freebsd man page for pcap_breakloop

PCAP_BREAKLOOP(3)					     Library Functions Manual						 PCAP_BREAKLOOP(3)

NAME
       pcap_breakloop - force a pcap_dispatch() or pcap_loop() call to return

SYNOPSIS
       #include <pcap/pcap.h>

       void pcap_breakloop(pcap_t *);

DESCRIPTION
       pcap_breakloop()  sets  a flag that will force pcap_dispatch() or pcap_loop() to return rather than looping; they will return the number of
       packets that have been processed so far, or -2 if no packets have been processed so far.

       This routine is safe to use inside a signal handler on UNIX or a console control handler on Windows, as it  merely  sets  a  flag  that	is
       checked within the loop.

       The  flag  is  checked in loops reading packets from the OS - a signal by itself will not necessarily terminate those loops - as well as in
       loops processing a set of packets returned by the OS.  Note that if you are catching signals on UNIX systems that support restarting system
       calls  after a signal, and calling pcap_breakloop() in the signal handler, you must specify, when catching those signals, that system calls
       should NOT be restarted by that signal.	Otherwise, if the signal interrupted a call reading packets in a live capture,	when  your  signal
       handler	returns  after calling pcap_breakloop(), the call will be restarted, and the loop will not terminate until more packets arrive and
       the call completes.

       Note also that, in a multi-threaded application, if one thread is blocked in pcap_dispatch(), pcap_loop(), pcap_next(), or  pcap_next_ex(),
       a  call to pcap_breakloop() in a different thread will not unblock that thread; you will need to use whatever mechanism the OS provides for
       breaking a thread out of blocking calls in order to unblock the thread, such as thread cancellation in systems that support POSIX threads.

       Note that pcap_next() and pcap_next_ex() will, on some platforms, loop reading packets from the OS; that loop will not necessarily be  ter-
       minated by a signal, so pcap_breakloop() should be used to terminate packet processing even if pcap_next() or pcap_next_ex() is being used.

       pcap_breakloop() does not guarantee that no further packets will be processed by pcap_dispatch() or pcap_loop() after it is called; at most
       one more packet might be processed.

       If -2 is returned from pcap_dispatch() or pcap_loop(), the flag is cleared, so a subsequent call will resume reading packets.  If  a  posi-
       tive number is returned, the flag is not cleared, so a subsequent call will return -2 and clear the flag.

SEE ALSO
       pcap(3), pcap_loop(3), pcap_next_ex(3)

								   5 April 2008 						 PCAP_BREAKLOOP(3)