85 lines
2.8 KiB
Plaintext
85 lines
2.8 KiB
Plaintext
.\" Copyright (c) 1994, 1996, 1997
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that: (1) source code distributions
|
|
.\" retain the above copyright notice and this paragraph in its entirety, (2)
|
|
.\" distributions including binary code include the above copyright notice and
|
|
.\" this paragraph in its entirety in the documentation or other materials
|
|
.\" provided with the distribution, and (3) all advertising materials mentioning
|
|
.\" features or use of this software display the following acknowledgement:
|
|
.\" ``This product includes software developed by the University of California,
|
|
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
|
|
.\" the University nor the names of its contributors may be used to endorse
|
|
.\" or promote products derived from this software without specific prior
|
|
.\" written permission.
|
|
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
|
|
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
|
|
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
|
|
.\"
|
|
.TH PCAP_GET_REQUIRED_SELECT_TIMEOUT 3PCAP "19 January 2018"
|
|
.SH NAME
|
|
pcap_get_required_select_timeout \- get a file descriptor on which a
|
|
select() can be done for a live capture
|
|
.SH SYNOPSIS
|
|
.nf
|
|
.ft B
|
|
#include <pcap/pcap.h>
|
|
.ft
|
|
.LP
|
|
.ft B
|
|
struct timeval *pcap_get_required_select_timeout(pcap_t *p);
|
|
.ft
|
|
.fi
|
|
.SH DESCRIPTION
|
|
.B pcap_get_required_select_timeout()
|
|
returns, on UNIX, a pointer to a
|
|
.B struct timeval
|
|
containing a value that must be used as the minimum timeout in
|
|
.BR select() ,
|
|
.BR poll() ,
|
|
.BR epoll_wait() ,
|
|
and
|
|
.B kevent()
|
|
calls if
|
|
.B pcap_get_selectable_fd()
|
|
returns \-1.
|
|
.PP
|
|
The timeout that should be used in those calls must be no larger than
|
|
the smallest of all timeouts returned by
|
|
.B pcap_get_required_select_timeout()
|
|
for devices from which packets will be captured.
|
|
.PP
|
|
The device for which
|
|
.B pcap_get_selectable_fd()
|
|
returned \-1 must be put in non-blocking mode with
|
|
.BR pcap_setnonblock() ,
|
|
and an attempt must always be made to read packets from the device
|
|
when the
|
|
.BR select() ,
|
|
.BR poll() ,
|
|
.BR epoll_wait() ,
|
|
or
|
|
.B kevent()
|
|
call returns.
|
|
.PP
|
|
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
|
|
timeout has expired. A call to
|
|
.B pcap_dispatch()
|
|
or
|
|
.B pcap_next_ex()
|
|
will return 0 in this case, but will not block.
|
|
.PP
|
|
.B pcap_get_required_select_timeout()
|
|
is not available on Windows.
|
|
.SH RETURN VALUE
|
|
A pointer to a
|
|
.B struct timeval
|
|
is returned if the timeout is required; otherwise
|
|
.B NULL
|
|
is returned.
|
|
.SH SEE ALSO
|
|
pcap(3PCAP), pcap_get_selectable_fd(3PCAP), select(2), poll(2),
|
|
epoll_wait(2), kqueue(2)
|