How to create future that completes once tokio::process::Child has exited without closing stdin

Question

How can I create a future that completes upon the termination of a tokio::process::Child without closing stdin. I know there is try_wait for testing if a process has terminated without closing stdin, but I want to have this behavior with future semantics.

I tried to prepare a MRE for this question where my code panics as a result of writing to stdin after calling wait, but what I observe does not match the behavior stated in the documentation for tokio::process::Child's wait method. I would expect to see that the line stdin.write_u8(24).await.unwrap(); crashes with a broken pipe since stdin should have been closed by wait.

use tokio::{time, io::AsyncWriteExt}; // 1.0.1

use std::time::Duration;

#[tokio::main]
pub async fn main() {
    let mut child = tokio::process::Command::new("nano")
        .stdin(std::process::Stdio::piped())
        .spawn()
        .unwrap();
    
    let mut stdin = child.stdin.take().unwrap();

    let tasklet = tokio::spawn(async move {
        child.wait().await
    });

    // this delay should give tokio::spawn plenty of time to spin up
    // and call `wait` on the child (closing stdin)
    time::sleep(Duration::from_millis(1000)).await;

    // write character 24 (CANcel, ^X) to stdin to close nano
    stdin.write_u8(24).await.unwrap();

    match tasklet.await {
        Ok(exit_result) => match exit_result {
            Ok(exit_status) => eprintln!("exit_status: {}", exit_status),
            Err(terminate_error) => eprintln!("terminate_error: {}", terminate_error)
        }
        Err(join_error) => eprintln!("join_error: {}", join_error)
    }
}

Answer 1

So the answer to this question is to Option::take ChildStdin out of tokio::process::Child as described in this Github issue. In this case, wait will not close stdin and the programmer is responsible for not causing deadlocks.

The MRE above doesn't fail for two reasons: (i) I took ChildStdin out of tokio::process::Child and (ii) even if I hadn't taken it out, it still would not have been closed due to a bug in the code that will be fixed in this pull request.