Upgrade rust/crates/tokio to 1.7.1

Test: make
Change-Id: I7ebd839df13023db6f2057e09d8b73967436b856

5 files changed, 1249 insertions, 1 deletions

diff --git a/src/net/mod.rs b/src/net/mod.rs
index 2f17f9e..0b8c1ec 100644
--- a/src/net/mod.rs
+++ b/src/net/mod.rs
@@ -46,3 +46,7 @@ cfg_net_unix! {
     pub use unix::listener::UnixListener;
     pub use unix::stream::UnixStream;
 }
+
+cfg_net_windows! {
+    pub mod windows;
+}
diff --git a/src/net/tcp/socket.rs b/src/net/tcp/socket.rs
index 4bcbe3f..02cb637 100644
--- a/src/net/tcp/socket.rs
+++ b/src/net/tcp/socket.rs
@@ -482,6 +482,48 @@ impl TcpSocket {
         let mio = self.inner.listen(backlog)?;
         TcpListener::new(mio)
     }
+
+    /// Converts a [`std::net::TcpStream`] into a `TcpSocket`. The provided
+    /// socket must not have been connected prior to calling this function. This
+    /// function is typically used together with crates such as [`socket2`] to
+    /// configure socket options that are not available on `TcpSocket`.
+    ///
+    /// [`std::net::TcpStream`]: struct@std::net::TcpStream
+    /// [`socket2`]: https://docs.rs/socket2/
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::net::TcpSocket;
+    /// use socket2::{Domain, Socket, Type};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> std::io::Result<()> {
+    ///     
+    ///     let socket2_socket = Socket::new(Domain::IPV4, Type::STREAM, None)?;
+    ///
+    ///     let socket = TcpSocket::from_std_stream(socket2_socket.into());
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn from_std_stream(std_stream: std::net::TcpStream) -> TcpSocket {
+        #[cfg(unix)]
+        {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+            let raw_fd = std_stream.into_raw_fd();
+            unsafe { TcpSocket::from_raw_fd(raw_fd) }
+        }
+
+        #[cfg(windows)]
+        {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+
+            let raw_socket = std_stream.into_raw_socket();
+            unsafe { TcpSocket::from_raw_socket(raw_socket) }
+        }
+    }
 }
 
 impl fmt::Debug for TcpSocket {
diff --git a/src/net/unix/ucred.rs b/src/net/unix/ucred.rs
index 5c7c198..b95a8f6 100644
--- a/src/net/unix/ucred.rs
+++ b/src/net/unix/ucred.rs
@@ -73,7 +73,7 @@ pub(crate) mod impl_linux {
 
             // These paranoid checks should be optimized-out
             assert!(mem::size_of::<u32>() <= mem::size_of::<usize>());
-            assert!(ucred_size <= u32::max_value() as usize);
+            assert!(ucred_size <= u32::MAX as usize);
 
             let mut ucred_size = ucred_size as socklen_t;
 
diff --git a/src/net/windows/mod.rs b/src/net/windows/mod.rs
new file mode 100644
index 0000000..060b68e
--- /dev/null
+++ b/src/net/windows/mod.rs
@@ -0,0 +1,3 @@
+//! Windows specific network types.
+
+pub mod named_pipe;
diff --git a/src/net/windows/named_pipe.rs b/src/net/windows/named_pipe.rs
new file mode 100644
index 0000000..8013d6f
--- /dev/null
+++ b/src/net/windows/named_pipe.rs
@@ -0,0 +1,1199 @@
+//! Tokio support for [Windows named pipes].
+//!
+//! [Windows named pipes]: https://docs.microsoft.com/en-us/windows/win32/ipc/named-pipes
+
+use std::ffi::c_void;
+use std::ffi::OsStr;
+use std::io;
+use std::pin::Pin;
+use std::ptr;
+use std::task::{Context, Poll};
+
+use crate::io::{AsyncRead, AsyncWrite, Interest, PollEvented, ReadBuf};
+use crate::os::windows::io::{AsRawHandle, FromRawHandle, RawHandle};
+
+// Hide imports which are not used when generating documentation.
+#[cfg(not(docsrs))]
+mod doc {
+    pub(super) use crate::os::windows::ffi::OsStrExt;
+    pub(super) use crate::winapi::shared::minwindef::{DWORD, FALSE};
+    pub(super) use crate::winapi::um::fileapi;
+    pub(super) use crate::winapi::um::handleapi;
+    pub(super) use crate::winapi::um::namedpipeapi;
+    pub(super) use crate::winapi::um::winbase;
+    pub(super) use crate::winapi::um::winnt;
+
+    pub(super) use mio::windows as mio_windows;
+}
+
+// NB: none of these shows up in public API, so don't document them.
+#[cfg(docsrs)]
+mod doc {
+    pub type DWORD = crate::doc::NotDefinedHere;
+
+    pub(super) mod mio_windows {
+        pub type NamedPipe = crate::doc::NotDefinedHere;
+    }
+}
+
+use self::doc::*;
+
+/// A [Windows named pipe] server.
+///
+/// Accepting client connections involves creating a server with
+/// [`ServerOptions::create`] and waiting for clients to connect using
+/// [`NamedPipeServer::connect`].
+///
+/// To avoid having clients sporadically fail with
+/// [`std::io::ErrorKind::NotFound`] when they connect to a server, we must
+/// ensure that at least one server instance is available at all times. This
+/// means that the typical listen loop for a server is a bit involved, because
+/// we have to ensure that we never drop a server accidentally while a client
+/// might connect.
+///
+/// So a correctly implemented server looks like this:
+///
+/// ```no_run
+/// use std::io;
+/// use tokio::net::windows::named_pipe::ServerOptions;
+///
+/// const PIPE_NAME: &str = r"\\.\pipe\named-pipe-idiomatic-server";
+///
+/// # #[tokio::main] async fn main() -> std::io::Result<()> {
+/// // The first server needs to be constructed early so that clients can
+/// // be correctly connected. Otherwise calling .wait will cause the client to
+/// // error.
+/// //
+/// // Here we also make use of `first_pipe_instance`, which will ensure that
+/// // there are no other servers up and running already.
+/// let mut server = ServerOptions::new()
+///     .first_pipe_instance(true)
+///     .create(PIPE_NAME)?;
+///
+/// // Spawn the server loop.
+/// let server = tokio::spawn(async move {
+///     loop {
+///         // Wait for a client to connect.
+///         let connected = server.connect().await?;
+///
+///         // Construct the next server to be connected before sending the one
+///         // we already have of onto a task. This ensures that the server
+///         // isn't closed (after it's done in the task) before a new one is
+///         // available. Otherwise the client might error with
+///         // `io::ErrorKind::NotFound`.
+///         server = ServerOptions::new().create(PIPE_NAME)?;
+///
+///         let client = tokio::spawn(async move {
+///             /* use the connected client */
+/// #           Ok::<_, std::io::Error>(())
+///         });
+/// #       if true { break } // needed for type inference to work
+///     }
+///
+///     Ok::<_, io::Error>(())
+/// });
+///
+/// /* do something else not server related here */
+/// # Ok(()) }
+/// ```
+///
+/// [`ERROR_PIPE_BUSY`]: crate::winapi::shared::winerror::ERROR_PIPE_BUSY
+/// [Windows named pipe]: https://docs.microsoft.com/en-us/windows/win32/ipc/named-pipes
+#[derive(Debug)]
+pub struct NamedPipeServer {
+    io: PollEvented<mio_windows::NamedPipe>,
+}
+
+impl NamedPipeServer {
+    /// Construct a new named pipe server from the specified raw handle.
+    ///
+    /// This function will consume ownership of the handle given, passing
+    /// responsibility for closing the handle to the returned object.
+    ///
+    /// This function is also unsafe as the primitives currently returned have
+    /// the contract that they are the sole owner of the file descriptor they
+    /// are wrapping. Usage of this function could accidentally allow violating
+    /// this contract which can cause memory unsafety in code that relies on it
+    /// being true.
+    ///
+    /// # Errors
+    ///
+    /// This errors if called outside of a [Tokio Runtime], or in a runtime that
+    /// has not [enabled I/O], or if any OS-specific I/O errors occur.
+    ///
+    /// [Tokio Runtime]: crate::runtime::Runtime
+    /// [enabled I/O]: crate::runtime::Builder::enable_io
+    pub unsafe fn from_raw_handle(handle: RawHandle) -> io::Result<Self> {
+        let named_pipe = mio_windows::NamedPipe::from_raw_handle(handle);
+
+        Ok(Self {
+            io: PollEvented::new(named_pipe)?,
+        })
+    }
+
+    /// Retrieves information about the named pipe the server is associated
+    /// with.
+    ///
+    /// ```no_run
+    /// use tokio::net::windows::named_pipe::{PipeEnd, PipeMode, ServerOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-server-info";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let server = ServerOptions::new()
+    ///     .pipe_mode(PipeMode::Message)
+    ///     .max_instances(5)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let server_info = server.info()?;
+    ///
+    /// assert_eq!(server_info.end, PipeEnd::Server);
+    /// assert_eq!(server_info.mode, PipeMode::Message);
+    /// assert_eq!(server_info.max_instances, 5);
+    /// # Ok(()) }
+    /// ```
+    pub fn info(&self) -> io::Result<PipeInfo> {
+        // Safety: we're ensuring the lifetime of the named pipe.
+        unsafe { named_pipe_info(self.io.as_raw_handle()) }
+    }
+
+    /// Enables a named pipe server process to wait for a client process to
+    /// connect to an instance of a named pipe. A client process connects by
+    /// creating a named pipe with the same name.
+    ///
+    /// This corresponds to the [`ConnectNamedPipe`] system call.
+    ///
+    /// [`ConnectNamedPipe`]: https://docs.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-connectnamedpipe
+    ///
+    /// ```no_run
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\mynamedpipe";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let pipe = ServerOptions::new().create(PIPE_NAME)?;
+    ///
+    /// // Wait for a client to connect.
+    /// pipe.connect().await?;
+    ///
+    /// // Use the connected client...
+    /// # Ok(()) }
+    /// ```
+    pub async fn connect(&self) -> io::Result<()> {
+        loop {
+            match self.io.connect() {
+                Ok(()) => break,
+                Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.registration().readiness(Interest::WRITABLE).await?;
+                }
+                Err(e) => return Err(e),
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Disconnects the server end of a named pipe instance from a client
+    /// process.
+    ///
+    /// ```
+    /// use tokio::io::AsyncWriteExt;
+    /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    /// use winapi::shared::winerror;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-disconnect";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let server = ServerOptions::new()
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let mut client = ClientOptions::new()
+    ///     .open(PIPE_NAME)?;
+    ///
+    /// // Wait for a client to become connected.
+    /// server.connect().await?;
+    ///
+    /// // Forcibly disconnect the client.
+    /// server.disconnect()?;
+    ///
+    /// // Write fails with an OS-specific error after client has been
+    /// // disconnected.
+    /// let e = client.write(b"ping").await.unwrap_err();
+    /// assert_eq!(e.raw_os_error(), Some(winerror::ERROR_PIPE_NOT_CONNECTED as i32));
+    /// # Ok(()) }
+    /// ```
+    pub fn disconnect(&self) -> io::Result<()> {
+        self.io.disconnect()
+    }
+}
+
+impl AsyncRead for NamedPipeServer {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        unsafe { self.io.poll_read(cx, buf) }
+    }
+}
+
+impl AsyncWrite for NamedPipeServer {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write(cx, buf)
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write_vectored(cx, bufs)
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.poll_flush(cx)
+    }
+}
+
+impl AsRawHandle for NamedPipeServer {
+    fn as_raw_handle(&self) -> RawHandle {
+        self.io.as_raw_handle()
+    }
+}
+
+/// A [Windows named pipe] client.
+///
+/// Constructed using [`ClientOptions::open`].
+///
+/// Connecting a client correctly involves a few steps. When connecting through
+/// [`ClientOptions::open`], it might error indicating one of two things:
+///
+/// * [`std::io::ErrorKind::NotFound`] - There is no server available.
+/// * [`ERROR_PIPE_BUSY`] - There is a server available, but it is busy. Sleep
+///   for a while and try again.
+///
+/// So a correctly implemented client looks like this:
+///
+/// ```no_run
+/// use std::time::Duration;
+/// use tokio::net::windows::named_pipe::ClientOptions;
+/// use tokio::time;
+/// use winapi::shared::winerror;
+///
+/// const PIPE_NAME: &str = r"\\.\pipe\named-pipe-idiomatic-client";
+///
+/// # #[tokio::main] async fn main() -> std::io::Result<()> {
+/// let client = loop {
+///     match ClientOptions::new().open(PIPE_NAME) {
+///         Ok(client) => break client,
+///         Err(e) if e.raw_os_error() == Some(winerror::ERROR_PIPE_BUSY as i32) => (),
+///         Err(e) => return Err(e),
+///     }
+///
+///     time::sleep(Duration::from_millis(50)).await;
+/// };
+///
+/// /* use the connected client */
+/// # Ok(()) }
+/// ```
+///
+/// [`ERROR_PIPE_BUSY`]: crate::winapi::shared::winerror::ERROR_PIPE_BUSY
+/// [Windows named pipe]: https://docs.microsoft.com/en-us/windows/win32/ipc/named-pipes
+#[derive(Debug)]
+pub struct NamedPipeClient {
+    io: PollEvented<mio_windows::NamedPipe>,
+}
+
+impl NamedPipeClient {
+    /// Construct a new named pipe client from the specified raw handle.
+    ///
+    /// This function will consume ownership of the handle given, passing
+    /// responsibility for closing the handle to the returned object.
+    ///
+    /// This function is also unsafe as the primitives currently returned have
+    /// the contract that they are the sole owner of the file descriptor they
+    /// are wrapping. Usage of this function could accidentally allow violating
+    /// this contract which can cause memory unsafety in code that relies on it
+    /// being true.
+    ///
+    /// # Errors
+    ///
+    /// This errors if called outside of a [Tokio Runtime], or in a runtime that
+    /// has not [enabled I/O], or if any OS-specific I/O errors occur.
+    ///
+    /// [Tokio Runtime]: crate::runtime::Runtime
+    /// [enabled I/O]: crate::runtime::Builder::enable_io
+    pub unsafe fn from_raw_handle(handle: RawHandle) -> io::Result<Self> {
+        let named_pipe = mio_windows::NamedPipe::from_raw_handle(handle);
+
+        Ok(Self {
+            io: PollEvented::new(named_pipe)?,
+        })
+    }
+
+    /// Retrieves information about the named pipe the client is associated
+    /// with.
+    ///
+    /// ```no_run
+    /// use tokio::net::windows::named_pipe::{ClientOptions, PipeEnd, PipeMode};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-client-info";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let client = ClientOptions::new()
+    ///     .open(PIPE_NAME)?;
+    ///
+    /// let client_info = client.info()?;
+    ///
+    /// assert_eq!(client_info.end, PipeEnd::Client);
+    /// assert_eq!(client_info.mode, PipeMode::Message);
+    /// assert_eq!(client_info.max_instances, 5);
+    /// # Ok(()) }
+    /// ```
+    pub fn info(&self) -> io::Result<PipeInfo> {
+        // Safety: we're ensuring the lifetime of the named pipe.
+        unsafe { named_pipe_info(self.io.as_raw_handle()) }
+    }
+}
+
+impl AsyncRead for NamedPipeClient {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        unsafe { self.io.poll_read(cx, buf) }
+    }
+}
+
+impl AsyncWrite for NamedPipeClient {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write(cx, buf)
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write_vectored(cx, bufs)
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.poll_flush(cx)
+    }
+}
+
+impl AsRawHandle for NamedPipeClient {
+    fn as_raw_handle(&self) -> RawHandle {
+        self.io.as_raw_handle()
+    }
+}
+
+// Helper to set a boolean flag as a bitfield.
+macro_rules! bool_flag {
+    ($f:expr, $t:expr, $flag:expr) => {{
+        let current = $f;
+
+        if $t {
+            $f = current | $flag;
+        } else {
+            $f = current & !$flag;
+        };
+    }};
+}
+
+/// A builder structure for construct a named pipe with named pipe-specific
+/// options. This is required to use for named pipe servers who wants to modify
+/// pipe-related options.
+///
+/// See [`ServerOptions::create`].
+#[derive(Debug, Clone)]
+pub struct ServerOptions {
+    open_mode: DWORD,
+    pipe_mode: DWORD,
+    max_instances: DWORD,
+    out_buffer_size: DWORD,
+    in_buffer_size: DWORD,
+    default_timeout: DWORD,
+}
+
+impl ServerOptions {
+    /// Creates a new named pipe builder with the default settings.
+    ///
+    /// ```
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-new";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let server = ServerOptions::new().create(PIPE_NAME)?;
+    /// # Ok(()) }
+    /// ```
+    pub fn new() -> ServerOptions {
+        ServerOptions {
+            open_mode: winbase::PIPE_ACCESS_DUPLEX | winbase::FILE_FLAG_OVERLAPPED,
+            pipe_mode: winbase::PIPE_TYPE_BYTE | winbase::PIPE_REJECT_REMOTE_CLIENTS,
+            max_instances: winbase::PIPE_UNLIMITED_INSTANCES,
+            out_buffer_size: 65536,
+            in_buffer_size: 65536,
+            default_timeout: 0,
+        }
+    }
+
+    /// The pipe mode.
+    ///
+    /// The default pipe mode is [`PipeMode::Byte`]. See [`PipeMode`] for
+    /// documentation of what each mode means.
+    ///
+    /// This corresponding to specifying [`dwPipeMode`].
+    ///
+    /// [`dwPipeMode`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    pub fn pipe_mode(&mut self, pipe_mode: PipeMode) -> &mut Self {
+        self.pipe_mode = match pipe_mode {
+            PipeMode::Byte => winbase::PIPE_TYPE_BYTE,
+            PipeMode::Message => winbase::PIPE_TYPE_MESSAGE,
+        };
+
+        self
+    }
+
+    /// The flow of data in the pipe goes from client to server only.
+    ///
+    /// This corresponds to setting [`PIPE_ACCESS_INBOUND`].
+    ///
+    /// [`PIPE_ACCESS_INBOUND`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea#pipe_access_inbound
+    ///
+    /// # Errors
+    ///
+    /// Server side prevents connecting by denying inbound access, client errors
+    /// with [`std::io::ErrorKind::PermissionDenied`] when attempting to create
+    /// the connection.
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-access-inbound-err1";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let _server = ServerOptions::new()
+    ///     .access_inbound(false)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let e = ClientOptions::new()
+    ///     .open(PIPE_NAME)
+    ///     .unwrap_err();
+    ///
+    /// assert_eq!(e.kind(), io::ErrorKind::PermissionDenied);
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// Disabling writing allows a client to connect, but errors with
+    /// [`std::io::ErrorKind::PermissionDenied`] if a write is attempted.
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::io::AsyncWriteExt;
+    /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-access-inbound-err2";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let server = ServerOptions::new()
+    ///     .access_inbound(false)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let mut client = ClientOptions::new()
+    ///     .write(false)
+    ///     .open(PIPE_NAME)?;
+    ///
+    /// server.connect().await?;
+    ///
+    /// let e = client.write(b"ping").await.unwrap_err();
+    /// assert_eq!(e.kind(), io::ErrorKind::PermissionDenied);
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// # Examples
+    ///
+    /// A unidirectional named pipe that only supports server-to-client
+    /// communication.
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-access-inbound";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let mut server = ServerOptions::new()
+    ///     .access_inbound(false)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let mut client = ClientOptions::new()
+    ///     .write(false)
+    ///     .open(PIPE_NAME)?;
+    ///
+    /// server.connect().await?;
+    ///
+    /// let write = server.write_all(b"ping");
+    ///
+    /// let mut buf = [0u8; 4];
+    /// let read = client.read_exact(&mut buf);
+    ///
+    /// let ((), read) = tokio::try_join!(write, read)?;
+    ///
+    /// assert_eq!(read, 4);
+    /// assert_eq!(&buf[..], b"ping");
+    /// # Ok(()) }
+    /// ```
+    pub fn access_inbound(&mut self, allowed: bool) -> &mut Self {
+        bool_flag!(self.open_mode, allowed, winbase::PIPE_ACCESS_INBOUND);
+        self
+    }
+
+    /// The flow of data in the pipe goes from server to client only.
+    ///
+    /// This corresponds to setting [`PIPE_ACCESS_OUTBOUND`].
+    ///
+    /// [`PIPE_ACCESS_OUTBOUND`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea#pipe_access_outbound
+    ///
+    /// # Errors
+    ///
+    /// Server side prevents connecting by denying outbound access, client
+    /// errors with [`std::io::ErrorKind::PermissionDenied`] when attempting to
+    /// create the connection.
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-access-outbound-err1";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let server = ServerOptions::new()
+    ///     .access_outbound(false)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let e = ClientOptions::new()
+    ///     .open(PIPE_NAME)
+    ///     .unwrap_err();
+    ///
+    /// assert_eq!(e.kind(), io::ErrorKind::PermissionDenied);
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// Disabling reading allows a client to connect, but attempting to read
+    /// will error with [`std::io::ErrorKind::PermissionDenied`].
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::io::AsyncReadExt;
+    /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-access-outbound-err2";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let server = ServerOptions::new()
+    ///     .access_outbound(false)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let mut client = ClientOptions::new()
+    ///     .read(false)
+    ///     .open(PIPE_NAME)?;
+    ///
+    /// server.connect().await?;
+    ///
+    /// let mut buf = [0u8; 4];
+    /// let e = client.read(&mut buf).await.unwrap_err();
+    /// assert_eq!(e.kind(), io::ErrorKind::PermissionDenied);
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// # Examples
+    ///
+    /// A unidirectional named pipe that only supports client-to-server
+    /// communication.
+    ///
+    /// ```
+    /// use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-access-outbound";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let mut server = ServerOptions::new()
+    ///     .access_outbound(false)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// let mut client = ClientOptions::new()
+    ///     .read(false)
+    ///     .open(PIPE_NAME)?;
+    ///
+    /// server.connect().await?;
+    ///
+    /// let write = client.write_all(b"ping");
+    ///
+    /// let mut buf = [0u8; 4];
+    /// let read = server.read_exact(&mut buf);
+    ///
+    /// let ((), read) = tokio::try_join!(write, read)?;
+    ///
+    /// println!("done reading and writing");
+    ///
+    /// assert_eq!(read, 4);
+    /// assert_eq!(&buf[..], b"ping");
+    /// # Ok(()) }
+    /// ```
+    pub fn access_outbound(&mut self, allowed: bool) -> &mut Self {
+        bool_flag!(self.open_mode, allowed, winbase::PIPE_ACCESS_OUTBOUND);
+        self
+    }
+
+    /// If you attempt to create multiple instances of a pipe with this flag
+    /// set, creation of the first server instance succeeds, but creation of any
+    /// subsequent instances will fail with
+    /// [`std::io::ErrorKind::PermissionDenied`].
+    ///
+    /// This option is intended to be used with servers that want to ensure that
+    /// they are the only process listening for clients on a given named pipe.
+    /// This is accomplished by enabling it for the first server instance
+    /// created in a process.
+    ///
+    /// This corresponds to setting [`FILE_FLAG_FIRST_PIPE_INSTANCE`].
+    ///
+    /// # Errors
+    ///
+    /// If this option is set and more than one instance of the server for a
+    /// given named pipe exists, calling [`create`] will fail with
+    /// [`std::io::ErrorKind::PermissionDenied`].
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-first-instance-error";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let server1 = ServerOptions::new()
+    ///     .first_pipe_instance(true)
+    ///     .create(PIPE_NAME)?;
+    ///
+    /// // Second server errs, since it's not the first instance.
+    /// let e = ServerOptions::new()
+    ///     .first_pipe_instance(true)
+    ///     .create(PIPE_NAME)
+    ///     .unwrap_err();
+    ///
+    /// assert_eq!(e.kind(), io::ErrorKind::PermissionDenied);
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-first-instance";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let mut builder = ServerOptions::new();
+    /// builder.first_pipe_instance(true);
+    ///
+    /// let server = builder.create(PIPE_NAME)?;
+    /// let e = builder.create(PIPE_NAME).unwrap_err();
+    /// assert_eq!(e.kind(), io::ErrorKind::PermissionDenied);
+    /// drop(server);
+    ///
+    /// // OK: since, we've closed the other instance.
+    /// let _server2 = builder.create(PIPE_NAME)?;
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// [`create`]: ServerOptions::create
+    /// [`FILE_FLAG_FIRST_PIPE_INSTANCE`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea#pipe_first_pipe_instance
+    pub fn first_pipe_instance(&mut self, first: bool) -> &mut Self {
+        bool_flag!(
+            self.open_mode,
+            first,
+            winbase::FILE_FLAG_FIRST_PIPE_INSTANCE
+        );
+        self
+    }
+
+    /// Indicates whether this server can accept remote clients or not. Remote
+    /// clients are disabled by default.
+    ///
+    /// This corresponds to setting [`PIPE_REJECT_REMOTE_CLIENTS`].
+    ///
+    /// [`PIPE_REJECT_REMOTE_CLIENTS`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea#pipe_reject_remote_clients
+    pub fn reject_remote_clients(&mut self, reject: bool) -> &mut Self {
+        bool_flag!(self.pipe_mode, reject, winbase::PIPE_REJECT_REMOTE_CLIENTS);
+        self
+    }
+
+    /// The maximum number of instances that can be created for this pipe. The
+    /// first instance of the pipe can specify this value; the same number must
+    /// be specified for other instances of the pipe. Acceptable values are in
+    /// the range 1 through 254. The default value is unlimited.
+    ///
+    /// This corresponds to specifying [`nMaxInstances`].
+    ///
+    /// [`nMaxInstances`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    ///
+    /// # Errors
+    ///
+    /// The same numbers of `max_instances` have to be used by all servers. Any
+    /// additional servers trying to be built which uses a mismatching value
+    /// might error.
+    ///
+    /// ```
+    /// use std::io;
+    /// use tokio::net::windows::named_pipe::{ServerOptions, ClientOptions};
+    /// use winapi::shared::winerror;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-max-instances";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let mut server = ServerOptions::new();
+    /// server.max_instances(2);
+    ///
+    /// let s1 = server.create(PIPE_NAME)?;
+    /// let c1 = ClientOptions::new().open(PIPE_NAME);
+    ///
+    /// let s2 = server.create(PIPE_NAME)?;
+    /// let c2 = ClientOptions::new().open(PIPE_NAME);
+    ///
+    /// // Too many servers!
+    /// let e = server.create(PIPE_NAME).unwrap_err();
+    /// assert_eq!(e.raw_os_error(), Some(winerror::ERROR_PIPE_BUSY as i32));
+    ///
+    /// // Still too many servers even if we specify a higher value!
+    /// let e = server.max_instances(100).create(PIPE_NAME).unwrap_err();
+    /// assert_eq!(e.raw_os_error(), Some(winerror::ERROR_PIPE_BUSY as i32));
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if more than 254 instances are specified. If
+    /// you do not wish to set an instance limit, leave it unspecified.
+    ///
+    /// ```should_panic
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let builder = ServerOptions::new().max_instances(255);
+    /// # Ok(()) }
+    /// ```
+    pub fn max_instances(&mut self, instances: usize) -> &mut Self {
+        assert!(instances < 255, "cannot specify more than 254 instances");
+        self.max_instances = instances as DWORD;
+        self
+    }
+
+    /// The number of bytes to reserve for the output buffer.
+    ///
+    /// This corresponds to specifying [`nOutBufferSize`].
+    ///
+    /// [`nOutBufferSize`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    pub fn out_buffer_size(&mut self, buffer: u32) -> &mut Self {
+        self.out_buffer_size = buffer as DWORD;
+        self
+    }
+
+    /// The number of bytes to reserve for the input buffer.
+    ///
+    /// This corresponds to specifying [`nInBufferSize`].
+    ///
+    /// [`nInBufferSize`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    pub fn in_buffer_size(&mut self, buffer: u32) -> &mut Self {
+        self.in_buffer_size = buffer as DWORD;
+        self
+    }
+
+    /// Create the named pipe identified by `addr` for use as a server.
+    ///
+    /// This uses the [`CreateNamedPipe`] function.
+    ///
+    /// [`CreateNamedPipe`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    ///
+    /// # Errors
+    ///
+    /// This errors if called outside of a [Tokio Runtime], or in a runtime that
+    /// has not [enabled I/O], or if any OS-specific I/O errors occur.
+    ///
+    /// [Tokio Runtime]: crate::runtime::Runtime
+    /// [enabled I/O]: crate::runtime::Builder::enable_io
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-create";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let server = ServerOptions::new().create(PIPE_NAME)?;
+    /// # Ok(()) }
+    /// ```
+    pub fn create(&self, addr: impl AsRef<OsStr>) -> io::Result<NamedPipeServer> {
+        // Safety: We're calling create_with_security_attributes_raw w/ a null
+        // pointer which disables it.
+        unsafe { self.create_with_security_attributes_raw(addr, ptr::null_mut()) }
+    }
+
+    /// Create the named pipe identified by `addr` for use as a server.
+    ///
+    /// This is the same as [`create`] except that it supports providing the raw
+    /// pointer to a structure of [`SECURITY_ATTRIBUTES`] which will be passed
+    /// as the `lpSecurityAttributes` argument to [`CreateFile`].
+    ///
+    /// # Errors
+    ///
+    /// This errors if called outside of a [Tokio Runtime], or in a runtime that
+    /// has not [enabled I/O], or if any OS-specific I/O errors occur.
+    ///
+    /// [Tokio Runtime]: crate::runtime::Runtime
+    /// [enabled I/O]: crate::runtime::Builder::enable_io
+    ///
+    /// # Safety
+    ///
+    /// The `attrs` argument must either be null or point at a valid instance of
+    /// the [`SECURITY_ATTRIBUTES`] structure. If the argument is null, the
+    /// behavior is identical to calling the [`create`] method.
+    ///
+    /// [`create`]: ServerOptions::create
+    /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
+    /// [`SECURITY_ATTRIBUTES`]: crate::winapi::um::minwinbase::SECURITY_ATTRIBUTES
+    pub unsafe fn create_with_security_attributes_raw(
+        &self,
+        addr: impl AsRef<OsStr>,
+        attrs: *mut c_void,
+    ) -> io::Result<NamedPipeServer> {
+        let addr = encode_addr(addr);
+
+        let h = namedpipeapi::CreateNamedPipeW(
+            addr.as_ptr(),
+            self.open_mode,
+            self.pipe_mode,
+            self.max_instances,
+            self.out_buffer_size,
+            self.in_buffer_size,
+            self.default_timeout,
+            attrs as *mut _,
+        );
+
+        if h == handleapi::INVALID_HANDLE_VALUE {
+            return Err(io::Error::last_os_error());
+        }
+
+        NamedPipeServer::from_raw_handle(h)
+    }
+}
+
+/// A builder suitable for building and interacting with named pipes from the
+/// client side.
+///
+/// See [`ClientOptions::open`].
+#[derive(Debug, Clone)]
+pub struct ClientOptions {
+    desired_access: DWORD,
+    security_qos_flags: DWORD,
+}
+
+impl ClientOptions {
+    /// Creates a new named pipe builder with the default settings.
+    ///
+    /// ```
+    /// use tokio::net::windows::named_pipe::{ServerOptions, ClientOptions};
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-client-new";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// // Server must be created in order for the client creation to succeed.
+    /// let server = ServerOptions::new().create(PIPE_NAME)?;
+    /// let client = ClientOptions::new().open(PIPE_NAME)?;
+    /// # Ok(()) }
+    /// ```
+    pub fn new() -> Self {
+        Self {
+            desired_access: winnt::GENERIC_READ | winnt::GENERIC_WRITE,
+            security_qos_flags: winbase::SECURITY_IDENTIFICATION | winbase::SECURITY_SQOS_PRESENT,
+        }
+    }
+
+    /// If the client supports reading data. This is enabled by default.
+    ///
+    /// This corresponds to setting [`GENERIC_READ`] in the call to [`CreateFile`].
+    ///
+    /// [`GENERIC_READ`]: https://docs.microsoft.com/en-us/windows/win32/secauthz/generic-access-rights
+    /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
+    pub fn read(&mut self, allowed: bool) -> &mut Self {
+        bool_flag!(self.desired_access, allowed, winnt::GENERIC_READ);
+        self
+    }
+
+    /// If the created pipe supports writing data. This is enabled by default.
+    ///
+    /// This corresponds to setting [`GENERIC_WRITE`] in the call to [`CreateFile`].
+    ///
+    /// [`GENERIC_WRITE`]: https://docs.microsoft.com/en-us/windows/win32/secauthz/generic-access-rights
+    /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
+    pub fn write(&mut self, allowed: bool) -> &mut Self {
+        bool_flag!(self.desired_access, allowed, winnt::GENERIC_WRITE);
+        self
+    }
+
+    /// Sets qos flags which are combined with other flags and attributes in the
+    /// call to [`CreateFile`].
+    ///
+    /// By default `security_qos_flags` is set to [`SECURITY_IDENTIFICATION`],
+    /// calling this function would override that value completely with the
+    /// argument specified.
+    ///
+    /// When `security_qos_flags` is not set, a malicious program can gain the
+    /// elevated privileges of a privileged Rust process when it allows opening
+    /// user-specified paths, by tricking it into opening a named pipe. So
+    /// arguably `security_qos_flags` should also be set when opening arbitrary
+    /// paths. However the bits can then conflict with other flags, specifically
+    /// `FILE_FLAG_OPEN_NO_RECALL`.
+    ///
+    /// For information about possible values, see [Impersonation Levels] on the
+    /// Windows Dev Center site. The `SECURITY_SQOS_PRESENT` flag is set
+    /// automatically when using this method.
+    ///
+    /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
+    /// [`SECURITY_IDENTIFICATION`]: crate::winapi::um::winbase::SECURITY_IDENTIFICATION
+    /// [Impersonation Levels]: https://docs.microsoft.com/en-us/windows/win32/api/winnt/ne-winnt-security_impersonation_level
+    pub fn security_qos_flags(&mut self, flags: u32) -> &mut Self {
+        // See: https://github.com/rust-lang/rust/pull/58216
+        self.security_qos_flags = flags | winbase::SECURITY_SQOS_PRESENT;
+        self
+    }
+
+    /// Open the named pipe identified by `addr`.
+    ///
+    /// This opens the client using [`CreateFile`] with the
+    /// `dwCreationDisposition` option set to `OPEN_EXISTING`.
+    ///
+    /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
+    ///
+    /// # Errors
+    ///
+    /// This errors if called outside of a [Tokio Runtime], or in a runtime that
+    /// has not [enabled I/O], or if any OS-specific I/O errors occur.
+    ///
+    /// There are a few errors you need to take into account when creating a
+    /// named pipe on the client side:
+    ///
+    /// * [`std::io::ErrorKind::NotFound`] - This indicates that the named pipe
+    ///   does not exist. Presumably the server is not up.
+    /// * [`ERROR_PIPE_BUSY`] - This error is raised when the named pipe exists,
+    ///   but the server is not currently waiting for a connection. Please see the
+    ///   examples for how to check for this error.
+    ///
+    /// [`ERROR_PIPE_BUSY`]: crate::winapi::shared::winerror::ERROR_PIPE_BUSY
+    /// [`winapi`]: crate::winapi
+    /// [enabled I/O]: crate::runtime::Builder::enable_io
+    /// [Tokio Runtime]: crate::runtime::Runtime
+    ///
+    /// A connect loop that waits until a socket becomes available looks like
+    /// this:
+    ///
+    /// ```no_run
+    /// use std::time::Duration;
+    /// use tokio::net::windows::named_pipe::ClientOptions;
+    /// use tokio::time;
+    /// use winapi::shared::winerror;
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\mynamedpipe";
+    ///
+    /// # #[tokio::main] async fn main() -> std::io::Result<()> {
+    /// let client = loop {
+    ///     match ClientOptions::new().open(PIPE_NAME) {
+    ///         Ok(client) => break client,
+    ///         Err(e) if e.raw_os_error() == Some(winerror::ERROR_PIPE_BUSY as i32) => (),
+    ///         Err(e) => return Err(e),
+    ///     }
+    ///
+    ///     time::sleep(Duration::from_millis(50)).await;
+    /// };
+    ///
+    /// // use the connected client.
+    /// # Ok(()) }
+    /// ```
+    pub fn open(&self, addr: impl AsRef<OsStr>) -> io::Result<NamedPipeClient> {
+        // Safety: We're calling open_with_security_attributes_raw w/ a null
+        // pointer which disables it.
+        unsafe { self.open_with_security_attributes_raw(addr, ptr::null_mut()) }
+    }
+
+    /// Open the named pipe identified by `addr`.
+    ///
+    /// This is the same as [`open`] except that it supports providing the raw
+    /// pointer to a structure of [`SECURITY_ATTRIBUTES`] which will be passed
+    /// as the `lpSecurityAttributes` argument to [`CreateFile`].
+    ///
+    /// # Safety
+    ///
+    /// The `attrs` argument must either be null or point at a valid instance of
+    /// the [`SECURITY_ATTRIBUTES`] structure. If the argument is null, the
+    /// behavior is identical to calling the [`open`] method.
+    ///
+    /// [`open`]: ClientOptions::open
+    /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
+    /// [`SECURITY_ATTRIBUTES`]: crate::winapi::um::minwinbase::SECURITY_ATTRIBUTES
+    pub unsafe fn open_with_security_attributes_raw(
+        &self,
+        addr: impl AsRef<OsStr>,
+        attrs: *mut c_void,
+    ) -> io::Result<NamedPipeClient> {
+        let addr = encode_addr(addr);
+
+        // NB: We could use a platform specialized `OpenOptions` here, but since
+        // we have access to winapi it ultimately doesn't hurt to use
+        // `CreateFile` explicitly since it allows the use of our already
+        // well-structured wide `addr` to pass into CreateFileW.
+        let h = fileapi::CreateFileW(
+            addr.as_ptr(),
+            self.desired_access,
+            0,
+            attrs as *mut _,
+            fileapi::OPEN_EXISTING,
+            self.get_flags(),
+            ptr::null_mut(),
+        );
+
+        if h == handleapi::INVALID_HANDLE_VALUE {
+            return Err(io::Error::last_os_error());
+        }
+
+        NamedPipeClient::from_raw_handle(h)
+    }
+
+    fn get_flags(&self) -> u32 {
+        self.security_qos_flags | winbase::FILE_FLAG_OVERLAPPED
+    }
+}
+
+/// The pipe mode of a named pipe.
+///
+/// Set through [`ServerOptions::pipe_mode`].
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[non_exhaustive]
+pub enum PipeMode {
+    /// Data is written to the pipe as a stream of bytes. The pipe does not
+    /// distinguish bytes written during different write operations.
+    ///
+    /// Corresponds to [`PIPE_TYPE_BYTE`][crate::winapi::um::winbase::PIPE_TYPE_BYTE].
+    Byte,
+    /// Data is written to the pipe as a stream of messages. The pipe treats the
+    /// bytes written during each write operation as a message unit. Any reading
+    /// on a named pipe returns [`ERROR_MORE_DATA`] when a message is not read
+    /// completely.
+    ///
+    /// Corresponds to [`PIPE_TYPE_MESSAGE`][crate::winapi::um::winbase::PIPE_TYPE_MESSAGE].
+    ///
+    /// [`ERROR_MORE_DATA`]: crate::winapi::shared::winerror::ERROR_MORE_DATA
+    Message,
+}
+
+/// Indicates the end of a named pipe.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[non_exhaustive]
+pub enum PipeEnd {
+    /// The named pipe refers to the client end of a named pipe instance.
+    ///
+    /// Corresponds to [`PIPE_CLIENT_END`][crate::winapi::um::winbase::PIPE_CLIENT_END].
+    Client,
+    /// The named pipe refers to the server end of a named pipe instance.
+    ///
+    /// Corresponds to [`PIPE_SERVER_END`][crate::winapi::um::winbase::PIPE_SERVER_END].
+    Server,
+}
+
+/// Information about a named pipe.
+///
+/// Constructed through [`NamedPipeServer::info`] or [`NamedPipeClient::info`].
+#[derive(Debug)]
+#[non_exhaustive]
+pub struct PipeInfo {
+    /// Indicates the mode of a named pipe.
+    pub mode: PipeMode,
+    /// Indicates the end of a named pipe.
+    pub end: PipeEnd,
+    /// The maximum number of instances that can be created for this pipe.
+    pub max_instances: u32,
+    /// The number of bytes to reserve for the output buffer.
+    pub out_buffer_size: u32,
+    /// The number of bytes to reserve for the input buffer.
+    pub in_buffer_size: u32,
+}
+
+/// Encode an address so that it is a null-terminated wide string.
+fn encode_addr(addr: impl AsRef<OsStr>) -> Box<[u16]> {
+    let len = addr.as_ref().encode_wide().count();
+    let mut vec = Vec::with_capacity(len + 1);
+    vec.extend(addr.as_ref().encode_wide());
+    vec.push(0);
+    vec.into_boxed_slice()
+}
+
+/// Internal function to get the info out of a raw named pipe.
+unsafe fn named_pipe_info(handle: RawHandle) -> io::Result<PipeInfo> {
+    let mut flags = 0;
+    let mut out_buffer_size = 0;
+    let mut in_buffer_size = 0;
+    let mut max_instances = 0;
+
+    let result = namedpipeapi::GetNamedPipeInfo(
+        handle,
+        &mut flags,
+        &mut out_buffer_size,
+        &mut in_buffer_size,
+        &mut max_instances,
+    );
+
+    if result == FALSE {
+        return Err(io::Error::last_os_error());
+    }
+
+    let mut end = PipeEnd::Client;
+    let mut mode = PipeMode::Byte;
+
+    if flags & winbase::PIPE_SERVER_END != 0 {
+        end = PipeEnd::Server;
+    }
+
+    if flags & winbase::PIPE_TYPE_MESSAGE != 0 {
+        mode = PipeMode::Message;
+    }
+
+    Ok(PipeInfo {
+        end,
+        mode,
+        out_buffer_size,
+        in_buffer_size,
+        max_instances,
+    })
+}