fix: signal handling

[baerrach]

What:

Signals should delegate to the child process to determine what to do as cross-env is a facade to spawning them cross platform.

SIGINT, in particular, can decide swallow the signal and continue on.

cross-env needs to wait for the child to decide when it's time to exit.

fixed leaking process.on listeners.

Why:

See https:github.com/jtlapp/node-cleanup

When you hit Ctrl-C, you send a SIGINT signal to each process in the current process group. A process group is set of processes that are all supposed to end together as a group instead of persisting independently. However, some programs, such as Emacs, intercept and repurpose SIGINT so that it does not end the process. In such cases, SIGINT should not end any processes of the group.

The current implementation delegates the SIGINT received by the parent to child, so the child receives two signals. And the process terminates abruptly.

How:

Created a delegateSignalToChild that checked to see if child still exists before delegating signals. Doesn't delegate SIGINT.

Removed process listeners when child exits.

Sets process.exitCode as per https://nodejs.org/api/process.html#process_process_exit_code instead of called process.exit(errorCode).

Checklist:

• [x] Documentation
• [x] Tests
• [x] Ready to be merged

I've only tested it on Windows...

[baerrach]

The issues #178 #180 don't fix the problem deep enough.

[codecov[bot]]

Codecov Report

Merging #227 into master will not change coverage. The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #227   +/-   ##
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  Coverage     100%   100%           
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  Files           4      4           
  Lines          93     93           
  Branches       19     19           
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  Hits           93     93

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[kentcdodds]

:tada: This PR is included in version 7.0.1 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket:

[XhmikosR]

FYI, I see processes hanging after hitting Ctrl+C on Windows (also one ctrl+C does not close all processes like before). Going back to 7.0.0 works fine.

[kentcdodds]

This PR has been reverted. Sorry for the trouble @XhmikosR. Thanks for letting us know of the problem.

Let's ensure that we address the core issues and handle cases like this.

[XhmikosR]

Thanks @kentcdodds! Not sure if you had CI run on Windows would help. Maybe it's time to try GitHub Actions CI? :)

PS. I opened a new issue this morning, because I wasn't sure if you'd notice my comment here #230. Feel free to close it.

[kentcdodds]

We do have CI for windows set up.

[XhmikosR]

Indeed, I missed appveyor.yml. Oh, well, not sure what else could be done, then, assuming your tests cover this case.