otp 26 messes up the tty

[mbj4668]

Describe the bug
Run an escript that prodcues (slow) output, pipe it to less, and hit q to quit less. The tty is now in a bad state (e.g., with bash, prev history doesn't work). reset or stty sane is needed to fix it.

To Reproduce
Save the script below as test, make it executable and run test <name of a large text file> | less in bash. Hit q. Wait. When you get the bash prompt, try ctrl-p etc.

#!/usr/bin/env escript
%% -*- erlang -*-

main([FName]) ->
    {ok, Fd} = file:open(FName, [read]),
    loop(Fd),
    file:close(Fd).

loop(Fd) ->
    case file:read(Fd, 1024) of
        {ok, Data} ->
            io:put_chars(Data),
            timer:sleep(500),
            loop(Fd);
        _ ->
            done
    end.

Expected behavior
The tty should not be messed up. Also, it takes several seconds more than in 25 to get the prompt back.

Affected versions
I have tried 26.1.2 and 26.2.5.

[garazdawi]

I dug into this and what happens is that when we try to be clever and restore the tty settings after the exit of Erlang we restore them to the values set by less... I'll see if I can add some bandaid, but it would seem like no matter what we do the shell will end up broken in some scenario.

[garazdawi]

Fix merged to be part of 27.2.