nstdlib-nightly/lib/internal/process/signal.mjs

Node.js standard library converted to runtime-agnostic ES modules.

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/internal/process/signal.js

import { ErrnoException } from "nstdlib/lib/internal/errors";

const { signals } = require("binding/constants").os;

let Signal;
const signalWraps = new Map();

function isSignal(event) {
  return typeof event === "string" && signals[event] !== undefined;
}

// Detect presence of a listener for the special signal types
function startListeningIfSignal(type) {
  if (isSignal(type) && !signalWraps.has(type)) {
    if (Signal === undefined) Signal = require("binding/signal_wrap").Signal;
    const wrap = new Signal();

    wrap.unref();

    wrap.onsignal = Function.prototype.bind.call(
      process.emit,
      process,
      type,
      type,
    );

    const signum = signals[type];
    const err = wrap.start(signum);
    if (err) {
      wrap.close();
      throw new ErrnoException(err, "uv_signal_start");
    }

    signalWraps.set(type, wrap);
  }
}

function stopListeningIfSignal(type) {
  const wrap = signalWraps.get(type);
  if (wrap !== undefined && process.listenerCount(type) === 0) {
    wrap.close();
    signalWraps.delete(type);
  }
}

export { startListeningIfSignal };
export { stopListeningIfSignal };