From 7dc36739cf48996615f9d4134ff4971a2af36ee1 Mon Sep 17 00:00:00 2001
From: Weilin Du <weilindu@php.net>
Date: Sun, 11 Oct 2026 23:00:09 +0800
Subject: [PATCH] Fix non-ASCII completion append characters in readline_info()

Store the first byte as unsigned char to keep completion_append_character
within the valid range of the one-character string table.
---
 NEWS                                          |  4 +++
 ext/readline/readline.c                       |  2 +-
 ...line_info_completion_append_character.phpt | 27 +++++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 ext/readline/tests/readline_info_completion_append_character.phpt

diff --git a/NEWS b/NEWS
index aaed43baa2c8..43eaf4dbad43 100644
--- a/NEWS
+++ b/NEWS
@@ -44,6 +44,10 @@ PHP                                                                        NEWS
 - Phpdbg:
   . Fix wrong command names. (ndossche, Weilin Du)
 
+- Readline:
+  . Fixed a crash in readline_info() when completion_append_character
+    contains a non-ASCII byte. (Weilin Du)
+
 - SOAP:
   . Fixed use of uninitialized func in do_request() on OOM bailout.
     (David Carlier)
diff --git a/ext/readline/readline.c b/ext/readline/readline.c
index 838c74da86ce..f9287af2eff6 100644
--- a/ext/readline/readline.c
+++ b/ext/readline/readline.c
@@ -248,7 +248,7 @@ PHP_FUNCTION(readline_info)
 				if (!try_convert_to_string(value)) {
 					RETURN_THROWS();
 				}
-				rl_completion_append_character = (int)Z_STRVAL_P(value)[0];
+				rl_completion_append_character = (unsigned char)Z_STRVAL_P(value)[0];
 			}
 			RETVAL_INTERNED_STR(
 				oldval == 0 ? ZSTR_EMPTY_ALLOC() : ZSTR_CHAR(oldval));
diff --git a/ext/readline/tests/readline_info_completion_append_character.phpt b/ext/readline/tests/readline_info_completion_append_character.phpt
new file mode 100644
index 000000000000..88a0cf003388
--- /dev/null
+++ b/ext/readline/tests/readline_info_completion_append_character.phpt
@@ -0,0 +1,27 @@
+--TEST--
+readline_info(): completion_append_character supports non-ASCII bytes
+--EXTENSIONS--
+readline
+--SKIPIF--
+<?php
+if (READLINE_LIB !== 'readline') die('skip readline only');
+?>
+--FILE--
+<?php
+readline_info('completion_append_character', '');
+foreach (["\x7f", "\x80", "\xfftail", ''] as $value) {
+    $old = readline_info('completion_append_character', $value);
+    $current = readline_info('completion_append_character');
+    $info = readline_info();
+    printf("old=%s current=%s info=%s\n",
+        bin2hex($old),
+        bin2hex($current),
+        bin2hex($info['completion_append_character'])
+    );
+}
+?>
+--EXPECT--
+old= current=7f info=7f
+old=7f current=80 info=80
+old=80 current=ff info=ff
+old=ff current= info=