fs: rmSync with recursive returns without throwing while the directory still exists #67010

// fs.rmSync(dir, { recursive: true, force: true }) returns without throwing
// while `dir` still exists, when another thread removes an entry inside `dir`
// during the walk.
import { existsSync, mkdirSync, mkdtempSync, readdirSync, rmSync, unlinkSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { Worker, isMainThread, workerData } from "node:worker_threads";

if (!isMainThread) {
  // Churn: keep creating and removing one file inside the tree being removed.
  const { lock, stop } = workerData;
  const flag = new Int32Array(stop);
  while (Atomics.load(flag, 0) === 0) {
    try {
      writeFileSync(lock, "");
      unlinkSync(lock);
    } catch {}
  }
  process.exit(0);
}

const TRIALS = Number(process.argv[2] ?? 200);
const counts = { removed: 0, threw: 0, survivedSilently: 0 };
let example;

for (let i = 0; i < TRIALS; i++) {
  const dir = mkdtempSync(join(tmpdir(), "rmsync-"));
  const busy = join(dir, "busy");
  mkdirSync(busy);
  for (let d = 0; d < 20; d++) {
    mkdirSync(join(dir, `d${d}`));
    for (let f = 0; f < 20; f++) writeFileSync(join(dir, `d${d}`, `f${f}`), "x");
  }
  const stop = new SharedArrayBuffer(4);
  const worker = new Worker(new URL(import.meta.url), { workerData: { lock: join(busy, "lock"), stop } });
  await new Promise((resolve) => worker.once("online", resolve));

  try {
    rmSync(dir, { recursive: true, force: true });
    if (existsSync(dir)) {
      counts.survivedSilently++;
      example ??= readdirSync(dir, { recursive: true });
    } else {
      counts.removed++;
    }
  } catch (error) {
    counts.threw++;
  }

  Atomics.store(new Int32Array(stop), 0, 1);
  await new Promise((resolve) => worker.once("exit", resolve));
  rmSync(dir, { recursive: true, force: true, maxRetries: 5 });
}

console.log(`node ${process.version}`, JSON.stringify(counts));
if (example) console.log("left behind after rmSync returned:", JSON.stringify(example));