pcap_open_offline() and pcap_open_offline_with_tstamp_precision()
are called to open a ``savefile'' for reading.
fname specifies the name of the file to open. The file can have
the pcap file format as described in pcap-savefile(5), which is
the file format used by, among other programs, tcpdump(1) and
tcpslice(1), or can have the pcapng file format, although not all
pcapng files can be read. The name "-" is a synonym for stdin.
pcap_open_offline_with_tstamp_precision() takes an additional
precision argument specifying the time stamp precision desired;
if PCAP_TSTAMP_PRECISION_MICRO is specified, packet time stamps
will be supplied in seconds and microseconds, and if
PCAP_TSTAMP_PRECISION_NANO is specified, packet time stamps will
be supplied in seconds and nanoseconds. If the time stamps in
the file do not have the same precision as the requested
precision, they will be scaled up or down as necessary before
Alternatively, you may call pcap_fopen_offline() or
pcap_fopen_offline_with_tstamp_precision() to read dumped data
from an existing open stream fp.
pcap_fopen_offline_with_tstamp_precision() takes an additional
precision argument as described above. Note that on Windows,
that stream should be opened in binary mode.
pcap_fopen_offline_with_tstamp_precision() return a pcap_t * on
success and NULL on failure. If NULL is returned, errbuf is
filled in with an appropriate error message. errbuf is assumed
to be able to hold at least PCAP_ERRBUF_SIZE chars.
pcap_fopen_offline_with_tstamp_precision() became available in
libpcap release 1.5.1. In previous releases, time stamps from a
savefile are always given in seconds and microseconds.
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 2021-08-27.
(At that time, the date of the most recent commit that was found
in the repository was 2021-08-17.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better 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
23 August 2018 PCAP_OPEN_OFFLINE(3PCAP)