From 6c947eeccf61ab9f5893e054c26d8d3967ba12a8 Mon Sep 17 00:00:00 2001
From: "Loren M. Lang" <lorenl@north-winds.org>
Date: Fri, 5 Jul 2024 19:45:06 -0700
Subject: [PATCH] Make macro safer when strlcpy() is not available

Macro would previously trigger an out-of-bound write if passed a size of
zero. Also, the size was not protected against a possible operator
precedence issue.

Signed-off-by: Loren M. Lang <lorenl@north-winds.org>
Signed-off-by: Aaron Conole <aconole@redhat.com>
---
 include/lldp.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/lldp.h b/include/lldp.h
index 03f5c7e..8e36141 100644
--- a/include/lldp.h
+++ b/include/lldp.h
@@ -58,8 +58,10 @@ typedef __u64 u64;
 #else
 #define STRNCPY_TERMINATED(DEST, SRC, N) \
   do { \
-    strncpy (DEST, SRC, N - 1); \
-    DEST[N - 1] = '\0'; \
+    if((N) > 0) { \
+      strncpy (DEST, SRC, (N) - 1); \
+      DEST[(N) - 1] = '\0'; \
+    } \
   } while (false)
 #endif