From e439bb5fdd48fb9558e4ea29623689d15ec7c3dd Mon Sep 17 00:00:00 2001
From: "Tarn W. Burton" <twburton@gmail.com>
Date: Fri, 10 May 2024 06:38:21 -0400
Subject: [PATCH] Add test for buffer overun in encoding buffer

---
 src/tests/normal-tests/mixed.lsp | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/tests/normal-tests/mixed.lsp b/src/tests/normal-tests/mixed.lsp
index 956d192fc..eff6b1634 100644
--- a/src/tests/normal-tests/mixed.lsp
+++ b/src/tests/normal-tests/mixed.lsp
@@ -561,3 +561,19 @@
   (is (equal (multiple-value-list (read-line (make-instance 'character-input-stream :value "a
 ")))
              '("a" nil))))
+
+;;;; Author:   Tarn W. Burton
+;;;; Created:  2024-05-19
+;;;; Description:
+;;;;     Test to ensure that write-char returns the correct value. An
+;;;;     incorrect value or stack smashing indicated a buffer overrun
+;;;;     caused by an encoding buffer that is too small.
+
+(test mix.0030.write-char-encode-buffer
+  (is (equal (with-open-file (s "/tmp/whatever.txt"
+                                :if-does-not-exist :create
+                                :if-exists :supersede
+                                :external-format :ucs-4
+                                :direction :output)
+               (write-char #\a s))
+             #\a)))