Drop stderr/stdout reader may cause some unexpected behavior

[DCjanus]

From this function, we took and drop stderr reader, which in my test, not a good idea.

In my simple test, parent process drop reader from child stdout, and child would got a broken pipe error if it's trying to put something to stdout, In Rust, this would cause panic because of this line, but I don't know what would happen in CPP program.

parent code:

fn main() {
    let file = "target/release/child";
    let mut result = std::process::Command::new(file)
        .stdout(Stdio::piped())
        .spawn()
        .unwrap();
    let stdout = result.stdout.take().unwrap();
    let mut reader = BufReader::new(stdout);
    let mut line = String::new();
    reader.read_line(&mut line).unwrap();
    println!("read {} bytes", line.len());
    drop(reader);
    loop {
        println!("waiting");
        sleep(Duration::from_secs(1));
    }
}

child code

fn main() {
    loop {
        println!("{}", "FOOFOOFOOFOOFOO".repeat(128));
        std::fs::write(
            "child.timestamp",
            UNIX_EPOCH.elapsed().unwrap().as_secs().to_string(),
        )
        .unwrap();
        sleep(Duration::from_secs(1));
    }
}