Keyboard interrupt (SIGINT) during a shell.RunInteractiveShell call from a plugin stops the editor itself

[Andriamanitra]

Description of the problem or steps to reproduce

1. Make a plugin that uses shell.RunInteractiveShell() in ~/.config/micro/plug/exectest/exectest.lua:

local micro = import("micro")
local config = import("micro/config")
local shell = import("micro/shell")

function init()
	config.MakeCommand("exec", exec, config.NoComplete)
end

function exec()
	shell.RunInteractiveShell("sh -c 'echo press ctrl+c && sleep 10'", true, false)
end

2. Run the plugin (ctrl+e and type exec)
3. Press ctrl+c during execution

I would expect this to stop the interactive shell and return to the file I was editing. What happens instead is it kills the entire micro-editor process. It looks like this is also not what the code for shell.RunInteractiveShell was intended to do:

micro/internal/shell/shell.go

Lines 103 to 111 in c8c7ad5

	// This is a trap for Ctrl-C so that it doesn't kill micro
	// Instead we trap Ctrl-C to kill the program we're running
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt)
	go func() {
	for range c {
	cmd.Process.Kill()
	}
	}()

Version information

OS: Linux (OpenSUSE Tumbleweed)
Version: 0.0.0-unknown
Commit hash: c8c7ad5
Compiled on October 31, 2022

[Andriamanitra]

I spent some time trying to fix this and realized the issue stems from the sigterm handler defined in the main package:

micro/cmd/micro/micro.go

Line 352 in c8c7ad5

signal.Notify(sigterm, syscall.SIGTERM, syscall.SIGINT, syscall.SIGQUIT)

Making a new signal handler for os.Interrupt does not affect the existing handler which will still terminate the program. I attempted to fix it by calling signal.Reset(os.Interrupt) before adding the new handler to get rid of the existing handler, but I was not able to find a way to re-enable it afterwards. This caused micro to not clean up after itself properly when closed from outside with kill -INT micro.

I think the RunInteractiveShell function would need to have access to the sigterm channel from the main package to be able to re-enable the handler. I have no idea how to accomplish that in a sensible way so I am giving up on trying to fix this issue myself for now.

[niten94]

I think moving sigterm in the main package to internal/util and readding it in channels receiving SIGINT using signal.Notify in shell.RunInteractiveShell after the command is run can be done.

I do not how is the signal sent but SIGINT is sent to processes in the foreground process group of the terminal where Ctrl+C is pressed. Commands run in micro will be in the same process group so I think the command being run in RunInteractiveShell does not also have to be killed in micro.

I have created a branch in my fork but I realized it may not be good not posting a comment instead first, so I apologize.