From b4bd1aeaffb60a62099855113e06f63aed15aded Mon Sep 17 00:00:00 2001
From: Himmelt <master@void-3.cn>
Date: Tue, 15 Aug 2023 18:04:22 +0800
Subject: [PATCH] Return expected length substring rather than throw an
 exception when reading strings

---
 S7.Net/Types/S7String.cs  | 3 ++-
 S7.Net/Types/S7WString.cs | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/S7.Net/Types/S7String.cs b/S7.Net/Types/S7String.cs
index d45c5349..2d1c3d8c 100644
--- a/S7.Net/Types/S7String.cs
+++ b/S7.Net/Types/S7String.cs
@@ -42,7 +42,8 @@ public static string FromByteArray(byte[] bytes)
 
             try
             {
-                return StringEncoding.GetString(bytes, 2, length);
+                int expect_length = bytes.Length - 2;
+                return StringEncoding.GetString(bytes, 2, Math.Min(expect_length, length));
             }
             catch (Exception e)
             {
diff --git a/S7.Net/Types/S7WString.cs b/S7.Net/Types/S7WString.cs
index 001c7ef3..b63f3b39 100644
--- a/S7.Net/Types/S7WString.cs
+++ b/S7.Net/Types/S7WString.cs
@@ -31,7 +31,8 @@ public static string FromByteArray(byte[] bytes)
 
             try
             {
-                return Encoding.BigEndianUnicode.GetString(bytes, 4, length * 2);
+                int expect_length = (bytes.Length - 4) / 2;
+                return Encoding.BigEndianUnicode.GetString(bytes, 4, Math.Min(expect_length, length) * 2);
             }
             catch (Exception e)
             {