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.TH PCAP_INIT 3PCAP "17 January 2023"
.SH NAME
pcap_init \- initialize the library
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.nf
.ft B
char errbuf[PCAP_ERRBUF_SIZE];
.ft
.LP
.ft B
int pcap_init(unsigned int opts, char *errbuf);
.ft
.fi
.SH DESCRIPTION
.BR pcap_init ()
is used to initialize the Packet Capture library.
.I opts
specifies options for the library;
.I errbuf
is a buffer large enough to hold at least
.B PCAP_ERRBUF_SIZE
chars.
.PP
Currently, the options that can be specified in
.I opts
are:
.TP
.B PCAP_MMAP_32BIT
Map packet buffers with 32-bit addresses.
.TP
.B PCAP_CHAR_ENC_LOCAL
Treat all strings supplied as arguments, and return all strings to the
caller, as being in the local character encoding.
.TP
.B PCAP_CHAR_ENC_UTF_8
Treat all strings supplied as arguments, and return all strings to the
caller, as being in UTF-8.
.PP
On UNIX-like systems, the local character encoding is assumed to be
UTF-8, so no character encoding transformations are done.
.PP
On Windows, the local character encoding is the local ANSI code page.
.PP
If
.BR pcap_init ()
is not called, strings are treated as being in the local ANSI code page
on Windows,
.BR pcap_lookupdev (3PCAP)
will succeed if there is a device on which to capture, and
.BR pcap_create (3PCAP)
makes an attempt to check whether the string passed as an argument is a
UTF-16LE string - note that this attempt is unsafe, as it may run past
the end of the string - to handle
.BR pcap_lookupdev ()
returning a UTF-16LE string. Programs that don't call
.BR pcap_init ()
should, on Windows, call
.BR pcap_wsockinit ()
to initialize Winsock; this is not necessary if
.BR pcap_init ()
is called, as
.BR pcap_init ()
will initialize Winsock itself on Windows.
.SH RETURN VALUE
.BR pcap_init ()
returns
.B 0
on success and
.B PCAP_ERROR
on failure.
If
.B PCAP_ERROR
is returned,
.I errbuf
is filled in with an appropriate error message.
.SH BACKWARD COMPATIBILITY
This function became available in libpcap release 1.9.0.  In previous
releases, on Windows, all strings supplied as arguments, and all strings
returned to the caller, are in the local character encoding.
.SH SEE ALSO
.BR pcap (3PCAP)