[PATCH] Core: copy a NULL string in memcpy is undefined behavior

[Zexuan Luo]

# HG changeset patch
# User Zexuan Luo <spacewanderlzx at gmail.com>
# Date 1648192098 -28800
#      Fri Mar 25 15:08:18 2022 +0800
# Node ID a94f838a469ed158e421cbc8187db6ae79153921
# Parent  a736a7a613ea6e182ff86fbadcb98bb0f8891c0b
Core: copy a NULL string in memcpy is undefined behavior

diff -r a736a7a613ea -r a94f838a469e src/core/ngx_string.c
--- a/src/core/ngx_string.c     Tue Feb 08 17:35:27 2022 +0300
+++ b/src/core/ngx_string.c     Fri Mar 25 15:08:18 2022 +0800
@@ -81,7 +81,9 @@
         return NULL;
     }

-    ngx_memcpy(dst, src->data, src->len);
+    if (src->len > 0) {
+        ngx_memcpy(dst, src->data, src->len);
+    }

     return dst;
 }