title: Can file size be a negative number? Why?
body: <p>On <code>/coreutils-8.12/src/ls.c</code>, I've found this comment:</p>
  
  <pre><code>/* POSIX requires that a file size be printed without a sign, even
  when negative.  Assume the typical case where negative sizes are
  actually positive values that have wrapped around.  */
  </code></pre>
  
  <p>on line 2639.</p>
  
  <p>My questions are: 
  - What is this typical case they refer to? 
  - Can file size be a negative number, other than in overflowing problems with BIG files and old systems?
  - If yes, why?(and why should I care like they are doing in the comment above?)</p>
  
  <p>I'm interested also in other systems, not only POSIX</p>