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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
PCAP_SETNONBLOCK(3PCAP) PCAP_SETNONBLOCK(3PCAP)
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);
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, PCAP_ERROR 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(3PCAP) and pcap_next_ex(3PCAP) will, if
no packets are currently available to be read, return 0 immediately
rather than blocking waiting for packets to arrive.
pcap_loop(3PCAP) will loop forever, consuming CPU time when no
packets are currently available; pacp_dispatch() should be used
instead. pcap_next(3PCAP) will return NULL if there are no packets
currently available to read; this is indistinguishable from an error,
so pcap_next_ex() should be used instead.
When first activated with pcap_activate(3PCAP) or opened with
pcap_open_live(3PCAP), 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.
pcap_getnonblock() returns the current ``non-blocking'' state of the
capture descriptor; it always returns 0 on ``savefiles''. If there
is an error, PCAP_ERROR 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.
pcap(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP)
This page is part of the libpcap (packet capture library) project.
Information about the project can be found at
⟨http://www.tcpdump.org/⟩. If you have a bug report for this manual
page, see ⟨http://www.tcpdump.org/#patches⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/the-tcpdump-group/libpcap.git⟩ on 2020-08-13.
(At that time, the date of the most recent commit that was found in
the repository was 2020-08-10.) If you discover any rendering prob‐
lems in this HTML version of the page, or you believe there is a bet‐
ter or more up-to-date source for the page, or you have corrections
or improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to man-pages@man7.org
25 July 2018 PCAP_SETNONBLOCK(3PCAP)