Rustyline crashes in linux if you hold enter

[sophiajt]

Repro:

> cargo run --example example
1> [now hold enter here]

Once you hold enter, after a few seconds you'll see:

1> 
Line: 
2> 
Line: 
3> 
Line: 
4> 
Line: 
5> 
Line: 

Error: Io(Kind(InvalidData))

[gwenn]

Sorry,
I cannot reproduce.

• x86_64-apple-darwin / rustc 1.40.0-nightly (c27f7568b 2019-10-13) (macOS Catalina)
• x86_64-unknown-linux-gnu / rustc 1.38.0 (625451e37 2019-09-23) (archlinux VM)

[sophiajt]

My platform:

Linux pop-os 5.0.0-25-generic #26-Ubuntu SMP Thu Aug 1 12:04:58 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
rustc 1.39.0-nightly (521d78407 2019-08-25)

[gwenn]

I've also tried rustc on linux but still no error:
I guess that the VM/VirtualBox layer prevents me to reproduce the bug.

[sophiajt]

That could be it. My guess is that it comes from the speed that the enter is happening, so trying it on a native install of Linux might be the best way to try to repro.

[Detegr]

@jonathandturner which terminal and shell are you using? My machine is native Arch Linux Linux 5.3.5-arch1-1-ARCH #1 SMP PREEMPT Mon Oct 7 19:03:08 UTC 2019 x86_64 GNU/Linux, compiled with rustc 1.39.0-nightly (9eae1fc0e 2019-08-23) and I'm unable to repro this in Alacritty or xterm, zsh/bash. I tried setting key repeat to an absurdly high value with xset r rate 200 250 but it does not have any effect.

[sophiajt]

I can't repro in alacritty, but I can repro inside the default GNOME terminal for Pop! OS (an Ubuntu-based distro)

[gwenn]

@jonathandturner Would you mind trying to generate a backtrace (RUST_BACKTRACE=1) ?

[sophiajt]

@gwenn - it panics without a backtrace, but experimenting a bit, I see that it's originating here:

rustyline/src/tty/unix.rs

Line 689 in 39f3578

return Err(error::ReadlineError::from(io::ErrorKind::InvalidData));

[sophiajt]

With a bit more experimenting: I understand that this is verifying that you should be properly reset, but commenting it out doesn't seem to show any issues of not getting reset correctly:

rustyline/src/tty/unix.rs

Lines 688 to 699 in 39f3578

	if rdr.next_char()? != '\x1b' {
	return Err(error::ReadlineError::from(io::ErrorKind::InvalidData));
	}
	if rdr.next_char()? != '[' {
	return Err(error::ReadlineError::from(io::ErrorKind::InvalidData));
	}
	read_digits_until(rdr, ';')?;
	let col = read_digits_until(rdr, 'R')?;
	debug!(target: "rustyline", "initial cursor location: {:?}", col);
	if col != 1 {
	self.write_and_flush(b"\n")?;
	}

I was wondering what kinds of issues this was trying to protect from. Maybe there's another way to do it?

[gwenn]

My wild guess is that we receive Enter/'\r' instead of Esc/\x1b because the key press happens after:

rustyline/src/tty/unix.rs

Line 677 in 39f3578

if rdr.poll(0)? != 0 {

But before:

rustyline/src/tty/unix.rs

Line 682 in 39f3578

self.write_and_flush(b"\x1b[6n")?;

We can still ignore unexpected/user input in this case.

[gwenn]

See #292

[gwenn]

Liner seems to always write "⏎":
https://github.com/redox-os/liner/blob/master/src/editor.rs#L156

[sophiajt]

@gwenn - I tried out #292 and it fixes the issue for me.

[gwenn]

Fix by release 5.0.4