interact method on spawn_bash session doesn't echoes input

[zhiburt]

My guess for some reason when we do an expect of initial prompt something is changed so type ENTER
causes a production of CTRL-M(^M) where without it it causes \r\n

[zhiburt]

related: #3

[zhiburt]

A research showed - reading changes a terminal line settings:

Here use cargo run --example interact and type stty command.

With read before interact

stty^Mspeed 38400 baud; line = 0;
-brkint -imaxbel
-echo

Without presiding read

EXPECT_PROMPT>stty
speed 38400 baud; line = 0;
-brkint -imaxbel

[zhiburt]

Here's a termios flags differences

Termios { inner: RefCell { value: termios { c_iflag: 1024, c_oflag: 5, c_cflag: 191, c_lflag: 35385, c_line: 0, c_cc: [3, 28, 127, 21, 4, 0, 1, 0, 17, 19, 26, 0, 18, 0, 23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], c_ispeed: 15, c_ospeed: 15 } }, input_flags: IXON, output_flags: OPOST | ONLCR, control_flags: CS6 | CS7 | CS8 | CREAD | CSIZE, local_flags: ECHOKE | ECHOE | ECHOK | ECHO | ECHOCTL | ISIG | IEXTEN, control_chars: [3, 28, 127, 21, 4, 0, 1, 0, 17, 19, 26, 0, 18, 0, 23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

Termios { inner: RefCell { value: termios { c_iflag: 1024, c_oflag: 5, c_cflag: 191, c_lflag: 35377, c_line: 0, c_cc: [3, 28, 127, 21, 4, 0, 1, 0, 17, 19, 26, 0, 18, 0, 23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], c_ispeed: 15, c_ospeed: 15 } }, input_flags: IXON, output_flags: OPOST | ONLCR, control_flags: CS6 | CS7 | CS8 | CREAD | CSIZE, local_flags: ECHOKE | ECHOE | ECHOK | ECHOCTL | ISIG | IEXTEN, control_chars: [3, 28, 127, 21, 4, 0, 1, 0, 17, 19, 26, 0, 18, 0, 23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] }

[zhiburt]

related https://stackoverflow.com/questions/68643312/why-reading-from-pty-slave-changes-linediscipline-settings

[zhiburt]

There was an idea that it may be an issue of spawned program. As it may change termios settings at any point.
And it may be true.

Spawning cat doesn't have such an issue wherewith python && bash there are.

Code which reproduces an issue

fn main() {
    use expectrl::Session;

    let mut bash = Session::spawn("python").expect("Error while spawning bash");

    bash.expect(">>> ").unwrap();

    let status = bash.interact().expect("Failed to start interact");

    println!("Quiting status {:?}", status);
}

[zhiburt]

If we would read only preamble but don't >>> chars everything but be fine.

So the actual issue is in reading exactly PROMPT.

Why?

[zhiburt]

It seems like bash cab override tty mode at any time.

I am trying to create a powershell repl and pwsh behaives completely differently.

Here I am typing a random chars pimode and an each input pwsh seems to clear old one.

PS /home/mzhiburt/projects/expectrl> 
INPUT "p"                                              
OUTPUT "p"                                                       
pINPUT "i"                                                                  
OUTPUT "\u{1b}[12;38H"                    
OUTPUT "pi"   
piINPUT "m"             
OUTPUT "\u{1b}[12;38Hpim"               
pimINPUT "o" 
OUTPUT "\u{1b}[12;38Hpimo"             
pimoINPUT "d"
OUTPUT "\u{1b}[12;38Hpimod"           
pimodINPUT "e"           
OUTPUT "\u{1b}[12;38H"       
OUTPUT "pimode"                       
pimodeINPUT "\r"                                             
OUTPUT "\r\n"