Function ReadStream

lib/internal/fs/streams.js:163–228

(path, options)

}

function ReadStream(path, options) {
  if (!(this instanceof ReadStream))
    return new ReadStream(path, options);

  // A little bit bigger buffer and water marks by default
  options = copyObject(getOptions(options, kEmptyObject));
  if (options.highWaterMark === undefined)
    options.highWaterMark = 64 * 1024;

  if (options.autoDestroy === undefined) {
    options.autoDestroy = false;
  }

  if (options.fd == null) {
    this.fd = null;
    this[kFs] = options.fs || fs;
    validateFunction(this[kFs].open, 'options.fs.open');

    // Path will be ignored when fd is specified, so it can be falsy
    this.path = toPathIfFileURL(path);
    this.flags = options.flags === undefined ? 'r' : options.flags;
    this.mode = options.mode === undefined ? 0o666 : options.mode;

    validatePath(this.path);
  } else {
    this.fd = getValidatedFd(importFd(this, options));
  }

  options.autoDestroy = options.autoClose === undefined ?
    true : options.autoClose;

  validateFunction(this[kFs].read, 'options.fs.read');

  if (options.autoDestroy) {
    validateFunction(this[kFs].close, 'options.fs.close');
  }

  this.start = options.start;
  this.end = options.end;
  this.pos = undefined;
  this.bytesRead = 0;
  this[kIsPerformingIO] = false;

  if (this.start !== undefined) {
    validateInteger(this.start, 'start', 0);

    this.pos = this.start;
  }


  if (this.end === undefined) {
    this.end = Infinity;
  } else if (this.end !== Infinity) {
    validateInteger(this.end, 'end', 0);

    if (this.start !== undefined && this.start > this.end) {
      throw new ERR_OUT_OF_RANGE(
        'start',