From a949bb5d7d160c412c3a5f9d48b54b9377611e1e Mon Sep 17 00:00:00 2001
From: Hamza El-Saawy <hamzaelsaawy@microsoft.com>
Date: Mon, 7 Feb 2022 18:25:37 -0500
Subject: [PATCH] `HvsockConn` shutdown, and `.IsClosed()` function

Corrected `HvsockConn` `CloseRead`/`Write` to check if the socket
has been closed before attempting to shutdown reading or writing.
Additionally, `shutdown` was not respecting whether to shutdown reading
or writing, and only shutting down reading.

Added a `CloseReadWrite` function to `HvsockConn` to expose shutting
down both ends of the connection.

Added `IsClosed` function to `win32File` (and therefore `win32Pipe` and
`win32MessageBytePipe`) and `HvsockConn` to check if the socket/pipe
has been closed already.

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>
---
 file.go   |  6 ++++++
 hvsock.go | 22 ++++++++++++++++++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/file.go b/file.go
index 0385e410..293ab54c 100644
--- a/file.go
+++ b/file.go
@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package winio
@@ -143,6 +144,11 @@ func (f *win32File) Close() error {
 	return nil
 }
 
+// IsClosed checks if the file has been closed
+func (f *win32File) IsClosed() bool {
+	return f.closing.isSet()
+}
+
 // prepareIo prepares for a new IO operation.
 // The caller must call f.wg.Done() when the IO is finished, prior to Close() returning.
 func (f *win32File) prepareIo() (*ioOperation, error) {
diff --git a/hvsock.go b/hvsock.go
index b632f8f8..fa627e61 100644
--- a/hvsock.go
+++ b/hvsock.go
@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package winio
@@ -252,15 +253,23 @@ func (conn *HvsockConn) Close() error {
 	return conn.sock.Close()
 }
 
+func (conn *HvsockConn) IsClosed() bool {
+	return conn.sock.IsClosed()
+}
+
 func (conn *HvsockConn) shutdown(how int) error {
-	err := syscall.Shutdown(conn.sock.handle, syscall.SHUT_RD)
+	if conn.IsClosed() {
+		return ErrFileClosed
+	}
+
+	err := syscall.Shutdown(conn.sock.handle, how)
 	if err != nil {
 		return os.NewSyscallError("shutdown", err)
 	}
 	return nil
 }
 
-// CloseRead shuts down the read end of the socket.
+// CloseRead shuts down the read end of the socket, preventing future read operations.
 func (conn *HvsockConn) CloseRead() error {
 	err := conn.shutdown(syscall.SHUT_RD)
 	if err != nil {
@@ -279,6 +288,15 @@ func (conn *HvsockConn) CloseWrite() error {
 	return nil
 }
 
+// CloseReadWrite shuts down both the read and write end of the socket, preventing future operations.
+func (conn *HvsockConn) CloseReadWrite() error {
+	err := conn.shutdown(syscall.SHUT_RDWR)
+	if err != nil {
+		return conn.opErr("close", err)
+	}
+	return nil
+}
+
 // LocalAddr returns the local address of the connection.
 func (conn *HvsockConn) LocalAddr() net.Addr {
 	return &conn.local