ction opens the given archive by name and turn the filehandle
  to  <code><a href="#zzip_disk_mmap">zzip_disk_mmap</a></code> for bringing it to main memory. If it can not
  be <a href="http://www.opengroup.org/onlinepubs/000095399/functions/mmap.html"><code>mmap(2)</code></a>'ed then we slurp the whole file into a newly <a href="http://www.opengroup.org/onlinepubs/000095399/functions/malloc.html"><code>malloc(2)</code></a>'ed
  memory block. Only if that fails too then we return null. Since handling
  of d