pcap_file - get the standard I/O stream for a savefile being read
#include <pcap/pcap.h>
FILE *pcap_file(pcap_t *p);
pcap_file() returns the standard I/O stream of the ``savefile,'' if a
  ``savefile'' was opened with pcap_open_offline(3), or NULL, if a
  network device was opened with pcap_create(3) and
  pcap_activate(3), or with pcap_open_live(3).
Note that the Packet Capture library is usually built with large
    file support, so the standard I/O stream of the ``savefile'' might refer to
    a file larger than 2 gigabytes; applications that use pcap_file()
    should, if possible, use calls that support large files on the return value
    of pcap_file() or the value returned by fileno(3) when passed
    the return value of pcap_file().