✨Use "killer" strategy, so parent process doesn't need to get its hands dirty 🔪

[cowboyd]

We were having race conditions where the console of the parent process console was getting into an inconsistent state. We think this was because we were calling FreeConsole, AttachConsole, FreeConsole, and AttachConsole again.

This avoids having to make the parent process detach from its console temporarily by spawning a "killer" process whose only purpose is to throw away its own console, attach to the target process's console and then send a ctrl-c event to it. Then the "killer" process can die itself and we never have to worry about the parent process.

We still do have to temporarily disable ctrl-c handling in the parent process since it is possible that it shares a console with the target process.

Some caveats:

• If the childs console window is not hidden, it will force a prompt in the parent process. In node, this means you must call "spawn()with thewindowsHide: true` set.
• It is possible, though not verified that because of the technique used here, all processes that share the console with the target process will be also sent a ctrl-c. We should confirm this behavior and then perhaps explore at a later time what it would take to create child processes with their own unique consoles.

[jnicklas]

Why are the yields necessary?

As for spam from cmd.exe, you could silence that by piping its stdout into null. https://doc.rust-lang.org/std/process/struct.Command.html#method.stdout

We could also build our own binary which does nothing. Maybe that complicates things too much though?

std::process::Command - Rust

API documentation for the Rust `Command` struct in crate `std`.

[cowboyd]

Why are the yields necessary?

The yields were necessary because without them there was some really undefined behavior. It felt like every time I ran the test it was a different kind of failure. I tried taking some of them out, but it would either cause mocha to hang, kill mocha, exit, but never print any result, or some combination of the above but with the console output mucked with external characters.

[cowboyd]

Hmm, piping to null almost worked. there's still some "Terminate Batch Job (Y/n)" weirdness to track down after the weekend

> C:\Users\cowboyd\ctrlc-windows>yarn test
yarn run v1.22.10
$ mocha -r ts-node/register "test/**/*.test.ts"

  ctrlc
    on a process that does not exist
      √ is is just a no-op
    on a running process
Terminate batch job (Y/N)?       √ causes that process to exit

  2 passing (203ms)

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[cowboyd]

@jbolda I went ahead and removed the unix compilation entirely