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.TH PCAP_LIST_DATALINKS 3PCAP "25 July 2018"
.SH NAME
pcap_list_datalinks, pcap_free_datalinks \- get a list of link-layer header
types supported by a capture device, and free that list
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.ft B
int pcap_list_datalinks(pcap_t *p, int **dlt_buf);
void pcap_free_datalinks(int *dlt_list);
.ft
.fi
.SH DESCRIPTION
.B pcap_list_datalinks()
is used to get a list of the supported link-layer header types of the
interface associated with the pcap descriptor.
.B pcap_list_datalinks()
allocates an array to hold the list and sets
.IR *dlt_buf
to point to that array.
.LP
The caller is responsible for freeing the array with
.BR pcap_free_datalinks() ,
which frees the list of link-layer header types pointed to by
.IR dlt_list .
.LP
It must not be called on a pcap descriptor created by
.B \%pcap_create(3PCAP)
that has not yet been activated by
.BR \%pcap_activate(3PCAP) .
.SH RETURN VALUE
.B pcap_list_datalinks()
returns the number of link-layer header types in the array on success,
.B PCAP_ERROR_NOT_ACTIVATED
if called on a capture handle that has been created but not activated,
and
.B PCAP_ERROR
on other errors.
If
.B PCAP_ERROR
is returned,
.B pcap_geterr(3PCAP)
or
.B \%pcap_perror(3PCAP)
may be called with
.I p
as an argument to fetch or display the error text.
.SH SEE ALSO
pcap(3PCAP),
pcap_datalink_val_to_name(3PCAP),
pcap-linktype(7)