From e98e36dfca28404a6f5c8dd71de3b3d27bfb0f05 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Kochma=C5=84ski?= <daniel@turtleware.eu>
Date: Wed, 23 Jul 2025 15:54:40 +0200
Subject: [PATCH] streams: fix a braino in str_in_unread_char

We've tested a wrong variable so this function allowed us to plum into negative
indexes.
---
 src/c/streams/strm_string.d | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/c/streams/strm_string.d b/src/c/streams/strm_string.d
index 2543d492e..cfd97450a 100644
--- a/src/c/streams/strm_string.d
+++ b/src/c/streams/strm_string.d
@@ -219,7 +219,7 @@ static void
 str_in_unread_char(cl_object strm, ecl_character c)
 {
   cl_fixnum curr_pos = STRING_INPUT_POSITION(strm);
-  unlikely_if (c <= 0) {
+  unlikely_if (curr_pos <= 0) {
     ecl_unread_error(strm);
   }
   STRING_INPUT_POSITION(strm) = curr_pos - 1;