Replace the notification system with events. Events can carry a payload of

additional payload (to reduce problems with lifetime of objects) and are
delivered to one or more event sinks. This is more powerful and reduces the
complex dependencies between control mode and hooks. Events are now used for
hooks, control mode notifications and for monitors (set-hook -B).

wait-for can now wait for an event to fire (-E flag, with -F to for filter),
with -v to print the payload, as well as listing (-l) waiting clients on an
event and forcing one to wake (-w).

A few additional hooks are also now available (pane-created, pane-resized, etc)
and some of the existing ones have additional format variables available.

control-notify.c

@@ -1,4 +1,4 @@
-/* $OpenBSD$ */
+/* $OpenBSD: control-notify.c,v 1.37 2026/07/10 13:38:45 nicm Exp $ */
 
 /*
  * Copyright (c) 2012 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -23,32 +23,56 @@
 
 #include "tmux.h"
 
+/* Should this client be sent events? */
 #define CONTROL_SHOULD_NOTIFY_CLIENT(c) \
-	((c) != NULL && ((c)->flags & CLIENT_CONTROL) && \
+	((c) != NULL && \
+	 ((c)->flags & CLIENT_CONTROL) && \
 	 (~(c)->flags & CLIENT_EXIT) && \
 	 (c)->control_state != NULL)
 
-void
-control_notify_pane_mode_changed(int pane)
+/* Notify control clients that pane mode changed. */
+static void
+control_pane_mode_changed_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
 {
-	struct client	*c;
+	struct window_pane	*wp;
+	struct client		*c;
+	char			*value;
 
-	TAILQ_FOREACH(c, &clients, entry) {
-		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c))
-			continue;
-
-		control_write(c, "%%pane-mode-changed %%%u", pane);
+	wp = event_payload_get_pane(ep, "pane");
+	if (wp != NULL) {
+		TAILQ_FOREACH(c, &clients, entry) {
+			if (!CONTROL_SHOULD_NOTIFY_CLIENT(c))
+				continue;
+			control_write(c, "%%pane-mode-changed %%%u", wp->id);
+		}
+		return;
 	}
+
+	value = event_payload_print(ep, "pane");
+	if (value == NULL)
+		return;
+	TAILQ_FOREACH(c, &clients, entry) {
+		if (CONTROL_SHOULD_NOTIFY_CLIENT(c))
+			control_write(c, "%%pane-mode-changed %s", value);
+	}
+	free(value);
 }
 
-void
-control_notify_window_layout_changed(struct window *w)
+/* Notify control clients that window layout changed. */
+static void
+control_window_layout_changed_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
 {
-	struct client	*c;
-	struct session	*s;
-	struct winlink	*wl;
-	const char	*template;
-	char		*cp;
+	struct client		*c;
+	struct session		*s;
+	struct winlink		*wl;
+	struct window		*w = event_payload_get_window(ep, "window");
+	const char		*template;
+	char			*cp;
+
+	if (w == NULL)
+		return;
 
 	template = "%layout-change #{window_id} #{window_layout} "
 	    "#{window_visible_layout} #{window_raw_flags}";
@@ -73,12 +97,15 @@ control_notify_window_layout_changed(struct window *w)
 	free(cp);
 }
 
-void
-control_notify_window_pane_changed(struct window *w)
+/* Notify control clients that window pane changed. */
+static void
+control_window_pane_changed_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
 {
 	struct client	*c;
+	struct window	*w = event_payload_get_window(ep, "window");
 
-	if (w->active == NULL)
+	if (w == NULL || w->active == NULL)
 		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c))
@@ -89,12 +116,17 @@ control_notify_window_pane_changed(struct window *w)
 	}
 }
 
-void
-control_notify_window_unlinked(__unused struct session *s, struct window *w)
+/* Notify control clients that a window was unlinked. */
+static void
+control_window_unlinked_cb(__unused const char *name, struct event_payload *ep,
+    __unused void *sink_data)
 {
-	struct client	*c;
-	struct session	*cs;
+	struct client		*c;
+	struct session		*cs;
+	struct window		*w = event_payload_get_window(ep, "window");
 
+	if (w == NULL)
+		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c) || c->session == NULL)
 			continue;
@@ -107,12 +139,17 @@ control_notify_window_unlinked(__unused struct session *s, struct window *w)
 	}
 }
 
-void
-control_notify_window_linked(__unused struct session *s, struct window *w)
+/* Notify control clients that a window was linked. */
+static void
+control_window_linked_cb(__unused const char *name, struct event_payload *ep,
+    __unused void *sink_data)
 {
-	struct client	*c;
-	struct session	*cs;
+	struct client		*c;
+	struct session		*cs;
+	struct window		*w = event_payload_get_window(ep, "window");
 
+	if (w == NULL)
+		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c) || c->session == NULL)
 			continue;
@@ -125,12 +162,17 @@ control_notify_window_linked(__unused struct session *s, struct window *w)
 	}
 }
 
-void
-control_notify_window_renamed(struct window *w)
+/* Notify control clients that a window was renamed. */
+static void
+control_window_renamed_cb(__unused const char *name, struct event_payload *ep,
+    __unused void *sink_data)
 {
-	struct client	*c;
-	struct session	*cs;
+	struct client		*c;
+	struct session		*cs;
+	struct window		*w = event_payload_get_window(ep, "window");
 
+	if (w == NULL)
+		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c) || c->session == NULL)
 			continue;
@@ -146,13 +188,16 @@ control_notify_window_renamed(struct window *w)
 	}
 }
 
-void
-control_notify_client_session_changed(struct client *cc)
+/* Notify control clients that a client changed session. */
+static void
+control_client_session_changed_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
 {
-	struct client	*c;
-	struct session	*s;
+	struct client		*cc = event_payload_get_client(ep, "client");
+	struct client		*c;
+	struct session		*s;
 
-	if (cc->session == NULL)
+	if (cc == NULL || cc->session == NULL)
 		return;
 	s = cc->session;
 
@@ -170,22 +215,32 @@ control_notify_client_session_changed(struct client *cc)
 	}
 }
 
-void
-control_notify_client_detached(struct client *cc)
+/* Notify control clients that a client detached. */
+static void
+control_client_detached_cb(__unused const char *name, struct event_payload *ep,
+    __unused void *sink_data)
 {
-	struct client	*c;
+	struct client		*cc = event_payload_get_client(ep, "client");
+	struct client		*c;
 
+	if (cc == NULL)
+		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (CONTROL_SHOULD_NOTIFY_CLIENT(c))
 			control_write(c, "%%client-detached %s", cc->name);
 	}
 }
 
-void
-control_notify_session_renamed(struct session *s)
+/* Notify control clients that a session was renamed. */
+static void
+control_session_renamed_cb(__unused const char *name, struct event_payload *ep,
+    __unused void *sink_data)
 {
-	struct client	*c;
+	struct session		*s = event_payload_get_session(ep, "session");
+	struct client		*c;
 
+	if (s == NULL)
+		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c))
 			continue;
@@ -194,8 +249,10 @@ control_notify_session_renamed(struct session *s)
 	}
 }
 
-void
-control_notify_session_created(__unused struct session *s)
+/* Notify control clients that sessions changed. */
+static void
+control_session_created_cb(__unused const char *name,
+    __unused struct event_payload *ep, __unused void *sink_data)
 {
 	struct client	*c;
 
@@ -207,8 +264,10 @@ control_notify_session_created(__unused struct session *s)
 	}
 }
 
-void
-control_notify_session_closed(__unused struct session *s)
+/* Notify control clients that sessions changed. */
+static void
+control_session_closed_cb(__unused const char *name,
+    __unused struct event_payload *ep, __unused void *sink_data)
 {
 	struct client	*c;
 
@@ -220,9 +279,12 @@ control_notify_session_closed(__unused struct session *s)
 	}
 }
 
-void
-control_notify_session_window_changed(struct session *s)
+/* Notify control clients that the current window changed. */
+static void
+control_session_window_changed_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
 {
+	struct session	*s = event_payload_get_session(ep, "session");
 	struct client	*c;
 
 	/*
@@ -230,7 +292,7 @@ control_notify_session_window_changed(struct session *s)
 	 * session has been destroyed (which sets curw to NULL) but is kept
 	 * alive by the notification's reference. Skip the notification.
 	 */
-	if (s->curw == NULL)
+	if (s == NULL || s->curw == NULL)
 		return;
 
 	TAILQ_FOREACH(c, &clients, entry) {
@@ -242,28 +304,68 @@ control_notify_session_window_changed(struct session *s)
 	}
 }
 
-void
-control_notify_paste_buffer_changed(const char *name)
+/* Notify control clients that a paste buffer changed. */
+static void
+control_paste_buffer_changed_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
 {
+	const char	*pbname = event_payload_get_string(ep, "paste_buffer");
 	struct client	*c;
 
+	if (pbname == NULL)
+		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c))
 			continue;
 
-		control_write(c, "%%paste-buffer-changed %s", name);
+		control_write(c, "%%paste-buffer-changed %s", pbname);
 	}
 }
 
-void
-control_notify_paste_buffer_deleted(const char *name)
+/* Notify control clients that a paste buffer was deleted. */
+static void
+control_paste_buffer_deleted_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
 {
+	const char	*pbname = event_payload_get_string(ep, "paste_buffer");
 	struct client	*c;
 
+	if (pbname == NULL)
+		return;
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c))
 			continue;
 
-		control_write(c, "%%paste-buffer-deleted %s", name);
+		control_write(c, "%%paste-buffer-deleted %s", pbname);
 	}
 }
+
+/* Build control event sinks. */
+void
+control_build_events(void)
+{
+	/* Control event sink callbacks. */
+	static struct {
+		const char	*name;
+		events_cb	 cb;
+	} events[] = {
+		{ "pane-mode-changed", control_pane_mode_changed_cb },
+		{ "window-layout-changed", control_window_layout_changed_cb },
+		{ "window-pane-changed", control_window_pane_changed_cb },
+		{ "window-unlinked", control_window_unlinked_cb },
+		{ "window-linked", control_window_linked_cb },
+		{ "window-renamed", control_window_renamed_cb },
+		{ "client-session-changed", control_client_session_changed_cb },
+		{ "client-detached", control_client_detached_cb },
+		{ "session-renamed", control_session_renamed_cb },
+		{ "session-created", control_session_created_cb },
+		{ "session-closed", control_session_closed_cb },
+		{ "session-window-changed", control_session_window_changed_cb },
+		{ "paste-buffer-changed", control_paste_buffer_changed_cb },
+		{ "paste-buffer-deleted", control_paste_buffer_deleted_cb }
+	};
+	u_int	i;
+
+	for (i = 0; i < nitems(events); i++)
+		events_add_sink(events[i].name, events[i].cb, NULL);
+}