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.TH PCAP_SETNONBLOCK 3PCAP "18 October 2014"
.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, \-1 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()
will, if no packets are currently available to be read, return 0
immediately rather than blocking waiting for packets to arrive.
.B pcap_loop()
and
.B pcap_next()
will not work in ``non-blocking'' mode.
.PP
When first activated with
.B pcap_activate()
or opened with
.B pcap_open_live() ,
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, \-1 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_loop(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP)