From dd710ec3080183eb7cc2c0ddc32e3b2b5f03790f Mon Sep 17 00:00:00 2001
From: Adam Hathcock <adam@hathcock.co.uk>
Date: Sun, 21 Feb 2021 13:37:58 +0000
Subject: [PATCH] fixed read only sub stream

---
 src/SharpCompress/IO/ReadOnlySubStream.cs | 25 +++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/SharpCompress/IO/ReadOnlySubStream.cs b/src/SharpCompress/IO/ReadOnlySubStream.cs
index 7b39a45b..fb576c09 100644
--- a/src/SharpCompress/IO/ReadOnlySubStream.cs
+++ b/src/SharpCompress/IO/ReadOnlySubStream.cs
@@ -34,12 +34,37 @@ namespace SharpCompress.IO
 
         public override long Position { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }
 
+        public override async ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
+        {
+            var count = buffer.Length;
+            if (BytesLeftToRead < count)
+            {
+                count = (int)BytesLeftToRead;
+            }
+
+            if (count == 0)
+            {
+                return 0;
+            }
+            int read = await Stream.ReadAsync(buffer.Slice(0, count), cancellationToken);
+            if (read > 0)
+            {
+                BytesLeftToRead -= read;
+            }
+            return read;
+        }
+        
         public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
         {
             if (BytesLeftToRead < count)
             {
                 count = (int)BytesLeftToRead;
             }
+
+            if (count == 0)
+            {
+                return 0;
+            }
             int read = await Stream.ReadAsync(buffer, offset, count, cancellationToken);
             if (read > 0)
             {