From 8d2d0895229cfbe39c1c5c16e61e426812a72e8b Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 7 Jul 2022 18:27:02 +0900
Subject: [PATCH] time-util: fix buffer-over-run

Fixes #23928.
Conflict:adapt test context
Reference:https://github.com/systemd/systemd/pull/23933/commits/8d2d0895229cfbe39c1c5c16e61e426812a72e8b
---
 src/basic/time-util.c     | 2 +-
 src/test/test-time-util.c | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/basic/time-util.c b/src/basic/time-util.c
index 5d162e8..2cc0b92 100644
--- a/src/basic/time-util.c
+++ b/src/basic/time-util.c
@@ -590,7 +590,7 @@ char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
                         t = b;
                 }
 
-                n = MIN((size_t) k, l);
+                n = MIN((size_t) k, l-1);
 
                 l -= n;
                 p += n;
diff --git a/src/test/test-time-util.c b/src/test/test-time-util.c
index 6f4675a..d7cb71c 100644
--- a/src/test/test-time-util.c
+++ b/src/test/test-time-util.c
@@ -241,6 +241,11 @@ static void test_format_timespan(usec_t accuracy) {
         test_format_timespan_one(500 * USEC_PER_MSEC, accuracy);
         test_format_timespan_one(9*USEC_PER_YEAR/5 - 23, accuracy);
         test_format_timespan_one(USEC_INFINITY, accuracy);
+
+        /* See issue #23928. */
+        _cleanup_free_ char *buf;
+        assert_se(buf = new(char, 5));
+        assert_se(buf == format_timespan(buf, 5, 100005, 1000));
 }
 
 static void test_verify_timezone(void) {
-- 
2.27.0