Allow formats to be specified as functions (in the code) so they are

only evaluated on demand rather than each time a format tree is
constructed. Use this for expensive formats like pane_current_command.

format.c

@@ -35,14 +35,23 @@
  * string.
  */
 
+struct format_entry;
+typedef void (*format_cb)(struct format_tree *, struct format_entry *);
+
 void	 format_job_callback(struct job *);
 const char *format_job_get(struct format_tree *, const char *);
 void	 format_job_timer(int, short, void *);
 
+void	 format_cb_host(struct format_tree *, struct format_entry *);
+void	 format_cb_host_short(struct format_tree *, struct format_entry *);
+void	 format_cb_pid(struct format_tree *, struct format_entry *);
+void	 format_cb_start_command(struct format_tree *, struct format_entry *);
+void	 format_cb_current_command(struct format_tree *, struct format_entry *);
+
+void	 format_add_cb(struct format_tree *, const char *, format_cb);
 int	 format_replace(struct format_tree *, const char *, size_t, char **,
 	     size_t *, size_t *);
 char	*format_time_string(time_t);
-char	*format_get_command(struct window_pane *);
 
 void	 format_defaults_pane_tabs(struct format_tree *, struct window_pane *);
 void	 format_defaults_session(struct format_tree *, struct session *);
@@ -79,18 +88,19 @@ format_job_cmp(struct format_job *fj1, struct format_job *fj2)
 
 /* Entry in format tree. */
 struct format_entry {
-	char		       *key;
+	char			*key;
-	char		       *value;
+	char			*value;
-
+	format_cb		 cb;
-	RB_ENTRY(format_entry)	entry;
+	RB_ENTRY(format_entry)	 entry;
 };
 
 /* Format entry tree. */
 struct format_tree {
-	struct window	*w;
+	struct window		*w;
-	struct session	*s;
+	struct session		*s;
+	struct window_pane	*wp;
 
-	int		 status;
+	int			 status;
 
 	RB_HEAD(format_entry_tree, format_entry) tree;
 };
@@ -257,6 +267,75 @@ format_job_timer(unused int fd, unused short events, unused void *arg)
 	evtimer_add(&format_job_event, &tv);
 }
 
+/* Callback for host. */
+void
+format_cb_host(unused struct format_tree *ft, struct format_entry *fe)
+{
+	char host[HOST_NAME_MAX + 1];
+
+	if (gethostname(host, sizeof host) != 0)
+		fe->value = xstrdup("");
+	else
+		fe->value = xstrdup(host);
+}
+
+/* Callback for host_short. */
+void
+format_cb_host_short(unused struct format_tree *ft, struct format_entry *fe)
+{
+	char host[HOST_NAME_MAX + 1], *cp;
+
+	if (gethostname(host, sizeof host) != 0)
+		fe->value = xstrdup("");
+	else {
+		if ((cp = strchr(host, '.')) != NULL)
+			*cp = '\0';
+		fe->value = xstrdup(host);
+	}
+}
+
+/* Callback for pid. */
+void
+format_cb_pid(unused struct format_tree *ft, struct format_entry *fe)
+{
+	xasprintf(&fe->value, "%ld", (long)getpid());
+}
+
+/* Callback for pane_start_command. */
+void
+format_cb_start_command(struct format_tree *ft, struct format_entry *fe)
+{
+	struct window_pane	*wp = ft->wp;
+
+	if (wp == NULL)
+		return;
+
+	fe->value = cmd_stringify_argv(wp->argc, wp->argv);
+}
+
+/* Callback for pane_current_command. */
+void
+format_cb_current_command(struct format_tree *ft, struct format_entry *fe)
+{
+	struct window_pane	*wp = ft->wp;
+	char			*cmd;
+
+	if (wp == NULL)
+		return;
+
+	cmd = get_proc_name(wp->fd, wp->tty);
+	if (cmd == NULL || *cmd == '\0') {
+		free(cmd);
+		cmd = cmd_stringify_argv(wp->argc, wp->argv);
+		if (cmd == NULL || *cmd == '\0') {
+			free(cmd);
+			cmd = xstrdup(wp->shell);
+		}
+	}
+	fe->value = parse_window_name(cmd);
+	free(cmd);
+}
+
 /* Create a new tree. */
 struct format_tree *
 format_create(void)
@@ -269,7 +348,6 @@ struct format_tree *
 format_create_status(int status)
 {
 	struct format_tree	*ft;
-	char			 host[HOST_NAME_MAX + 1], *ptr;
 
 	if (!event_initialized(&format_job_event)) {
 		evtimer_set(&format_job_event, format_job_timer, NULL);
@@ -280,13 +358,9 @@ format_create_status(int status)
 	RB_INIT(&ft->tree);
 	ft->status = status;
 
-	if (gethostname(host, sizeof host) == 0) {
+	format_add_cb(ft, "host", format_cb_host);
-		format_add(ft, "host", "%s", host);
+	format_add_cb(ft, "host_short", format_cb_host_short);
-		if ((ptr = strchr(host, '.')) != NULL)
+	format_add_cb(ft, "pid", format_cb_pid);
-			*ptr = '\0';
-		format_add(ft, "host_short", "%s", host);
-	}
-	format_add(ft, "pid", "%ld", (long) getpid());
 
 	return (ft);
 }
@@ -318,17 +392,42 @@ format_add(struct format_tree *ft, const char *key, const char *fmt, ...)
 	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;
+
 	va_start(ap, fmt);
 	xvasprintf(&fe->value, fmt, ap);
 	va_end(ap);
+}
+
+/* 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_now->value);
-		fe_now->value = fe->value;
 		free(fe->key);
 		free(fe);
+		free(fe_now->value);
+		fe = fe_now;
 	}
+
+	fe->cb = cb;
+
+	fe->value = NULL;
 }
 
 /* Find a format entry. */
@@ -363,8 +462,11 @@ format_find(struct format_tree *ft, const char *key)
 
 	fe_find.key = (char *) key;
 	fe = RB_FIND(format_entry_tree, &ft->tree, &fe_find);
-	if (fe != NULL)
+	if (fe != NULL) {
+		if (fe->value == NULL && fe->cb != NULL)
+			fe->cb(ft, fe);
 		return (fe->value);
+	}
 
 	envent = NULL;
 	if (ft->s != NULL)
@@ -506,7 +608,7 @@ char *
 format_expand(struct format_tree *ft, const char *fmt)
 {
 	char		*buf, *tmp, *cmd;
-	const char	*ptr, *s;
+	const char	*ptr, *s, *saved = fmt;
 	size_t		 off, len, n, slen;
 	int     	 ch, brackets;
 
@@ -610,29 +712,10 @@ format_expand(struct format_tree *ft, const char *fmt)
 	}
 	buf[off] = '\0';
 
+	log_debug("format '%s' -> '%s'", saved, buf);
 	return (buf);
 }
 
-/* Get command name for format. */
-char *
-format_get_command(struct window_pane *wp)
-{
-	char	*cmd, *out;
-
-	cmd = get_proc_name(wp->fd, wp->tty);
-	if (cmd == NULL || *cmd == '\0') {
-		free(cmd);
-		cmd = cmd_stringify_argv(wp->argc, wp->argv);
-		if (cmd == NULL || *cmd == '\0') {
-			free(cmd);
-			cmd = xstrdup(wp->shell);
-		}
-	}
-	out = parse_window_name(cmd);
-	free(cmd);
-	return (out);
-}
-
 /* Get time as a string. */
 char *
 format_time_string(time_t t)
@@ -863,11 +946,11 @@ format_defaults_pane(struct format_tree *ft, struct window_pane *wp)
 	struct grid_line	*gl;
 	unsigned long long	 size;
 	u_int			 i, idx;
-	char			*cmd;
 	int			 status;
 
 	if (ft->w == NULL)
 		ft->w = wp->window;
+	ft->wp = wp;
 
 	size = 0;
 	for (i = 0; i < gd->hsize; i++) {
@@ -908,14 +991,8 @@ format_defaults_pane(struct format_tree *ft, struct window_pane *wp)
 
 	format_add(ft, "pane_tty", "%s", wp->tty);
 	format_add(ft, "pane_pid", "%ld", (long) wp->pid);
-	if ((cmd = cmd_stringify_argv(wp->argc, wp->argv)) != NULL) {
+	format_add_cb(ft, "pane_start_command", format_cb_start_command);
-		format_add(ft, "pane_start_command", "%s", cmd);
+	format_add_cb(ft, "pane_current_command", format_cb_current_command);
-		free(cmd);
-	}
-	if ((cmd = format_get_command(wp)) != NULL) {
-		format_add(ft, "pane_current_command", "%s", cmd);
-		free(cmd);
-	}
 
 	format_add(ft, "cursor_x", "%u", wp->base.cx);
 	format_add(ft, "cursor_y", "%u", wp->base.cy);