[Unix]: AcceptAsync with existing AcceptSocket support on Unix

src/libraries/System.Net.Sockets/src/System/Net/Sockets/SafeSocketHandle.cs

@@ -50,6 +50,8 @@ public SafeSocketHandle(IntPtr preexistingHandle, bool ownsHandle)
 
         internal bool OwnsHandle { get; }
 
+        internal bool HasShutdownSend => _hasShutdownSend;
+
         private bool TryOwnClose()
         {
             return OwnsHandle && Interlocked.CompareExchange(ref _ownClose, 1, 0) == 0;

src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.Unix.cs

@@ -6,6 +6,8 @@
 using System.Threading.Tasks;
 using System.Runtime.Versioning;
 using Microsoft.Win32.SafeHandles;
+using System.Reflection;
+using System.Collections;
 
 namespace System.Net.Sockets
 {
@@ -166,16 +168,20 @@ private static void ThrowMultiConnectNotSupported()
         }
 
 #pragma warning disable CA1822
-        private Socket? GetOrCreateAcceptSocket(Socket? acceptSocket, bool unused, string propertyName, out SafeSocketHandle? handle)
+        private Socket? GetOrCreateAcceptSocket(Socket? acceptSocket, bool checkDisconnected, string propertyName, out SafeSocketHandle? handle)
         {
-            // AcceptSocket is not supported on Unix.
-            if (acceptSocket != null)
+            if (acceptSocket != null && acceptSocket._handle.HasShutdownSend)
             {
-                throw new PlatformNotSupportedException(SR.PlatformNotSupported_AcceptSocket);
+                throw new SocketException((int)SocketError.InvalidArgument);
+            }
+
+            if (acceptSocket != null && acceptSocket._rightEndPoint != null && (!checkDisconnected || !acceptSocket._isDisconnected))
+            {
+                throw new InvalidOperationException(SR.Format(SR.net_sockets_namedmustnotbebound, propertyName));
             }
 
             handle = null;
-            return null;
+            return acceptSocket;
         }
 #pragma warning restore CA1822
 
@@ -228,5 +234,81 @@ private void SendFileInternal(string? fileName, ReadOnlySpan<byte> preBuffer, Re
                 Send(postBuffer);
             }
         }
+
+        internal void DisposeHandle()
+        {
+            _handle.Dispose();
+        }
+
+        internal void ClearHandle()
+        {
+            _handle = null!;
+        }
+
+        internal Socket CopyStateFromSource(Socket source)
+        {
+            _addressFamily = source._addressFamily;
+            _closeTimeout = source._closeTimeout;
+            _disposed = source._disposed;
+            _handle = source._handle;
+            _isConnected = source._isConnected;
+            _isDisconnected = source._isDisconnected;
+            _isListening = source._isListening;
+            _nonBlockingConnectInProgress = source._nonBlockingConnectInProgress;
+            _protocolType = source._protocolType;
+            _receivingPacketInformation = source._receivingPacketInformation;
+            _remoteEndPoint = source._remoteEndPoint;
+            _rightEndPoint = source._rightEndPoint;
+            _socketType = source._socketType;
+            _willBlock = source._willBlock;
+            _willBlockInternal = source._willBlockInternal;
+            _localEndPoint = source._localEndPoint;
+            _multiBufferReceiveEventArgs = source._multiBufferReceiveEventArgs;
+            _multiBufferSendEventArgs = source._multiBufferSendEventArgs;
+            _pendingConnectRightEndPoint = source._pendingConnectRightEndPoint;
+            _singleBufferReceiveEventArgs = source._singleBufferReceiveEventArgs;
+#if DEBUG
+            // Try to detect if a property gets added that we're not copying correctly.
+            foreach (PropertyInfo pi in typeof(Socket).GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly))
+            {
+                object? origValue = pi.GetValue(source);
+                object? cloneValue = pi.GetValue(this);
+
+                if (origValue is IEnumerable origEnumerable)
+                {
+                    IEnumerable? cloneEnumerable = cloneValue as IEnumerable;
+                    Debug.Assert(cloneEnumerable != null, $"{pi.Name}. Expected enumerable cloned value.");
+
+                    IEnumerator e1 = origEnumerable.GetEnumerator();
+                    try
+                    {
+                        IEnumerator e2 = cloneEnumerable.GetEnumerator();
+                        try
+                        {
+                            while (e1.MoveNext())
+                            {
+                                Debug.Assert(e2.MoveNext(), $"{pi.Name}. Cloned enumerator too short.");
+                                Debug.Assert(Equals(e1.Current, e2.Current), $"{pi.Name}. Cloned enumerator's values don't match.");
+                            }
+                            Debug.Assert(!e2.MoveNext(), $"{pi.Name}. Cloned enumerator too long.");
+                        }
+                        finally
+                        {
+                            (e2 as IDisposable)?.Dispose();
+                        }
+                    }
+                    finally
+                    {
+                        (e1 as IDisposable)?.Dispose();
+                    }
+                }
+                else
+                {
+                    Debug.Assert(Equals(origValue, cloneValue), $"{pi.Name}. Expected: {origValue}, Actual: {cloneValue}");
+                }
+            }
+#endif
+            return this;
+        }
     }
 }

src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncEventArgs.Unix.cs

@@ -335,9 +335,21 @@ internal void LogBuffer(int size)
         private SocketError FinishOperationAccept(Internals.SocketAddress remoteSocketAddress)
         {
             System.Buffer.BlockCopy(_acceptBuffer!, 0, remoteSocketAddress.Buffer, 0, _acceptAddressBufferCount);
+            Socket? sukru = _acceptSocket;
             _acceptSocket = _currentSocket!.CreateAcceptSocket(
                 SocketPal.CreateSocket(_acceptedFileDescriptor),
                 _currentSocket._rightEndPoint!.Create(remoteSocketAddress));
+            if (sukru != null)
+            {
+                sukru.DisposeHandle();
+                sukru.CopyStateFromSource(_acceptSocket);
+                // We keep this socket to make clean-up.
+                Socket temp = _acceptSocket;
+                _acceptSocket = sukru;
+                temp.ClearHandle();
+                temp.Dispose();
+                GC.SuppressFinalize(temp);
+            }
             return SocketError.Success;
         }
 

src/libraries/System.Net.Sockets/tests/FunctionalTests/Accept.cs

@@ -144,7 +144,6 @@ public async Task Accept_ConcurrentAcceptsAfterConnects_Success(int numberAccept
 
         [OuterLoop]
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/1483", TestPlatforms.AnyUnix)]
         public async Task Accept_WithTargetSocket_Success()
         {
             if (!SupportsAcceptIntoExistingSocket)
@@ -166,7 +165,6 @@ public async Task Accept_WithTargetSocket_Success()
             }
         }
 
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/1483", TestPlatforms.AnyUnix)]
         [OuterLoop]
         [Theory]
         [InlineData(false)]
@@ -221,7 +219,6 @@ public async Task Accept_WithTargetSocket_ReuseAfterDisconnect_Success(bool reus
 
         [OuterLoop]
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/1483", TestPlatforms.AnyUnix)]
         public async Task Accept_WithAlreadyBoundTargetSocket_Fails()
         {
             if (!SupportsAcceptIntoExistingSocket)
@@ -242,7 +239,6 @@ public async Task Accept_WithAlreadyBoundTargetSocket_Fails()
 
         [OuterLoop]
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/1483", TestPlatforms.AnyUnix)]
         public async Task Accept_WithInUseTargetSocket_Fails()
         {
             if (!SupportsAcceptIntoExistingSocket)