Implement sock_accept

With the addition of `sock_accept()` in `wasi-0.11.0`, wasmtime can now
implement basic networking for pre-opened sockets.

For Windows `AsHandle` was replaced with `AsRawHandleOrSocket` to cope
with the duality of Handles and Sockets.

For Unix a `wasi_cap_std_sync::net::Socket` enum was created to handle
the {Tcp,Unix}{Listener,Stream} more efficiently in
`WasiCtxBuilder::preopened_socket()`.

The addition of that many `WasiFile` implementors was mainly necessary,
because of the difference in the `num_ready_bytes()` function.

A known issue is Windows now busy polling on sockets, because except
for `stdin`, nothing is querying the status of windows handles/sockets.

Another know issue on Windows, is that there is no crate providing
support for `fcntl(fd, F_GETFL, 0)` on a socket.

Signed-off-by: Harald Hoyer <harald@profian.com>

crates/wasi-common/tokio/src/file.rs

@@ -1,8 +1,8 @@
 use crate::block_on_dummy_executor;
+#[cfg(windows)]
+use io_extras::os::windows::{AsRawHandleOrSocket, RawHandleOrSocket};
 #[cfg(not(windows))]
 use io_lifetimes::AsFd;
-#[cfg(windows)]
-use io_lifetimes::{AsHandle, BorrowedHandle};
 use std::any::Any;
 use std::io;
 use wasi_common::{
@@ -21,6 +21,54 @@ impl File {
     }
 }
 
+pub struct TcpListener(wasi_cap_std_sync::net::TcpListener);
+
+impl TcpListener {
+    pub(crate) fn from_inner(listener: wasi_cap_std_sync::net::TcpListener) -> Self {
+        TcpListener(listener)
+    }
+    pub fn from_cap_std(listener: cap_std::net::TcpListener) -> Self {
+        Self::from_inner(wasi_cap_std_sync::net::TcpListener::from_cap_std(listener))
+    }
+}
+
+pub struct TcpStream(wasi_cap_std_sync::net::TcpStream);
+
+impl TcpStream {
+    pub(crate) fn from_inner(stream: wasi_cap_std_sync::net::TcpStream) -> Self {
+        TcpStream(stream)
+    }
+    pub fn from_cap_std(stream: cap_std::net::TcpStream) -> Self {
+        Self::from_inner(wasi_cap_std_sync::net::TcpStream::from_cap_std(stream))
+    }
+}
+
+#[cfg(unix)]
+pub struct UnixListener(wasi_cap_std_sync::net::UnixListener);
+
+#[cfg(unix)]
+impl UnixListener {
+    pub(crate) fn from_inner(listener: wasi_cap_std_sync::net::UnixListener) -> Self {
+        UnixListener(listener)
+    }
+    pub fn from_cap_std(listener: cap_std::os::unix::net::UnixListener) -> Self {
+        Self::from_inner(wasi_cap_std_sync::net::UnixListener::from_cap_std(listener))
+    }
+}
+
+#[cfg(unix)]
+pub struct UnixStream(wasi_cap_std_sync::net::UnixStream);
+
+#[cfg(unix)]
+impl UnixStream {
+    fn from_inner(stream: wasi_cap_std_sync::net::UnixStream) -> Self {
+        UnixStream(stream)
+    }
+    pub fn from_cap_std(stream: cap_std::os::unix::net::UnixStream) -> Self {
+        Self::from_inner(wasi_cap_std_sync::net::UnixStream::from_cap_std(stream))
+    }
+}
+
 pub struct Stdin(wasi_cap_std_sync::stdio::Stdin);
 
 pub fn stdin() -> Stdin {
@@ -175,17 +223,28 @@ macro_rules! wasi_file_impl {
                 use wasi_common::ErrorExt;
                 Err(Error::badf())
             }
+
+            async fn sock_accept(&mut self, fdflags: FdFlags) -> Result<Box<dyn WasiFile>, Error> {
+                block_on_dummy_executor(|| self.0.sock_accept(fdflags))
+            }
         }
         #[cfg(windows)]
-        impl AsHandle for $ty {
-            fn as_handle(&self) -> BorrowedHandle<'_> {
-                self.0.as_handle()
+        impl AsRawHandleOrSocket for $ty {
+            #[inline]
+            fn as_raw_handle_or_socket(&self) -> RawHandleOrSocket {
+                self.0.as_raw_handle_or_socket()
             }
         }
     };
 }
 
 wasi_file_impl!(File);
+wasi_file_impl!(TcpListener);
+wasi_file_impl!(TcpStream);
+#[cfg(unix)]
+wasi_file_impl!(UnixListener);
+#[cfg(unix)]
+wasi_file_impl!(UnixStream);
 wasi_file_impl!(Stdin);
 wasi_file_impl!(Stdout);
 wasi_file_impl!(Stderr);