1 files changed, 172 insertions, 0 deletions
diff --git a/users/aspen/xanthous/server/src/pty.rs b/users/aspen/xanthous/server/src/pty.rs
new file mode 100644
index 000000000000..234ecd8f2336
--- /dev/null
+++ b/users/aspen/xanthous/server/src/pty.rs
@@ -0,0 +1,172 @@
+use std::io::{self};
+use std::os::unix::prelude::{AsRawFd, CommandExt, FromRawFd};
+use std::pin::Pin;
+use std::process::{abort, Command};
+use std::task::{Context, Poll};
+
+use eyre::{bail, Result};
+use futures::Future;
+use nix::pty::{forkpty, Winsize};
+use nix::sys::termios::Termios;
+use nix::sys::wait::{waitpid, WaitPidFlag, WaitStatus};
+use nix::unistd::{ForkResult, Pid};
+use tokio::fs::File;
+use tokio::io::{AsyncRead, AsyncWrite};
+use tokio::signal::unix::{signal, Signal, SignalKind};
+use tokio::task::spawn_blocking;
+
+mod ioctl {
+    use super::Winsize;
+    use libc::TIOCSWINSZ;
+    use nix::ioctl_write_ptr_bad;
+
+    ioctl_write_ptr_bad!(tiocswinsz, TIOCSWINSZ, Winsize);
+}
+
+async fn asyncify<F, T>(f: F) -> Result<T>
+where
+    F: FnOnce() -> Result<T> + Send + 'static,
+    T: Send + 'static,
+{
+    match spawn_blocking(f).await {
+        Ok(res) => res,
+        Err(_) => bail!("background task failed",),
+    }
+}
+
+pub struct Child {
+    pub tty: File,
+    pub pid: Pid,
+}
+
+pub struct ChildHandle {
+    pub tty: File,
+}
+
+pub struct WaitPid {
+    pid: Pid,
+    signal: Signal,
+}
+
+impl WaitPid {
+    pub fn new(pid: Pid) -> Self {
+        Self {
+            pid,
+            signal: signal(SignalKind::child()).unwrap(),
+        }
+    }
+}
+
+impl Future for WaitPid {
+    type Output = nix::Result<WaitStatus>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let _ = self.signal.poll_recv(cx);
+        match waitpid(self.pid, Some(WaitPidFlag::WNOHANG)) {
+            Ok(WaitStatus::StillAlive) => Poll::Pending,
+            result => Poll::Ready(result),
+        }
+    }
+}
+
+impl Child {
+    pub async fn handle(&self) -> io::Result<ChildHandle> {
+        Ok(ChildHandle {
+            tty: self.tty.try_clone().await?,
+        })
+    }
+}
+
+impl ChildHandle {
+    pub async fn resize_window(&mut self, winsize: Winsize) -> Result<()> {
+        let fd = self.tty.as_raw_fd();
+        asyncify(move || unsafe {
+            ioctl::tiocswinsz(fd, &winsize as *const Winsize)?;
+            Ok(())
+        })
+        .await
+    }
+}
+
+pub async fn spawn(
+    mut cmd: Command,
+    winsize: Option<Winsize>,
+    termios: Option<Termios>,
+) -> Result<Child> {
+    asyncify(move || unsafe {
+        let res = forkpty(winsize.as_ref(), termios.as_ref())?;
+        match res.fork_result {
+            ForkResult::Parent { child } => Ok(Child {
+                pid: child,
+                tty: File::from_raw_fd(res.master),
+            }),
+            ForkResult::Child => {
+                cmd.exec();
+                abort();
+            }
+        }
+    })
+    .await
+}
+
+impl AsyncRead for Child {
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut tokio::io::ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.tty).poll_read(cx, buf)
+    }
+}
+
+impl AsyncWrite for Child {
+    fn poll_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<Result<usize, io::Error>> {
+        Pin::new(&mut self.tty).poll_write(cx, buf)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_flush(cx)
+    }
+
+    fn poll_shutdown(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_shutdown(cx)
+    }
+}
+
+impl AsyncRead for ChildHandle {
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut tokio::io::ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.tty).poll_read(cx, buf)
+    }
+}
+
+impl AsyncWrite for ChildHandle {
+    fn poll_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<Result<usize, io::Error>> {
+        Pin::new(&mut self.tty).poll_write(cx, buf)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_flush(cx)
+    }
+
+    fn poll_shutdown(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_shutdown(cx)
+    }
+}