Merge pull request protocolbuffers#8740 from kiwidev/master

[csharp] ByteString.CreateCodedInput should use ArraySegment offset and count

Author: jtattermusch

csharp/src/Google.Protobuf.Test/ByteStringTest.cs

@@ -210,6 +210,22 @@ public void UnsafeWrap()
             Assert.AreEqual(byte.MaxValue, s[0]);
         }
 
+        [Test]
+        public void CreateCodedInput_FromArraySegment()
+        {
+            byte[] data = new byte[] { 0, 1, 2, 3, 4, 5, 6 };
+            ByteString bs = UnsafeByteOperations.UnsafeWrap(data.AsMemory(2, 3));
+            CodedInputStream codedInputStream = bs.CreateCodedInput();
+
+            byte[] bytes = codedInputStream.ReadRawBytes(3);
+
+            Assert.AreEqual(3, bytes.Length);
+            Assert.AreEqual(2, bytes[0]);
+            Assert.AreEqual(3, bytes[1]);
+            Assert.AreEqual(4, bytes[2]);
+            Assert.IsTrue(codedInputStream.IsAtEnd);
+        }
+
         [Test]
         public void WriteToStream()
         {

csharp/src/Google.Protobuf/ByteString.cs

@@ -325,7 +325,7 @@ public CodedInputStream CreateCodedInput()
             if (MemoryMarshal.TryGetArray(bytes, out ArraySegment<byte> segment) && segment.Count == bytes.Length)
             {
                 // Fast path. ByteString was created with a complete array.
-                return new CodedInputStream(segment.Array);
+                return new CodedInputStream(segment.Array, segment.Offset, segment.Count);
             }
             else
             {