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.TH PCAP_SETNONBLOCK 3PCAP "25 July 2018"

.SH NAME

pcap_setnonblock, pcap_getnonblock \- set or get the state of

non-blocking mode on a capture device

.SH SYNOPSIS

.nf

.ft B

#include <pcap/pcap.h>

.ft

.LP

.nf

.ft B

char errbuf[PCAP_ERRBUF_SIZE];

.ft

.LP

.ft B

int pcap_setnonblock(pcap_t *p, int nonblock, char *errbuf);

int pcap_getnonblock(pcap_t *p, char *errbuf);

.ft

.fi

.SH DESCRIPTION

.B pcap_setnonblock()

puts a capture handle into ``non-blocking'' mode, or takes it out

of ``non-blocking'' mode, depending on whether the

.I nonblock

argument is non-zero or zero.  It has no effect on ``savefiles''.

If there is an error,

.B PCAP_ERROR

is returned and

.I errbuf

is filled in with an appropriate error message; otherwise, 0 is

returned.

In

``non-blocking'' mode, an attempt to read from the capture descriptor

with

.B pcap_dispatch(3PCAP)

will, if no packets are currently available to be read, return 0

immediately rather than blocking waiting for packets to arrive.

.B pcap_loop(3PCAP)

and

.B pcap_next(3PCAP)

will not work in ``non-blocking'' mode.

.PP

When first activated with

.B pcap_activate(3PCAP)

or opened with

.B pcap_open_live(3PCAP) ,

a capture handle is not in ``non-blocking mode''; a call to

.B pcap_setnonblock()

is required in order to put it into ``non-blocking'' mode.

.SH RETURN VALUE

.B pcap_getnonblock()

returns the current ``non-blocking'' state of the capture descriptor; it

always returns 0 on ``savefiles''.

If there is an error,

.B PCAP_ERROR

is returned and

.I errbuf

is filled in with an appropriate error message.

.PP

.I errbuf

is assumed to be able to hold at least

.B PCAP_ERRBUF_SIZE

chars.

.SH SEE ALSO

pcap(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP)