From 3f065cf7892824919e440ab899bfadef52e857cd Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Sun, 5 Jul 2026 18:37:57 +0000
Subject: [PATCH] Add a window pane reference count.

---
 tmux.h   |  4 ++++
 window.c | 49 ++++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/tmux.h b/tmux.h
index 3e5a4eae5..ddcb96146 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1231,6 +1231,7 @@ struct visible_ranges {
 /* Child window structure. */
 struct window_pane {
 	u_int		 id;
+	int		 references;
 	u_int		 active_point;
 
 	struct window	*window;
@@ -1262,6 +1263,7 @@ struct window_pane {
 #define PANE_THEMECHANGED 0x2000
 #define PANE_UNSEENCHANGES 0x4000
 #define PANE_REDRAWSCROLLBAR 0x8000
+#define PANE_DESTROYED 0x10000
 
 	bitstr_t	*sync_dirty;
 	u_int		 sync_dirty_size;
@@ -3603,6 +3605,8 @@ void		 window_pane_stack_remove(struct window_panes *,
 void		 window_set_name(struct window *, const char *, int);
 void		 window_add_ref(struct window *, const char *);
 void		 window_remove_ref(struct window *, const char *);
+void		 window_pane_add_ref(struct window_pane *, const char *);
+void		 window_pane_remove_ref(struct window_pane *, const char *);
 void		 winlink_clear_flags(struct winlink *);
 int		 winlink_shuffle_up(struct session *, struct winlink *, int);
 int		 window_pane_start_input(struct window_pane *,
diff --git a/window.c b/window.c
index 93cb1cc74..8035e6b40 100644
--- a/window.c
+++ b/window.c
@@ -73,6 +73,7 @@ struct window_pane_input_data {
 static struct window_pane *window_pane_create(struct window *, u_int, u_int,
 		    u_int);
 static void	window_pane_destroy(struct window_pane *);
+static void	window_pane_free(struct window_pane *);
 static void	window_pane_scrollbar_timer(int, short, void *);
 static void	window_pane_full_size_offset(struct window_pane *wp,
 		    int *xoff, int *yoff, u_int *sx, u_int *sy);
@@ -421,6 +422,25 @@ window_remove_ref(struct window *w, const char *from)
 		window_destroy(w);
 }
 
+void
+window_pane_add_ref(struct window_pane *wp, const char *from)
+{
+	wp->references++;
+	log_debug("%s: %%%u %s, now %d", __func__, wp->id, from,
+	    wp->references);
+}
+
+void
+window_pane_remove_ref(struct window_pane *wp, const char *from)
+{
+	wp->references--;
+	log_debug("%s: %%%u %s, now %d", __func__, wp->id, from,
+	    wp->references);
+
+	if (wp->references == 0)
+		window_pane_free(wp);
+}
+
 void
 window_set_name(struct window *w, const char *new_name, int untrusted)
 {
@@ -1073,6 +1093,7 @@ window_pane_create(struct window *w, u_int sx, u_int sy, u_int hlimit)
 	char			 host[HOST_NAME_MAX + 1];
 
 	wp = xcalloc(1, sizeof *wp);
+	wp->references = 1;
 	wp->window = w;
 	wp->options = options_create(w->options);
 	wp->flags = PANE_STYLECHANGED;
@@ -1201,25 +1222,28 @@ window_pane_destroy(struct window_pane *wp)
 	spawn_editor_finish(wp);
 
 	window_pane_clear_prompt(wp);
+	RB_REMOVE(window_pane_tree, &all_window_panes, wp);
+	wp->flags |= PANE_DESTROYED;
 
 	window_pane_free_modes(wp);
 	screen_write_clear_dirty(wp);
-	free(wp->searchstr);
 
 	if (wp->fd != -1) {
 		bufferevent_free(wp->event);
+		wp->event = NULL;
 		close(wp->fd);
+		wp->fd = -1;
 	}
-	if (wp->ictx != NULL)
+	if (wp->ictx != NULL) {
 		input_free(wp->ictx);
-
-	screen_free(&wp->status_screen);
-
-	screen_free(&wp->base);
+		wp->ictx = NULL;
+	}
 
 	if (wp->pipe_fd != -1) {
 		bufferevent_free(wp->pipe_event);
+		wp->pipe_event = NULL;
 		close(wp->pipe_fd);
+		wp->pipe_fd = -1;
 	}
 
 	if (event_initialized(&wp->resize_timer))
@@ -1230,7 +1254,18 @@ window_pane_destroy(struct window_pane *wp)
 		event_del(&wp->sb_auto_timer);
 	window_pane_clear_resizes(wp, NULL);
 
-	RB_REMOVE(window_pane_tree, &all_window_panes, wp);
+	window_pane_remove_ref(wp, __func__);
+}
+
+static void
+window_pane_free(struct window_pane *wp)
+{
+	log_debug("pane %%%u freed (%d references)", wp->id, wp->references);
+
+	free(wp->searchstr);
+
+	screen_free(&wp->status_screen);
+	screen_free(&wp->base);
 
 	options_free(wp->options);
 	free((void *)wp->cwd);