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  20 .TH PCAP_INIT 3PCAP "11 April 2020"
  21 .SH NAME
  22 pcap_init \- initialize the library
  23 .SH SYNOPSIS
  24 .nf
  25 .ft B
  26 #include <pcap/pcap.h>
  27 .ft
  28 .LP
  29 .nf
  30 .ft B
  31 char errbuf[PCAP_ERRBUF_SIZE];
  32 .ft
  33 .LP
  34 .ft B
  35 int pcap_init(unsigned int opts, char *errbuf);
  36 .ft
  37 .fi
  38 .SH DESCRIPTION
  39 .BR pcap_init ()
  40 is used to initialize the Packet Capture library.
  41 .I opts
  42 specifies options for the library;
  43 currently, the options are:
  44 .TP
  45 .B PCAP_CHAR_ENC_LOCAL
  46 Treat all strings supplied as arguments, and return all strings to the
  47 caller, as being in the local character encoding.
  48 .TP
  49 .B PCAP_CHAR_ENC_UTF_8
  50 Treat all strings supplied as arguments, and return all strings to the
  51 caller, as being in UTF-8.
  52 .PP
  53 On UNIX-like systems, the local character encoding is assumed to be
  54 UTF-8, so no character encoding transformations are done.
  55 .PP
  56 On Windows, the local character encoding is the local ANSI code page.
  57 .PP
  58 If
  59 .BR pcap_init ()
  60 is not called, strings are treated as being in the local ANSI code page
  61 on Windows,
  62 .BR pcap_lookupdev (3PCAP)
  63 will succeed if there is a device on which to capture, and
  64 .BR pcap_create (3PCAP)
  65 makes an attempt to check whether the string passed as an argument is a
  66 UTF-16LE string - note that this attempt is unsafe, as it may run past
  67 the end of the string - to handle
  68 .BR pcap_lookupdev ()
  69 returning a UTF-16LE string. Programs that don't call
  70 .BR pcap_init ()
  71 should, on Windows, call
  72 .BR pcap_wsockinit ()
  73 to initialize Winsock; this is not necessary if
  74 .BR pcap_init ()
  75 is called, as
  76 .BR pcap_init ()
  77 will initialize Winsock itself on Windows.
  78 .SH RETURN VALUE
  79 .BR pcap_init ()
  80 returns 0 on success and \-1 on failure.
  81 If \-1 is returned,
  82 .I errbuf
  83 is filled in with an appropriate error message.
  84 .I errbuf
  85 is assumed to be able to hold at least
  86 .B PCAP_ERRBUF_SIZE
  87 chars.
  88 .SH SEE ALSO
  89 .BR pcap (3PCAP)