PCAP_DUMP_OPEN(3)      FreeBSD Library Functions Manual      PCAP_DUMP_OPEN(3)

NAME

     pcap_dump_open, pcap_dump_open_append, pcap_dump_fopen - open a file to
     which to write packets

SYNOPSIS

     #include <pcap/pcap.h>

     pcap_dumper_t *pcap_dump_open(pcap_t *p, const char *fname);
     pcap_dumper_t *pcap_dump_open_append(pcap_t *p, const char *fname);
     pcap_dumper_t *pcap_dump_fopen(pcap_t *p, FILE *fp);

DESCRIPTION

     pcap_dump_open() is called to open a ``savefile'' for writing.  fname
     specifies the name of the file to open. The file will have the same
     format as those used by tcpdump(1) and tcpslice(1).  If the file does not
     exist, it will be created; if the file exists, it will be truncated and
     overwritten.  The name "-" is a synonym for stdout.

     pcap_dump_fopen() is called to write data to an existing open stream fp;
     this stream will be closed by a subsequent call to pcap_dump_close(3).
     The stream is assumed to be at the beginning of a file that has been
     newly created or truncated, so that writes will start at the beginning of
     the file.  Note that on Windows, that stream should be opened in binary
     mode.

     p is a capture or ``savefile'' handle returned by an earlier call to
     pcap_create(3) and activated by an earlier call to pcap_activate(3), or
     returned by an earlier call to pcap_open_offline(3), pcap_open_live(3),
     or pcap_open_dead(3).  The time stamp precision, link-layer type, and
     snapshot length from p are used as the link-layer type and snapshot
     length of the output file.

     pcap_dump_open_append() is like pcap_dump_open() but, if the file already
     exists, and is a pcap file with the same byte order as the host opening
     the file, and has the same time stamp precision, link-layer header type,
     and snapshot length as p, it will write new packets at the end of the
     file.

RETURN VALUE

     A pointer to a pcap_dumper_t structure to use in subsequent pcap_dump(3)
     and pcap_dump_close(3) calls is returned on success.  NULL is returned on
     failure.  If NULL is returned, pcap_geterr(3) can be used to get the
     error text.

BACKWARD COMPATIBILITY

     The pcap_dump_open_append() function became available in libpcap release
     1.7.2.  In previous releases, there is no support for appending packets
     to an existing savefile.

SEE ALSO

     pcap(3), pcap-savefile(5)

                                  3 July 2020                PCAP_DUMP_OPEN(3)