title: `Type L: not enough input` when to unpack the target data
body: <p>I get the job done to parse data from target file in binary form with the help of stackoverflow's friends.</p>
  
  <pre><code>&lt;?php
      $handle = fopen('data', 'rb');
      fread($handle,64);
      while (!feof($handle)) {
          $bytes= fread($handle,32);
          print_r(unpack("La/fb/fc/fd/fe/ff/fg/fh",$bytes));
          echo "&lt;br/&gt;";
          }
      echo "finish";
      fclose($handle);
  ?&gt;
  </code></pre>
  
  <p>I got the result ,one last bug remains here that can't solve myself.<br>
  1.why  unpack(): Type L: not enough input, need 4, have 0 ?<br>
  2.how to fix it?</p>
  
  <p><img src="https://i.stack.imgur.com/1gloc.png" alt="enter image description here"></p>