRAWN)
      return (&wp->dead_time);
    return (NULL);
  }
  return (NULL);
}

/* Callback for pane_last_output_time. */
static void *
format_cb_pane_last_output_time(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  static struct timeval  tv;

  if (wp != NULL && wp->last_output_time != 0) {
    tv.tv_sec = wp->last_output_time;
    tv.tv_usec = 0;
    return (&tv);
  }
  return (NULL);
}

/* Callback for pane_last_prompt_time. */
static void *
format_cb_pane_last_prompt_time(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  static struct timeval  tv;

  if (wp != NULL && wp->last_prompt_time != 0) {
    tv.tv_sec = wp->last_prompt_time;
    tv.tv_usec = 0;
    return (&tv);
  }
  return (NULL);
}

/* Callback for pane_command_start_time. */
static void *
format_cb_pane_command_start_time(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  static struct timeval  tv;

  if (wp != NULL && wp->cmd_start_time != 0) {
    tv.tv_sec = wp->cmd_start_time;
    tv.tv_usec = 0;
    return (&tv);
  }
  return (NULL);
}

/* Callback for pane_command_end_time. */
static void *
format_cb_pane_command_end_time(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  static struct timeval  tv;

  if (wp != NULL && wp->cmd_end_time != 0) {
    tv.tv_sec = wp->cmd_end_time;
    tv.tv_usec = 0;
    return (&tv);
  }
  return (NULL);
}

/* Callback for pane_command_running. */
static void *
format_cb_pane_command_running(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL)
    return (format_printf("%d", !!(wp->flags & PANE_CMDRUNNING)));
  return (NULL);
}

/* Callback for pane_command_duration. */
static void *
format_cb_pane_command_duration(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  time_t       end;

  if (wp == NULL || wp->cmd_start_time == 0)
    return (NULL);
  if (wp->flags & PANE_CMDRUNNING)
    end = time(NULL);
  else
    end = wp->cmd_end_time;
  if (end < wp->cmd_start_time)
    end = wp->cmd_start_time;
  return (format_printf("%lld", (long long)(end - wp->cmd_start_time)));
}

/* Callback for pane_command_status. */
static void *
format_cb_pane_command_status(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL && wp->cmd_status != -1)
    return (format_printf("%d", wp->cmd_status));
  return (NULL);
}

/* Callback for pane_format. */
static void *
format_cb_pane_format(struct format_tree *ft)
{
  if (ft->type == FORMAT_TYPE_PANE)
    return (xstrdup("1"));
  return (xstrdup("0"));
}

/* Callback for pane_height. */
static void *
format_cb_pane_height(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->sy));
  return (NULL);
}

/* Callback for pane_id. */
static void *
format_cb_pane_id(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%%%u", ft->wp->id));
  return (NULL);
}

/* Callback for pane_index. */
static void *
format_cb_pane_index(struct format_tree *ft)
{
  u_int idx;

  if (ft->wp != NULL && window_pane_index(ft->wp, &idx) == 0)
    return (format_printf("%u", idx));
  return (NULL);
}

/* Callback for pane_input_off. */
static void *
format_cb_pane_input_off(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->flags & PANE_INPUTOFF)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_unseen_changes. */
static void *
format_cb_pane_unseen_changes(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->flags & PANE_UNSEENCHANGES)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_key_mode. */
static void *
format_cb_pane_key_mode(struct format_tree *ft)
{
  if (ft->wp != NULL && ft->wp->screen != NULL) {
    switch (ft->wp->screen->mode & EXTENDED_KEY_MODES) {
    case MODE_KEYS_EXTENDED:
      return (xstrdup("Ext 1"));
    case MODE_KEYS_EXTENDED_2:
      return (xstrdup("Ext 2"));
    default:
      return (xstrdup("VT10x"));
    }
  }
  return (NULL);
}

/* Callback for pane_last. */
static void *
format_cb_pane_last(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp == TAILQ_FIRST(&ft->wp->window->last_panes))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_left. */
static void *
format_cb_pane_left(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%d", ft->wp->xoff));
  return (NULL);
}

/* Callback for pane_marked. */
static void *
format_cb_pane_marked(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (server_check_marked() && marked_pane.wp == ft->wp)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_marked_set. */
static void *
format_cb_pane_marked_set(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (server_check_marked())
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_mode. */
static void *
format_cb_pane_mode(struct format_tree *ft)
{
  struct window_mode_entry  *wme;

  if (ft->wp != NULL) {
    wme = TAILQ_FIRST(&ft->wp->modes);
    if (wme != NULL)
      return (xstrdup(wme->mode->name));
    return (NULL);
  }
  return (NULL);
}

/* Callback for pane_path. */
static void *
format_cb_pane_path(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.path == NULL)
      return (xstrdup(""));
    return (xstrdup(ft->wp->base.path));
  }
  return (NULL);
}

/* Callback for pane_pid. */
static void *
format_cb_pane_pid(struct format_tree *ft)
{
  if (ft->wp != NULL && ft->wp->fd != -1)
    return (format_printf("%ld", (long)ft->wp->pid));
  return (NULL);
}

/* Callback for pane_pipe. */
static void *
format_cb_pane_pipe(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->pipe_fd != -1)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_pipe_pid. */
static void *
format_cb_pane_pipe_pid(struct format_tree *ft)
{
  char  *value = NULL;

  if (ft->wp != NULL && ft->wp->pipe_fd != -1)
    xasprintf(&value, "%ld", (long)ft->wp->pipe_pid);
  return (value);
}

/* Callback for pane_pb_progress. */
static void *
format_cb_pane_pb_progress(struct format_tree *ft)
{
  char  *value = NULL;

  if (ft->wp != NULL)
    xasprintf(&value, "%d", ft->wp->base.progress_bar.progress);
  return (value);
}

/* Callback for pane_pb_state. */
static void *
format_cb_pane_pb_state(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    switch (ft->wp->base.progress_bar.state) {
    case PROGRESS_BAR_HIDDEN:
      return xstrdup("hidden");
    case PROGRESS_BAR_NORMAL:
      return xstrdup("normal");
    case PROGRESS_BAR_ERROR:
      return xstrdup("error");
    case PROGRESS_BAR_INDETERMINATE:
      return xstrdup("indeterminate");
    case PROGRESS_BAR_PAUSED:
      return xstrdup("paused");
    }
  }
  return (NULL);
}

/* Callback for pane_right. */
static void *
format_cb_pane_right(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL)
    return (format_printf("%d", wp->xoff + (int)wp->sx - 1));
  return (NULL);
}

/* Callback for pane_search_string. */
static void *
format_cb_pane_search_string(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->searchstr == NULL)
      return (xstrdup(""));
    return (xstrdup(ft->wp->searchstr));
  }
  return (NULL);
}

/* Callback for pane_synchronized. */
static void *
format_cb_pane_synchronized(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (options_get_number(ft->wp->options, "synchronize-panes"))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for pane_title. */
static void *
format_cb_pane_title(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (xstrdup(ft->wp->base.title));
  return (NULL);
}

/* Callback for pane_top. */
static void *
format_cb_pane_top(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%d", ft->wp->yoff));
  return (NULL);
}

/* Callback for pane_tty. */
static void *
format_cb_pane_tty(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (xstrdup(ft->wp->tty));
  return (NULL);
}

/* Callback for pane_unzoomed_height. */
static void *
format_cb_pane_unzoomed_height(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct window   *w;
  struct layout_cell  *lc, *root;
  int      status, floating;
  u_int      sy;

  if (wp == NULL)
    return (NULL);
  w = wp->window;

  lc = wp->saved_layout_cell;
  if (lc == NULL)
    lc = wp->layout_cell;
  if (lc == NULL)
    return (NULL);
  sy = lc->g.sy;
  floating = (lc->flags & LAYOUT_CELL_FLOATING);

  root = w->saved_layout_root;
  if (root == NULL)
    root = w->layout_root;
  if (lc == wp->saved_layout_cell && !floating)
    status = window_get_pane_status(w);
  else
    status = window_pane_get_pane_status(wp);
  if (!floating &&
      root != NULL &&
      layout_add_horizontal_border(root, lc, status) &&
      sy > 1)
    sy--;

  return (format_printf("%u", sy));
}

/* Callback for pane_unzoomed_width. */
static void *
format_cb_pane_unzoomed_width(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;
  struct layout_cell  *lc;
  int      saved, sb_w, sb_pad;
  u_int      sx;

  if (wp == NULL)
    return (NULL);

  lc = wp->saved_layout_cell;
  saved = (lc != NULL);
  if (lc == NULL)
    lc = wp->layout_cell;
  if (lc == NULL)
    return (NULL);
  sx = lc->g.sx;

  if ((saved && !SCREEN_IS_ALTERNATE(&wp->base) &&
      wp->window->sb == PANE_SCROLLBARS_ALWAYS) ||
      (!saved && window_pane_scrollbar_reserve(wp))) {
    sb_w = wp->scrollbar_style.width;
    sb_pad = wp->scrollbar_style.pad;
    if (sb_w < 1)
      sb_w = 1;
    if (sb_pad < 0)
      sb_pad = 0;
    if ((int)sx - sb_w - sb_pad < PANE_MINIMUM)
      sx = PANE_MINIMUM;
    else
      sx -= sb_w + sb_pad;
  }

  return (format_printf("%u", sx));
}

/* Callback for pane_width. */
static void *
format_cb_pane_width(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->sx));
  return (NULL);
}

/* Callback for pane_x. */
static void *
format_cb_pane_x(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%d", ft->wp->xoff));
  return (NULL);
}

/* Callback for pane_y. */
static void *
format_cb_pane_y(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%d", ft->wp->yoff));
  return (NULL);
}

/* Callback for pane_z. */
static void *
format_cb_pane_z(struct format_tree *ft)
{
  u_int idx;

  if (ft->wp != NULL && window_pane_zindex(ft->wp, &idx) == 0)
    return (format_printf("%u", idx));
  return (NULL);
}

/* Callback for pane_zoomed_flag. */
static void *
format_cb_pane_zoomed_flag(struct format_tree *ft)
{
  struct window_pane  *wp = ft->wp;

  if (wp != NULL) {
    if (wp->flags & PANE_ZOOMED)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for scroll_region_lower. */
static void *
format_cb_scroll_region_lower(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.rlower));
  return (NULL);
}

/* Callback for scroll_region_upper. */
static void *
format_cb_scroll_region_upper(struct format_tree *ft)
{
  if (ft->wp != NULL)
    return (format_printf("%u", ft->wp->base.rupper));
  return (NULL);
}

/* Callback for server_sessions. */
static void *
format_cb_server_sessions(__unused struct format_tree *ft)
{
  struct session  *s;
  u_int    n = 0;

  RB_FOREACH(s, sessions, &sessions)
    n++;
  return (format_printf("%u", n));
}

/* Callback for session_active. */
static void *
format_cb_session_active(struct format_tree *ft)
{
  if (ft->s == NULL || ft->c == NULL)
    return (NULL);

  if (ft->c->session == ft->s)
    return (xstrdup("1"));
  return (xstrdup("0"));
}

/* Callback for session_activity_flag. */
static void *
format_cb_session_activity_flag(struct format_tree *ft)
{
  struct winlink    *wl;

  if (ft->s != NULL) {
    RB_FOREACH(wl, winlinks, &ft->s->windows) {
      if (ft->wl->flags & WINLINK_ACTIVITY)
        return (xstrdup("1"));
      return (xstrdup("0"));
    }
  }
  return (NULL);
}

/* Callback for session_bell_flag. */
static void *
format_cb_session_bell_flag(struct format_tree *ft)
{
  struct winlink    *wl;

  if (ft->s != NULL) {
    RB_FOREACH(wl, winlinks, &ft->s->windows) {
      if (wl->flags & WINLINK_BELL)
        return (xstrdup("1"));
      return (xstrdup("0"));
    }
  }
  return (NULL);
}

/* Callback for session_silence_flag. */
static void *
format_cb_session_silence_flag(struct format_tree *ft)
{
  struct winlink    *wl;

  if (ft->s != NULL) {
    RB_FOREACH(wl, winlinks, &ft->s->windows) {
      if (ft->wl->flags & WINLINK_SILENCE)
        return (xstrdup("1"));
      return (xstrdup("0"));
    }
  }
  return (NULL);
}

/* Callback for session_attached. */
static void *
format_cb_session_attached(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (format_printf("%u", ft->s->attached));
  return (NULL);
}

/* Callback for session_format. */
static void *
format_cb_session_format(struct format_tree *ft)
{
  if (ft->type == FORMAT_TYPE_SESSION)
    return (xstrdup("1"));
  return (xstrdup("0"));
}

/* Callback for session_group. */
static void *
format_cb_session_group(struct format_tree *ft)
{
  struct session_group  *sg;

  if (ft->s != NULL && (sg = session_group_contains(ft->s)) != NULL)
    return (xstrdup(sg->name));
  return (NULL);
}

/* Callback for session_group_attached. */
static void *
format_cb_session_group_attached(struct format_tree *ft)
{
  struct session_group  *sg;

  if (ft->s != NULL && (sg = session_group_contains(ft->s)) != NULL)
    return (format_printf("%u", session_group_attached_count (sg)));
  return (NULL);
}

/* Callback for session_group_many_attached. */
static void *
format_cb_session_group_many_attached(struct format_tree *ft)
{
  struct session_group  *sg;

  if (ft->s != NULL && (sg = session_group_contains(ft->s)) != NULL) {
    if (session_group_attached_count (sg) > 1)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for session_group_size. */
static void *
format_cb_session_group_size(struct format_tree *ft)
{
  struct session_group  *sg;

  if (ft->s != NULL && (sg = session_group_contains(ft->s)) != NULL)
    return (format_printf("%u", session_group_count (sg)));
  return (NULL);
}

/* Callback for session_grouped. */
static void *
format_cb_session_grouped(struct format_tree *ft)
{
  if (ft->s != NULL) {
    if (session_group_contains(ft->s) != NULL)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for session_id. */
static void *
format_cb_session_id(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (format_printf("$%u", ft->s->id));
  return (NULL);
}

/* Callback for session_many_attached. */
static void *
format_cb_session_many_attached(struct format_tree *ft)
{
  if (ft->s != NULL) {
    if (ft->s->attached > 1)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for session_marked. */
static void *
format_cb_session_marked(struct format_tree *ft)
{
  if (ft->s != NULL) {
    if (server_check_marked() && marked_pane.s == ft->s)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for session_name. */
static void *
format_cb_session_name(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (xstrdup(ft->s->name));
  return (NULL);
}

/* Callback for session_path. */
static void *
format_cb_session_path(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (xstrdup(ft->s->cwd));
  return (NULL);
}

/* Callback for session_windows. */
static void *
format_cb_session_windows(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (format_printf("%u", winlink_count(&ft->s->windows)));
  return (NULL);
}

/* Callback for socket_path. */
static void *
format_cb_socket_path(__unused struct format_tree *ft)
{
  return (xstrdup(socket_path));
}

/* Callback for version. */
static void *
format_cb_version(__unused struct format_tree *ft)
{
  return (xstrdup(getversion()));
}

/* Callback for sixel_support. */
static void *
format_cb_sixel_support(__unused struct format_tree *ft)
{
#ifdef ENABLE_SIXEL
  return (xstrdup("1"));
#else
  return (xstrdup("0"));
#endif
}

/* Callback for active_window_index. */
static void *
format_cb_active_window_index(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (format_printf("%u", ft->s->curw->idx));
  return (NULL);
}

/* Callback for last_window_index. */
static void *
format_cb_last_window_index(struct format_tree *ft)
{
  struct winlink  *wl;

  if (ft->s != NULL) {
    wl = RB_MAX(winlinks, &ft->s->windows);
    return (format_printf("%u", wl->idx));
  }
  return (NULL);
}

/* Callback for window_active. */
static void *
format_cb_window_active(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (ft->wl == ft->wl->session->curw)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_activity_flag. */
static void *
format_cb_window_activity_flag(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (ft->wl->flags & WINLINK_ACTIVITY)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_bell_flag. */
static void *
format_cb_window_bell_flag(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (ft->wl->flags & WINLINK_BELL)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_bigger. */
static void *
format_cb_window_bigger(struct format_tree *ft)
{
  u_int ox, oy, sx, sy;

  if (ft->c != NULL) {
    if (tty_window_offset(&ft->c->tty, &ox, &oy, &sx, &sy))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_cell_height. */
static void *
format_cb_window_cell_height(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (format_printf("%u", ft->w->ypixel));
  return (NULL);
}

/* Callback for window_cell_width. */
static void *
format_cb_window_cell_width(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (format_printf("%u", ft->w->xpixel));
  return (NULL);
}

/* Callback for window_end_flag. */
static void *
format_cb_window_end_flag(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (ft->wl == RB_MAX(winlinks, &ft->wl->session->windows))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_flags. */
static void *
format_cb_window_flags(struct format_tree *ft)
{
  if (ft->wl != NULL)
    return (xstrdup(window_printable_flags(ft->wl, 1)));
  return (NULL);
}

/* Callback for window_format. */
static void *
format_cb_window_format(struct format_tree *ft)
{
  if (ft->type == FORMAT_TYPE_WINDOW)
    return (xstrdup("1"));
  return (xstrdup("0"));
}

/* Callback for window_height. */
static void *
format_cb_window_height(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (format_printf("%u", ft->w->sy));
  return (NULL);
}

/* Callback for window_manual_height. */
static void *
format_cb_window_manual_height(struct format_tree *ft)
{
  struct window *w = ft->w;

  if (w == NULL)
    return (NULL);
  if (options_get_number(w->options, "window-size") != WINDOW_SIZE_MANUAL)
    return (xstrdup(""));
  return (format_printf("%u", w->manual_sy));
}

/* Callback for window_id. */
static void *
format_cb_window_id(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (format_printf("@%u", ft->w->id));
  return (NULL);
}

/* Callback for window_index. */
static void *
format_cb_window_index(struct format_tree *ft)
{
  if (ft->wl != NULL)
    return (format_printf("%d", ft->wl->idx));
  return (NULL);
}

/* Callback for window_last_flag. */
static void *
format_cb_window_last_flag(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (ft->wl == TAILQ_FIRST(&ft->wl->session->lastw))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_linked. */
static void *
format_cb_window_linked(struct format_tree *ft)
{
  struct winlink  *wl;
  struct session  *s;
  int    found = 0;

  if (ft->wl != NULL) {
    RB_FOREACH(s, sessions, &sessions) {
      RB_FOREACH(wl, winlinks, &s->windows) {
        if (wl->window == ft->wl->window) {
          if (found)
            return (xstrdup("1"));
          found = 1;
        }
      }
    }
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_linked_sessions. */
static void *
format_cb_window_linked_sessions(struct format_tree *ft)
{
  struct window   *w;
  struct session_group  *sg;
  struct session    *s;
  u_int      n = 0;

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

  RB_FOREACH(sg, session_groups, &session_groups) {
    s = TAILQ_FIRST(&sg->sessions);
    if (winlink_find_by_window(&s->windows, w) != NULL)
      n++;
  }
  RB_FOREACH(s, sessions, &sessions) {
    if (session_group_contains(s) != NULL)
      continue;
    if (winlink_find_by_window(&s->windows, w) != NULL)
      n++;
  }
  return (format_printf("%u", n));
}

/* Callback for window_marked_flag. */
static void *
format_cb_window_marked_flag(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (server_check_marked() && marked_pane.wl == ft->wl)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_modal_pane. */
static void *
format_cb_window_modal_pane(struct format_tree *ft)
{
  if (ft->w != NULL && ft->w->modal != NULL)
    return (format_printf("%%%u", ft->w->modal->id));
  return (NULL);
}

/* Callback for window_name. */
static void *
format_cb_window_name(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (format_printf("%s", ft->w->name));
  return (NULL);
}

/* Callback for window_offset_x. */
static void *
format_cb_window_offset_x(struct format_tree *ft)
{
  u_int ox, oy, sx, sy;

  if (ft->c != NULL) {
    if (tty_window_offset(&ft->c->tty, &ox, &oy, &sx, &sy))
      return (format_printf("%u", ox));
    return (NULL);
  }
  return (NULL);
}

/* Callback for window_offset_y. */
static void *
format_cb_window_offset_y(struct format_tree *ft)
{
  u_int ox, oy, sx, sy;

  if (ft->c != NULL) {
    if (tty_window_offset(&ft->c->tty, &ox, &oy, &sx, &sy))
      return (format_printf("%u", oy));
    return (NULL);
  }
  return (NULL);
}

/* Callback for window_panes. */
static void *
format_cb_window_panes(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (format_printf("%u", window_count_panes(ft->w, 1)));
  return (NULL);
}

/* Callback for window_raw_flags. */
static void *
format_cb_window_raw_flags(struct format_tree *ft)
{
  if (ft->wl != NULL)
    return (xstrdup(window_printable_flags(ft->wl, 0)));
  return (NULL);
}

/* Callback for window_silence_flag. */
static void *
format_cb_window_silence_flag(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (ft->wl->flags & WINLINK_SILENCE)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_start_flag. */
static void *
format_cb_window_start_flag(struct format_tree *ft)
{
  if (ft->wl != NULL) {
    if (ft->wl == RB_MIN(winlinks, &ft->wl->session->windows))
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for window_width. */
static void *
format_cb_window_width(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (format_printf("%u", ft->w->sx));
  return (NULL);
}

/* Callback for window_manual_width. */
static void *
format_cb_window_manual_width(struct format_tree *ft)
{
  struct window *w = ft->w;

  if (w == NULL)
    return (NULL);
  if (options_get_number(w->options, "window-size") != WINDOW_SIZE_MANUAL)
    return (xstrdup(""));
  return (format_printf("%u", w->manual_sx));
}

/* Callback for window_zoomed_flag. */
static void *
format_cb_window_zoomed_flag(struct format_tree *ft)
{
  if (ft->w != NULL) {
    if (ft->w->flags & WINDOW_ZOOMED)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for wrap_flag. */
static void *
format_cb_wrap_flag(struct format_tree *ft)
{
  if (ft->wp != NULL) {
    if (ft->wp->base.mode & MODE_WRAP)
      return (xstrdup("1"));
    return (xstrdup("0"));
  }
  return (NULL);
}

/* Callback for buffer_created. */
static void *
format_cb_buffer_created(struct format_tree *ft)
{
  static struct timeval  tv;

  if (ft->pb != NULL) {
    timerclear(&tv);
    tv.tv_sec = paste_buffer_created(ft->pb);
    return (&tv);
  }
  return (NULL);
}

/* Callback for client_activity. */
static void *
format_cb_client_activity(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (&ft->c->activity_time);
  return (NULL);
}

/* Callback for client_created. */
static void *
format_cb_client_created(struct format_tree *ft)
{
  if (ft->c != NULL)
    return (&ft->c->creation_time);
  return (NULL);
}

/* Callback for session_activity. */
static void *
format_cb_session_activity(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (&ft->s->activity_time);
  return (NULL);
}

/* Callback for session_created. */
static void *
format_cb_session_created(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (&ft->s->creation_time);
  return (NULL);
}

/* Callback for session_last_attached. */
static void *
format_cb_session_last_attached(struct format_tree *ft)
{
  if (ft->s != NULL)
    return (&ft->s->last_attached_time);
  return (NULL);
}

/* Callback for start_time. */
static void *
format_cb_start_time(__unused struct format_tree *ft)
{
  return (&start_time);
}

/* Callback for window_activity. */
static void *
format_cb_window_activity(struct format_tree *ft)
{
  if (ft->w != NULL)
    return (&ft->w->activity_time);
  return (NULL);
}

/* Callback for buffer_mode_format, */
static void *
format_cb_buffer_mode_format(__unused struct format_tree *ft)
{
  return (xstrdup(window_buffer_mode.default_format));
}

/* Callback for client_mode_format, */
static void *
format_cb_client_mode_format(__unused struct format_tree *ft)
{
  return (xstrdup(window_client_mode.default_format));
}

/* Callback for tree_mode_format, */
static void *
format_cb_tree_mode_format(__unused struct format_tree *ft)
{
  return (xstrdup(window_tree_mode.default_format));
}

/* Callback for uid. */
static void *
format_cb_uid(__unused struct format_tree *ft)
{
  return (format_printf("%ld", (long)getuid()));
}

/* Callback for user. */
static void *
format_cb_user(__unused struct format_tree *ft)
{
  static char *cached;
  struct passwd *pw;

  if (cached == NULL && (pw = getpwuid(getuid())) != NULL)
    cached = xstrdup(pw->pw_name);
  if (cached != NULL)
    return (xstrdup(cached));
  return (NULL);
}

/* Format table type. */
enum format_table_type {
  FORMAT_TABLE_STRING,
  FORMAT_TABLE_TIME
};

/* Format table entry. */
struct format_table_entry {
  const char    *key;
  enum format_table_type   type;
  format_cb    cb;
};

/*
 * Format table. Default format variables (that are almost always in the tree
 * and where the value is expanded by a callback in this file) are listed here.
 * Only variables which are added by the caller go into the tree.
 */
static const struct format_table_entry format_table[] = {
  { "active_window_index", FORMAT_TABLE_STRING,
    format_cb_active_window_index
  },
  { "alternate_on", FORMAT_TABLE_STRING,
    format_cb_alternate_on
  },
  { "alternate_saved_x", FORMAT_TABLE_STRING,
    format_cb_alternate_saved_x
  },
  { "alternate_saved_y", FORMAT_TABLE_STRING,
    format_cb_alternate_saved_y
  },
  { "bracket_paste_flag", FORMAT_TABLE_STRING,
    format_cb_bracket_paste_flag
  },
  { "buffer_created", FORMAT_TABLE_TIME,
    format_cb_buffer_created
  },
  { "buffer_full", FORMAT_TABLE_STRING,
    format_cb_buffer_full
  },
  { "buffer_mode_format", FORMAT_TABLE_STRING,
    format_cb_buffer_mode_format
  },
  { "buffer_name", FORMAT_TABLE_STRING,
    format_cb_buffer_name
  },
  { "buffer_sample", FORMAT_TABLE_STRING,
    format_cb_buffer_sample
  },
  { "buffer_size", FORMAT_TABLE_STRING,
    format_cb_buffer_size
  },
  { "client_activity", FORMAT_TABLE_TIME,
    format_cb_client_activity
  },
  { "client_cell_height", FORMAT_TABLE_STRING,
    format_cb_client_cell_height
  },
  { "client_cell_width", FORMAT_TABLE_STRING,
    format_cb_client_cell_width
  },
  { "client_colours", FORMAT_TABLE_STRING,
    format_cb_client_colours
  },
  { "client_control_mode", FORMAT_TABLE_STRING,
    format_cb_client_control_mode
  },
  { "client_created", FORMAT_TABLE_TIME,
    format_cb_client_created
  },
  { "client_discarded", FORMAT_TABLE_STRING,
    format_cb_client_discarded
  },
  { "client_flags", FORMAT_TABLE_STRING,
    format_cb_client_flags
  },
  { "client_height", FORMAT_TABLE_STRING,
    format_cb_client_height
  },
  { "client_key_table", FORMAT_TABLE_STRING,
    format_cb_client_key_table
  },
  { "client_last_session", FORMAT_TABLE_STRING,
    format_cb_client_last_session
  },
  { "client_mode_format", FORMAT_TABLE_STRING,
    format_cb_client_mode_format
  },
  { "client_name", FORMAT_TABLE_STRING,
    format_cb_client_name
  },
  { "client_pid", FORMAT_TABLE_STRING,
    format_cb_client_pid
  },
  { "client_prefix", FORMAT_TABLE_STRING,
    format_cb_client_prefix
  },
  { "client_readonly", FORMAT_TABLE_STRING,
    format_cb_client_readonly
  },
  { "client_session", FORMAT_TABLE_STRING,
    format_cb_client_session
  },
  { "client_termfeatures", FORMAT_TABLE_STRING,
    format_cb_client_termfeatures
  },
  { "client_termname", FORMAT_TABLE_STRING,
    format_cb_client_termname
  },
  { "client_termtype", FORMAT_TABLE_STRING,
    format_cb_client_termtype
  },
  { "client_theme", FORMAT_TABLE_STRING,
    format_cb_client_theme
  },
  { "client_tty", FORMAT_TABLE_STRING,
    format_cb_client_tty
  },
  { "client_uid", FORMAT_TABLE_STRING,
    format_cb_client_uid
  },
  { "client_user", FORMAT_TABLE_STRING,
    format_cb_client_user
  },
  { "client_utf8", FORMAT_TABLE_STRING,
    format_cb_client_utf8
  },
  { "client_width", FORMAT_TABLE_STRING,
    format_cb_client_width
  },
  { "client_written", FORMAT_TABLE_STRING,
    format_cb_client_written
  },
  { "config_files", FORMAT_TABLE_STRING,
    format_cb_config_files
  },
  { "cursor_blinking", FORMAT_TABLE_STRING,
    format_cb_cursor_blinking
  },
  { "cursor_character", FORMAT_TABLE_STRING,
    format_cb_cursor_character
  },
  { "cursor_colour", FORMAT_TABLE_STRING,
    format_cb_cursor_colour
  },
  { "cursor_flag", FORMAT_TABLE_STRING,
    format_cb_cursor_flag
  },
  { "cursor_shape", FORMAT_TABLE_STRING,
    format_cb_cursor_shape
  },
  { "cursor_very_visible", FORMAT_TABLE_STRING,
    format_cb_cursor_very_visible
  },
  { "cursor_x", FORMAT_TABLE_STRING,
    format_cb_cursor_x
  },
  { "cursor_y", FORMAT_TABLE_STRING,
    format_cb_cursor_y
  },
  { "history_all_bytes", FORMAT_TABLE_STRING,
    format_cb_history_all_bytes
  },
  { "history_bytes", FORMAT_TABLE_STRING,
    format_cb_history_bytes
  },
  { "history_limit", FORMAT_TABLE_STRING,
    format_cb_history_limit
  },
  { "history_size", FORMAT_TABLE_STRING,
    format_cb_history_size
  },
  { "host", FORMAT_TABLE_STRING,
    format_cb_host
  },
  { "host_short", FORMAT_TABLE_STRING,
    format_cb_host_short
  },
  { "insert_flag", FORMAT_TABLE_STRING,
    format_cb_insert_flag
  },
  { "keypad_cursor_flag", FORMAT_TABLE_STRING,
    format_cb_keypad_cursor_flag
  },
  { "keypad_flag", FORMAT_TABLE_STRING,
    format_cb_keypad_flag
  },
  { "last_window_index", FORMAT_TABLE_STRING,
    format_cb_last_window_index
  },
  { "mouse_all_flag", FORMAT_TABLE_STRING,
    format_cb_mouse_all_flag
  },
  { "mouse_any_flag", FORMAT_TABLE_STRING,
    format_cb_mouse_any_flag
  },
  { "mouse_button_flag", FORMAT_TABLE_STRING,
    format_cb_mouse_button_flag
  },
  { "mouse_hyperlink", FORMAT_TABLE_STRING,
    format_cb_mouse_hyperlink
  },
  { "mouse_line", FORMAT_TABLE_STRING,
    format_cb_mouse_line
  },
  { "mouse_pane", FORMAT_TABLE_STRING,
    format_cb_mouse_pane
  },
  { "mouse_sgr_flag", FORMAT_TABLE_STRING,
    format_cb_mouse_sgr_flag
  },
  { "mouse_standard_flag", FORMAT_TABLE_STRING,
    format_cb_mouse_standard_flag
  },
  { "mouse_status_line", FORMAT_TABLE_STRING,
    format_cb_mouse_status_line
  },
  { "mouse_status_range", FORMAT_TABLE_STRING,
    format_cb_mouse_status_range
  },
  { "mouse_utf8_flag", FORMAT_TABLE_STRING,
    format_cb_mouse_utf8_flag
  },
  { "mouse_word", FORMAT_TABLE_STRING,
    format_cb_mouse_word
  },
  { "mouse_x", FORMAT_TABLE_STRING,
    format_cb_mouse_x
  },
  { "mouse_y", FORMAT_TABLE_STRING,
    format_cb_mouse_y
  },
  { "next_session_id", FORMAT_TABLE_STRING,
    format_cb_next_session_id
  },
  { "origin_flag", FORMAT_TABLE_STRING,
    format_cb_origin_flag
  },
  { "pane_active", FORMAT_TABLE_STRING,
    format_cb_pane_active
  },
  { "pane_at_bottom", FORMAT_TABLE_STRING,
    format_cb_pane_at_bottom
  },
  { "pane_at_left", FORMAT_TABLE_STRING,
    format_cb_pane_at_left
  },
  { "pane_at_right", FORMAT_TABLE_STRING,
    format_cb_pane_at_right
  },
  { "pane_at_top", FORMAT_TABLE_STRING,
    format_cb_pane_at_top
  },
  { "pane_bg", FORMAT_TABLE_STRING,
    format_cb_pane_bg
  },
  { "pane_bottom", FORMAT_TABLE_STRING,
    format_cb_pane_bottom
  },
  { "pane_command_duration", FORMAT_TABLE_STRING,
    format_cb_pane_command_duration
  },
  { "pane_command_end_time", FORMAT_TABLE_TIME,
    format_cb_pane_command_end_time
  },
  { "pane_command_running", FORMAT_TABLE_STRING,
    format_cb_pane_command_running
  },
  { "pane_command_start_time", FORMAT_TABLE_TIME,
    format_cb_pane_command_start_time
  },
  { "pane_command_status", FORMAT_TABLE_STRING,
    format_cb_pane_command_status
  },
  { "pane_current_command", FORMAT_TABLE_STRING,
    format_cb_current_command
  },
  { "pane_current_path", FORMAT_TABLE_STRING,
    format_cb_current_path
  },
  { "pane_dead", FORMAT_TABLE_STRING,
    format_cb_pane_dead
  },
  { "pane_dead_signal", FORMAT_TABLE_STRING,
    format_cb_pane_dead_signal
  },
  { "pane_dead_status", FORMAT_TABLE_STRING,
    format_cb_pane_dead_status
  },
  { "pane_dead_time", FORMAT_TABLE_TIME,
    format_cb_pane_dead_time
  },
  { "pane_fg", FORMAT_TABLE_STRING,
    format_cb_pane_fg
  },
  { "pane_flags", FORMAT_TABLE_STRING,
    format_cb_pane_flags
  },
  { "pane_floating_flag", FORMAT_TABLE_STRING,
    format_cb_pane_floating_flag
  },
  { "pane_format", FORMAT_TABLE_STRING,
    format_cb_pane_format
  },
  { "pane_height", FORMAT_TABLE_STRING,
    format_cb_pane_height
  },
  { "pane_id", FORMAT_TABLE_STRING,
    format_cb_pane_id
  },
  { "pane_in_mode", FORMAT_TABLE_STRING,
    format_cb_pane_in_mode
  },
  { "pane_index", FORMAT_TABLE_STRING,
    format_cb_pane_index
  },
  { "pane_input_off", FORMAT_TABLE_STRING,
    format_cb_pane_input_off
  },
  { "pane_key_mode", FORMAT_TABLE_STRING,
    format_cb_pane_key_mode
  },
  { "pane_last", FORMAT_TABLE_STRING,
    format_cb_pane_last
  },
  { "pane_last_output_time", FORMAT_TABLE_TIME,
    format_cb_pane_last_output_time
  },
  { "pane_last_prompt_time", FORMAT_TABLE_TIME,
    format_cb_pane_last_prompt_time
  },
  { "pane_left", FORMAT_TABLE_STRING,
    format_cb_pane_left
  },
  { "pane_marked", FORMAT_TABLE_STRING,
    format_cb_pane_marked
  },
  { "pane_marked_set", FORMAT_TABLE_STRING,
    format_cb_pane_marked_set
  },
  { "pane_modal_flag", FORMAT_TABLE_STRING,
    format_cb_pane_modal_flag
  },
  { "pane_mode", FORMAT_TABLE_STRING,
    format_cb_pane_mode
  },
  { "pane_path", FORMAT_TABLE_STRING,
    format_cb_pane_path
  },
  { "pane_pb_progress", FORMAT_TABLE_STRING,
    format_cb_pane_pb_progress
  },
  { "pane_pb_state", FORMAT_TABLE_STRING,
    format_cb_pane_pb_state
  },
  { "pane_pid", FORMAT_TABLE_STRING,
    format_cb_pane_pid
  },
  { "pane_pipe", FORMAT_TABLE_STRING,
    format_cb_pane_pipe
  },
  { "pane_pipe_pid", FORMAT_TABLE_STRING,
    format_cb_pane_pipe_pid
  },
  { "pane_right", FORMAT_TABLE_STRING,
    format_cb_pane_right
  },
  { "pane_search_string", FORMAT_TABLE_STRING,
    format_cb_pane_search_string
  },
  { "pane_start_command", FORMAT_TABLE_STRING,
    format_cb_start_command
  },
  { "pane_start_command_list", FORMAT_TABLE_STRING,
    format_cb_start_command_list
  },
  { "pane_start_path", FORMAT_TABLE_STRING,
    format_cb_start_path
  },
  { "pane_synchronized", FORMAT_TABLE_STRING,
    format_cb_pane_synchronized
  },
  { "pane_tabs", FORMAT_TABLE_STRING,
    format_cb_pane_tabs
  },
  { "pane_title", FORMAT_TABLE_STRING,
    format_cb_pane_title
  },
  { "pane_top", FORMAT_TABLE_STRING,
    format_cb_pane_top
  },
  { "pane_tty", FORMAT_TABLE_STRING,
    format_cb_pane_tty
  },
  { "pane_unseen_changes", FORMAT_TABLE_STRING,
    format_cb_pane_unseen_changes
  },
  { "pane_unzoomed_height", FORMAT_TABLE_STRING,
    format_cb_pane_unzoomed_height
  },
  { "pane_unzoomed_width", FORMAT_TABLE_STRING,
    format_cb_pane_unzoomed_width
  },
  { "pane_width", FORMAT_TABLE_STRING,
    format_cb_pane_width
  },
  { "pane_x", FORMAT_TABLE_STRING,
    format_cb_pane_x
  },
  { "pane_y", FORMAT_TABLE_STRING,
    format_cb_pane_y
  },
  { "pane_z", FORMAT_TABLE_STRING,
    format_cb_pane_z
  },
  { "pane_zoomed_flag", FORMAT_TABLE_STRING,
    format_cb_pane_zoomed_flag
  },
  { "pid", FORMAT_TABLE_STRING,
    format_cb_pid
  },
  { "scroll_region_lower", FORMAT_TABLE_STRING,
    format_cb_scroll_region_lower
  },
  { "scroll_region_upper", FORMAT_TABLE_STRING,
    format_cb_scroll_region_upper
  },
  { "server_sessions", FORMAT_TABLE_STRING,
    format_cb_server_sessions
  },
  { "session_active", FORMAT_TABLE_STRING,
    format_cb_session_active
  },
  { "session_activity", FORMAT_TABLE_TIME,
    format_cb_session_activity
  },
  { "session_activity_flag", FORMAT_TABLE_STRING,
    format_cb_session_activity_flag
  },
  { "session_alert", FORMAT_TABLE_STRING,
    format_cb_session_alert
  },
  { "session_alerts", FORMAT_TABLE_STRING,
    format_cb_session_alerts
  },
  { "session_attached", FORMAT_TABLE_STRING,
    format_cb_session_attached
  },
  { "session_attached_list", FORMAT_TABLE_STRING,
    format_cb_session_attached_list
  },
  { "session_bell_flag", FORMAT_TABLE_STRING,
    format_cb_session_bell_flag
  },
  { "session_created", FORMAT_TABLE_TIME,
    format_cb_session_created
  },
  { "session_format", FORMAT_TABLE_STRING,
    format_cb_session_format
  },
  { "session_group", FORMAT_TABLE_STRING,
    format_cb_session_group
  },
  { "session_group_attached", FORMAT_TABLE_STRING,
    format_cb_session_group_attached
  },
  { "session_group_attached_list", FORMAT_TABLE_STRING,
    format_cb_session_group_attached_list
  },
  { "session_group_list", FORMAT_TABLE_STRING,
    format_cb_session_group_list
  },
  { "session_group_many_attached", FORMAT_TABLE_STRING,
    format_cb_session_group_many_attached
  },
  { "session_group_size", FORMAT_TABLE_STRING,
    format_cb_session_group_size
  },
  { "session_grouped", FORMAT_TABLE_STRING,
    format_cb_session_grouped
  },
  { "session_id", FORMAT_TABLE_STRING,
    format_cb_session_id
  },
  { "session_last_attached", FORMAT_TABLE_TIME,
    format_cb_session_last_attached
  },
  { "session_many_attached", FORMAT_TABLE_STRING,
    format_cb_session_many_attached
  },
  { "session_marked", FORMAT_TABLE_STRING,
    format_cb_session_marked,
  },
  { "session_name", FORMAT_TABLE_STRING,
    format_cb_session_name
  },
  { "session_path", FORMAT_TABLE_STRING,
    format_cb_session_path
  },
  { "session_silence_flag", FORMAT_TABLE_STRING,
    format_cb_session_silence_flag
  },
  { "session_stack", FORMAT_TABLE_STRING,
    format_cb_session_stack
  },
  { "session_windows", FORMAT_TABLE_STRING,
    format_cb_session_windows
  },
  { "sixel_support", FORMAT_TABLE_STRING,
    format_cb_sixel_support
  },
  { "socket_path", FORMAT_TABLE_STRING,
    format_cb_socket_path
  },
  { "start_time", FORMAT_TABLE_TIME,
    format_cb_start_time
  },
  { "synchronized_output_flag", FORMAT_TABLE_STRING,
    format_cb_synchronized_output_flag
  },
  { "tree_mode_format", FORMAT_TABLE_STRING,
    format_cb_tree_mode_format
  },
  { "uid", FORMAT_TABLE_STRING,
    format_cb_uid
  },
  { "user", FORMAT_TABLE_STRING,
    format_cb_user
  },
  { "version", FORMAT_TABLE_STRING,
    format_cb_version
  },
  { "window_active", FORMAT_TABLE_STRING,
    format_cb_window_active
  },
  { "window_active_clients", FORMAT_TABLE_STRING,
    format_cb_window_active_clients
  },
  { "window_active_clients_list", FORMAT_TABLE_STRING,
    format_cb_window_active_clients_list
  },
  { "window_active_sessions", FORMAT_TABLE_STRING,
    format_cb_window_active_sessions
  },
  { "window_active_sessions_list", FORMAT_TABLE_STRING,
    format_cb_window_active_sessions_list
  },
  { "window_activity", FORMAT_TABLE_TIME,
    format_cb_window_activity
  },
  { "window_activity_flag", FORMAT_TABLE_STRING,
    format_cb_window_activity_flag
  },
  { "window_bell_flag", FORMAT_TABLE_STRING,
    format_cb_window_bell_flag
  },
  { "window_bigger", FORMAT_TABLE_STRING,
    format_cb_window_bigger
  },
  { "window_cell_height", FORMAT_TABLE_STRING,
    format_cb_window_cell_height
  },
  { "window_cell_width", FORMAT_TABLE_STRING,
    format_cb_window_cell_width
  },
  { "window_end_flag", FORMAT_TABLE_STRING,
    format_cb_window_end_flag
  },
  { "window_flags", FORMAT_TABLE_STRING,
    format_cb_window_flags
  },
  { "window_format", FORMAT_TABLE_STRING,
    format_cb_window_format
  },
  { "window_height", FORMAT_TABLE_STRING,
    format_cb_window_height
  },
  { "window_id", FORMAT_TABLE_STRING,
    format_cb_window_id
  },
  { "window_index", FORMAT_TABLE_STRING,
    format_cb_window_index
  },
  { "window_last_flag", FORMAT_TABLE_STRING,
    format_cb_window_last_flag
  },
  { "window_layout", FORMAT_TABLE_STRING,
    format_cb_window_layout
  },
  { "window_linked", FORMAT_TABLE_STRING,
    format_cb_window_linked
  },
  { "window_linked_sessions", FORMAT_TABLE_STRING,
    format_cb_window_linked_sessions
  },
  { "window_linked_sessions_list", FORMAT_TABLE_STRING,
    format_cb_window_linked_sessions_list
  },
  { "window_manual_height", FORMAT_TABLE_STRING,
    format_cb_window_manual_height
  },
  { "window_manual_width", FORMAT_TABLE_STRING,
    format_cb_window_manual_width
  },
  { "window_marked_flag", FORMAT_TABLE_STRING,
    format_cb_window_marked_flag
  },
  { "window_modal_pane", FORMAT_TABLE_STRING,
    format_cb_window_modal_pane
  },
  { "window_name", FORMAT_TABLE_STRING,
    format_cb_window_name
  },
  { "window_offset_x", FORMAT_TABLE_STRING,
    format_cb_window_offset_x
  },
  { "window_offset_y", FORMAT_TABLE_STRING,
    format_cb_window_offset_y
  },
  { "window_panes", FORMAT_TABLE_STRING,
    format_cb_window_panes
  },
  { "window_raw_flags", FORMAT_TABLE_STRING,
    format_cb_window_raw_flags
  },
  { "window_silence_flag", FORMAT_TABLE_STRING,
    format_cb_window_silence_flag
  },
  { "window_stack_index", FORMAT_TABLE_STRING,
    format_cb_window_stack_index
  },
  { "window_start_flag", FORMAT_TABLE_STRING,
    format_cb_window_start_flag
  },
  { "window_visible_layout", FORMAT_TABLE_STRING,
    format_cb_window_visible_layout
  },
  { "window_width", FORMAT_TABLE_STRING,
    format_cb_window_width
  },
  { "window_zoomed_flag", FORMAT_TABLE_STRING,
    format_cb_window_zoomed_flag
  },
  { "wrap_flag", FORMAT_TABLE_STRING,
    format_cb_wrap_flag
  }
};

/* Compare format table entries. */
static int
format_table_compare(const void *key0, const void *entry0)
{
  const char      *key = key0;
  const struct format_table_entry *entry = entry0;

  return (strcmp(key, entry->key));
}

/* Get a format callback. */
static const struct format_table_entry *
format_table_get(const char *key)
{
  return (bsearch(key, format_table, nitems(format_table),
      sizeof *format_table, format_table_compare));
}

/* Merge one format tree into another. */
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);
  }
}

/* Get format pane. */
struct window_pane *
format_get_pane(struct format_tree *ft)
{
  return (ft->wp);
}

/* Add item bits to tree. */
static void
format_create_add_item(struct format_tree *ft, struct cmdq_item *item)
{
  struct key_event  *event = cmdq_get_event(item);
  struct mouse_event  *m = &event->m;

  cmdq_merge_formats(item, ft);
  memcpy(&ft->m, m, sizeof ft->m);
}

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

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

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

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

  if (item != NULL)
    format_create_add_item(ft, item);

  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);
}

/* Log each format. */
static void
format_log_debug_cb(const char *key, const char *value, void *arg)
{
  const char  *prefix = arg;

  log_debug("%s: %s=%s", prefix, key, value);
}

/* Log a format tree. */
void
format_log_debug(struct format_tree *ft, const char *prefix)
{
  format_each(ft, format_log_debug_cb, (void *)prefix);
}

/* Walk each format. */
void
format_each(struct format_tree *ft, void (*cb)(const char *, const char *,
    void *), void *arg)
{
  const struct format_table_entry *fte;
  struct format_entry   *fe;
  u_int        i;
  char         s[64];
  void        *value;
  struct timeval      *tv;

  for (i = 0; i < nitems(format_table); i++) {
    fte = &format_table[i];

    value = fte->cb(ft);
    if (value == NULL)
      continue;
    if (fte->type == FORMAT_TABLE_TIME) {
      tv = value;
      xsnprintf(s, sizeof s, "%lld", (long long)tv->tv_sec);
      cb(fte->key, s, arg);
    } else {
      cb(fte->key, value, arg);
      free(value);
    }
  }
  RB_FOREACH(fe, format_entry_tree, &ft->tree) {
    if (fe->time != 0) {
      xsnprintf(s, sizeof s, "%lld", (long long)fe->time);
      cb(fe->key, s, arg);
    } else {
      if (fe->value == NULL && fe->cb != NULL) {
        fe->value = fe->cb(ft);
        if (fe->value == NULL)
          fe->value = xstrdup("");
      }
      cb(fe->key, fe->value, arg);
    }
  }
}

/* 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->time = 0;

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

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

  fe->value = NULL;
}

/* Add a key and function. */
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->time = 0;

  fe->value = NULL;
}

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

  at = out = xmalloc(strlen(s) * 2 + 1);
  for (cp = s; *cp != '\0'; cp++) {
    if (strchr("|&;<>()$`\\\"'*?[# =%\n\t", *cp) != NULL)
      *at++ = '\\';
    *at++ = *cp;
  }
  *at = '\0';
  return (out);
}

/* Quote string with POSIX shell single quotes. */
static char *
format_quote_shell_single(const char *s)
{
  const char  *cp;
  char    *out, *at;

  at = out = xmalloc(strlen(s) * 4 + 3);
  *at++ = '\'';
  for (cp = s; *cp != '\0'; cp++) {
    if (*cp == '\'') {
      *at++ = '\'';
      *at++ = '\\';
      *at++ = '\'';
      *at++ = '\'';
    } else
      *at++ = *cp;
  }
  *at++ = '\'';
  *at = '\0';
  return (out);
}

/* Quote #s in string. */
static char *
format_quote_style(const char *s)
{
  const char  *cp;
  char    *out, *at;

  at = out = xmalloc(strlen(s) * 2 + 1);
  for (cp = s; *cp != '\0'; cp++) {
    if (*cp == '#')
      *at++ = '#';
    *at++ = *cp;
  }
  *at = '\0';
  return (out);
}

/* Make a prettier time. */
char *
format_pretty_time(time_t t, int seconds)
{
  struct tm now_tm, tm;
  time_t    now, age;
  char    s[9];

  time(&now);
  if (now < t)
    now = t;
  age = now - t;

  localtime_r(&now, &now_tm);
  localtime_r(&t, &tm);

  /* Last 24 hours. */
  if (age < 24 * 3600) {
    if (seconds)
      strftime(s, sizeof s, "%H:%M:%S", &tm);
    else
      strftime(s, sizeof s, "%H:%M", &tm);
    return (xstrdup(s));
  }

  /* This month or last 28 days. */
  if ((tm.tm_year == now_tm.tm_year && tm.tm_mon == now_tm.tm_mon) ||
      age < 28 * 24 * 3600) {
    strftime(s, sizeof s, "%a%d", &tm);
    return (xstrdup(s));
  }

  /* Last 12 months. */
  if ((tm.tm_year == now_tm.tm_year && tm.tm_mon < now_tm.tm_mon) ||
      (tm.tm_year == now_tm.tm_year - 1 && tm.tm_mon > now_tm.tm_mon)) {
    strftime(s, sizeof s, "%d%b", &tm);
    return (xstrdup(s));
  }

  /* Older than that. */
  strftime(s, sizeof s, "%h%y", &tm);
  return (xstrdup(s));
}

/* Make a relative time. */
static char *
format_relative_time(time_t t)
{
  time_t  now, age;
  u_int d, h, m, s;
  char  out[32];

  time(&now);
  if (t > now)
    return (NULL);
  if (t == now)
    return (xstrdup("0s"));
  age = now - t;

  d = age / 86400;
  h = (age % 86400) / 3600;
  m = (age % 3600) / 60;
  s = age % 60;

  if (d != 0) {
    if (h != 0)
      xsnprintf(out, sizeof out, "%ud%uh", d, h);
    else
      xsnprintf(out, sizeof out, "%ud", d);
  } else if (h != 0) {
    if (m != 0)
      xsnprintf(out, sizeof out, "%uh%um", h, m);
    else
      xsnprintf(out, sizeof out, "%uh", h);
  } else if (m != 0) {
    if (s != 0)
      xsnprintf(out, sizeof out, "%um%us", m, s);
    else
      xsnprintf(out, sizeof out, "%um", m);
  } else
    xsnprintf(out, sizeof out, "%us", s);
  return (xstrdup(out));
}

/* Make a time difference in seconds. */
static char *
format_time_difference(time_t t)
{
  time_t   now = time(NULL);
  char  *out;

  xasprintf(&out, "%ld", (long)now - (long)t);
  return (out);
}

/* Find a format entry. */
static char *
format_find(struct format_tree *ft, const char *key, uint64_t modifiers,
    const char *time_format)
{
  const struct format_table_entry *fte;
  void        *value;
  struct format_entry   *fe, fe_find;
  struct environ_entry    *envent;
  struct options_entry    *o;
  char        *found = NULL, *saved, s[512];
  char        *array_key = NULL;
  const char      *errstr;
  time_t         t = 0;
  struct tm      tm;

  o = options_parse_get(global_options, key, &array_key, 0);
  if (o == NULL && ft->wp != NULL)
    o = options_parse_get(ft->wp->options, key, &array_key, 0);
  if (o == NULL && ft->w != NULL)
    o = options_parse_get(ft->w->options, key, &array_key, 0);
  if (o == NULL)
    o = options_parse_get(global_w_options, key, &array_key, 0);
  if (o == NULL && ft->s != NULL)
    o = options_parse_get(ft->s->options, key, &array_key, 0);
  if (o == NULL)
    o = options_parse_get(global_s_options, key, &array_key, 0);
  if (o != NULL) {
    found = options_to_string(o, array_key, 1);
    free(array_key);
    goto found;
  }

  fte = format_table_get(key);
  if (fte != NULL) {
    value = fte->cb(ft);
    if (fte->type == FORMAT_TABLE_TIME && value != NULL)
      t = ((struct timeval *)value)->tv_sec;
    else
      found = value;
    goto found;
  }
  fe_find.key = (char *)key;
  fe = RB_FIND(format_entry_tree, &ft->tree, &fe_find);
  if (fe != NULL) {
    if (fe->time != 0) {
      t = fe->time;
      goto found;
    }
    if (fe->value == NULL && fe->cb != NULL) {
      fe->value = fe->cb(ft);
      if (fe->value == NULL)
        fe->value = xstrdup("");
    }
    found = xstrdup(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 && envent->value != NULL) {
      found = xstrdup(envent->value);
      goto found;
    }
  }

  return (NULL);

found:
  if (modifiers & FORMAT_TIMESTRING) {
    if (t == 0 && found != NULL) {
      t = strtonum(found, 0, INT64_MAX, &errstr);
      if (errstr != NULL)
        t = 0;
      free(found);
    }
    if (t == 0)
      return (NULL);
    if (modifiers & FORMAT_RELATIVE)
      found = format_relative_time(t);
    else if (modifiers & FORMAT_DIFFERENCE)
      found = format_time_difference(t);
    else if (modifiers & FORMAT_PRETTY)
      found = format_pretty_time(t, 0);
    else {
      if (time_format != NULL) {
        localtime_r(&t, &tm);
        format_strftime(s, sizeof s, time_format, &tm);
      } else {
        ctime_r(&t, s);
        s[strcspn(s, "\n")] = '\0';
      }
      found = xstrdup(s);
    }
    return (found);
  }

  if (t != 0)
    xasprintf(&found, "%lld", (long long)t);
  else if (found == NULL)
    return (NULL);
  if (modifiers & FORMAT_BASENAME) {
    saved = found;
    found = xstrdup(basename(saved));
    free(saved);
  }
  if (modifiers & FORMAT_DIRNAME) {
    saved = found;
    found = xstrdup(dirname(saved));
    free(saved);
  }
  if (modifiers & FORMAT_QUOTE_SHELL) {
    saved = found;
    found = format_quote_shell(saved);
    free(saved);
  }
  if (modifiers & FORMAT_QUOTE_SHELL_SQ) {
    saved = found;
    found = format_quote_shell_single(saved);
    free(saved);
  }
  if (modifiers & FORMAT_QUOTE_STYLE) {
    saved = found;
    found = format_quote_style(saved);
    free(saved);
  }
  if (modifiers & FORMAT_QUOTE_ARGUMENTS) {
    saved = found;
    found = args_escape(saved);
    free(saved);
  }
  return (found);
}

/* Check if format has not taken too long. */
static int
format_check_time(struct format_expand_state *es, u_int *check)
{
  uint64_t t;

  if (check != NULL && ++*check % FORMAT_TIME_LOOP_CHECK != 0)
    return (1);

  t = get_timer();
  if (t - es->start_time < FORMAT_TIME_LIMIT)
    return (1);
  t -= es->start_time;

  format_log(es, "reached time limit (%llu)", (unsigned long long)t);
  return (0);
}

/* Unescape escaped characters. */
static char *
format_unescape(struct format_expand_state *es, const char *s, size_t n)
{
  const char  *end = s + n;
  char    *out, *cp;
  int    brackets = 0;
  u_int    check = 0;

  cp = out = xmalloc(n + 1);
  for (; s != end; s++) {
    if (!format_check_time(es, &check)) {
      free(out);
      return (xstrdup(""));
    }
    if (*s == '#' && s + 1 != end && s[1] == '{')
      brackets++;
    if (brackets == 0 &&
        *s == '#' &&
        s + 1 != end &&
        strchr(",#{}:", s[1]) != NULL) {
      *cp++ = *++s;
      continue;
    }
    if (*s == '}')
      brackets--;
    *cp++ = *s;
  }
  *cp = '\0';
  return (out);
}

/* Remove escaped characters. */
static char *
format_strip(struct format_expand_state *es, const char *s)
{
  char  *out, *cp;
  int  brackets = 0;
  u_int  check = 0;

  cp = out = xmalloc(strlen(s) + 1);
  for (; *s != '\0'; s++) {
    if (!format_check_time(es, &check)) {
      free(out);
      return (xstrdup(""));
    }
    if (*s == '#' && s[1] == '{')
      brackets++;
    if (*s == '#' && strchr(",#{}:", s[1]) != NULL) {
      if (brackets != 0)
        *cp++ = *s;
      continue;
    }
    if (*s == '}')
      brackets--;
    *cp++ = *s;
  }
  *cp = '\0';
  return (out);
}

/* Skip until end. */
static const char *
format_skip1(struct format_expand_state *es, const char *s, const char *end)
{
  int brackets = 0;
  u_int check = 0;

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

/* Skip until end. */
const char *
format_skip(const char *s, const char *end)
{
    return (format_skip1(NULL, s, end));
}

/* Return left and right alternatives separated by commas. */
static int
format_choose(struct format_expand_state *es, const char *s, char **left,
    char **right, int expand)
{
  const char  *cp;
  char    *left0, *right0;

  cp = format_skip1(es, s, ",");
  if (cp == NULL)
    return (-1);
  left0 = xstrndup(s, cp - s);
  right0 = xstrdup(cp + 1);

  if (expand) {
    *left = format_expand1(es, left0);
    free(left0);
    *right = format_expand1(es, right0);
    free(right0);
  } else {
    *left = left0;
    *right = right0;
  }
  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);
}

/* Check if modifier end. */
static int
format_is_end(char c)
{
  return (c == ';' || c == ':');
}

/* Add to modifier list. */
static void
format_add_modifier(struct format_modifier **list, u_int *count,
    const char *c, size_t n, char **argv, int argc)
{
  struct format_modifier *fm;

  *list = xreallocarray(*list, (*count) + 1, sizeof **list);
  fm = &(*list)[(*count)++];

  memcpy(fm->modifier, c, n);
  fm->modifier[n] = '\0';
  fm->size = n;

  fm->argv = argv;
  fm->argc = argc;
}

/* Free modifier list. */
static void
format_free_modifiers(struct format_modifier *list, u_int count)
{
  u_int i;

  for (i = 0; i < count; i++)
    cmd_free_argv(list[i].argc, list[i].argv);
  free(list);
}

/* Build modifier list. */
static struct format_modifier *
format_build_modifiers(struct format_expand_state *es, const char **s,
    u_int *count)
{
  const char    *cp = *s, *end;
  struct format_modifier  *list = NULL;
  char       c, last[] = "X;:", **argv, *value;
  int      argc;

  /*
   * Modifiers are a ; separated list of the forms:
   *  l,m,C,a,b,c,d,I,n,t,w,q,E,T,S,W,P,O,V,R,A,<,>
   *  =a
   *  =/a
   *  =/a/
   *  s/a/b/
   *  s/a/b
   *  ||,&&,!=,==,<=,>=
   */

  *count = 0;

  while (*cp != '\0' && *cp != ':') {
    /* Skip any separator character. */
    if (*cp == ';')
      cp++;
    if (*cp == '\0')
      break;

    /* Check single character modifiers with no arguments. */
    if (strchr("labdnwETSWPOVL!<>A", cp[0]) != NULL &&
        format_is_end(cp[1])) {
      format_add_modifier(&list, count, cp, 1, NULL, 0);
      cp++;
      continue;
    }

    /* Then try double character with no arguments. */
    if ((memcmp("||", cp, 2) == 0 ||
        memcmp("&&", cp, 2) == 0 ||
        memcmp("!!", cp, 2) == 0 ||
        memcmp("!=", cp, 2) == 0 ||
        memcmp("==", cp, 2) == 0 ||
        memcmp("<=", cp, 2) == 0 ||
        memcmp(">=", cp, 2) == 0) &&
        format_is_end(cp[2])) {
      format_add_modifier(&list, count, cp, 2, NULL, 0);
      cp += 2;
      continue;
    }

    /* Now try single character with arguments. */
    if (strchr("ImCLNPSOVst=pReqWcA", cp[0]) == NULL)
      break;
    c = cp[0];

    /* No arguments provided. */
    if (format_is_end(cp[1])) {
      format_add_modifier(&list, count, cp, 1, NULL, 0);
      cp++;
      continue;
    }
    argv = NULL;
    argc = 0;

    /* Single argument with no wrapper character. */
    if (!ispunct((u_char)cp[1]) || cp[1] == '-') {
      end = format_skip1(es, cp + 1, ":;");
      if (end == NULL)
        break;

      argv = xcalloc(1, sizeof *argv);
      value = format_unescape(es, cp + 1, end - (cp + 1));
      argv[0] = format_expand1(es, value);
      free(value);
      argc = 1;

      format_add_modifier(&list, count, &c, 1, argv, argc);
      cp = end;
      continue;
    }

    /* Multiple arguments with a wrapper character. */
    last[0] = cp[1];
    cp++;
    do {
      if (cp[0] == last[0] && format_is_end(cp[1])) {
        cp++;
        break;
      }
      end = format_skip1(es, cp + 1, last);
      if (end == NULL)
        break;
      cp++;

      argv = xreallocarray(argv, argc + 1, sizeof *argv);
      value = format_unescape(es, cp, end - cp);
      argv[argc++] = format_expand1(es, value);
      free(value);

      cp = end;
    } while (!format_is_end(cp[0]));
    format_add_modifier(&list, count, &c, 1, argv, argc);
  }
  if (*cp != ':') {
    format_free_modifiers(list, *count);
    *count = 0;
    return (NULL);
  }
  *s = cp + 1;
  return (list);
}

/* Match using the fuzzy matcher. */
static char *
format_match_fuzzy(const char *pattern, const char *text, int positions)
{
  struct evbuffer *buffer;
  bitstr_t  *bs;
  char    *value;
  size_t     size;
  u_int    i, width;

  width = format_width(text);
  if (width == 0)
    width = 1;
  bs = fuzzy_match(pattern, text, width, NULL);
  if (bs == NULL)
    return (xstrdup(positions ? "" : "0"));

  if (!positions) {
    free(bs);
    return (xstrdup("1"));
  }

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");
  for (i = 0; i < width; i++) {
    if (!bit_test(bs, i))
      continue;
    if (EVBUFFER_LENGTH(buffer) != 0)
      evbuffer_add(buffer, ",", 1);
    evbuffer_add_printf(buffer, "%u", i);
  }
  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  else
    value = xstrdup("");
  evbuffer_free(buffer);
  free(bs);
  return (value);
}

/* Match against an fnmatch(3) pattern or regular expression. */
static char *
format_match(struct format_modifier *fm, const char *pattern, const char *text)
{
  const char  *s = "";
  regex_t    r;
  int    flags = 0;

  if (fm->argc >= 1)
    s = fm->argv[0];
  if (strchr(s, 'p') != NULL)
    return (format_match_fuzzy(pattern, text, 1));
  if (strchr(s, 'z') != NULL)
    return (format_match_fuzzy(pattern, text, 0));
  if (strchr(s, 'r') == NULL) {
    if (strchr(s, 'i') != NULL)
      flags |= FNM_CASEFOLD;
    if (fnmatch(pattern, text, flags) != 0)
      return (xstrdup("0"));
  } else {
    flags = REG_EXTENDED|REG_NOSUB;
    if (strchr(s, 'i') != NULL)
      flags |= REG_ICASE;
    if (regcomp(&r, pattern, flags) != 0)
      return (xstrdup("0"));
    if (regexec(&r, text, 0, NULL, 0) != 0) {
      regfree(&r);
      return (xstrdup("0"));
    }
    regfree(&r);
  }
  return (xstrdup("1"));
}

/* Perform substitution in string. */
static char *
format_sub(struct format_modifier *fm, const char *text, const char *pattern,
    const char *with)
{
  char  *value;
  int  flags = REG_EXTENDED;

  if (fm->argc >= 3 && strchr(fm->argv[2], 'i') != NULL)
    flags |= REG_ICASE;
  value = regsub(pattern, with, text, flags);
  if (value == NULL)
    return (xstrdup(text));
  return (value);
}

/* Search inside pane. */
static char *
format_search(struct format_modifier *fm, struct window_pane *wp, const char *s)
{
  int  ignore = 0, regex = 0;
  char  *value;

  if (fm->argc >= 1) {
    if (strchr(fm->argv[0], 'i') != NULL)
      ignore = 1;
    if (strchr(fm->argv[0], 'r') != NULL)
      regex = 1;
  }
  xasprintf(&value, "%u", window_pane_search(wp, s, regex, ignore));
  return (value);
}

/* Handle unary boolean operators, "!" and "!!". */
static char *
format_bool_op_1(struct format_expand_state *es, const char *fmt, int not)
{
  int  result;
  char  *expanded;

  expanded = format_expand1(es, fmt);
  result = format_true(expanded);
  if (not)
    result = !result;
  free(expanded);

  return (xstrdup(result ? "1" : "0"));
}

/* Handle n-ary boolean operators, "&&" and "||". */
static char *
format_bool_op_n(struct format_expand_state *es, const char *fmt, int and)
{
  int    result;
  const char  *cp1, *cp2;
  char    *raw, *expanded;

  result = and ? 1 : 0;
  cp1 = fmt;

  while (and ? result : !result) {
    cp2 = format_skip1(es, cp1, ",");

    if (cp2 == NULL)
      raw = xstrdup(cp1);
    else
      raw = xstrndup(cp1, cp2 - cp1);
    expanded = format_expand1(es, raw);
    free(raw);
    format_log(es, "operator %s has operand: %s",
        and ? "&&" : "||", expanded);

    if (and)
      result = result && format_true(expanded);
    else
      result = result || format_true(expanded);
    free(expanded);

    if (cp2 == NULL)
      break;
    else
      cp1 = cp2 + 1;
  }

  return (xstrdup(result ? "1" : "0"));
}

/* Does session name exist? */
static char *
format_session_name(struct format_expand_state *es, const char *fmt)
{
  char    *name;
  struct session  *s;

  name = format_expand1(es, fmt);
  RB_FOREACH(s, sessions, &sessions) {
    if (strcmp(s->name, name) == 0) {
      free(name);
      return (xstrdup("1"));
    }
  }
  free(name);
  return (xstrdup("0"));
}

/* Loop over sessions. */
static char *
format_loop_sessions(struct format_expand_state *es, const char *fmt)
{
  struct sort_criteria     *sc = &sort_crit;
  struct format_tree     *ft = es->ft;
  struct client      *c = ft->client;
  struct cmdq_item     *item = ft->item;
  struct format_tree     *nft;
  struct format_expand_state    next;
  char         *all, *active, *use, *expanded, *value;
  struct evbuffer      *buffer;
  size_t          size;
  struct session       *s, **l;
  int         i, n;

  if (format_choose(es, fmt, &all, &active, 0) != 0) {
    all = xstrdup(fmt);
    active = NULL;
  }

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  l = sort_get_sessions(&n, sc);
  for (i = 0; i < n; i++) {
    s = l[i];
    format_log(es, "session loop: $%u", s->id);
    if (active != NULL &&
        ft->c != NULL &&
        s->id == ft->c->session->id)
      use = active;
    else
      use = all;
    nft = format_create(c, item, FORMAT_NONE, ft->flags);

    format_add(nft, "loop_index", "%d", i);
    format_add(nft, "loop_last_flag", "%d", i == n - 1);

    format_defaults(nft, ft->c, s, NULL, NULL);
    format_copy_state(&next, es, 0);
    next.ft = nft;

    expanded = format_expand1(&next, use);
    format_free(next.ft);

    evbuffer_add(buffer, expanded, strlen(expanded));
    free(expanded);
  }

  free(active);
  free(all);

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  else
    value = xstrdup("");
  evbuffer_free(buffer);
  return (value);
}

/* Does window name exist? */
static char *
format_window_name(struct format_expand_state *es, const char *fmt)
{
  struct format_tree  *ft = es->ft;
  char      *name;
  struct winlink    *wl;

  if (ft->s == NULL) {
    format_log(es, "window name but no session");
    return (NULL);
  }

  name = format_expand1(es, fmt);
  RB_FOREACH(wl, winlinks, &ft->s->windows) {
    if (strcmp(wl->window->name, name) == 0) {
      free(name);
      return (xstrdup("1"));
    }
  }
  free(name);
  return (xstrdup("0"));
}

/* Add neighbour window variables to the format tree. */
static void
format_add_window_neighbour(struct format_tree *nft, struct winlink *wl,
    struct session *s, const char *prefix)
{
  struct options_entry  *o;
  const char    *oname;
  char      *key, *prefixed, *oval;

  xasprintf(&key, "%s_window_index", prefix);
  format_add(nft, key, "%u", wl->idx);
  free(key);

  xasprintf(&key, "%s_window_active", prefix);
  format_add(nft, key, "%d", wl == s->curw);
  free(key);

  o = options_first(wl->window->options);
  while (o != NULL) {
    oname = options_name(o);
    if (*oname == '@') {
      xasprintf(&prefixed, "%s_%s", prefix, oname);
      oval = options_to_string(o, NULL, 1);
      format_add(nft, prefixed, "%s", oval);
      free(oval);
      free(prefixed);
    }
    o = options_next(o);
  }
}

/* Loop over windows. */
static char *
format_loop_windows(struct format_expand_state *es, const char *fmt)
{
  struct sort_criteria    *sc = &sort_crit;
  struct format_tree    *ft = es->ft;
  struct client     *c = ft->client;
  struct session      *s = ft->s;
  struct cmdq_item    *item = ft->item;
  struct format_tree    *nft;
  struct format_expand_state   next;
  char        *all, *active, *use, *expanded, *value;
  struct evbuffer     *buffer;
  size_t         size;
  struct winlink      *wl, **l;
  struct window     *w;
  int        i, n;

  if (s == NULL) {
    format_log(es, "window loop but no session");
    return (NULL);
  }

  if (format_choose(es, fmt, &all, &active, 0) != 0) {
    all = xstrdup(fmt);
    active = NULL;
  }

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  l = sort_get_winlinks_session(s, &n, sc);
  for (i = 0; i < n; i++) {
    wl = l[i];
    w = wl->window;
    format_log(es, "window loop: %u @%u", wl->idx, w->id);
    if (active != NULL && wl == s->curw)
      use = active;
    else
      use = all;
    nft = format_create(c, item, FORMAT_WINDOW|w->id, ft->flags);

    format_add(nft, "loop_index", "%d", i);
    format_add(nft, "loop_last_flag", "%d", i == n - 1);

    /* Add neighbour window data to the format tree. */
    if (i > 0 && l[i - 1] == s->curw)
      format_add(nft, "window_after_active", "1");
    else
      format_add(nft, "window_after_active", "0");
    if (i + 1 < n && l[i + 1] == s->curw)
      format_add(nft, "window_before_active", "1");
    else
      format_add(nft, "window_before_active", "0");
    if (i + 1 < n)
      format_add_window_neighbour(nft, l[i + 1], s, "next");
    if (i > 0)
      format_add_window_neighbour(nft, l[i - 1], s, "prev");

    format_defaults(nft, ft->c, s, wl, NULL);
    format_copy_state(&next, es, 0);
    next.ft = nft;

    expanded = format_expand1(&next, use);
    format_free(nft);

    evbuffer_add(buffer, expanded, strlen(expanded));
    free(expanded);
  }

  free(active);
  free(all);

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  else
    value = xstrdup("");
  evbuffer_free(buffer);
  return (value);
}

/* Loop over panes. */
static char *
format_loop_panes(struct format_expand_state *es, const char *fmt)
{
  struct sort_criteria    *sc = &sort_crit;
  struct format_tree    *ft = es->ft;
  struct client     *c = ft->client;
  struct cmdq_item    *item = ft->item;
  struct format_tree    *nft;
  struct format_expand_state   next;
  char        *all, *active, *use, *expanded, *value;
  struct evbuffer     *buffer;
  size_t         size;
  struct window_pane    *wp, **l;
  int         i, n;

  if (ft->w == NULL) {
    format_log(es, "pane loop but no window");
    return (NULL);
  }

  if (format_choose(es, fmt, &all, &active, 0) != 0) {
    all = xstrdup(fmt);
    active = NULL;
  }

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  l = sort_get_panes_window(ft->w, &n, sc);
  for (i = 0; i < n; i++) {
    wp = l[i];
    format_log(es, "pane loop: %%%u", wp->id);
    if (active != NULL && wp == ft->w->active)
      use = active;
    else
      use = all;
    nft = format_create(c, item, FORMAT_PANE|wp->id, ft->flags);

    format_add(nft, "loop_index", "%d", i);
    format_add(nft, "loop_last_flag", "%d", i == n - 1);

    format_defaults(nft, ft->c, ft->s, ft->wl, wp);
    format_copy_state(&next, es, 0);
    next.ft = nft;

    expanded = format_expand1(&next, use);
    format_free(nft);

    evbuffer_add(buffer, expanded, strlen(expanded));
    free(expanded);
  }

  free(active);
  free(all);

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  else
    value = xstrdup("");
  evbuffer_free(buffer);
  return (value);
}

/* Add an option to an options loop. */
static void
format_loop_add_option(struct format_expand_state *es, const char *fmt,
    struct evbuffer *buffer, struct options_entry *o, u_int n, u_int i)
{
  struct format_tree      *ft = es->ft, *nft;
  struct format_expand_state     next;
  const struct options_table_entry  *oe = options_table_entry(o);
  const char        *name = options_name(o);
  char          *expanded, *s;
  int          is_array = options_is_array(o);

  format_log(es, "option loop: %s", name);
  nft = format_create(ft->client, ft->item, FORMAT_NONE, ft->flags);

  format_add(nft, "option_name", "%s", name);
  s = options_to_string(o, NULL, 0);
  format_add(nft, "option_value", "%s", s);
  free(s);

  format_add(nft, "option_is_array", "%d", is_array);
  format_add(nft, "option_array_key", "%s", "");
  format_add(nft, "option_array_index", "%s", "");
  format_add(nft, "option_array_first", "%d", is_array);
  format_add(nft, "option_array_last", "%d", is_array);
  format_add(nft, "option_array_count", "%u", n);

  if (oe != NULL && (oe->flags & OPTIONS_TABLE_IS_HOOK))
    format_add(nft, "option_is_hook", "1");
  else
    format_add(nft, "option_is_hook", "0");
  format_add(nft, "option_is_user", "%d", oe == NULL);

  if (options_next(o) == NULL)
    format_add(nft, "loop_last_flag", "1");
  else
    format_add(nft, "loop_last_flag", "0");
  format_add(nft, "loop_index", "%u", i);

  format_defaults(nft, ft->c, ft->s, ft->wl, ft->wp);
  format_copy_state(&next, es, 0);
  next.ft = nft;

  expanded = format_expand1(&next, fmt);
  format_free(nft);
  evbuffer_add(buffer, expanded, strlen(expanded));
  free(expanded);
}

/* Add an array option item to an options loop. */
static void
format_loop_add_array_item(struct format_expand_state *es, const char *fmt,
    struct evbuffer *buffer, struct options_entry *o,
    struct options_array_item *a, int n, u_int i)
{
  struct format_tree      *ft = es->ft, *nft;
  struct format_expand_state     next;
  const struct options_table_entry  *oe = options_table_entry(o);
  const char        *name = options_name(o);
  const char        *array_key;
  char          *expanded, *s;

  array_key = options_array_item_key(a);
  format_log(es, "option loop: %s[%s]", name, array_key);
  nft = format_create(ft->client, ft->item, FORMAT_NONE, ft->flags);

  format_add(nft, "option_name", "%s", name);
  s = options_to_string(o, array_key, 0);
  format_add(nft, "option_value", "%s", s);
  free(s);

  format_add(nft, "option_is_array", "1");
  format_add(nft, "option_array_key", "%s", array_key);
  format_add(nft, "option_array_index", "%s", array_key);
  if (a == options_array_first(o))
    format_add(nft, "option_array_first", "1");
  else
    format_add(nft, "option_array_first", "0");
  if (options_array_next(a) == NULL)
    format_add(nft, "option_array_last", "1");
  else
    format_add(nft, "option_array_last", "0");
  format_add(nft, "option_array_count", "%u", n);

  if (oe != NULL && (oe->flags & OPTIONS_TABLE_IS_HOOK))
    format_add(nft, "option_is_hook", "1");
  else
    format_add(nft, "option_is_hook", "0");
  format_add(nft, "option_is_user", "%d", oe == NULL);

  if (options_array_next(a) == NULL && options_next(o) == NULL)
    format_add(nft, "loop_last_flag", "1");
  else
    format_add(nft, "loop_last_flag", "0");
  format_add(nft, "loop_index", "%u", i);

  format_defaults(nft, ft->c, ft->s, ft->wl, ft->wp);
  format_copy_state(&next, es, 0);
  next.ft = nft;

  expanded = format_expand1(&next, fmt);
  format_free(nft);
  evbuffer_add(buffer, expanded, strlen(expanded));
  free(expanded);
}

/* Loop over options. */
static char *
format_loop_options(struct format_expand_state *es, const char *fmt,
    const char *flags)
{
  struct format_tree    *ft = es->ft;
  struct options      *oo = NULL;
  struct options_entry    *o;
  struct options_array_item *a;
  char        *value;
  struct evbuffer     *buffer;
  size_t         size;
  u_int        i = 0, n;
  int        global = 0;

  if (flags == NULL || *flags == '\0')
    flags = "s";
  if (strchr(flags, 'v') != NULL)
    oo = global_options;
  else {
    if (strchr(flags, 'g') != NULL)
      global = 1;
    if (strchr(flags, 'w') != NULL) {
      if (global)
        oo = global_w_options;
      else if (ft->w != NULL)
        oo = ft->w->options;
    } else if (strchr(flags, 's') != NULL) {
      if (global)
        oo = global_s_options;
      else if (ft->s != NULL)
        oo = ft->s->options;
    } else if (strchr(flags, 'p') != NULL) {
      if (global)
        /* invalid */;
      else if (ft->wp != NULL)
        oo = ft->wp->options;
    } else if (global)
      oo = global_s_options;
  }
  if (oo == NULL)
    return (xstrdup(""));

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  o = options_first(oo);
  while (o != NULL) {

    n = 0;
    if (options_is_array(o)) {
      a = options_array_first(o);
      while (a != NULL) {
        n++;
        a = options_array_next(a);
      }
    }

    if (!options_is_array(o) || n == 0) {
      format_loop_add_option(es, fmt, buffer, o, n, i);
      i++;
      o = options_next(o);
      continue;
    }

    a = options_array_first(o);
    while (a != NULL) {
      format_loop_add_array_item(es, fmt, buffer, o, a, n, i);
      i++;
      a = options_array_next(a);
    }
    o = options_next(o);
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  else
    value = xstrdup("");
  evbuffer_free(buffer);
  return (value);
}

/* Loop over an environment. */
static char *
format_loop_environ(struct format_expand_state *es, const char *fmt,
    const char *flags)
{
  struct format_tree    *ft = es->ft, *nft;
  struct client     *c = ft->client;
  struct cmdq_item    *item = ft->item;
  struct format_expand_state   next;
  struct environ      *env = NULL;
  struct environ_entry    *envent;
  char        *expanded, *value;
  struct evbuffer     *buffer;
  size_t         size;
  u_int        i = 0;

  if (flags == NULL || *flags == '\0' || strcmp(flags, "s") == 0) {
    if (ft->s != NULL)
      env = ft->s->environ;
  } else if (strcmp(flags, "g") == 0)
    env = global_environ;
  else if (strcmp(flags, "c") == 0) {
    if (ft->client != NULL)
      env = ft->client->environ;
  }
  if (env == NULL)
    return (xstrdup(""));

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  envent = environ_first(env);
  while (envent != NULL) {
    format_log(es, "environment loop: %s", envent->name);
    nft = format_create(c, item, FORMAT_NONE, ft->flags);

    format_add(nft, "environ_name", "%s", envent->name);
    if (envent->value == NULL)
      format_add(nft, "environ_value", "%s", "");
    else
      format_add(nft, "environ_value", "%s", envent->value);

    if (envent->flags & ENVIRON_HIDDEN)
      format_add(nft, "environ_hidden", "1");
    else
      format_add(nft, "environ_hidden", "0");
    format_add(nft, "environ_removed", "%d", envent->value == NULL);

    if (environ_next(envent) == NULL)
      format_add(nft, "loop_last_flag", "1");
    else
      format_add(nft, "loop_last_flag", "0");
    format_add(nft, "loop_index", "%u", i);

    format_defaults(nft, ft->c, ft->s, ft->wl, ft->wp);
    format_copy_state(&next, es, 0);
    next.ft = nft;

    expanded = format_expand1(&next, fmt);
    format_free(nft);
    evbuffer_add(buffer, expanded, strlen(expanded));
    free(expanded);

    i++;
    envent = environ_next(envent);
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  else
    value = xstrdup("");
  evbuffer_free(buffer);
  return (value);
}

/* Loop over clients. */
static char *
format_loop_clients(struct format_expand_state *es, const char *fmt)
{
  struct sort_criteria     *sc = &sort_crit;
  struct format_tree     *ft = es->ft;
  struct client      *c, **l;
  struct cmdq_item     *item = ft->item;
  struct format_tree     *nft;
  struct format_expand_state    next;
  char         *expanded, *value;
  struct evbuffer      *buffer;
  size_t          size;
  int         i, n;

  buffer = evbuffer_new();
  if (buffer == NULL)
    fatalx("out of memory");

  l = sort_get_clients(&n, sc);
  for (i = 0; i < n; i++) {
    c = l[i];
    format_log(es, "client loop: %s", c->name);
    nft = format_create(c, item, 0, ft->flags);

    format_add(nft, "loop_index", "%d", i);
    format_add(nft, "loop_last_flag", "%d", i == n - 1);

    format_defaults(nft, c, ft->s, ft->wl, ft->wp);
    format_copy_state(&next, es, 0);
    next.ft = nft;

    expanded = format_expand1(&next, fmt);
    format_free(nft);
    evbuffer_add(buffer, expanded, strlen(expanded));
    free(expanded);
  }

  if ((size = EVBUFFER_LENGTH(buffer)) != 0)
    value = xmemdup(EVBUFFER_DATA(buffer), size);
  else
    value = xstrdup("");
  evbuffer_free(buffer);
  return (value);
}

static char *
format_replace_expression(struct format_modifier *mexp,
    struct format_expand_state *es, const char *copy)
{
  int      argc = mexp->argc;
  const char    *errstr;
  char      *endch, *value, *left = NULL, *right = NULL;
  int      use_fp = 0;
  u_int      prec = 0;
  double       mleft, mright, result;
  enum { ADD,
         SUBTRACT,
         MULTIPLY,
         DIVIDE,
         MODULUS,
         EQUAL,
         NOT_EQUAL,
         GREATER_THAN,
         GREATER_THAN_EQUAL,
         LESS_THAN,
         LESS_THAN_EQUAL } operator;

  if (strcmp(mexp->argv[0], "+") == 0)
    operator = ADD;
  else if (strcmp(mexp->argv[0], "-") == 0)
    operator = SUBTRACT;
  else if (strcmp(mexp->argv[0], "*") == 0)
    operator = MULTIPLY;
  else if (strcmp(mexp->argv[0], "/") == 0)
    operator = DIVIDE;
  else if (strcmp(mexp->argv[0], "%") == 0 ||
      strcmp(mexp->argv[0], "m") == 0)
    operator = MODULUS;
  else if (strcmp(mexp->argv[0], "==") == 0)
    operator = EQUAL;
  else if (strcmp(mexp->argv[0], "!=") == 0)
    operator = NOT_EQUAL;
  else if (strcmp(mexp->argv[0], ">") == 0)
    operator = GREATER_THAN;
  else if (strcmp(mexp->argv[0], "<") == 0)
    operator = LESS_THAN;
  else if (strcmp(mexp->argv[0], ">=") == 0)
    operator = GREATER_THAN_EQUAL;
  else if (strcmp(mexp->argv[0], "<=") == 0)
    operator = LESS_THAN_EQUAL;
  else {
    format_log(es, "expression has no valid operator: '%s'",
        mexp->argv[0]);
    goto fail;
  }

  /* The second argument may be flags. */
  if (argc >= 2 && strchr(mexp->argv[1], 'f') != NULL) {
    use_fp = 1;
    prec = 2;
  }

  /* The third argument may be precision. */
  if (argc >= 3) {
    prec = strtonum(mexp->argv[2], -FORMAT_MAX_PRECISION,
        FORMAT_MAX_PRECISION, &errstr);
    if (errstr != NULL) {
      format_log(es, "expression precision %s: %s", errstr,
          mexp->argv[2]);
      goto fail;
    }
  }

  if (format_choose(es, copy, &left, &right, 1) != 0) {
    format_log(es, "expression syntax error");
    goto fail;
  }

  mleft = strtod(left, &endch);
  if (*endch != '\0') {
    format_log(es, "expression left side is invalid: %s", left);
    goto fail;
  }

  mright = strtod(right, &endch);
  if (*endch != '\0') {
    format_log(es, "expression right side is invalid: %s", right);
    goto fail;
  }

  if (!use_fp) {
    mleft = (long long)mleft;
    mright = (long long)mright;
  }
  format_log(es, "expression left side is: %.*f", prec, mleft);
  format_log(es, "expression right side is: %.*f", prec, mright);

  switch (operator) {
  case ADD:
    result = mleft + mright;
    break;
  case SUBTRACT:
    result = mleft - mright;
    break;
  case MULTIPLY:
    result = mleft * mright;
    break;
  case DIVIDE:
    result = mleft / mright;
    break;
  case MODULUS:
    result = fmod(mleft, mright);
    break;
  case EQUAL:
    result = fabs(mleft - mright) < 1e-9;
    break;
  case NOT_EQUAL:
    result = fabs(mleft - mright) > 1e-9;
    break;
  case GREATER_THAN:
    result = (mleft > mright);
    break;
  case GREATER_THAN_EQUAL:
    result = (mleft >= mright);
    break;
  case LESS_THAN:
    result = (mleft < mright);
    break;
  case LESS_THAN_EQUAL:
    result = (mleft <= mright);
    break;
  }
  if (use_fp)
    xasprintf(&value, "%.*f", prec, result);
  else
    xasprintf(&value, "%.*f", prec, (double)(long long)result);
  format_log(es, "expression result is %s", value);

  free(right);
  free(left);
  return (value);

fail:
  free(right);
  free(left);
  return (NULL);
}

/* Callback for the cycle timer; redraw the status line. */
static void
format_cycle_callback(__unused int fd, __unused short events, void *arg)
{
  struct client *c = arg;

  if (c->message_string == NULL && c->prompt == NULL)
    c->flags |= CLIENT_REDRAWSTATUS;
}

/* Arm the cycle timer to redraw the status line if it is not already. */
static void
format_cycle_start_timer(struct client *c)
{
  struct timeval  tv;

  tv.tv_sec = FORMAT_CYCLE_PERIOD / 1000;
  tv.tv_usec = (FORMAT_CYCLE_PERIOD % 1000) * 1000L;

  if (!event_initialized(&c->cycle_timer))
    evtimer_set(&c->cycle_timer, format_cycle_callback, c);
  if (!evtimer_pending(&c->cycle_timer, NULL))
    evtimer_add(&c->cycle_timer, &tv);
}

/* Expand the "A" animation modifier; see the manual for the syntax. */
static char *
format_cycle(struct format_expand_state *es, const char *frames, u_int count)
{
  struct format_tree  *ft = es->ft;
  const char    *start, *end, *cp;
  u_int      n, index, i;

  /*
   * A cycle is only expanded in a status format, and never in the
   * command or output of #() where it would change on every frame and
   * make the job run again.
   */
  if (!(ft->flags & FORMAT_STATUS) || (es->flags & FORMAT_EXPAND_NOCYCLE))
    return (xstrdup(""));
  if (*frames == '\0')
    return (xstrdup(""));

  /* Count the comma-separated frames (there is at least one). */
  n = 1;
  for (cp = frames; *cp != '\0'; cp++) {
    if (*cp == ',')
      n++;
  }
  index = (es->start_time / (count * FORMAT_CYCLE_PERIOD)) % n;

  /*
   * Redraw the status line so the frames advance on their own; a
   * single frame never changes so there is nothing to redraw for.
   */
  if (n > 1 && ft->client != NULL)
    format_cycle_start_timer(ft->client);

  /* Walk to the chosen frame and return a copy of it. */
  start = frames;
  for (i = 0; i < index; i++)
    start = strchr(start, ',') + 1;
  end = strchr(start, ',');
  if (end == NULL)
    end = start + strlen(start);
  return (xstrndup(start, end - start));
}

/* Replace a key. */
static int
format_replace(struct format_expand_state *es, const char *key, size_t keylen,
    char **buf, size_t *len, size_t *off)
{
  struct sort_criteria     *sc = &sort_crit;
  struct format_tree     *ft = es->ft;
  struct window_pane     *wp = ft->wp;
  const char       *errstr, *copy, *cp, *cp2;
  const char       *marker = NULL;
  char         *time_format = NULL;
  char         *copy0, *condition, *found, *new;
  char         *value, *left, *right;
  size_t          valuelen;
  uint64_t        modifiers = 0;
  int         limit = 0, width = 0;
  int         j, c;
  struct format_modifier     *list, *cmp = NULL, *search = NULL;
  struct format_modifier    **sub = NULL, *mexp = NULL, *fm;
  struct format_modifier     *bool_op_n = NULL;
  u_int         cycle_count = 1;
  u_int         i, count, nsub = 0, nrep, check = 0;
  const char       *loop_flags = "";
  struct format_expand_state    next;
  struct environ_entry     *envent;

  /* Set sorting defaults. */
  sc->order = SORT_ORDER;
  sc->reversed = 0;

  /* Make a copy of the key. */
  copy = copy0 = xstrndup(key, keylen);

  /* Process modifier list. */
  list = format_build_modifiers(es, &copy, &count);
  for (i = 0; i < count; i++) {
    fm = &list[i];
    if (format_logging(ft)) {
      format_log(es, "modifier %u is %s", i, fm->modifier);
      for (j = 0; j < fm->argc; j++) {
        format_log(es, "modifier %u argument %d: %s", i,
            j, fm->argv[j]);
      }
    }
    if (fm->size == 1) {
      switch (fm->modifier[0]) {
      case 'm':
      case '<':
      case '>':
        cmp = fm;
        break;
      case '!':
        modifiers |= FORMAT_NOT;
        break;
      case 'C':
        search = fm;
        break;
      case 's':
        if (fm->argc < 2)
          break;
        sub = xreallocarray(sub, nsub + 1, sizeof *sub);
        sub[nsub++] = fm;
        break;
      case '=':
        if (fm->argc < 1)
          break;
        limit = strtonum(fm->argv[0], -FORMAT_MAX_WIDTH,
            FORMAT_MAX_WIDTH, &errstr);
        if (errstr != NULL)
          limit = 0;
        if (fm->argc >= 2 && fm->argv[1] != NULL)
          marker = fm->argv[1];
        break;
      case 'p':
        if (fm->argc < 1)
          break;
        width = strtonum(fm->argv[0], -FORMAT_MAX_WIDTH,
            FORMAT_MAX_WIDTH, &errstr);
        if (errstr != NULL)
          width = 0;
        break;
      case 'A':
        modifiers |= FORMAT_CYCLE;
        if (fm->argc < 1)
          break;
        cycle_count = strtonum(fm->argv[0], 1, 100,
            &errstr);
        if (errstr != NULL)
          cycle_count = 1;
        break;
      case 'w':
        modifiers |= FORMAT_WIDTH;
        break;
      case 'e':
        if (fm->argc < 1 || fm->argc > 3)
          break;
        mexp = fm;
        break;
      case 'l':
        modifiers |= FORMAT_LITERAL;
        break;
      case 'a':
        modifiers |= FORMAT_CHARACTER;
        break;
      case 'b':
        modifiers |= FORMAT_BASENAME;
        break;
      case 'c':
        modifiers |= FORMAT_COLOUR;
        if (fm->argc < 1)
          break;
        if (strchr(fm->argv[0], 'f') != NULL)
          modifiers |= FORMAT_COLOUR_ESC_FG;
        if (strchr(fm->argv[0], 'b') != NULL)
          modifiers |= FORMAT_COLOUR_ESC_BG;
        break;
      case 'd':
        modifiers |= FORMAT_DIRNAME;
        break;
      case 'n':
        modifiers |= FORMAT_LENGTH;
        break;
      case 'I':
        if (fm->argc < 1)
          break;
        if (strchr(fm->argv[0], 'f') != NULL)
          modifiers |= FORMAT_CLIENT_TERMFEAT;
        if (strchr(fm->argv[0], 'c') != NULL)
          modifiers |= FORMAT_CLIENT_TERMCAP;
        if (strchr(fm->argv[0], 'e') != NULL)
          modifiers |= FORMAT_CLIENT_ENVIRON;
        break;
      case 't':
        modifiers |= FORMAT_TIMESTRING;
        if (fm->argc < 1)
          break;
        if (strchr(fm->argv[0], 'p') != NULL)
          modifiers |= FORMAT_PRETTY;
        else if (strchr(fm->argv[0], 'r') != NULL)
          modifiers |= FORMAT_RELATIVE;
        else if (strchr(fm->argv[0], 'd') != NULL)
          modifiers |= FORMAT_DIFFERENCE;
        else if (fm->argc >= 2 &&
            strchr(fm->argv[0], 'f') != NULL) {
          free(time_format);
          time_format = format_strip(es,
              fm->argv[1]);
        }
        break;
      case 'q':
        if (fm->argc < 1)
          modifiers |= FORMAT_QUOTE_SHELL;
        else if (strchr(fm->argv[0], 's') != NULL)
          modifiers |= FORMAT_QUOTE_SHELL_SQ;
        else if (strchr(fm->argv[0], 'e') != NULL ||
            strchr(fm->argv[0], 'h') != NULL)
          modifiers |= FORMAT_QUOTE_STYLE;
        else if (strchr(fm->argv[0], 'a') != NULL)
          modifiers |= FORMAT_QUOTE_ARGUMENTS;
        break;
      case 'E':
        modifiers |= FORMAT_EXPAND;
        break;
      case 'T':
        modifiers |= FORMAT_EXPANDTIME;
        break;
      case 'N':
        if (fm->argc < 1 ||
            strchr(fm->argv[0], 'w') != NULL)
          modifiers |= FORMAT_WINDOW_NAME;
        else if (strchr(fm->argv[0], 's') != NULL)
          modifiers |= FORMAT_SESSION_NAME;
        break;
      case 'S':
        modifiers |= FORMAT_SESSIONS;
        if (fm->argc < 1) {
          sc->order= SORT_INDEX;
          sc->reversed = 0;
          break;
        }
        if (strchr(fm->argv[0], 'i') != NULL)
          sc->order = SORT_INDEX;
        else if (strchr(fm->argv[0], 'n') != NULL)
          sc->order = SORT_NAME;
        else if (strchr(fm->argv[0], 't') != NULL)
          sc->order = SORT_ACTIVITY;
        else
          sc->order = SORT_INDEX;
        if (strchr(fm->argv[0], 'r') != NULL)
          sc->reversed = 1;
        else
          sc->reversed = 0;
        break;
      case 'W':
        modifiers |= FORMAT_WINDOWS;
        if (fm->argc < 1) {
          sc->order = SORT_ORDER;
          sc->reversed = 0;
          break;
        }
        if (strchr(fm->argv[0], 'i') != NULL)
          sc->order = SORT_ORDER;
        else if (strchr(fm->argv[0], 'n') != NULL)
          sc->order = SORT_NAME;
        else if (strchr(fm->argv[0], 't') != NULL)
          sc->order = SORT_ACTIVITY;
        else
          sc->order = SORT_ORDER;
        if (strchr(fm->argv[0], 'r') != NULL)
          sc->reversed = 1;
        else
          sc->reversed = 0;
        break;
      case 'P':
        modifiers |= FORMAT_PANES;
        sc->order = SORT_CREATION;
        if (fm->argc < 1) {
          sc->reversed = 0;
          break;
        }
        if (strchr(fm->argv[0], 'i') != NULL)
          sc->order = SORT_INDEX;
        else if (strchr(fm->argv[0], 'z') != NULL)
          sc->order = SORT_Z;
        else
          sc->order = SORT_CREATION;
        if (strchr(fm->argv[0], 'r') != NULL)
          sc->reversed = 1;
        else
          sc->reversed = 0;
        break;
      case 'O':
        modifiers |= FORMAT_OPTIONS;
        if (fm->argc == 1)
          loop_flags = fm->argv[0];
        break;
      case 'V':
        modifiers |= FORMAT_ENVIRON;
        if (fm->argc == 1)
          loop_flags = fm->argv[0];
        break;
      case 'L':
        modifiers |= FORMAT_CLIENTS;
        if (fm->argc < 1) {
          sc->order = SORT_ORDER;
          sc->reversed = 0;
          break;
        }
        if (strchr(fm->argv[0], 'i') != NULL)
          sc->order = SORT_ORDER;
        else if (strchr(fm->argv[0], 'n') != NULL)
          sc->order = SORT_NAME;
        else if (strchr(fm->argv[0], 't') != NULL)
          sc->order = SORT_ACTIVITY;
        else
          sc->order = SORT_ORDER;
        if (strchr(fm->argv[0], 'r') != NULL)
          sc->reversed = 1;
        else
          sc->reversed = 0;
        break;
      case 'R':
        modifiers |= FORMAT_REPEAT;
        break;
      }
    } else if (fm->size == 2) {
      if (strcmp(fm->modifier, "||") == 0 ||
          strcmp(fm->modifier, "&&") == 0)
        bool_op_n = fm;
      else if (strcmp(fm->modifier, "!!") == 0)
        modifiers |= FORMAT_NOT_NOT;
      else if (strcmp(fm->modifier, "==") == 0 ||
          strcmp(fm->modifier, "!=") == 0 ||
          strcmp(fm->modifier, ">=") == 0 ||
          strcmp(fm->modifier, "<=") == 0)
        cmp = fm;
    }
  }

  /* Look up client capability, feature or environment. */
  if ((modifiers & FORMAT_CLIENT_TERMCAP) ||
      (modifiers & FORMAT_CLIENT_TERMFEAT) ||
      (modifiers & FORMAT_CLIENT_ENVIRON)) {
    if (ft->c == NULL ||
        ft->c->tty.term == NULL ||
        ft->c->flags & CLIENT_UNATTACHEDFLAGS) {
      value = xstrdup("");
      goto done;
    }
    if (modifiers & FORMAT_CLIENT_TERMCAP) {
      if (tty_term_has_name(ft->c->tty.term, copy))
        value = xstrdup("1");
      else
        value = xstrdup("0");
    }
    if (modifiers & FORMAT_CLIENT_TERMFEAT) {
      if (tty_feature_present(ft->c->tty.term, copy))
        value = xstrdup("1");
      else
        value = xstrdup("0");
    }
    if (modifiers & FORMAT_CLIENT_ENVIRON) {
      envent = environ_find(ft->c->environ, copy);
      if (envent != NULL && envent->value != NULL)
        value = xstrdup(envent->value);
      else
        value = xstrdup("");
    }
    goto done;
  }

  /* Is this an animation cycle? */
  if (modifiers & FORMAT_CYCLE) {
    value = format_cycle(es, copy, cycle_count);
    format_log(es, "cycle '%s' is: %s", copy, value);
    goto done;
  }

  /* Is this a literal string? */
  if (modifiers & FORMAT_LITERAL) {
    format_log(es, "literal string is '%s'", copy);
    value = format_unescape(es, copy, strlen(copy));
    goto done;
  }

  /* Is this a character? */
  if (modifiers & FORMAT_CHARACTER) {
    new = format_expand1(es, copy);
    c = strtonum(new, 32, 126, &errstr);
    if (errstr != NULL)
      value = xstrdup("");
    else
      xasprintf(&value, "%c", c);
    free(new);
    goto done;
  }

  /* Is this a colour? */
  if (modifiers & FORMAT_COLOUR) {
    new = format_expand1(es, copy);
    if (modifiers & (FORMAT_COLOUR_ESC_FG|FORMAT_COLOUR_ESC_BG)) {
      if (strcasecmp(new, "none") == 0)
        value = xstrdup("\033[0m");
      else if ((c = colour_fromstring(new)) == -1)
        value = xstrdup("");
      else {
        if (modifiers & FORMAT_COLOUR_ESC_BG)
          cp = colour_toescape(ft->c, c, 1);
        else
          cp = colour_toescape(ft->c, c, 0);
        if (cp == NULL)
          value = xstrdup("");
        else
          value = xstrdup(cp);
      }
    } else {
      c = colour_fromstring(new);
      if (c == -1 || (c = colour_force_rgb(c)) == -1)
        value = xstrdup("");
      else
        xasprintf(&value, "%06x", c & 0xffffff);
    }
    free(new);
    goto done;
  }

  /* Is this a loop, operator, comparison or condition? */
  if (modifiers & FORMAT_SESSIONS) {
    value = format_loop_sessions(es, copy);
    if (value == NULL)
      goto fail;
  } else if (modifiers & FORMAT_WINDOWS) {
    value = format_loop_windows(es, copy);
    if (value == NULL)
      goto fail;
  } else if (modifiers & FORMAT_PANES) {
    value = format_loop_panes(es, copy);
    if (value == NULL)
      goto fail;
  } else if (modifiers & FORMAT_CLIENTS) {
    value = format_loop_clients(es, copy);
    if (value == NULL)
      goto fail;
  } else if (modifiers & FORMAT_OPTIONS) {
    value = format_loop_options(es, copy, loop_flags);
    if (value == NULL)
      goto fail;
  } else if (modifiers & FORMAT_ENVIRON) {
    value = format_loop_environ(es, copy, loop_flags);
    if (value == NULL)
      goto fail;
  } else if (modifiers & FORMAT_WINDOW_NAME) {
    value = format_window_name(es, copy);
    if (value == NULL)
      goto fail;
  } else if (modifiers & FORMAT_SESSION_NAME) {
    value = format_session_name(es, copy);
    if (value == NULL)
      goto fail;
  } else if (search != NULL) {
    /* Search in pane. */
    new = format_expand1(es, copy);
    if (wp == NULL) {
      format_log(es, "search '%s' but no pane", new);
      value = xstrdup("0");
    } else {
      format_log(es, "search '%s' pane %%%u", new, wp->id);
      value = format_search(search, wp, new);
    }
    free(new);
  } else if (modifiers & FORMAT_REPEAT) {
    /* Repeat multiple times. */
    if (format_choose(es, copy, &left, &right, 1) != 0) {
      format_log(es, "repeat syntax error: %s", copy);
      goto fail;
    }
    nrep = strtonum(right, 1, FORMAT_MAX_REPEAT, &errstr);
    if (errstr != NULL)
      value = xstrdup("");
    else {
      value = xstrdup("");
      for (i = 0; i < nrep; i++) {
        if (!format_check_time(es, &check)) {
          free(right);
          free(left);
          free(value);
          goto fail;
        }
        xasprintf(&new, "%s%s", value, left);
        free(value);
        value = new;
      }
    }
    free(right);
    free(left);
  } else if (modifiers & FORMAT_NOT) {
    value = format_bool_op_1(es, copy, 1);
  } else if (modifiers & FORMAT_NOT_NOT) {
    value = format_bool_op_1(es, copy, 0);
  } else if (bool_op_n != NULL) {
    /* n-ary boolean operator. */
    if (strcmp(bool_op_n->modifier, "||") == 0)
      value = format_bool_op_n(es, copy, 0);
    else if (strcmp(bool_op_n->modifier, "&&") == 0)
      value = format_bool_op_n(es, copy, 1);
  } else if (cmp != NULL) {
    /* Comparison of left and right. */
    if (format_choose(es, copy, &left, &right, 1) != 0) {
      format_log(es, "compare %s syntax error: %s",
          cmp->modifier, copy);
      goto fail;
    }
    format_log(es, "compare %s left is: %s", cmp->modifier, left);
    format_log(es, "compare %s right is: %s", cmp->modifier, right);

    if (strcmp(cmp->modifier, "==") == 0) {
      if (strcmp(left, right) == 0)
        value = xstrdup("1");
      else
        value = xstrdup("0");
    } else if (strcmp(cmp->modifier, "!=") == 0) {
      if (strcmp(left, right) != 0)
        value = xstrdup("1");
      else
        value = xstrdup("0");
    } else if (strcmp(cmp->modifier, "<") == 0) {
      if (strcmp(left, right) < 0)
        value = xstrdup("1");
      else
        value = xstrdup("0");
    } else if (strcmp(cmp->modifier, ">") == 0) {
      if (strcmp(left, right) > 0)
        value = xstrdup("1");
      else
        value = xstrdup("0");
    } else if (strcmp(cmp->modifier, "<=") == 0) {
      if (strcmp(left, right) <= 0)
        value = xstrdup("1");
      else
        value = xstrdup("0");
    } else if (strcmp(cmp->modifier, ">=") == 0) {
      if (strcmp(left, right) >= 0)
        value = xstrdup("1");
      else
        value = xstrdup("0");
    } else if (strcmp(cmp->modifier, "m") == 0)
      value = format_match(cmp, left, right);

    free(right);
    free(left);
  } else if (*copy == '?') {
    /*
     * Conditional: For each pair of (condition, value), check the
     * condition and return the value if true. If no condition
     * matches, return the last unpaired arg if there is one, or the
     * empty string if not.
     */
    cp = copy + 1;
    while (1) {
      cp2 = format_skip1(es, cp, ",");
      if (cp2 == NULL) {
        format_log(es,
            "no condition matched in '%s'; using last "
            "arg", copy + 1);
        value = format_expand1(es, cp);
        break;
      }

      condition = xstrndup(cp, cp2 - cp);
      format_log(es, "condition is: %s", condition);

      found = format_find(ft, condition, modifiers,
          time_format);
      if (found == NULL) {
        /*
         * If the condition not found, try to expand it.
         * If the expansion doesn't have any effect,
         * then assume false.
         */
        found = format_expand1(es, condition);
        if (strcmp(found, condition) == 0) {
          free(found);
          found = xstrdup("");
          format_log(es,
              "condition '%s' not found; "
              "assuming false",
              condition);
        }
      } else {
        format_log(es, "condition '%s' found: %s",
            condition, found);
      }

      cp = cp2 + 1;
      cp2 = format_skip1(es, cp, ",");
      if (format_true(found)) {
        format_log(es, "condition '%s' is true",
            condition);
        if (cp2 == NULL)
          value = format_expand1(es, cp);
        else {
          right = xstrndup(cp, cp2 - cp);
          value = format_expand1(es, right);
          free(right);
        }
        free(condition);
        free(found);
        break;
      } else {
        format_log(es, "condition '%s' is false",
            condition);
      }

      free(condition);
      free(found);

      if (cp2 == NULL) {
        format_log(es,
            "no condition matched in '%s'; using empty "
            "string", copy + 1);
        value = xstrdup("");
        break;
      }

      cp = cp2 + 1;
    }
  } else if (mexp != NULL) {
    value = format_replace_expression(mexp, es, copy);
    if (value == NULL)
      value = xstrdup("");
  } else {
    if (strstr(copy, "#{") != 0) {
      format_log(es, "expanding inner format '%s'", copy);
      value = format_expand1(es, copy);
    } else {
      value = format_find(ft, copy, modifiers, time_format);
      if (value == NULL) {
        format_log(es, "format '%s' not found", copy);
        value = xstrdup("");
      } else {
        format_log(es, "format '%s' found: %s", copy,
            value);
      }
    }
  }

done:
  /* Expand again if required. */
  if (modifiers & FORMAT_EXPAND) {
    new = format_expand1(es, value);
    free(value);
    value = new;
  } else if (modifiers & FORMAT_EXPANDTIME) {
    format_copy_state(&next, es, FORMAT_EXPAND_TIME);
    new = format_expand1(&next, value);
    free(value);
    value = new;
  }

  /* Perform substitution if any. */
  for (i = 0; i < nsub; i++) {
    left = format_expand1(es, sub[i]->argv[0]);
    right = format_expand1(es, sub[i]->argv[1]);
    new = format_sub(sub[i], value, left, right);
    format_log(es, "substitute '%s' to '%s': %s", left, right, new);
    free(value);
    value = new;
    free(right);
    free(left);
  }

  /* Truncate the value if needed. */
  if (limit > 0) {
    new = format_trim_left(value, limit);
    if (marker != NULL && strcmp(new, value) != 0) {
      free(value);
      xasprintf(&value, "%s%s", new, marker);
      free(new);
    } else {
      free(value);
      value = new;
    }
    format_log(es, "applied length limit %d: %s", limit, value);
  } else if (limit < 0) {
    new = format_trim_right(value, -limit);
    if (marker != NULL && strcmp(new, value) != 0) {
      free(value);
      xasprintf(&value, "%s%s", marker, new);
      free(new);
    } else {
      free(value);
      value = new;
    }
    format_log(es, "applied length limit %d: %s", limit, value);
  }

  /* Pad the value if needed. */
  if (width > 0) {
    new = utf8_padcstr(value, width);
    free(value);
    value = new;
    format_log(es, "applied padding width %d: %s", width, value);
  } else if (width < 0) {
    new = utf8_rpadcstr(value, -width);
    free(value);
    value = new;
    format_log(es, "applied padding width %d: %s", width, value);
  }

  /* Replace with the length or width if needed. */
  if (modifiers & FORMAT_LENGTH) {
    xasprintf(&new, "%zu", strlen(value));
    free(value);
    value = new;
    format_log(es, "replacing with length: %s", new);
  }
  if (modifiers & FORMAT_WIDTH) {
    xasprintf(&new, "%u", format_width(value));
    free(value);
    value = new;
    format_log(es, "replacing with width: %s", new);
  }

  /* 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;

  format_log(es, "replaced '%s' with '%s'", copy0, value);
  free(value);

  free(sub);
  format_free_modifiers(list, count);
  free(copy0);
  free(time_format);
  return (0);

fail:
  format_log(es, "failed %s", copy0);

  free(sub);
  format_free_modifiers(list, count);
  free(copy0);
  free(time_format);
  return (-1);
}

/* Expand keys in a template. */
static char *
format_expand1(struct format_expand_state *es, const char *fmt)
{
  struct format_tree  *ft = es->ft;
  char      *buf, *out, *name;
  const char    *ptr, *s, *style_end = NULL;
  size_t       off, len, n, outlen;
  int      ch, brackets;
  char       expanded[8192];

  if (fmt == NULL || *fmt == '\0' || !format_check_time(es, NULL))
    return (xstrdup(""));

  if (es->loop == FORMAT_LOOP_LIMIT) {
    format_log(es, "reached loop limit (%u)", FORMAT_LOOP_LIMIT);
    return (xstrdup(""));
  }
  es->loop++;

  format_log(es, "expanding format: %s", fmt);

  if ((es->flags & FORMAT_EXPAND_TIME) && strchr(fmt, '%') != NULL) {
    if (es->time == 0) {
      es->time = time(NULL);
      localtime_r(&es->time, &es->tm);
    }
    if (format_strftime(expanded, sizeof expanded, fmt,
        &es->tm) == 0) {
      format_log(es, "format is too long");
      return (xstrdup(""));
    }
    if (format_logging(ft) && strcmp(expanded, fmt) != 0)
      format_log(es, "after time expanded: %s", expanded);
    fmt = expanded;
  }

  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;
    }
    if (*++fmt == '\0')
      break;

    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;

      name = xstrndup(fmt, n);
      format_log(es, "found #(): %s", name);

      if ((ft->flags & FORMAT_NOJOBS) ||
          (es->flags & FORMAT_EXPAND_NOJOBS)) {
        out = xstrdup("");
        format_log(es, "#() is disabled");
      } else {
        out = format_job_get(es, name);
        format_log(es, "#() result: %s", out);
      }
      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_skip1(es, (char *)fmt - 2, "}");
      if (ptr == NULL)
        break;
      n = ptr - fmt;

      format_log(es, "found #{}: %.*s", (int)n, fmt);
      if (format_replace(es, fmt, n, &buf, &len, &off) != 0)
        break;
      fmt += n + 1;
      continue;
    case '[':
    case '#':
      /*
       * If ##[ (with two or more #s), then it is a style and
       * can be left for format_draw to handle.
       */
      ptr = fmt - (ch == '[');
      n = 2 - (ch == '[');
      while (*ptr == '#') {
        ptr++;
        n++;
      }
      if (*ptr == '[') {
        style_end = format_skip1(es, fmt - 2, "]");
        format_log(es, "found #*%zu[", n);
        while (len - off < n + 2) {
          buf = xreallocarray(buf, 2, len);
          len *= 2;
        }
        memcpy(buf + off, fmt - 2, n + 1);
        off += n + 1;
        fmt = ptr + 1;
        continue;
      }
      /* FALLTHROUGH */
    case '}':
    case ',':
      format_log(es, "found #%c", ch);
      while (len - off < 2) {
        buf = xreallocarray(buf, 2, len);
        len *= 2;
      }
      buf[off++] = ch;
      continue;
    default:
      s = NULL;
      if (fmt > style_end) { /* skip inside #[] */
        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);
      format_log(es, "found #%c: %s", ch, s);
      if (format_replace(es, s, n, &buf, &len, &off) != 0)
        break;
      continue;
    }

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

  format_log(es, "result is: %s", buf);
  es->loop--;

  return (buf);
}

/* Expand keys in a template, passing through strftime first. */
char *
format_expand_time(struct format_tree *ft, const char *fmt)
{
  struct format_expand_state  es;

  memset(&es, 0, sizeof es);
  es.ft = ft;
  es.flags = FORMAT_EXPAND_TIME;
  es.start_time = get_timer();
  return (format_expand1(&es, fmt));
}

/* Expand keys in a template. */
char *
format_expand(struct format_tree *ft, const char *fmt)
{
  struct format_expand_state  es;

  memset(&es, 0, sizeof es);
  es.ft = ft;
  es.flags = 0;
  es.start_time = get_timer();
  return (format_expand1(&es, fmt));
}

/* 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;

  ft = format_create_defaults(item, c, s, wl, wp);
  expanded = format_expand(ft, fmt);
  format_free(ft);
  return (expanded);
}

/* Expand a single string using state. */
char *
format_single_from_state(struct cmdq_item *item, const char *fmt,
    struct client *c, struct cmd_find_state *fs)
{
  return (format_single(item, fmt, c, fs->s, fs->wl, fs->wp));
}

/* Expand a single string using target. */
char *
format_single_from_target(struct cmdq_item *item, const char *fmt)
{
  struct client *tc = cmdq_get_target_client(item);

  return (format_single_from_state(item, fmt, tc, cmdq_get_target(item)));
}

/* Create and add defaults. */
struct format_tree *
format_create_defaults(struct cmdq_item *item, struct client *c,
    struct session *s, struct winlink *wl, struct window_pane *wp)
{
  struct format_tree  *ft;

  if (item != NULL)
    ft = format_create(cmdq_get_client(item), item, FORMAT_NONE, 0);
  else
    ft = format_create(NULL, item, FORMAT_NONE, 0);
  format_defaults(ft, c, s, wl, wp);
  return (ft);
}

/* Create and add defaults using state. */
struct format_tree *
format_create_from_state(struct cmdq_item *item, struct client *c,
    struct cmd_find_state *fs)
{
  return (format_create_defaults(item, c, fs->s, fs->wl, fs->wp));
}

/* Create and add defaults using target. */
struct format_tree *
format_create_from_target(struct cmdq_item *item)
{
  struct client *tc = cmdq_get_target_client(item);

  return (format_create_from_state(item, tc, cmdq_get_target(item)));
}

/* 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)
{
  struct paste_buffer *pb;

  if (c != NULL && c->name != NULL)
    log_debug("%s: c=%s", __func__, c->name);
  else
    log_debug("%s: c=none", __func__);
  if (s != NULL)
    log_debug("%s: s=$%u", __func__, s->id);
  else
    log_debug("%s: s=none", __func__);
  if (wl != NULL)
    log_debug("%s: wl=%u", __func__, wl->idx);
  else
    log_debug("%s: wl=none", __func__);
  if (wp != NULL)
    log_debug("%s: wp=%%%u", __func__, wp->id);
  else
    log_debug("%s: wp=none", __func__);

  if (c != NULL && s != NULL && c->session != s)
    log_debug("%s: session does not match", __func__);

  if (wp != NULL)
    ft->type = FORMAT_TYPE_PANE;
  else if (wl != NULL)
    ft->type = FORMAT_TYPE_WINDOW;
  else if (s != NULL)
    ft->type = FORMAT_TYPE_SESSION;
  else
    ft->type = FORMAT_TYPE_UNKNOWN;

  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);

  pb = paste_get_top(NULL);
  if (pb != NULL)
    format_defaults_paste_buffer(ft, pb);
}

/* Set default format keys for a session. */
static void
format_defaults_session(struct format_tree *ft, struct session *s)
{
  ft->s = s;
}

/* Set default format keys for a client. */
static void
format_defaults_client(struct format_tree *ft, struct client *c)
{
  if (ft->s == NULL)
    ft->s = c->session;
  ft->c = c;
}

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

/* Set default format keys for a winlink. */
static void
format_defaults_winlink(struct format_tree *ft, struct winlink *wl)
{
  if (ft->w == NULL)
    format_defaults_window(ft, wl->window);
  ft->wl = wl;
}

/* Set default format keys for a window pane. */
void
format_defaults_pane(struct format_tree *ft, struct window_pane *wp)
{
  struct window_mode_entry  *wme;

  if (ft->w == NULL)
    format_defaults_window(ft, wp->window);
  ft->wp = wp;

  wme = TAILQ_FIRST(&wp->modes);
  if (wme != NULL && wme->mode->formats != NULL)
    wme->mode->formats(wme, ft);
}

/* Set default format keys for paste buffer. */
void
format_defaults_paste_buffer(struct format_tree *ft, struct paste_buffer *pb)
{
  ft->pb = pb;
}

static int
format_is_word_separator(const char *ws, const struct grid_cell *gc)
{
  if (utf8_cstrhas(ws, &gc->data))
    return (1);
  if (gc->flags & GRID_FLAG_TAB)
    return (1);
  return gc->data.size == 1 && *gc->data.data == ' ';
}

/* Return word at given coordinates. Caller frees. */
char *
format_grid_word(struct grid *gd, u_int x, u_int y)
{
  const struct grid_line  *gl;
  struct grid_cell   gc;
  const char    *ws;
  struct utf8_data  *ud = NULL;
  u_int      end;
  size_t       size = 0;
  int      found = 0;
  char      *s = NULL;

  ws = options_get_string(global_s_options, "word-separators");

  for (;;) {
    grid_get_cell(gd, x, y, &gc);
    if ((~gc.flags & GRID_FLAG_PADDING) &&
        format_is_word_separator(ws, &gc)) {
      found = 1;
      break;
    }

    if (x == 0) {
      if (y == 0)
        break;
      gl = grid_peek_line(gd, y - 1);
      if (~gl->flags & GRID_LINE_WRAPPED)
        break;
      y--;
      x = grid_line_length(gd, y);
      if (x == 0)
        break;
    }
    x--;
  }
  for (;;) {
    if (found) {
      end = grid_line_length(gd, y);
      if (end == 0 || x == end - 1) {
        if (y == gd->hsize + gd->sy - 1)
          break;
        gl = grid_peek_line(gd, y);
        if (~gl->flags & GRID_LINE_WRAPPED)
          break;
        y++;
        x = 0;
      } else
        x++;
    }
    found = 1;

    grid_get_cell(gd, x, y, &gc);
    if (gc.flags & GRID_FLAG_PADDING)
      continue;
    if (format_is_word_separator(ws, &gc))
      break;

    ud = xreallocarray(ud, size + 2, sizeof *ud);
    memcpy(&ud[size++], &gc.data, sizeof *ud);
  }
  if (size != 0) {
    ud[size].size = 0;
    s = utf8_tocstr(ud);
    free(ud);
  }
  return (s);
}

/* Return line at given coordinates. Caller frees. */
char *
format_grid_line(struct grid *gd, u_int y)
{
  struct grid_cell   gc;
  struct utf8_data  *ud = NULL;
  u_int      x;
  size_t       size = 0;
  char      *s = NULL;

  for (x = 0; x < grid_line_length(gd, y); x++) {
    grid_get_cell(gd, x, y, &gc);
    if (gc.flags & GRID_FLAG_PADDING)
      continue;

    ud = xreallocarray(ud, size + 2, sizeof *ud);
    if (gc.flags & GRID_FLAG_TAB)
      utf8_set(&ud[size++], '\t');
    else
      memcpy(&ud[size++], &gc.data, sizeof *ud);
  }
  if (size != 0) {
    ud[size].size = 0;
    s = utf8_tocstr(ud);
    free(ud);
  }
  return (s);
}

/* Return hyperlink at given coordinates. Caller frees. */
char *
format_grid_hyperlink(struct grid *gd, u_int x, u_int y, struct screen* s)
{
  const char    *uri;
  struct grid_cell   gc;

  for (;;) {
    grid_get_cell(gd, x, y, &gc);
    if (~gc.flags & GRID_FLAG_PADDING)
      break;
    if (x == 0)
      return (NULL);
    x--;
  }
  if (s->hyperlinks == NULL || gc.link == 0)
    return (NULL);
  if (!hyperlinks_get(s->hyperlinks, gc.link, &uri, NULL, NULL))
    return (NULL);
  return (xstrdup(uri));
}

Coverage Report

Created: 2026-07-30 07:06