title: How can I ensure that open source code I'm using is not malicious?
body: <p>I was wondering how can I be sure about safety of code in open source projects, particularly the ones with thousands lines of code, including calls to <code>popen()</code> or <code>system()</code>.
  How can I know there is no harmful and malicious code in there?
  Is there anyway I can examine the code safely?</p>