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| This man page documents libpcap version 1.9.1.                             |
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PCAP_GET_REQUIRED_SELECT_TIMEOUT(3PCAP)PCAP_GET_REQUIRED_SELECT_TIMEOUT(3PCAP)

NAME
       pcap_get_required_select_timeout - get a file descriptor on which a se-
       lect() 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(3PCAP) 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(3PCAP), and an at-
       tempt must always be made to read packets from the device when the  se-
       lect(), 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(3PCAP) or pcap_next_ex(3PCAP)
       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(3PCAP),    pcap_get_selectable_fd(3PCAP),    select(2),   poll(2),
       epoll_wait(2), kqueue(2)

                                 25 JulPCAP_GET_REQUIRED_SELECT_TIMEOUT(3PCAP)