title: maximum (and minimum) off_t
body: <p>I could not find something like <code>OFF_MAX</code> that would tell me the maximum allowed value for <code>off_t</code> so I wonder if I could perhaps use that:</p>
  
  <pre><code>#define OFF_MAX ~((off_t)1 &lt;&lt; (sizeof(off_t) * 8 - 1))
  #define OFF_MIN  ((off_t)1 &lt;&lt; (sizeof(off_t) * 8 - 1))
  </code></pre>
  
  <p>I know bit operations on signed values is generally undefined, but is it ok for x86 and ARM, Windows (mingw), Linux and Mac OS X?</p>