#!/usr/local/bin/perl

eval 'exec /usr/local/bin/perl  -S $0 ${1+"$@"}'
    if 0; # not running under some shell
#$Id: lclean,v 1.1.1.1 1998/02/25 21:13:00 schwartz Exp $
#
# lclean, Clean Structured Storage documents
#
# Copyright (C) 1997 Martin Schwartz 
#
# ATTENTION!
# 
# This program modifies some data in Structured Storage documents. Though I 
# think, the program works correctly, there might be errors or there might 
# be in future unpredictable changes in the document layout. Keep in mind, 
# that this program will change your document files! 
#
# Further more, this program can recognize only this garbage, that is not 
# specific to any special program. E.g., in Word 6 documents there are data 
# parts, that lclean can clean, and there are parts, that only Word could 
# clean. So please:
#
#    1. Keep a backup of all treated documents, until you are sure, 
#       that the cleaned documents are proper. 
#
#    2. Don't rely on, that *all* garbage will be cleaned.
#
# See also usage() of this file. General information at:
#    http://wwwwbs.cs.tu-berlin.de/~schwartz/pmh/index.html
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, you should find it at:
#
#    http://wwwwbs.cs.tu-berlin.de/~schwartz/pmh/COPYING
#
# You can contact me via schwartz@cs.tu-berlin.de
#

useress_global: {
#
# Please uncomment (remove '#') / change settings according to your system
#
   $global_targetdir = "doctrash"; # This is the output directory
}

sub error { $Startup->string() }

use Startup;
use Getopt::Std;
use OLE::Storage::Std;

global: {
   $|=1; $[=0;
   $REV = '$Revision: 1.1.1.1 $' =~ /: ([^ ]*)/ && $1;
   $DATE = '$Date: 1998/02/25 21:13:00 $' =~ / ..(..)\/(.{5})/ && "$2/$1";
   getopts ('acdefhi:lnrsz');
   usage() if !@ARGV || $opt_h;
   usage() if !@ARGV
      || $opt_h
      || !($opt_r||$opt_c||$opt_s||$opt_i||$opt_l||$opt_e)
   ;

   require OLE::Storage;

   $Startup = new Startup;
   $Var     = OLE::Storage->NewVar();	# Var Object
   $Doc     = undef;			# Document Object

   @crc32=();
   make_crc32_table();
   $hid_buf="";
   $hid_headerpart="";
}

main: {
   local($errnum); local($dont);
   local($status);
   local($fname);
   local($openmode)= ($opt_c||$opt_i) && 1;

   foreach $infile (@ARGV) {

      $errnum=0; $dont=0;

      print "Processing \"$infile\": ";
      next if !msg (
         $Doc = OLE::Storage->open($Startup, $Var, $infile, $openmode)
      );

      block_a: {
         if ($opt_r) {
            $dont++;
            $errnum++ if !msg (report_trash(-s $infile));
         }
         if ($opt_e) {
            print "Extracting...";
            ($status, $fname) = extract_hidden();
            $errnum++ if !msg ($status, "($fname)");
         }
         if ($opt_l) {
            $dont++;
            $errnum++ if !msg (list_hidden());
         } 
         if ($opt_s||$opt_d) {
            print "Saving... ";
            $errnum++ if !msg (save_all_trash($infile));
         }
      }

      if (!$errnum && !$dont) {
         if ($opt_c) {
            print "Cleaning...";
            ($status, $size) = clean_all_trash();
            msg ($status, "($size bytes)");
         }
         if ($opt_i) {
            print "Inserting... ";
            $status = insert_hidden($opt_i);
            print "Error!\n$status\n" if $status ne "ok";
         }
      }      
      $Doc->close($infile);
      print "Done.\n\n";
   }
   exit 0;
}


sub usage {
   print "\n";
   print "lclean  Modify trash sections of OLE documents, like Excel or Word.\n";
   print "        Version $REV from $DATE\n";
   print "usage:  lclean -r {document}              Report documents trash\n";
   print "        lclean -c [-n] {document}         Clean document\n";
   print "        lclean -s [-a][-d][-z] {document} Save documents trash sections\n";
   print "        lclean -i <file> [-a] {document}  Insert (hide) a file in OLE documents\n";
   print "        lclean -l {document}              List the hidden file in OLE documents\n";
   print "        lclean -e [-f][-z] {document}     Extract hidden file from OLE documents\n";
   print "-a  All. When saving the trash sections, use one big file.\n";
   print "    When inserting a hidden file, use all trash space (1+2+4+8).\n";
   print "-c  Clean trash sections. Will be done (after -s) and (before -i).\n";
   print "-d  Directory, store trash sections in own directory. ".
         "Eg \"test\" for \"test.doc\".\n";
   print "-e  Extract the hidden file out of OLE documents, if there is one.\n";
   print "-f  Force, always overwrite existing files when extracting.\n";
   print "-i  Insert a <file> into the document. Use only trash space (1+2).\n";
   print "-l  List the hidden file in OLE documents, if there is one.\n";
   print "-n  Null, use null bytes instead of random bytes for cleaning trash type 4.\n";
   print "-r  Report, gives a little report about the trash sections.\n";
   print "-s  Save all trash sections into directory \"$global_targetdir\".\n";
   print "-z  Zero, don't create zero length files.\n";
   print "\n";
   print "ATTENTION: when cleaning a document or when inserting a file into, ".
         "keep a\n".
         "           backup until you are sure, that the modified file will be ok!\n";
   print "\n";
   exit 0;
}


#
# ------------------- Report about trash sections ---------------------
#

sub report_trash {
    local($fsize)=shift;
    local($i);
    local(@l)=0;
    local($lsum)=0;
    local(@type) = ("Big blocks", "Small blocks", "File space", "System space");

    print "\n";
    print "Trash (and system) report:\n";
    for ($i=0; $i<=3; $i++) {
       $l[$i] = $Doc->size_trash(2**$i);
       printf ("   Type %d %15s %5d bytes\n", 
               2**$i, "(".$type[$i]."):", $l[$i]);
       $lsum+=$l[$i];
    }
    printf ("                 1+2:     %5d of %d bytes (%.1f %%)\n",
            $l[0]+$l[1], $fsize, 100*($l[0]+$l[1])/$fsize);
    printf ("                 1+2+4+8: %5d of %d bytes (%.1f %%)\n", 
            $lsum, $fsize, 100*($lsum/$fsize));
    "ok";
}

#
# ------------------ Save document trash into files -------------------
#

sub save_all_trash {
#
# Copies trash types to each a file as: 
# targetdir/basename.xx, where xx is the hex number the properties handle
#
   my $infile = shift;
   my $outpath = get_outpath($infile);
   return $Startup->err_str("No savepath given!\n") if !$outpath;
   my ($buf);

   # save block trash
   if (!$opt_a) {
      for (1..4) {
         $buf = "";
         return 0 if !$Doc->read_trash(1<<($_-1), \$buf);
         return 0 if !save_file($outpath.".tr$_", $buf);
      }
   } else {
      $buf = "";
      return 0 if !$Doc->read_trash(0, \$buf);
      return 0 if !save_file($outpath.".tra", $buf);
   }

1}

sub get_outpath {
#
# Get the path of the directory, where the trash sections shall be 
# stored. By default this is directory $global_targetdir. If command 
# line option "-d" is set, the directory is depending on the filename.
#
   my $basename = basename(shift);
   $global_targetdir = $basename if $opt_d;
   if (targetdir($global_targetdir)) {
      return $global_targetdir."/".$basename;
   } else {
      return "";
   }
}


#
# --------------------- Hidden file management -------------------------
#

#
# The "hidden" file is tried to be stored in trash type 1|2, that means in 
# the unused blocks. With option -a tries additionally type 8 and 4.
#
# Hidden file header:
#    0     1 byte   Used trash types
#    1     1 byte   magic = 0x38
#    2     4 bytes  mode of file (access permissions)
#    6     4 bytes  modification time of file
#   0a     4 bytes  size of file
#   0e     4 bytes  crc32 of file
#   12     2 bytes  = $fl == length of filename
#   14     $fl      filename
#   14+$fl filesize file
#

sub insert_hidden {
#
# "ok"||$error = insert_hidden($filepath)
#
   local($filepath)=shift;
   local($status,$fname) = readable_file($filepath);
   return $status if $status ne "ok";

   local($ttype, $tsize);
   local ($needed) = 0x14 + length($fname) + (-s $filepath);

   $ttype=1|2; 
   $tsize=$Doc->size_trash($ttype);
   if ($opt_a) {
      if ($tsize < $needed) {
         $ttype = 1|2|8; $tsize=$Doc->size_trash($ttype);
      }
      if ($tsize < $needed) {
         $ttype = 1|2|4|8; $tsize=$Doc->size_trash($ttype);
      }
   }
   if ($tsize < $needed) {
      return "Not enough trash space to insert \"$fname\"...";
   }

   $status = read_hidefile($filepath, $fname, $ttype);
   return $status if $status ne "ok";

   my $buf = byte($ttype).$hid_headerpart.$hid_buf;
   return "Error while inserting \"$filepath\" into document!" if
      !$Doc->modify_trash ($ttype, \$buf, 0, $needed)
   ;

   "ok";
}

sub read_hidefile {
#
# "ok"||error = read_hidefile ($filepath, $filename, $ttype)
#
# This works with global variables... The idea is, that the file to 
# hide will be read only once, if more than one document shall be 
# treated. Especially the crc32 has to be calculated then only once.
#
   return "ok" if $hid_headerpart;

   local($filepath, $fname, $ttype)=@_;
   local($crc);
   local($mode, $mtime) = (stat($filepath))[2,9];
   local($status)="ok";

   if (open(IO, $filepath)) {
      binmode(IO);
      if (read(IO, $hid_buf, -s $filepath) == -s $filepath) {
         $crc = get_crc32(\$hid_buf);
         $hid_headerpart = struct("BLLLLW", 
            [0x38, $mode, $mtime, -s $filepath, $crc, length($fname)]
         );
         $hid_headerpart .= $fname;
      } else {
         $status="Error while reading \"$filepath\"!";
      }
      close(IO);
   }
   $status;
}

sub list_hidden {
#
# void = list_hidden()
#
   local($ttype, @header)=get_hidden();
   if (!$ttype) {
      print "\nHidden file report:\n".
            "   No hidden file stored.\n";
      return "ok";
   }
   local($fname)="";
   local($status)="";

   local($ttype, $magic, $mode, $mtime, $fsize, $crc, $fnsize)=@header;
   return "Input error while retrieving information!" if 
      !$Doc->read_trash($ttype, \$fname, 0x14, $fnsize)
   ;

   local(@tim) = localtime($mtime);
   printf ("\nHidden file report:\n".
           "   Trash type is %d\n".
           "   %5d %02d/%02d/%02d %02d:%02d %s\n",
           $ttype,
           $fsize, 
           $tim[4]+1, $tim[3], $tim[5],
           $tim[2], $tim[1],
           $fname);
   "ok";
}

sub extract_hidden {
#
# ("ok"||error, $filename) = extract_hidden()
#
# Saves the file from a document to normal file system.
# - The document will not be modified. 
#
   local($ttype, @header)=get_hidden();
   return ("ok", "nothing to do") if !$ttype;

   local($fname)="";
   local($file)="";
   local($status)="";

   local($ttype, $magic, $mode, $mtime, $fsize, $crc, $fnsize)=@header;

   return "Input error while retrieving information!" if 
      !$Doc->read_trash($ttype, \$fname, 0x14, $fnsize)
   ;

   return "Error while reading data!" if 
      !$Doc->read_trash($ttype, \$file, 0x14+$fnsize, $fsize)
   ;

   return "File is corrupt!" if get_crc32(\$file) != $crc;

   return "Cannot save to file \"$fname\"!" if !replaceable_file($fname);
   $status = check_replace_file($fname);
   return ("ok", "") if !$status;

   return 0 if !save_file($fname, $file);
   chmod ($mode, $fname);
   utime (time, $mtime, $fname);

   return ("ok", $fname);
}


sub try_hidden {
#
# @header||() = try_hidden($ttype);
#
   local($ttype)=shift;
   local($header)="";
   local(@header);
   local(@empty)=();
   check: {
      my ($pstr, $plen) = packpar("BBLLLLW");
      last if !$Doc->read_trash($ttype, \$header, 0, $plen);
      @header = unpack ($pstr, $header);
      last if $header[0] != $ttype;
      last if $header[1] != 0x38;
      last if $header[4] > $Doc->size_trash($ttype);
      return @header;
   }
   return @empty;
}

sub get_hidden {
#
# ($ttype||0, @header) = get_hidden();
#
   local($ttype)=0;
   local(@header)=();

   if (@header = try_hidden(1|2)) {
      $ttype = 1|2;
   } elsif (@header = try_hidden(1|2|8)) {
      $ttype = 1|2|8;
   } elsif (@header = try_hidden(1|2|4|8)) {
      $ttype = 1|2|4|8;
   }
   return ($ttype, @header);
}


#
# ------------------------- Clean document -----------------------------
#

sub clean_all_trash {
#
# ($status, $allsize_trash) = clean_all_trash();
#
# Cleans trash types with different values
#
   local($bufsize, $status);
   local($allsize_trash)=0;

   clean: {
      # Free blocks. I prefer the byte "\00"
      ($status, $bufsize) = clean_trash(1|2, "\00");
      last if $status ne "ok";
      $allsize_trash += $bufsize;

      # Clean file trash, I prefer random strings. 
      # ("random" is a special word for clean_trash)
      ($status, $bufsize) = clean_trash(4, "random");
      last if $status ne "ok";
      $allsize_trash += $bufsize;

      # Unused system bytes, value 0xff looks nice
      ($status, $bufsize) = clean_trash(8, "\xff");
      last if $status ne "ok";
      $allsize_trash += $bufsize;
   }

   return ($status, $allsize_trash);
}

sub clean_trash {
#
# ("ok"||error, $bufsize) = clean_trash($type, $fill);
#
# The trash of type $type will be filled with the pattern of string $fill.
# If the $fill is "random", the trash will be filled with random bytes.
#
   local($type, $fill)=@_;
   local($buf, $bufsize, $status);
   $buf="";
   $bufsize = $Doc->size_trash($type);

   if ($fill =~ /^random$/i) {
      if (!$opt_n) {
         new_random_seed();
         $buf=get_random_shuffle_string(get_random_shuffle_sizes($bufsize));
      } else {
         $buf="\00" x $bufsize;
      }
   } else {
      $buf = $fill x ( int($bufsize/length($fill)) );
   }
   $buf .= substr($fill, 0, $bufsize % length($fill));

   $status = $Doc->modify_trash($type, \$buf, 0, $bufsize) && "ok"
      || error()
   ;
 
   return ($status, $bufsize);
}

#
# ------------------- (More or) Less Random Support ---------------------
#

sub new_random_seed {
#
# Random seed. *Not* secure!
#
   srand(time^$$);
}

sub get_random_shuffle_sizes {
#
# @size = &get_random_shuffle_sizes($size);
#
# Returns a list of randomly yielded sizes, that together have a 
# length of $size.
#
   local($maxsize)=shift;
   local(@size, $size, $chunk);

   local($chunk_avgnum) = 5 + int(rand(10)) + int(rand($maxsize/0x2000));
   local($avgsize) = int($maxsize/$chunk_avgnum);

   @size=(); $size=0;
   while ($size < $maxsize) {
      $chunk = int( rand($avgsize*2) );
      $chunk = ($maxsize - $size) if (($size+$chunk) > $maxsize);
      $size += $chunk;
      push (@size, $chunk);
   }
   return @size;
}

sub get_random_shuffle_string {
#
# $buf = &get_random_shuffle_string(@sizes);
#
# Return one string consisting out of $#sizes substrings, each 
# consisting out of $sizes[$i] random bytes.
#
   local($buf)="";
   foreach $size (@_) {
      $buf .= get_random_string($size);
   }
   random_shuffle_string($buf);
}

sub get_random_string {
#
# $buf = get_random_string($size)
#
# Return one string consisting out $size random bytes.
#
   local($len)=shift;
   local($buf)=""; 
   local($i); 
   for ($i=0; $i<$len; $i++) {
      $buf .= byte(rand(256));
   }
   $buf;
}

sub random_shuffle_string {
#
# $shuffled_buf = random_shuffle_string($buf);
# 
# Permutates the elements of $buf randomly.
#
   local($len)=length($_[0]);
   local($sbuf)=""; local(%sbuf)=();

   # Get a $len elements sized hash 
   # (hash == perl slang for associative array)
   # Keys are random integer numbers, values are elements of $buf.
   # Took integers, because sort is to slow for big lists of real.
   # 
   local($key); local($i)=0;
   while ($i < $len) {
      $key=int(rand($len*191));
      if (!$sbuf{$key}) {
         $sbuf{$key} = substr($_[0], $i++, 1);
      }
   }
   # Sort the hash array according to it's keys, create the buffer.
   for (sort {$a <=> $b} keys %sbuf) {
      $sbuf .= $sbuf{$_}; 
   }

   $sbuf;
}

#
# -------------------------- File treatment ----------------------------
#

sub targetdir {
#
# If none exists, create a target directory. This will be readable 
# only to the person owning the directory.
#
   local($dir)=shift;
   return 1 if -d $dir;
   if (mkdir $dir, 0700) {
      print "(created directory \"$global_targetdir\") "; 1;
   } else {
      print "Cannot create directory \"$global_targetdir\"!\n"; 0;
   }
}

sub save_file {
#
# 1||0 = save_file($path, $buf);
#
   if ($opt_z) {
      return 1 if !$_[1];
   }
   if (! (open(OUT, '>'.$_[0]) && binmode(OUT)) ) {
      $Startup->err_str("Cannot save to file \"$_[0]\"!");
      return 0;
   }
   print OUT $_[1];
   close(OUT); 
1}

sub replaceable_file {
#
# 1||0 = check_replaceable_file($filename)
#
   local($file)=shift;
   if (-e $file) {
      return 0 if !-f $file;
      return 0 if !-w $file;
   }
   1;
}

sub check_replace_file {
#
# 1||0 = check_replace_file($filename)
#
   local($file)=shift;
   local($key)="";

   return 1 if $opt_f;
   return 1 if !-e $file;
   return 0 if !-f $file;
   return 0 if !-w $file;
   print "\nFile \"$file\" exists. Replace it? (y/n) ";
   while (1) {
      last if ($key=getc) =~ /[yn]/;
      print "(y/n) " if $key eq "\x0a";
   }
   getc; # get \x0a from userEss input
   $key =~ /y/;
}

sub readable_file {
#
# ("ok"||error, $filename) = readable_file($filepath);
#
   local($filepath)=shift;
   return "No file given!"                if !$filepath;
   return "\"$filepath\" does not exist!" if !-e $filepath;
   return "\"$filepath\" is no file!"     if !-f $filepath;
   return "Cannot read \"$filepath\"!"    if !-r $filepath;
   local($fname)=substr($filepath, rindex($filepath,'/')+1);
   return ("ok", $fname);
}

#
# ------------------------------- CRC ---------------------------------
#

sub make_crc32_table {
#
# void = make_crc32_table()
#
   return if @crc32;
   local($crc, $i);
   for ($i=0; $i<=0xff; $i++) {
      $crc = $i;
      for (1 .. 8) { 
         if ($crc & 1) {
            ($crc /= 2) ^= 0xedb88320; 
         } else {
            $crc /= 2;
         }
      }
      push (@crc32, $crc);
   }
}

sub get_crc32 {
#
# $crc = &crc32 (\$buf)
#
# Computes a 32bit CRC for the specified buf. This might take some time!
#
   my $bufR = shift;
   my $crc = 0xffffffff;
   my @buf = get_nbyte(length($$bufR), $bufR, 0);
   while (@buf) {
      $crc = $crc32[$crc&0xff ^ shift(@buf)] ^ ($crc/0x100);
   }
   $crc;
}

#
# ------------------------------ utils --------------------------------
#

sub msg {
   local($status) = shift;
   if ($status) {
      if (defined $_[0]) {
         print "$_[0] ";
      }
      return 1;
   } else {
      $status = error();
      if ($status) {
         print "error!\nError: $status\n";
      } else {
         print "error!\n";
      }
      print "\n" if ! ($status =~ /\n$/);
      return 0;
   }
}

__END__

=head1 NAME

lclean - Detect and clean trash in Structured Storage documents

=head1 SYNOPSIS

lclean C<-r> || C<-c> || C<-s> || C<-i> || C<-l> || C<-e> document

I<Note!>
If you use switch C<-c> or C<-i>, lclean changes your document! Please keep
a backup of the treated documents, until you are sure they did not take any
harm! 

=head1 DESCRIPTION

lclean deals with documents created typically with MS Windows applications.
It gives a report about the trash sections in those "OLE / Structured
Storage" documents, cleans this trash or saves it to files. Further more a
file can be hidden into and extracted from those trash sections. 

=over 4

=item clean

lclean C<-c> [C<-n>] {document}

The trash sections will be cleaned. Unused blocks are filled with null
bytes. System data will be cleaned with 0xff bytes. File end trash 
(type 4) will be cleaned with random bytes. When using switch C<-n>, file 
end trash also will be filled with zero bytes (faster on files with 
lots of embedded objects).

=item extract

lclean C<-e> [C<-f>] [C<-z>] {document}

Extracts the hidden file. This makes a copy of the hidden file. If the file
got corrupted by what reason ever, it will not be extracted. The file will
get the date of its last modification. If the file already exists, you will
be prompted to overwrite it with the new extracted file. With switch C<-f>
you will not be prompted, but the file will be overwritten. With switch C<-z> 
no zero length files will be created.

=item insert

lclean C<-i> <file> [C<-a>] {document}

Insert a file into the document (hide it).
The trash in your document will be substituted by some <file>. This file
cannot be seen by any standard Windows application. The file must be smaller,
than the size of the trash in your documents (plus 20 bytes plus the size to
store the filename). Normally, only trash types 1 and 2 will be used for
this. If they offer not enough space, with switch C<-a> trash type 4 and 8
will be used additionally.

=item list

lclean C<-l> {document}

List if there is a file hidden in the documents trash.

=item report

lclean C<-r> {document}

Gets a small report about the trash in the documents.

=item save 

lclean C<-s> [C<-a>] [C<-d>] [C<-z>] {document}

The trash sections will be saved to own files. They will be stored to an
directory in your current directory. Normally it will be the directory
"C<doctrash>". E.g., if there is the example file "C<legacy.doc>" the
trashfiles will be stored as: "C<doctrash/legacy.tr1>",
"C<doctrash/legacy.tr2>", "C<doctrash/legacy.tr3>" and
"C<doctrash/legacy.tr4>".

=over 4

=item C<-a>

All trash will be stored into one big file "C<doctrash/legacy.tra>".

=item C<-d>

The trash file(s) will not be stored into directory "C<doctrash>",
but each into an own directory. E.g. into directory "C<legacy/>".

=item C<-z>

When using switch C<-z>, zero length files will not be created.

=back
=back

=head1 EXAMPLES

=over 4

=item lclean C<-cs> {document}

This would first save all trash chunks into separate files into 
directory "C<doctrash>", then it would clean the document.

=item lclean C<-aci> <file> {document}

This would first clean the document, then insert the hidden file by using
all trash types.

=back

=head1 HISTORY

Microsoft's first and still most spread OLE implementations had bugs. One
caused that some sections of documents that actually should be filled with
zero bytes contained more or less private data.

Management of OLE documents is a little bit difficult and takes some 
time. A way to fasten this up is not to care about the old data, but
simply to add the new data to the document. Cleaning up could be done later.
When switched on the "fast save" option, Microsoft Word uses this strategy.
So, thus saved files contain the new and the old version of a document. The
old data cannot be edited any more and stays invisible in the document.

Some programs seem to use the Microsoft OLE library not properly. 
For example, the Star Office 3.1. programs create documents, that 
always contain 1024 bytes of trash.

As far as I know, Microsoft offers a bugfix for 32 bit Windows 
systems, only.

The program "lclean" can access this kind of garbage in OLE documents. 
To do this it uses the C<modify_trash> method of OLE::Storage.
This library decides between four different types of trash. 

Overview:

=over 4

=item Type 1

Unused "big blocks". These blocks are not used by the document. Each of 
these blocks is 512 bytes long.

=item Type 2

Unused "small blocks". These blocks are not used by the document. Each of 
these blocks is 64 bytes long.

=item Type 4

File end space. This refers to the "streams" of an OLE document.
The space is made up of all the space between the end of a stream
and the end of a block.

=item Type 8

System space. These sections are required by file format, though
they are not used by OLE system. Actually this data is no garbage. 

=back

=head1 SEE ALSO

L<OLE::Storage>

=head1 AUTHOR

Martin Schwartz E<lt>F<schwartz@cs.tu-berlin.de>E<gt>. 

=cut