Barracuda/ArchiveStream: Wrapping remote files.

class.php

<?php

namespace Drupal\example;

class TarArchive extends \Barracuda\ArchiveStream\TarArchive {
  public function add_remote_file($name, $path, $size, array $opt = array())
  {
    // send file header
    $this->init_file_stream_transfer($name, $size, $opt);
    // open input file
    $fh = fopen($path, 'rb');
    // send file blocks
    while ($data = fread($fh, $this->block_size)) {
      // send data
      $this->stream_file_part($data);
    }
    // close input file
    fclose($fh);
    // complete the file stream
    $this->complete_file_stream();
  }
}

module.php

<?php

/**
 * @param $archive_name
 *   The name of the Zip archive.
 * @param array $files
 *   A list of files. Each file item is an array having the following keys:
 *   - "name": Required. The full file path inside the Zip archive.
 *   - "size": Required. The file size.
 *   - "path": Required. The Source file path.
 *   - "callback": Optional. A callback function that will be invoked prior to
 *     processing the file item. The function receives the complete file item
 *     and must return an array containing the keys "name", "path" and "size".
 */
function example_serve($archive_name, array $files) {
  $options = array(
    'large_files_only' => true,
  );
  drupal_set_time_limit(0);
  $user_agent = (isset($_SERVER['HTTP_USER_AGENT']) ? strtolower($_SERVER['HTTP_USER_AGENT']) : '');
  $archive = strpos($user_agent, 'macintosh') !== false
    ? new \Drupal\example\TarArchive("$archive_name.tar", $options)
    : new \Drupal\example\ZipArchive("$archive_name.zip", $options);
  foreach($files as $data) {
    if(isset($data['callback'])) {
      $data = $data['callback']($data);
      if(!$data) {
        continue;
      }
    }
    $archive->add_remote_file($data['name'], $data['path'], $data['size']);
  }
  $archive->finish();
}