fork.js

"use strict";
const ffi = require("ffi");
const ref = require("ref");
const ArrayType = require("ref-array");

let StringArray = ArrayType("string");
let voidPtr = ref.refType(ref.types.void);

let stdlib = ffi.Library(null, {
	"fork": ["int", []],
	"execvp": ["int", ["string", StringArray]],
	"dup2": ["int", ["int", "int"]],
	"wait4": ["int", ["int", "int", "int", voidPtr]],
});

const WNOHANG = 1;

process.on("SIGCHLD", () => {
	console.log("SIGCHLD!");
	while (true) {
		let pid = stdlib.wait4(-1, 0, WNOHANG, ref.NULL);
		if (pid <= 0) break;
		console.log(`reaped zombie ${pid}`);
	}
});

let pid = stdlib.fork();
if (pid === 0) {
	console.log("hello from child");
	
	setTimeout(() => {
		stdlib.dup2(process.stdin._handle.fd, 0);
		stdlib.dup2(process.stdout._handle.fd, 1);
		stdlib.dup2(process.stderr._handle.fd, 2);
		
		let result = stdlib.execvp("/bin/echo", ["/bin/echo", "luku", ref.NULL]);
		console.log("execvp", result);
	}, 1000);
	
} else if (pid < 0) {
	console.log("error forking");
} else {
	console.log("child has pid", pid);
	
	setInterval(() => {}, 100000);
}