From 215549117136eae526bc61f4aa71a922fc27b1fc Mon Sep 17 00:00:00 2001
From: Jack Stefani <jack@stefani.org>
Date: Sun, 4 Oct 2026 20:25:47 -0400
Subject: [PATCH] util: fix infinite loop in trim_string_to_width

when width was less than "..." the loop never ended.
break out of loop when gsub cannot make progress.

note: avoided empty string test in while condition as this
misses edge case of unmatchable stray UTF-8 continuation bytes.

clarify in ldoc that width is in pixels.

fixes #1636
---
 lua/lib/util.lua | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lua/lib/util.lua b/lua/lib/util.lua
index ca4d7105f..edfd9bd47 100644
--- a/lua/lib/util.lua
+++ b/lua/lib/util.lua
@@ -96,12 +96,14 @@ end
 
 --- trim string to a display width
 -- @tparam string s string to trim
--- @tparam number width maximum width
+-- @tparam number width maximum width in pixels
 -- @treturn string trimmed string
 util.trim_string_to_width = function(s, width)
   if _norns.screen_text_extents(s) > width then
     while _norns.screen_text_extents(s .. "...") > width do
-      s = string.gsub(s, "[^\128-\191][\128-\191]*$", "")
+      local n
+      s, n = string.gsub(s, "[^\128-\191][\128-\191]*$", "")
+      if n == 0 then break end
     end
     s = s .. "..."
   end