test-fs-read.js

// Copyright Joyent, Inc. and other Node contributors.
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//
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'use strict';
const common = require('../common');
const fixtures = require('../common/fixtures');
const assert = require('assert');
const fs = require('fs');
const filepath = fixtures.path('x.txt');
const fd = fs.openSync(filepath, 'r');

const expected = Buffer.from('xyz\n');

function test(bufferAsync, bufferSync, expected) {
  fs.read(fd,
          bufferAsync,
          0,
          expected.length,
          0,
          common.mustCall((err, bytesRead) => {
            assert.ifError(err);
            assert.strictEqual(bytesRead, expected.length);
            assert.deepStrictEqual(bufferAsync, expected);
          }));

  const r = fs.readSync(fd, bufferSync, 0, expected.length, 0);
  assert.deepStrictEqual(bufferSync, expected);
  assert.strictEqual(r, expected.length);
}

test(Buffer.allocUnsafe(expected.length),
     Buffer.allocUnsafe(expected.length),
     expected);

test(new Uint8Array(expected.length),
     new Uint8Array(expected.length),
     Uint8Array.from(expected));

{
  // Reading beyond file length (3 in this case) should return no data.
  // This is a test for a bug where reads > uint32 would return data
  // from the current position in the file.
  const fd = fs.openSync(filepath, 'r');
  const pos = 0xffffffff + 1; // max-uint32 + 1
  const nRead = fs.readSync(fd, Buffer.alloc(1), 0, 1, pos);
  assert.strictEqual(nRead, 0);

  fs.read(fd, Buffer.alloc(1), 0, 1, pos, common.mustCall((err, nRead) => {
    assert.ifError(err);
    assert.strictEqual(nRead, 0);
  }));
}

assert.throws(
  () => fs.read(null, Buffer.alloc(1), 0, 1, 0),
  {
    message: 'The "fd" argument must be of type number. Received type object',
    code: 'ERR_INVALID_ARG_TYPE',
  }
);