node_modules/node-firefox-install-app/node_modules/zip-folder/node_modules/archiver/node_modules/zip-stream/node_modules/compress-commons/lib/util/index.js

/**
 * node-compress-commons
 *
 * Copyright (c) 2014 Chris Talkington, contributors.
 * Licensed under the MIT license.
 * https://github.com/ctalkington/node-compress-commons/blob/master/LICENSE-MIT
 */
var Stream = require('stream').Stream;
var PassThrough = require('readable-stream').PassThrough;

var util = module.exports = {};

util.isStream = function(source) {
  return source instanceof Stream;
};

util.normalizeInputSource = function(source) {
  if (source === null) {
    return new Buffer(0);
  } else if (typeof source === 'string') {
    return new Buffer(source);
  } else if (util.isStream(source) && !source._readableState) {
    var normalized = new PassThrough();
    source.pipe(normalized);

    return normalized;
  }

  return source;
};