pcap_get_required_select_timeout(3) - NetBSD Manual Pages

PCAP_GET_REQUIRED_SELECT_TIMEOUT(3)        PCAP_GET_REQUIRED_SELECT_TIMEOUT(3)




NAME

       pcap_get_required_select_timeout  -  get  a  file descriptor on which a
       select() can be done for a live capture


SYNOPSIS

       #include <pcap/pcap.h>

       struct timeval *pcap_get_required_select_timeout(pcap_t *p);


DESCRIPTION

       pcap_get_required_select_timeout() returns, on UNIX,  a  pointer  to  a
       struct  timeval  containing  a  value  that must be used as the minimum
       timeout in select(2), poll(2), epoll_wait(2),  and  kevent()  calls  if
       pcap_get_selectable_fd(3) returns PCAP_ERROR.

       The  timeout  that should be used in those calls must be no larger than
       the      smallest      of      all      timeouts      returned       by
       pcap_get_required_select_timeout()  for devices from which packets will
       be captured.

       The device for which pcap_get_selectable_fd() returned PCAP_ERROR  must
       be  put  in  non-blocking mode with pcap_setnonblock(3), and an attempt
       must always be made to read packets from the device when the  select(),
       poll(), epoll_wait(), or kevent() call returns.

       Note that a device on which a read can be done without blocking may, on
       some platforms, not have any packets to read if the packet buffer time-
       out  has  expired.   A call to pcap_dispatch(3) or pcap_next_ex(3) will
       return 0 in this case, but will not block.

       pcap_get_required_select_timeout() is not available on Windows.


RETURN VALUE

       A pointer to a struct timeval is returned if the timeout  is  required;
       otherwise NULL is returned.


BACKWARD COMPATIBILITY

       This  function  became available in libpcap release 1.9.0.  In previous
       releases, select(), poll(), epoll_wait(), and kevent() cannot  be  used
       on any capture source for which pcap_get_selectable_fd returns -1.


SEE ALSO

       pcap(3),  pcap_get_selectable_fd(3), select(2), poll(2), epoll_wait(2),
       kqueue(2)



                                 25 July 20PCAP_GET_REQUIRED_SELECT_TIMEOUT(3)