#!/usr/bin/perl -w

# Randolph Langley, FSU, 2014

# a trivial Perl script to check if filesystem numbers obey Benford's law

#

use strict;
use File::stat;

my @counts; # the obvious; 1-> counts initial one's, 2-> counts initial two's

my $dir = ".";


if(defined($ARGV[0]))
{
    $dir = $ARGV[0];
    chdir($dir);
}

my $s = stat($dir);
my $devicenumber = $s->dev;
print "Device number is $devicenumber\n";


sub do_count
{
    my $dir = shift;

    my $s = stat($dir);
    return if ($s->dev != $devicenumber); # make sure that we didn't change devices

    chdir($dir) or return;
    opendir(DH,".") or goto end;
    my @entries = readdir(DH) or goto end;
    close(DH);
    foreach(@entries)
    {
	next if($_ eq ".");
	next if($_ eq "..");
	next if(-l $_);
	if(-f $_)
	{
	    my $st = stat($_) or next;
	    my $size = $st->size;
	    my $index = substr($size,0,1);
	    $counts[$index]++;
	}
	if(-d $_)
	{
	    do_count($_);
	}
    }
end:
    chdir("..");		  
}


&do_count($dir);

print("Starts with\n");
my $i;
my $sum = 0;
for($i=0;$i<10;$i++)
{
    $sum+=$counts[$i];
}

for($i=1;$i<10;$i++)
{
    my $ratio = $counts[$i] / $sum * 100;
    printf("  $i --> $counts[$i] times (%5.2f)\n",$ratio) if(defined($counts[$i]));
}
my $ratio = $counts[0] / $sum * 100;
printf("  0 --> $counts[0] times (%5.2f)\n",$ratio) if(defined($counts[$i]));