Skip critical on NO TTY case

[rushprint]

Hello Nelo.

I compared a few tools, but gow is the best.
However, when I am using it in Docker container I have a problem.
When it run and try to make terminal in raw mode it fails and finish because of critical(err).

state, err := makeTerminalRaw(syscall.Stdin)
critical(err)
                ===========> at this point gow quit with  "[gow] inappropriate ioctl for device" message.
termios = &state

The root cause is that docker containers may run without terminal.
I think we have a few solutions,

• just ignore errors on ENOTTY error case.
• a command-line flag to avoid terminal setting operation.
• catch every signals and forward them to sub-process.

I thought the first one is most easy and made a PR.
Please accept or deny it If you have different idea.

Best regards
Sungkyu Kim

[mitranim]

Thanks for reporting and fixing the issue. Glad to hear you like the tool! 🙂

I'm thinking of a slightly more general solution. Instead of ignoring termios errors, it would be better to have a mode where the terminal state is not altered at all. I haven't checked, but in addition to Docker, this probably also breaks on Windows, and possibly in some other places. Issue #6 about Windows support has been pending for a while.

Adding such a mode might require more than a boolean flag wrapping "alter terminal" and "restore terminal" calls, because of signal handling. It might even turn out that we don't need the raw state, and could just register signal handlers instead. It's been a while since I checked. Been meaning to get around to this, but not sure when...

[mitranim]

This is probably fine to merge, but it needs some fixes:

if err != nil {
	if errors.Is(err, syscall.ENOTTY) {
		log.Println("failed to set raw terminal mode: no terminal exists")
	} else {
		critical(err)
	}
} else {
	termios = &state
}

• Use errors.Is.
• Use log.Println and lowercase for consistency with other logging.
• Set termios to non-nil only if the terminal state was successfully altered. If no terminal exists, leave it nil so that cleanup doesn't try to alter the state again.

[mitranim]

Applied the patch locally and tested for a while. Doesn't seem to cause problems in normal operation. Pushed the changes, please see if this works for you in Docker. 🙂 Closing the pull for now, feel free to reopen if this doesn't work.