From 316136f428603481b78d8f6ca747c666e63fd210 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Tue, 6 Feb 2024 13:08:43 +0100
Subject: [PATCH] term: ignore attempts to set a title that contains an invalid
 UTF-8 sequence

Setting the title ultimately leads to a call to
xdg_toplevel::set_title(). It is a protocol violation to try to set a
title that contains an invalid UTF-8 sequence:

    The string must be encoded in UTF-8.

Closes #1552
---
 CHANGELOG.md | 3 +++
 terminal.c   | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 48cea306..b3255565 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -102,10 +102,13 @@
   set in `[environment]`.
 * Environment variables normally set by foot lost with `footclient
   -E,--client-environment` ([#1568][1568]).
+* XDG toplevel protocol violation, by trying to set a title that
+  contains an invalid UTF-8 sequence ([#1552][1552]).
 
 [1531]: https://codeberg.org/dnkl/foot/issues/1531
 [1573]: https://codeberg.org/dnkl/foot/issues/1573
 [1568]: https://codeberg.org/dnkl/foot/issues/1568
+[1552]: https://codeberg.org/dnkl/foot/issues/1552
 
 
 ### Security
diff --git a/terminal.c b/terminal.c
index ed13073e..f93e7abc 100644
--- a/terminal.c
+++ b/terminal.c
@@ -3249,6 +3249,13 @@ term_set_window_title(struct terminal *term, const char *title)
     if (term->window_title != NULL && streq(term->window_title, title))
         return;
 
+    if (mbsntoc32(NULL, title, strlen(title), 0) == (char32_t)-1) {
+        /* It's an xdg_toplevel::set_title() protocol violation to set
+           a title with an invalid UTF-8 sequence */
+        LOG_WARN("%s: title is not valid UTF-8, ignoring", title);
+        return;
+    }
+
     free(term->window_title);
     term->window_title = xstrdup(title);
     render_refresh_title(term);