#!/usr/bin/perl
# tp-theft-lcars v0.1 (http://thinkwiki.org/wiki/Script_for_theft_alarm_using_HDAPS)
# This script uses the HDAPS accelerometer found on recent ThinkPad models
# to emit an audio alarm when the laptop is tilted. In sufficiently
# populated environments, it can be used as a laptop theft deterrent.
#
# This file is placed in the public domain and may be freely distributed.
#
# Here comes a modified version which requires an internet connection and gnash.
# It shows a LCARS red alert flash animation from Star Trek Voyager instead of a beep.
use strict;
use warnings;
##############################
# Audio volume (0..100)
my $volume = 70;
my $play_cmd = "gtk-gnash --fullscreen http://www.lcars.org.uk/lcars_files/LCARS_prey_emergency_scan_analysis.swf";
##############################
# Other tweakables
my $thresh = 0.20; # tilt threshold (increase value to decrease sensitivity)
my $interval = 0.1; # sampling interval in seconds
my $depth = 10; # number of recent samples to analyze
my $pos_file='/sys/devices/platform/hdaps/position';
my $verbose = 1;
##############################
# Code
sub get_pos {
open(POS,"<",$pos_file) or die "Can't open HDAPS file $pos_file: $!\n";
$_=<POS>;
m/^\((-?\d+),(-?\d+)\)$/ or die "Can't parse $pos_file content\n";
return ($1,$2);
}
sub stddev {
my $sum=0;
my $sumsq=0;
my $n=$#_+1;
for my $v (@_) {
$sum += $v;
$sumsq += $v*$v;
}
return sqrt($n*$sumsq - $sum*$sum)/($n*($n-1));
}
my (@XHIST, @YHIST);
my ($x,$y) = get_pos;
for (1..$depth) {
push(@XHIST,$x);
push(@YHIST,$y);
}
my $alarm_file; # flags ongoing alarm (and stores saved mixer settings)
while (1) {
my ($x,$y) = get_pos;
shift(@XHIST); push(@XHIST,$x);
shift(@YHIST); push(@YHIST,$y);
my $xdev = stddev(@XHIST);
my $ydev = stddev(@YHIST);
# Print variance and history
print "X: v=$xdev (".join(',',@XHIST).") Y: v=$ydev (".join(",",@YHIST).")\n" if $verbose>1;
my $tilted = $xdev>$thresh || $ydev>$thresh;
if ($tilted && !(defined($alarm_file) && -f $alarm_file)) {
print "ALARM\n" if $verbose>0;
$alarm_file = `mktemp /tmp/hdaps-tilt.XXXXXXXX` or die "mktemp: $?";
chomp($alarm_file);
system('/bin/bash', '-c', <<"EOF")==0 or die "Failed: $?";
($play_cmd) &
EOF
}
select(undef, undef, undef, $interval); # sleep
}