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pcap_setnonblock, pcap_getnonblock - set or get the state of non-blocking mode on a capture device

#include <pcap/pcap.h>

char errbuf[PCAP_ERRBUF_SIZE];

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

 DESCRIPTION
 pcap_setnonblock() puts a capture handle into ``non-blocking'' mode, or takes it out
of ``non-blocking'' mode, depending on whether the
 nonblock argument is non-zero or zero. It has no effect on ``savefiles''.
If there is an error, -1 is returned and
 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
 pcap_dispatch() will, if no packets are currently available to be read, return 0
immediately rather than blocking waiting for packets to arrive.
 pcap_loop() and
 pcap_next() will not work in ``non-blocking'' mode.

When first activated with
 pcap_activate() or opened with
 pcap_open_live() , a capture handle is not in ``non-blocking mode''; a call to
 pcap_setnonblock() is required in order to put it into ``non-blocking'' mode.
 RETURN VALUE
 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
 errbuf is filled in with an appropriate error message.

 errbuf is assumed to be able to hold at least
 PCAP_ERRBUF_SIZE chars.
 SEE ALSO
pcap(3PCAP), pcap_loop(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP)