test-fs-sync-fd-leak.js

// Flags: --expose-internals
// Copyright Joyent, Inc. and other Node contributors.
//
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//
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'use strict';
require('../common');
const assert = require('assert');
const fs = require('fs');
const { internalBinding } = require('internal/test/binding');

// Ensure that (read|write|append)FileSync() closes the file descriptor
fs.openSync = function() {
  return 42;
};
fs.closeSync = function(fd) {
  assert.strictEqual(fd, 42);
  close_called++;
};
fs.readSync = function() {
  throw new Error('BAM');
};
fs.writeSync = function() {
  throw new Error('BAM');
};

// Internal fast paths are pure C++, can't error inside write
internalBinding('fs').writeFileUtf8 = function() {
  // Fake close
  close_called++;
  throw new Error('BAM');
};

internalBinding('fs').fstat = function() {
  throw new Error('EBADF: bad file descriptor, fstat');
};

let close_called = 0;
ensureThrows(function() {
  // Fast path: writeFileSync utf8
  fs.writeFileSync('dummy', 'xxx');
}, 'BAM');
ensureThrows(function() {
  // Non-fast path
  fs.writeFileSync('dummy', 'xxx', { encoding: 'base64' });
}, 'BAM');
ensureThrows(function() {
  // Fast path: writeFileSync utf8
  fs.appendFileSync('dummy', 'xxx');
}, 'BAM');
ensureThrows(function() {
  // Non-fast path
  fs.appendFileSync('dummy', 'xxx', { encoding: 'base64' });
}, 'BAM');

function ensureThrows(cb, message) {
  let got_exception = false;

  close_called = 0;
  try {
    cb();
  } catch (e) {
    assert.strictEqual(e.message, message);
    got_exception = true;
  }

  assert.strictEqual(close_called, 1);
  assert.strictEqual(got_exception, true);
}