NAME

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

SYNOPSIS

       #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''.
       errbuf is a buffer large enough to hold at least PCAP_ERRBUF_SIZE chars.

       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;
       pcap_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.

RETURN VALUE

       pcap_setnonblock()  return  0 on success, PCAP_ERROR_NOT_ACTIVATED if called on a capture handle that has
       been created but not activated, and PCAP_ERROR for other errors.  pcap_getnonblock() returns the  current
       ``non-blocking''  state  of  the capture descriptor on success; it always returns 0 on ``savefiles''.  It
       returns PCAP_ERROR_NOT_ACTIVATED if called on a capture handle that has been created but  not  activated,
       and  PCAP_ERROR  for  other  errors.   If PCAP_ERROR is returned, errbuf is filled in with an appropriate
       error message.

SEE ALSO

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

                                                30 November 2023                         PCAP_SETNONBLOCK(3PCAP)