invalid character input after ctrl+g input

[CyanMARgh]

if you enter ctrl+g and press by mistake, for example, F1, then ĉ will be entered into the terminal. The bug was discovered when i replaced default navigation keys with wasd in the config. The characters A/B/C/D were entered into the console when i pressed the arrows by mistake. I would like that when entering an invalid command, nothing would be printed.

[Kieran-Weaver]

Normal invalid commands do display nothing. Your bug won't be seen during normal usage because it doesn't happen with any of the normal keys, only special keys like the arrow keys and the F keys.

The reason this is happening is that the terminal representation for the arrow keys is longer than just one character. You can figure this out by doing ctrl-V and then pressing one of them in the terminal:

Left:  ^[ [ D
Right: ^[ [ C
Up: ^[ [ A
Down: ^[ [ B

where
^[ is escape.

To mtm, ctrl-G, left arrow is an invalid command. it's ctrl-G, [, then a D.

[dpeschel]

This annoyed me as well. Any keys you type that don't have DO(…) lines in mtm.c just fall through to the code that passes the input to the terminal. This explains characters such as ĉ. It might explain the escape sequences as well; I don't know though.

I propose a three-part fix. I already wrote it in my fork of the repo, and tested it a little bit. But I'd like other people's opinions.

1. When you have not typed the command character, and you type any unhandled special key, such as F20 or clear all tabs or help, mtm ignores it. Yes, these are real keys you could type, on various non-PC keyboards that ncurses knows about. This change doesn't affect normal ASCII or UTF-8 input. And if you want to handle a new special key, you can add a new line of code.

   Note, these are keys that ncurses knows about but mtm does not. I haven't tried generating escape sequences that ncurses doesn't know about.

2. When you have typed the command character, and you type any unhandled key (special or not), mtm cancels the command.

   In my opinion, after you have typed the command character, the next key should never turn into input, except for typing the command character twice in a row.

3. Then the BAILOUT key becomes unnecessary because all unknown keys bail out. (So the code and the configuration files should not define it.) And the manual should say explicitly that all unknown keys bail out.