===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/tmux/format.c,v
retrieving revision 1.147
retrieving revision 1.148
diff -u -r1.147 -r1.148
--- src/usr.bin/tmux/format.c	2017/10/12 11:32:27	1.147
+++ src/usr.bin/tmux/format.c	2017/11/02 18:27:35	1.148
@@ -1,4 +1,4 @@
-/* $OpenBSD: format.c,v 1.147 2017/10/12 11:32:27 nicm Exp $ */
+/* $OpenBSD: format.c,v 1.148 2017/11/02 18:27:35 nicm Exp $ */
 
 /*
  * Copyright (c) 2011 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -572,11 +572,41 @@
 			evbuffer_add(buffer, ",", 1);
 		evbuffer_add_printf(buffer, "%u", i);
 	}
-	size = EVBUFFER_LENGTH(buffer);
-	xasprintf(&fe->value, "%.*s", size, EVBUFFER_DATA(buffer));
+	if ((size = EVBUFFER_LENGTH(buffer)) != 0)
+		xasprintf(&fe->value, "%.*s", size, EVBUFFER_DATA(buffer));
 	evbuffer_free(buffer);
 }
 
+/* Callback for session_group_others. */
+static void
+format_cb_session_group_others(struct format_tree *ft, struct format_entry *fe)
+{
+	struct session		*s = ft->s;
+	struct session_group	*sg;
+	struct session		*loop;
+	struct evbuffer		*buffer;
+	int			 size;
+
+	if (s == NULL)
+		return;
+	sg = session_group_contains(s);
+	if (sg == NULL)
+		return;
+
+	buffer = evbuffer_new();
+	TAILQ_FOREACH(loop, &sg->sessions, gentry) {
+		if (loop == s)
+			continue;
+
+		if (EVBUFFER_LENGTH(buffer) > 0)
+			evbuffer_add(buffer, ",", 1);
+		evbuffer_add_printf(buffer, "%s", loop->name);
+	}
+	if ((size = EVBUFFER_LENGTH(buffer)) != 0)
+		xasprintf(&fe->value, "%.*s", size, EVBUFFER_DATA(buffer));
+	evbuffer_free(buffer);
+}
+
 /* Merge a format tree. */
 static void
 format_merge(struct format_tree *ft, struct format_tree *from)
@@ -1253,8 +1283,13 @@
 
 	sg = session_group_contains(s);
 	format_add(ft, "session_grouped", "%d", sg != NULL);
-	if (sg != NULL)
+	if (sg != NULL) {
 		format_add(ft, "session_group", "%s", sg->name);
+		format_add(ft, "session_group_size", "%u",
+		    session_group_count (sg));
+		format_add_cb(ft, "session_group_others",
+		    format_cb_session_group_others);
+	}
 
 	format_add_tv(ft, "session_created", &s->creation_time);
 	format_add_tv(ft, "session_last_attached", &s->last_attached_time);