From 1f50b39e99d12042fc2e2ce3b754719fa42af753 Mon Sep 17 00:00:00 2001
From: Fabrice Bellard <fabrice@bellard.org>
Date: Thu, 14 May 2026 16:21:10 +0200
Subject: [PATCH] memcpy() (currently) has undefined behavior if a pointer is
 NULL with zero size (#500)

---
 libunicode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libunicode.c b/libunicode.c
index 0c510cc..0b7b6d0 100644
--- a/libunicode.c
+++ b/libunicode.c
@@ -1189,7 +1189,8 @@ int unicode_normalize(uint32_t **pdst, const uint32_t *src, int src_len,
                 goto not_latin1;
         }
         buf = (int *)dbuf->buf;
-        memcpy(buf, src, src_len * sizeof(int));
+        if (src_len != 0)
+            memcpy(buf, src, src_len * sizeof(int));
         *pdst = (uint32_t *)buf;
         return src_len;
     not_latin1: ;