From d876542d39a27ed39d38f7d80d52e6460c541843 Mon Sep 17 00:00:00 2001
From: Jef Driesen <jefdriesen@users.sourceforge.net>
Date: Thu, 21 Feb 2019 21:54:58 +0100
Subject: [PATCH] Don't pass a NULL pointer to memcpy

The memcpy and related functions expects a valid pointer, even if the
size is zero. Most libc implementations will handle a NULL pointer just
fine, but that's not guaranteed.

Simply skip the call when there is nothing to copy.
---
 src/divesystem_idive.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/divesystem_idive.c b/src/divesystem_idive.c
index 2303186..180ccb6 100644
--- a/src/divesystem_idive.c
+++ b/src/divesystem_idive.c
@@ -319,7 +319,9 @@ divesystem_idive_packet (divesystem_idive_device_t *device, const unsigned char
 		goto error;
 	}
 
-	memcpy(answer, packet + 1, length - 2);
+	if (length > 2) {
+		memcpy (answer, packet + 1, length - 2);
+	}
 
 error:
 	if (errorcode) {