#!/usr/bin/perl
print "################################\n";
print "# wiperand.pl                  #\n";
print "# -----------                  #\n";
print "#                              #\n";
print "# File/Device wiper            #\n";
print "# 2006 phormix.com/Tyler Aviss #\n";
print "#                              #\n";
print "# (you probably should not use #\n";
print "#  this file unless you know   #\n";
print "#  what you are doing! I will  #\n";
print "#  not be held responsible if  #\n";
print "#  you erase something         #\n";
print "#  important!)                 #\n";
print "#                              #\n";
print "# Press CTRL+C now or continue #\n";
print "# at your own risk!!!          #\n";
print "#                              #\n";
print "################################\n\n";

$start=`date`;
$device=$ARGV[0];
$size=$ARGV[1];
$sizekb = $size/1000;
$onepercent = $size / 100;
$chunksize=10;

if ($device eq "" )
{
  print "No device specified\n";
  print "Usage $0 DEVICEorFILE SIZE\n\n";
  exit;
}

if ($size < 1 )
{
  print "Invalid/missing size\n";
  print "Usage $0 DEVICEorFILE SIZE\n\n";
  exit;
}
main();

sub main
{
  print "\n\n\n";
  print "File $device will be overwritten with $size bytes ($sizekb " . "kb) of semi-random data. Continue?\n";
  print "\n";
  print "(y/n): ";
  while (($key=getc) ) 
  {
    print "$key\n";
    last if $key ne "";
  };
  
  if ( $key ne "y" )
  {
    print "\nAborted by user\n\n";
    exit;
  }
  
  #if ( -b $device )
  #{
  #  print "$device is a device. This might be a partition or even a full disk. Are you REALLY sure you want to delete it?\n\n(y/n): ";
  #  
  #  while (($key2=getc) ) 
  #  {
  #    print "$key2\n";
  #    last if $key2 ne "";
  #   };
  # 
  #  if ( $key2 ne "y" )
  #  {
  #    print "\nAborted by user\n\n";
  #    exit;
  #  }
  #}
  
  if (  -f "/tmp/tmpfifo" )
  {
    `rm -f /tmp/tmpfifo`;
  }
  `mkfifo /tmp/tmpfifo`;

  
  unless ($pid = fork) {
    unless (fork) {
      #print "Fork-->\n";
      #exec "what you really wanna do";
      print "Creating process to dump FIFO\n";
      `dd if=/tmp/tmpfifo of=$device bs=1b count=$size`;
      print "End FIFO dump\n";
      exit 0;
    }
    exit 0;
  }
  print "Done\n";
  print "Creating process to generate random data\n";
  open(OUTFIFO, '>/tmp/tmpfifo');

  $written=0;
  print "-- Need to write $size bytes ($sizekb kb) of data...\n\n";
  while ($size > 0)
  {
    if ($size < $chunksize)
    {
      $chunksize = $size;
    }

    
    $chars = generate_random_string($chunksize);
    print OUTFIFO $chars;
    $written += $chunksize;
    
    $size-=$chunksize;
    if ($written % 100000 == 0 )
    {
      print "-- " . ($written/1000) . "kb written (" . ($size/1000) . " kb left)\n";
    }
  }
  close (OUTFIFO);
  print "done randomizing process\n";
  waitpid($pid,0);
  $end = `date`;
  print "Started $start\n";
  print "Ended $end\n";
  print "Generated and copied $size bytes ($sizekb kb) of semi-random data over $device\n";
}

# This function generates random strings of a given length
sub generate_random_string
{
  my $length_of_randomstring=shift;# the length of 
  # the random string to generate

  my @chars=('a'..'z','A'..'Z','0'..'9','_',"\n");
  my $random_string;
  foreach (1..$length_of_randomstring) 
  {
    # rand @chars will generate a random 
    # number between 0 and scalar @chars
    $random_string.=$chars[rand @chars];
  }
return $random_string;
}