#!/usr/bin/perl -w

use strict;

sub read_utmp_record {
    my $file=shift;
    my $record;
    my $rawdata;   
    my $bytes=read($file, $rawdata, 2);
    if ($bytes==0) { #no more
	return 0;
    }
    $record->{ut_type}=unpack("s", $rawdata);
    read($file, $rawdata, 2); #skip
    read($file, $rawdata, 4);
    $record->{ut_pid}=unpack("I", $rawdata);
    $record->{ut_line}='';
    for (my $i=0; $i<32; $i++) {
	read($file, $rawdata, 1);
	$record->{ut_line}=$record->{ut_line}.unpack("a", $rawdata);
    }
    $record->{ut_id}='';
    for (my $i=0; $i<4; $i++) {
        read($file, $rawdata, 1);
        $record->{ut_id}=$record->{ut_id}.unpack("a", $rawdata);
    }
    $record->{ut_user}='';
    for (my $i=0; $i<32; $i++) {
        read($file, $rawdata, 1);
        my $c=unpack("a", $rawdata);
	$record->{ut_user}=$record->{ut_user}.unpack("a", $rawdata);
    }
    $record->{ut_host}='';
    for (my $i=0; $i<256; $i++) {
        read($file, $rawdata, 1);
        $record->{ut_host}=$record->{ut_host}.unpack("a", $rawdata);
    }
    read($file, $rawdata, 2);
    $record->{e_termination}=unpack("s", $rawdata);
    read($file, $rawdata, 2);
    $record->{e_exit}=unpack("s", $rawdata);
    read($file, $rawdata, 4);
    $record->{ut_session}=unpack("I", $rawdata);
    read($file, $rawdata, 4);
    $record->{tv_sec}=unpack("I", $rawdata);
    read($file, $rawdata, 4);
    $record->{tv_usec}=unpack("I", $rawdata);
    #let's ignore the rest for now
    read($file, $rawdata, 36);
    return $record;
}


open(UTMP_FILE, "/var/run/utmp") || die('');
binmode(UTMP_FILE);
my @a=();
while (my $record=read_utmp_record(\*UTMP_FILE)) {
    push(@a, $record);
}
close(UTMP_FILE);

foreach my $record (@a) {
    if ($record->{ut_type}==7) {
	print $record->{ut_user}, "\t", $record->{ut_line}, "\t", scalar(localtime($record->{tv_sec})), "\t", "($record->{ut_host})", "\n";
    }
}