Imported Upstream version 6.4.0.137

Former-commit-id: 943baa9f16a098c33e129777827f3a9d20da00d6

mcs/class/referencesource/mscorlib/system/io/binaryreader.cs

@@ -511,6 +511,20 @@ namespace System.IO {
             return chars;
         }
 
+#if MONO
+        public virtual int Read(Span<char> buffer)
+        {
+            char[] bufferBytes = buffer.ToArray();
+            return Read(bufferBytes, 0, bufferBytes.Length);
+        }
+
+        public virtual int Read(Span<byte> buffer)
+        {
+            byte[] bufferBytes = buffer.ToArray();
+            return Read(bufferBytes, 0, bufferBytes.Length);
+        }
+#endif
+
         public virtual int Read(byte[] buffer, int index, int count) {
             if (buffer==null)
                 throw new ArgumentNullException("buffer", Environment.GetResourceString("ArgumentNull_Buffer"));

mcs/class/referencesource/mscorlib/system/io/binarywriter.cs

@@ -20,6 +20,7 @@ using System.Runtime;
 using System.Runtime.Serialization;
 using System.Text;
 using System.Diagnostics.Contracts;
+using System.Threading.Tasks;
 
 namespace System.IO {
     // This abstract base class represents a writer that can write
@@ -28,7 +29,7 @@ namespace System.IO {
     //
     [Serializable]
 [System.Runtime.InteropServices.ComVisible(true)]
-    public class BinaryWriter : IDisposable
+    public class BinaryWriter : IDisposable, IAsyncDisposable
     {
         public static readonly BinaryWriter Null = new BinaryWriter();
         
@@ -135,6 +136,45 @@ namespace System.IO {
         {
             return OutStream.Seek(offset, origin);
         }
+
+#if MONO
+        public virtual void Write(ReadOnlySpan<byte> buffer)
+        {
+            Write(buffer.ToArray());
+        }
+
+        public virtual void Write(ReadOnlySpan<char> buffer)
+        {
+            Write(buffer.ToArray());
+        }
+
+        public virtual ValueTask DisposeAsync()
+        {
+            try
+            {
+                if (GetType() == typeof(BinaryWriter))
+                {
+                    if (_leaveOpen)
+                    {
+                        return new ValueTask(OutStream.FlushAsync());
+                    }
+
+                    OutStream.Close();
+                }
+                else
+                {
+                    // Since this is a derived BinaryWriter, delegate to whatever logic
+                    // the derived implementation already has in Dispose.
+                    Dispose();
+                }
+                return default;
+            }
+            catch (Exception exc)
+            {
+                return new ValueTask(Task.FromException(exc));
+            }
+        }
+#endif
         
         // Writes a boolean to this stream. A single byte is written to the stream
         // with the value 0 representing false or the value 1 representing true.