On Linux if program exits when read_char() is blocking, the terminal will stay in raw mode

[JasonWei512]

Problem

Run the following code on Linux with console v0.15.7:

use std::{thread, time::Duration};

fn main() {
    println!("(This program will exit in 5 seconds.)");
    println!("Press any key, and the program will echo the key you pressed.");

    thread::spawn(|| {
        let terminal = console::Term::stdout();
        loop {
            let key_pressed = terminal.read_char().unwrap();    // ← Blocking
            println!("You pressed: {}", key_pressed);
        }
    });

    thread::sleep(Duration::from_secs(5));
    panic!("After the program exits, the terminal will stay in raw mode.")
}

After the program exits, the terminal will stay in raw mode. Anything I type in shell does not display on screen.

Related issues

• New lines do not start from column 0 #36
• read_char() breaks println! in other threads #136

[knutaf]

This reproes for me using Windows Subsystem for Linux, exactly as described by OP.

[mitsuhiko]

Unfortunately the only way to prevent this would be to hook ctrl+c and i'm not sure if that is something that should be done. Potentially there needs to be an API that can be called in your own ctrl+c handler.

[fadeevab]

@mitsuhiko The same issue with read_key, and it's reproduced even in dialoguer, there the cursor is not restored after ctrl-c, e.g. if you ctrl-c on the select component.

How to reproduce: dialoguer -> cargo run --example select -> ctrl-c -> no cursor (because term.show_cursor()? is never called).

Seems like crossterm just disables the ctrl-c in the raw mode, returning the ctrl-c key to the application.