test-fs-promises-file-handle-readFile.js

'use strict';

const common = require('../common');

// The following tests validate base functionality for the fs.promises
// FileHandle.readFile method.

const fs = require('fs');
const { open, readFile, writeFile } = fs.promises;
const path = require('path');
const tmpdir = require('../common/tmpdir');
const tick = require('../common/tick');
const assert = require('assert');
const tmpDir = tmpdir.path;

tmpdir.refresh();

async function validateReadFile() {
  const filePath = path.resolve(tmpDir, 'tmp-read-file.txt');
  const fileHandle = await open(filePath, 'w+');
  const buffer = Buffer.from('Hello world'.repeat(100), 'utf8');

  const fd = fs.openSync(filePath, 'w+');
  fs.writeSync(fd, buffer, 0, buffer.length);
  fs.closeSync(fd);

  const readFileData = await fileHandle.readFile();
  assert.deepStrictEqual(buffer, readFileData);

  await fileHandle.close();
}

async function validateReadFileProc() {
  // Test to make sure reading a file under the /proc directory works. Adapted
  // from test-fs-read-file-sync-hostname.js.
  // Refs:
  // - https://groups.google.com/forum/#!topic/nodejs-dev/rxZ_RoH1Gn0
  // - https://github.com/nodejs/node/issues/21331

  // Test is Linux-specific.
  if (!common.isLinux)
    return;

  const fileHandle = await open('/proc/sys/kernel/hostname', 'r');
  const hostname = await fileHandle.readFile();
  assert.ok(hostname.length > 0);
}

async function doReadAndCancel() {
  // Signal aborted from the start
  {
    const filePathForHandle = path.resolve(tmpDir, 'dogs-running.txt');
    const fileHandle = await open(filePathForHandle, 'w+');
    const buffer = Buffer.from('Dogs running'.repeat(10000), 'utf8');
    fs.writeFileSync(filePathForHandle, buffer);
    const controller = new AbortController();
    const { signal } = controller;
    controller.abort();
    assert.rejects(readFile(fileHandle, { signal }), {
      name: 'AbortError'
    });
  }

  // Signal aborted on first tick
  {
    const filePathForHandle = path.resolve(tmpDir, 'dogs-running1.txt');
    const fileHandle = await open(filePathForHandle, 'w+');
    const buffer = Buffer.from('Dogs running'.repeat(10000), 'utf8');
    fs.writeFileSync(filePathForHandle, buffer);
    const controller = new AbortController();
    const { signal } = controller;
    tick(1, () => controller.abort());
    assert.rejects(readFile(fileHandle, { signal }), {
      name: 'AbortError'
    });
  }

  // Signal aborted right before buffer read
  {
    const newFile = path.resolve(tmpDir, 'dogs-running2.txt');
    const buffer = Buffer.from('Dogs running'.repeat(1000), 'utf8');
    fs.writeFileSync(newFile, buffer);

    const fileHandle = await open(newFile, 'r');

    const controller = new AbortController();
    const { signal } = controller;
    tick(2, () => controller.abort());
    assert.rejects(fileHandle.readFile({ signal, encoding: 'utf8' }), {
      name: 'AbortError'
    });
  }

  // Validate file size is withing range for reading
  {
    // Variable taken from https://github.com/nodejs/node/blob/master/lib/internal/fs/promises.js#L5
    const kIoMaxLength = 2 ** 31 - 1;

    const newFile = path.resolve(tmpDir, 'dogs-running3.txt');
    const buffer = Buffer.alloc(kIoMaxLength + 1);
    await writeFile(newFile, buffer);

    const fileHandle = await open(newFile, 'r');

    assert.rejects(fileHandle.readFile(), {
      name: 'RangeError',
      code: 'ERR_FS_FILE_TOO_LARGE'
    });
  }
}

validateReadFile()
  .then(validateReadFileProc)
  .then(doReadAndCancel)
  .then(common.mustCall());