Unify the way sessions are used by callbacks - store the address and use

the reference count, then check it is still on the global sessions list
in the callback.

cmd-choose-window.c

@@ -129,20 +129,19 @@ void
 cmd_choose_window_callback(void *data, int idx)
 {
 	struct cmd_choose_window_data	*cdata = data;
+	struct session			*s = cdata->session;
 	struct cmd_list			*cmdlist;
 	struct cmd_ctx			 ctx;
 	char				*target, *template, *cause;
 
 	if (idx == -1)
 		return;
+	if (!session_alive(s))
+		return;
 	if (cdata->client->flags & CLIENT_DEAD)
 		return;
-	if (cdata->session->flags & SESSION_DEAD)
-		return;
-	if (cdata->client->session != cdata->session)
-		return;
 
-	xasprintf(&target, "%s:%d", cdata->session->name, idx);
+	xasprintf(&target, "%s:%d", s->name, idx);
 	template = cmd_template_replace(cdata->template, target, 1);
 	xfree(target);
 

cmd-find-window.c

@@ -30,6 +30,7 @@
 int	cmd_find_window_exec(struct cmd *, struct cmd_ctx *);
 
 void	cmd_find_window_callback(void *, int);
+void	cmd_find_window_free(void *);
 
 const struct cmd_entry cmd_find_window_entry = {
 	"find-window", "findw",
@@ -43,7 +44,7 @@ const struct cmd_entry cmd_find_window_entry = {
 };
 
 struct cmd_find_window_data {
-	u_int	session;
+	struct session	*session;
 };
 
 int
@@ -134,11 +135,11 @@ cmd_find_window_exec(struct cmd *self, struct cmd_ctx *ctx)
 	}
 
 	cdata = xmalloc(sizeof *cdata);
-	if (session_index(s, &cdata->session) != 0)
-		fatalx("session not found");
+	cdata->session = s;
+	cdata->session->references++;
 
-	window_choose_ready(
-	    wl->window->active, 0, cmd_find_window_callback, xfree, cdata);
+	window_choose_ready(wl->window->active,
+	    0, cmd_find_window_callback, cmd_find_window_free, cdata);
 
 out:
 	ARRAY_FREE(&list_idx);
@@ -151,12 +152,24 @@ void
 cmd_find_window_callback(void *data, int idx)
 {
 	struct cmd_find_window_data	*cdata = data;
-	struct session			*s;
+	struct session			*s = cdata->session;
 
-	if (idx != -1 && cdata->session <= ARRAY_LENGTH(&sessions) - 1) {
-		s = ARRAY_ITEM(&sessions, cdata->session);
-		if (s != NULL && session_select(s, idx) == 0)
+	if (idx == -1)
+		return;
+	if (!session_alive(s))
+		return;
+
+	if (session_select(s, idx) == 0) {
 		server_redraw_session(s);
 		recalculate_sizes();
 	}
 }
+
+void
+cmd_find_window_free(void *data)
+{
+	struct cmd_find_window_data	*cdata = data;
+
+	cdata->session->references--;
+	xfree(cdata);
+}

cmd-load-buffer.c

@@ -81,6 +81,7 @@ cmd_load_buffer_exec(struct cmd *self, struct cmd_ctx *ctx)
 
 		cdata = xmalloc(sizeof *cdata);
 		cdata->session = s;
+		cdata->session->references++;
 		cdata->buffer = data->buffer;
 		c->stdin_data = cdata;
 		c->stdin_callback = cmd_load_buffer_callback;
@@ -144,7 +145,6 @@ cmd_load_buffer_callback(struct client *c, void *data)
 	char				*pdata;
 	size_t				 psize;
 	u_int				 limit;
-	int				 idx;
 
 	/*
 	 * Event callback has already checked client is not dead and reduced
@@ -153,7 +153,7 @@ cmd_load_buffer_callback(struct client *c, void *data)
 	c->flags |= CLIENT_EXIT;
 
 	/* Does the target session still exist? */
-	if (session_index(s, &idx) != 0)
+	if (!session_alive(s))
 		goto out;
 
 	psize = EVBUFFER_LENGTH(c->stdin_event->input);
@@ -180,5 +180,6 @@ cmd_load_buffer_callback(struct client *c, void *data)
 	}
 
 out:
+	cdata->session->references--;
 	xfree(cdata);
 }

session.c

@@ -35,6 +35,18 @@ struct session_groups session_groups;
 struct winlink *session_next_alert(struct winlink *);
 struct winlink *session_previous_alert(struct winlink *);
 
+/*
+ * Find if session is still alive. This is true if it is still on the global
+ * sessions list.
+ */
+int
+session_alive(struct session *s)
+{
+	u_int	idx;
+
+	return (session_index(s, &idx) == 0);
+}
+
 /* Find session by name. */
 struct session *
 session_find(const char *name)

tmux.h

@@ -1968,6 +1968,7 @@ void clear_signals(int);
 extern struct sessions sessions;
 extern struct sessions dead_sessions;
 extern struct session_groups session_groups;
+int		 session_alive(struct session *);
 struct session	*session_find(const char *);
 struct session	*session_create(const char *, const char *, const char *,
 		     struct environ *, struct termios *, int, u_int, u_int,