source: gsdl/trunk/bin/script/gsConvert.pl@ 19763

#!/usr/bin/perl -w

###########################################################################
#
# gsConvert.pl -- convert documents to HTML or TEXT format
#
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright (C) 1999-2002 New Zealand Digital Library Project
#
# 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, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
###########################################################################

# gsConvert.pl converts documents in a range of formats to HTML or TEXT
# by exploiting third-party programs.  The sources of these are usually found
# in the $GSDLHOME/packages directory, and the executables should live in
# $GSDLHOME/bin/$GSDLOS (which is on the search path).
#
# Currently, we can convert the following formats by using external
# conversion utilities:
# Microsoft Word (versions 2,6,7 [==95?], 8[==97?], 9[==2000?]), RTF,
# Adobe PDF, PostScript, MS PowerPoint (95 and 97), and MS Excel (95 and 97).
#
# We can try to convert any file to text with a perl implementation of the
# UNIX strings command.
#
# We try to convert Postscript files to text using "gs" which is often on
# *nix machines. We fall back to performing weak text extraction by using
# regular expressions.

BEGIN {
    die "GSDLHOME not set\n" unless defined $ENV{'GSDLHOME'};
    unshift (@INC, "$ENV{'GSDLHOME'}/perllib");
}

use parsargv;
use util;
use Cwd;
use File::Basename;

# Are we running on WinNT or Win2000 (or later)?
my $is_winnt_2000=eval {require Win32; return (Win32::IsWinNT()); return 0;};
if (!defined($is_winnt_2000)) {$is_winnt_2000=0;}

my $use_strings;
my $pdf_complex;
my $pdf_nohidden;
my $pdf_zoom;
my $pdf_ignore_images;
my $pdf_allow_images_only;
my $windows_scripting;

sub print_usage
{
    print STDERR "\n";
    print STDERR "gsConvert.pl: Converts documents in a range of formats to html\n";
    print STDERR "              or text using third-party programs.\n\n";
    print STDERR "  usage: $0 [options] filename\n";
    print STDERR "  options:\n\t-type\tdoc|dot|pdf|ps|ppt|rtf|xls\t(input file type)\n";
    print STDERR "\t-errlog\t<filename>\t(append err messages)\n";
    print STDERR "\t-output\tauto|html|text|pagedimage_jpg|pagedimage_gif|pagedimage_png\t(output file type)\n";
    print STDERR "\t-timeout\t<max cpu seconds>\t(ulimit on unix systems)\n";
    print STDERR "\t-use_strings\tuse strings to extract text if conversion fails\n";
    print STDERR "\t-windows_scripting\tuse windows script when converting Microsoft Word and PPT via VB script\n";
    print STDERR "\t-pdf_complex\tuse complex output when converting PDF to HTML\n";
    print STDERR "\t-pdf_nohidden\tDon't attempt to extract hidden text from PDF files\n";
    print STDERR "\t-pdf_ignore_images\tdon't attempt to extract images when\n";
    print STDERR "\t\tconverting PDF to HTML\n";
    print STDERR "\t-pdf_allow_images_only\tallow images only (continue even if no text is present when converting to HTML)\n";
    print STDERR "\t-pdf_zoom\tfactor by which to zoom PDF (only useful if\n";
    print STDERR "\t\t-pdf_complex is set\n";
    exit(1);
}

my $faillogfile="";
my $timeout=0;

sub main
{
    my (@ARGV) = @_;
    my ($input_type,$output_type,$verbose);

    # read command-line arguments
    if (!parsargv::parse(\@ARGV,
             'type/(doc|dot|pdf|ps|ppt|rtf|xls)/', \$input_type,
             '/errlog/.*/', \$faillogfile,
             'output/(auto|html|text|pagedimage).*/', \$output_type,
             'timeout/\d+/0',\$timeout,
             'verbose/\d+/0', \$verbose,
             'use_strings', \$use_strings,
             'windows_scripting',\$windows_scripting,
             'pdf_complex', \$pdf_complex,
             'pdf_ignore_images', \$pdf_ignore_images,
             'pdf_allow_images_only', \$pdf_allow_images_only,
             'pdf_nohidden', \$pdf_nohidden,
             'pdf_zoom/\d+/2', \$pdf_zoom
             ))
    {
    print_usage();
    }
      
    # Make sure the input file exists and can be opened for reading
    if (scalar(@ARGV!=1)) {
    print_usage();
    }

    my $input_filename = $ARGV[0];
    if (!-r $input_filename) {
    print STDERR "Error: unable to open $input_filename for reading\n";
    exit(1);
    }

    # Deduce filenames
    my ($tailname,$dirname,$suffix) 
    = File::Basename::fileparse($input_filename, "\\.[^\\.]+\$");
    my $output_filestem = &util::filename_cat($dirname, "$tailname");

    if ($input_type eq "")
    {
    $input_type = lc (substr($suffix,1,length($suffix)-1));
    }
    
    # Change to temporary working directory
    my $stored_dir = cwd();
    chdir ($dirname) || die "Unable to change to directory $dirname";

    # Select convert utility
    if (!defined $input_type) {
    print STDERR "Error: No filename extension or input type defined\n";
    exit(1);
    } 
    elsif ($input_type eq "doc" || $input_type eq "dot") {
    print &convertDOC($input_filename, $output_filestem, $output_type);
    print "\n";
    } 
    elsif ($input_type eq "rtf") {
    print &convertRTF($input_filename, $output_filestem, $output_type);
    print "\n";
    } 
    elsif ($input_type eq "pdf") {
    print &convertPDF($dirname, $input_filename, $output_filestem, $output_type);
    print "\n";
    } 
    elsif ($input_type eq "ps") {
    print &convertPS($input_filename, $output_filestem, $output_type);
    print "\n";
    } 
    elsif ($input_type eq "ppt") {
    print &convertPPT($input_filename, $output_filestem, $output_type);
    print "\n";
    } 
    elsif ($input_type eq "xls") {
    print &convertXLS($input_filename, $output_filestem, $output_type);
    print "\n";
    } 
    else {
    print STDERR "Error: Unable to convert type '$input_type'\n";
    exit(1);
    }
    
    # restore to original working directory
    chdir ($stored_dir) || die "Unable to return to directory $stored_dir";

}

&main(@ARGV);



# Document-type conversion functions
#
# The following functions attempt to convert documents from their
# input type to the specified output type.  If no output type was
# given, then they first attempt HTML, and then TEXT.
#
# Each returns the output type ("html" or "text") or "fail" if no 
# conversion is possible.

# Convert a Microsoft word document

sub convertDOC {
    ($input_filename, $output_filestem, $output_type) = @_;

    # Many .doc files are not in fact word documents!
    my $realtype = &find_docfile_type($input_filename);

    if ($realtype eq "word6" || $realtype eq "word7" || $realtype eq "word8") {
    return &convertWord678($input_filename, $output_filestem, $output_type);
    } elsif ($realtype eq "rtf") {
    return &convertRTF($input_filename, $output_filestem, $output_type);
    } else {
    return &convertAnything($input_filename, $output_filestem, $output_type);
    }
}

# Convert a Microsoft word 6/7/8 document

sub convertWord678 {
    ($input_filename, $output_filestem, $output_type) = @_;

    my $success = 0;
    if (!$output_type || ($output_type =~ m/html/i)){
    if ($windows_scripting) {
        $success = &native_doc_to_html($input_filename, $output_filestem);
    }
    else {
        $success = &doc_to_html($input_filename, $output_filestem);    
    }
    if ($success) {
       return "html";
    }
    }
    return &convertAnything($input_filename, $output_filestem, $output_type);
}


# Convert a Rich Text Format (RTF) file

sub convertRTF {
    ($input_filename, $output_filestem, $output_type) = @_;

    my $success = 0;

    # Attempt specialised conversion to HTML
    if (!$output_type || ($output_type =~ m/html/i)) {

    if ($windows_scripting) {
        $success = &native_doc_to_html($input_filename, $output_filestem);
    }
    else {
        $success = &rtf_to_html($input_filename, $output_filestem);
    }
    if ($success) {
        return "html";
    }
    }

# rtf is so ugly that's it's not worth running strings over.
# One day I'll write some quick'n'dirty regexps to try to extract text - jrm21
#    return &convertAnything($input_filename, $output_filestem, $output_type);
    return "fail";
}


# Convert an unidentified file

sub convertAnything {
    ($input_filename, $output_filestem, $output_type) = @_;
    
    my $success = 0;
  
    # Attempt simple conversion to HTML
    if (!$output_type || ($output_type =~ m/html/i)) {
    $success = &any_to_html($input_filename, $output_filestem);
    if ($success) {
        return "html";
    }
    }

    # Convert to text
    if (!$output_type || ($output_type =~ m/text/i)) {
    $success = &any_to_text($input_filename, $output_filestem);
    if ($success) {
        return "text";
    }
    }
    return "fail";
}



# Convert an Adobe PDF document

sub convertPDF {
    my ($dirname, $input_filename, $output_filestem, $output_type) = @_;

    my $success = 0;
    $output_type =~ s/.*\-(.*)/$1/i;
    # Attempt coversion to Image
    if ($output_type =~ m/jp?g|gif|png/i) {
    $success = &pdfps_to_img($dirname, $input_filename, $output_filestem, $output_type);
    if ($success){
        return "item";
    }
    }

    # Attempt conversion to HTML
    if (!$output_type || ($output_type =~ m/html/i)) {
    $success = &pdf_to_html($dirname, $input_filename, $output_filestem);
    if ($success) {
        return "html";
    }
    }

    # Attempt conversion to TEXT
    if (!$output_type || ($output_type =~ m/text/i)) {
    $success = &pdf_to_text($dirname, $input_filename, $output_filestem);
    if ($success) {
        return "text";
    }
    }

    return "fail";

}


# Convert an Adobe PostScript document

sub convertPS {
    ($input_filename, $output_filestem, $output_type) = @_;

    my $success = 0;
    $output_type =~ s/.*\-(.*)/$1/i;
    # Attempt coversion to Image
    if ($output_type =~ m/jp?g|gif|png/i) {
    $success = &pdfps_to_img($dirname, $input_filename, $output_filestem, $output_type);
    if ($success){
        return "item";
    }
    }

    # Attempt conversion to TEXT
    if (!$output_type || ($output_type =~ m/text/i)) {
    $success = &ps_to_text($input_filename, $output_filestem);
    if ($success) {
        return "text";
    }
    }
    return "fail";
}


sub convertPPT {
    my ($input_filename, $output_filestem, $output_type) = @_;
    my $success = 0;

    my $ppt_convert_type = "";
    #if (!$output_type || $windows_scripting || ($output_type !~ m/html/i) || ($output_type !~ m/text/i)){
    if ($windows_scripting && ($output_type !~ m/html/i) && ($output_type !~ m/text/i)){
    if ($output_type =~ m/gif/i) {
        $ppt_convert_type = "-g";
    } elsif ($output_type =~ m/jp?g/i){
        $ppt_convert_type = "-j";
    } elsif ($output_type =~ m/png/i){
        $ppt_convert_type = "-p";
    }
    my $vbScript = &util::filename_cat($ENV{'GSDLHOME'}, "bin",
                       $ENV{'GSDLOS'}, "pptextract");
    $vbScript = "pptextract" if ($ENV{'GSDLOS'} =~ m/^windows$/i);
            
    $cmd = "";
    if ($timeout) {$cmd = "ulimit -t $timeout;";}
    # if the converting directory has already existed
    if (-d $output_filestem) {
        print STDERR "**The conversion directory has existed\n";
        return "item";
    } else {
        $cmd .=  "$vbScript $ppt_convert_type \"$input_filename\" \"$output_filestem\"";
        $cmd .= " 2>\"$output_filestem.err\""
        if ($ENV{'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000);
        if (system($cmd) !=0) {
        print STDERR "Powerpoint VB Scripting convert failed\n";
        } else {
        return "item";
        }
    }
    } elsif (!$output_type || ($output_type =~ m/html/i)) {
    # Attempt conversion to HTML
    #if (!$output_type || ($output_type =~ m/html/i)) {
    # formulate the command
    $cmd = "";
    $cmd .= "perl -S ppttohtml.pl ";
    $cmd .= " \"$input_filename\" \"$output_filestem.html\"";
    $cmd .= " 2>\"$output_filestem.err\""
        if ($ENV{'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000);

    # execute the command
    $!=0;
    if (system($cmd)!=0)
    {
        print STDERR "Powerpoint 95/97 converter failed $!\n";
    } else {
        return "html";
    }
    } 

    $success = &any_to_text($input_filename, $output_filestem);
    if ($success) {
    return "text";
    }
    
    return "fail";
}


sub convertXLS {
    my ($input_filename, $output_filestem, $output_type) = @_;

    my $success = 0;

    # Attempt conversion to HTML
    if (!$output_type || ($output_type =~ m/html/i)) {
    # formulate the command
    $cmd = "";
    $cmd .= "perl -S xlstohtml.pl ";
    $cmd .= " \"$input_filename\" \"$output_filestem.html\"";
    $cmd .= " 2>\"$output_filestem.err\""
        if ($ENV{'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000);
    
    
    # execute the command
    $!=0;
    if (system($cmd)!=0)
    {
        print STDERR "Excel 95/97 converter failed $!\n";
    } else {
        return "html";
    }
    }

    $success = &any_to_text($input_filename, $output_filestem);
    if ($success) {
    return "text";
    }

    return "fail";
}



# Find the real type of a .doc file
#
# We seem to have a lot of files with a .doc extension that are .rtf 
# files or Word 5 files.  This function attempts to tell the difference.
sub find_docfile_type {
    ($input_filename) = @_;
    
    open(CHK, "<$input_filename");
    binmode(CHK);
    my $line = "";
    my $first = 1;

    while (<CHK>) {
    
    $line = $_;

    if ($first) {
        # check to see if this is an rtf file
        if ($line =~ m/^\{\\rtf/) {
        close(CHK);
        return "rtf";
        }
        $first = 0;
    }
    
    # is this is a word 6/7/8 document?
    if ($line =~ m/Word\.Document\.([678])/) {
        close(CHK);
        return "word$1";
    }

    }

    return "unknown";
}


# Specific type-to-type conversions
#
# Each of the following functions attempts to convert a document from 
# a specific format to another.  If they succeed they return 1 and leave 
# the output document(s) in the appropriate place; if they fail they 
# return 0 and delete any working files.


# Attempt to convert a word document to html with the wv program
sub doc_to_html {
    ($input_filename, $output_filestem) = @_;

    my $wvWare = &util::filename_cat($ENV{'GSDLHOME'}, "bin", 
                     $ENV{'GSDLOS'}, "wvWare");

    # don't include path on windows (to avoid having to play about
    # with quoting when GSDLHOME might contain spaces) but assume
    # that the PATH is set up correctly
    $wvWare = "wvWare" if ($ENV{'GSDLOS'} =~ m/^windows$/i);

    my $wv_conf = &util::filename_cat($ENV{'GSDLHOME'}, "etc", 
                      "packages", "wv", "wvHtml.xml");
    
    # Added the following to work with replace_srcdoc_with_html.pl:
    # Make wvWare put any associated (image) files of the word doc into
    # folder docname-without-extention_files. This folder should be at
    # the same level as the html file generated from the doc. 
    # wvWare will take care of proper interlinking. 

    # This step is necessary for replace_srcdoc_with_html.pl which will 
    # move the html and associated files into the import folder. We
    # want to ensure that the associated files won't overwrite similarly
    # named items already in import. Hence we put them in a folder first
    # (to which the html links properly) and that will allow
    # replace_srcdoc_with_html.pl to move them safely to /import.

    # To do all this, we need to use wvWare's --dir and --basename options
    # where dir is the full path to the image folder directory and
    # basename is the full path to the image folder appended to the name 
    # which is to be prepended to every image file:
    # eg. if the images were to have names like sample0.jpg to sampleN.jpg,
    # then the basename is "/full/path/to/imgdir/sample". 
    # In this case, basename is the full path to and name of the document.
    # HOWEVER: basename always takes full path, not relative url, so
    # the greenstone browser is unable to display the images (absolute paths
    # cause it to give an "external link" message)
    # See http://osdir.com/ml/lib.wvware.devel/2002-11/msg00014.html
    # and http://rpmfind.net/linux/RPM/freshmeat/rpms/wv/wv-0.5.44-1.i386.html
    # "added --dir option to wvHtml so that pictures can be placed in
    # a seperate directory"
    # "running wvWare through IMP to view word documents as html. It gets
    # invoked like this:
    # wvWare --dir=/tmp-wvWare --basename=/tmp-wvWare/img$$- $tmp_word >$tmp_output"
    
    # toppath is the folder where html is generated
    # docname is the name (without extension) of the html to be generated
    # suffix (extension) is thrown away
    my ($docname, $toppath) 
    = &File::Basename::fileparse($input_filename, "\\.[^\\.]+\$");

    # We want the image folder generated to have the same name as windows
    # would generate ($windows_scripting) when it converts from word to html.
    # That is, foldername=docname_files
    my $assoc_dir = &util::filename_cat($toppath, $docname."_files");
    #print "assoc_dir: ".$assoc_dir."\n";  # same as "$output_filestem._files"
    
    # ensure this image directory exists
    # if it exists already, just delete and recreate
    if(-e $assoc_dir) { 
    &util::rm_r($assoc_dir);
    }  
    &util::mk_dir($assoc_dir);

    # the images are all going to be called image0, image1,..., imageN
    my $img_basenames = &util::filename_cat($assoc_dir, $docname);
    
    #print STDERR "****toppath: $toppath\n****docname: $docname\n;
    #print STDERR "****img_basenames: $img_basenames\n" if($img_basenames);
    #print STDERR "****assoc_dir: $assoc_dir\n" if($assoc_dir);

    my $cmd = "";
    if ($timeout) {$cmd = "ulimit -t $timeout;";}
    # wvWare's --dir and --basename options for image directory. 
    # Replaced the next line with the *2 lines* following it:
               # $cmd .= "$wvWare --charset utf-8 --config \"$wv_conf\"";
    $cmd .= "$wvWare --dir \"$assoc_dir\" --basename \"$img_basenames\""; 
    $cmd .= " --charset utf-8 --config \"$wv_conf\"";
    $cmd .= " \"$input_filename\" > \"$output_filestem.html\"";

    # redirecting STDERR is a bad idea on windows 95/98
    $cmd .= " 2> \"$output_filestem.err\""
    if ($ENV{'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000);
    # execute the command
    $!=0;
    if (system($cmd)!=0)
    {
    print STDERR "Error executing wv converter:$!\n";
    if (-s "$output_filestem.err") {
        open (ERRFILE, "<$output_filestem.err");

        my $write_to_fail_log=0;
        if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile")))
        {$write_to_fail_log=1;}

        my $line;
        while ($line=<ERRFILE>) {
        if ($line =~ m/\w/) {
            print STDERR "$line";
            print FAILLOG "$line" if ($write_to_fail_log);
        }
        if ($line !~ m/startup error/) {next;}
        print STDERR " (given an invalid .DOC file?)\n";
        print FAILLOG " (given an invalid .DOC file?)\n"
        if ($write_to_fail_log);
        
        } # while ERRFILE
        close FAILLOG if ($write_to_fail_log);
    }
    return 0; # we can try any_to_text
    }

    # Was the conversion successful?

    if (-s "$output_filestem.html") { # if file has non-zero size (i.e. it has contents)
    open(TMP, "$output_filestem.html");
    $line = <TMP>;
    close(TMP);
    if ($line && $line =~ m/DOCTYPE HTML/) {
        &util::rm("$output_filestem.err") if -e "$output_filestem.err";    

        # Inserted this code to remove the images directory if it was still empty after 
        # the html was generated (in case there were no images in the word document)
        if (&util::is_dir_empty($assoc_dir)) {
        #print STDERR "***gsConvert.pl: Image dir $assoc_dir is empty, removing***\n";
        &util::rm_r($assoc_dir);
        } else { # there was an image folder (it was generated)
        # Therefore, the html file generated contains absolute links to the images
        # Replace them with relative links instead, so the folder can be moved elsewhere
        &make_links_to_assocdir_relative($toppath, $docname, "$output_filestem.html", $assoc_dir, $docname."_files");   
        }
        return 1;
    }
    }
    
    # If here, an error of some sort occurred
    &util::rm("$output_filestem.html") if -e "$output_filestem.html";
    if (-e "$output_filestem.err") {
    if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile"))) {
        open (ERRLOG,"$output_filestem.err");
        while (<ERRLOG>) {print FAILLOG $_;}
        close FAILLOG;
        close ERRLOG;
    }
    &util::rm("$output_filestem.err");
    }
    
    return 0;
}

# Method to work with doc_to_html - Word docs might contain images.
# When such word docs are converted with wvWare, we make it generate a 
# <filename>_files folder with the associated images, while the html file
# <filename> refers to the images using absolute paths to <filename>_files.
# This method reads in that html file and replaces all the absolute paths to 
# the images in <filename>_files with the relative paths to the images from
# that folder. (I.e. with <filename>_files/<imagename.ext>).
sub make_links_to_assocdir_relative{
    # toppath is the top-level folder in which the html file we're going to be fixing resides
    # docname is just the name (without extension) of the html file
    # html_file is the full path to the html file: /full/path/docname.html
    # assoc_dir_path is toppath/docname_files
    # assoc_dirname is the directory name of the folder with associated imgs: docname_files
    my ($toppath, $docname, $html_file, $assoc_dir_path, $assoc_dirname) = @_;

    # 1. Read all the contents of the html into a string
    # open the original file for reading
    unless(open(FIN, "<$html_file")) { 
    print STDERR "gsConvert.pl: Unable to open $html_file for reading absolute urls...ERROR: $!\n";
    return 0;
    }
    # From http://perl.plover.com/local.html
    # "It's cheaper to read the file all at once, without all the splitting and reassembling. 
    # (Some people call this slurping the file.) Perl has a special feature to support this: 
    # If the $/ variable is undefined, the <...> operator will read the entire file all at once"
    my $html_contents;
    {
    local $/ = undef;        # Read entire file at once
    $html_contents = <FIN>;  # Now file is read in as one single 'line'
    }
    close(FIN); # close the file
    #print STDERR $html_contents;
   
    # 2. Replace (substitute) *all* ocurrences of the assoc_dir_path in a hrefs and img src
    # values with assoc_dirname
    # At the end: g means substitute all occurrences (global), while s at the end means treat 
    # all new lines as a regular space. This interacts with g to consider all the lines 
    # together as a single line so that multi-occurrences can be replaced.

    # we can't just replace $assoc_dir_path with $assoc_dir
    # $assoc_dir_path represents a regular expression that needs to be replaced
    # if it contains ., -, [, ], or Windows style backslashes in paths  -- which all have special
    # meaning in Perl regular expressions -- we need to escape these first
    my $safe_reg_expression = $assoc_dir_path;
    $safe_reg_expression =~ s/\\/\\\\/g;
    $safe_reg_expression =~ s/\./\\./g;
    $safe_reg_expression =~ s/\-/\\-/g;
    $safe_reg_expression =~ s/\[/\\[/g;
    $safe_reg_expression =~ s/\]/\\]/g;
    $safe_reg_expression =~ s/ /%20/g; # wvWare put %20 in place of space, so we need to change our prefix to match

    # The following regular expression substitution looks for <a or <image, followed by any other 
    # attributes and values until it comes to the FIRST (indicated by ?) href= or src= 
    # followed by " or ' no quotes at all around path, followed by the associated folder's pathname 
    # followed by characters (for the img filename), then finally the optional closing quotes 
    # in " or ' form, followed by any other attributes and values until the first > to end the tag.
    # The substitution: all the parts preceding associated folder's pathname are retained,
    # the associated folder path name is replaced by associated folder directory name
    # and the rest upto and including the closing > tag is retained.
    # The sg at the end of the pattern match treats all of html_contents as a single line (s) 
    # and performs a global replace (g) meaning that all occurrences that match in that single line
    # are substituted.
    $html_contents =~ s/(<(a|img).*?(href|src)=(\"|\')?)$safe_reg_expression(.*?(\"|\')?.*?>)/$1$assoc_dirname$5/sg;
               #$html_contents =~ s/$safe_reg_expression/$assoc_dirname/gs; # this works, used as fall-back
    # now replace any %20 chars in filenames of href or src attributes to use literal space ' '. Calls a function for this
    $html_contents =~ s/(<(a|img).*?(href|src)=(\"|\')?)(.*)(.*?(\"|\')?.*?>)/&post_process_assocfile_urls($1, $5, $6)/sge;

    #print STDERR "****assoc_dirname: $assoc_dirname***\n";
    #print STDERR "****safe_reg_expression: $safe_reg_expression***\n";
   
    # delete the original file and recreate it
    my $copy_of_filename = $html_file;
    &util::rm($copy_of_filename); # deleted the file

    # Recreate the original file for writing the updated contents
    unless(open(FOUT, ">$html_file")) {  # open it as a new file for writing
    print STDERR "gsConvert.pl: Unable to open $html_file for writing relative links...ERROR: $!\n";
    return 0;
    }

    # write out the updated contents and close the file
    print FOUT $html_contents;
    close(FOUT);
    return 1;
}

# Utility routine to make sure HTML plugin gets img src/href link pathnames that contain 
# url slashes (/) instead of windows-style backwards slashes, and to convert all %20 
# introduced in link pathnames by wvWare into space again. Converts all percent signs
# introduced by URL encoding filenames generated into %25 in these url links referencing them
sub post_process_assocfile_urls
{
    my ($pre, $text, $post) = @_;

    $text =~ s/%20/ /g; # Convert %20s to space and not underscore since underscores mess with incremental rebuild 
    # $text =~ s/%20/_/g; # reinstated this line, since we no longer replace spaces with %20. We replace them with underscores
    $text =~ s/\\/\//g;
    $text =~ s/%/%25/g;

    return "$pre$text$post";
}

# Attempt to convert a word document to html with the word2html scripting program
sub native_doc_to_html {
    ($input_filename, $output_filestem) = @_;

    my $vbScript = &util::filename_cat($ENV{'GSDLHOME'}, "bin",
                       $ENV{'GSDLOS'}, "word2html");

    $vbScript = "word2html" if ($ENV{'GSDLOS'} =~ m/^windows$/i);
    if (-e "$output_filestem.html") {
    print STDERR "*** The conversion file has existed\n";
    return 1;
    }

    my $cmd = "";
    if ($timeout) {$cmd = "ulimit -t $timeout;";}
    #$cmd .= "$vbScript \"$input_filename\" \"$output_filestem.html\"";
    #$cmd .=  "$vbScript $input_filename $output_filestem.html";
    $cmd .=  "$vbScript \"$input_filename\" \"$output_filestem.html\"";

    # redirecting STDERR
    $cmd .= " 2> \"$output_filestem.err\""
    if ($ENV {'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000);
    
    # execute the command
    $!=0;
    if (system($cmd)!=0)
    {
    print STDERR "Error executing word2Html converter:$!\n";
    if (-s "$output_filestem.err") {
        open (ERRFILE, "<$output_filestem.err");
        
        my $write_to_fail_log=0;
        if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile")))
        {$write_to_fail_log=1;}

        my $line;
        while ($line=<ERRFILE>) {
        if ($line =~ m/\w/) {
            print STDERR "$line";
            print FAILLOG "$line" if ($write_to_fail_log);
        }
        if ($line !~ m/startup error/) {next;}
        print STDERR " (given an invalid .DOC file?)\n";
        print FAILLOG " (given an invalid .DOC file?)\n"
        if ($write_to_fail_log);
        
        } # while ERRFILE
        close FAILLOG if ($write_to_fail_log);
    }
    return 0; # we can try any_to_text
    }

    # Was the conversion successful?
    if (-s "$output_filestem.html") {
    open(TMP, "$output_filestem.html");
    $line = <TMP>;
    close(TMP);
    if ($line && $line =~ m/html/) {
        &util::rm("$output_filestem.err") if -e "$output_filestem.err";
        return 1;
    }
    }
    
    # If here, an error of some sort occurred
    &util::rm("$output_filestem.html") if -e "$output_filestem.html";
    if (-e "$output_filestem.err") {
    if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile"))) {
        open (ERRLOG,"$output_filestem.err");
        while (<ERRLOG>) {print FAILLOG $_;}
        close FAILLOG;
        close ERRLOG;
    }
    &util::rm("$output_filestem.err");
    }
    return 0;
}

# Attempt to convert an RTF document to html with rtftohtml

sub rtf_to_html {
    my ($input_filename, $output_filestem) = @_;

    # formulate the command
    $cmd = "";
    if ($timeout) {$cmd = "ulimit -t $timeout;";}
    $cmd .= "rtftohtml";
    #$cmd .= "rtf-converter";

    $cmd .= " -o \"$output_filestem.html\" \"$input_filename\"";

    $cmd .= " 2>\"$output_filestem.err\""
        if ($ENV{'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000);


    # execute the command
    $!=0;
    if (system($cmd)!=0)
    {
    print STDERR "Error executing rtf converter $!\n";
    # don't currently bother printing out error log...
    # keep going, in case it still created an HTML file...
    }

    # Was the conversion successful?
    my $was_successful=0;
    if (-s "$output_filestem.html") {
    # make sure we have some content other than header
    open (HTML, "$output_filestem.html"); # what to do if fail?
    my $line;
    my $past_header=0;
    while ($line=<HTML>) {

        if ($past_header == 0) {
        if ($line =~ m/<body>/) {$past_header=1;}
        next;
        }

        $line =~ s/<[^>]+>//g;
        if ($line =~ m/\w/ && $past_header) {  # we found some content...
        $was_successful=1;
        last;
        }
    }
    close HTML;
    }

    if ($was_successful) {
    &util::rm("$output_filestem.err")
        if (-e "$output_filestem.err");
    # insert the (modified) table of contents, if it exists.
    if (-e "${output_filestem}_ToC.html") {
        &util::mv("$output_filestem.html","$output_filestem.src");
        my $open_failed=0;
        open HTMLSRC, "$output_filestem.src" || ++$open_failed;
        open TOC, "${output_filestem}_ToC.html" || ++$open_failed;
        open HTML, ">$output_filestem.html" || ++$open_failed;
        
        if ($open_failed) {
        close HTMLSRC;
        close TOC;
        close HTML;
        &util::mv("$output_filestem.src","$output_filestem.html");
        return 1;
        }

        # print out header info from src html.
        while (defined($_ = <HTMLSRC>) && $_ =~ m/\w/) {
        print HTML "$_";
        }

        # print out table of contents, making links relative
        <TOC>; <TOC>; # ignore first 2 lines
        print HTML scalar(<TOC>); # line 3 = "<ol>\n"
        my $line;
        while ($line=<TOC>) {
        $line =~ s@</body></html>$@@ ; # only last line has this
        # make link relative
        $line =~ s@href=\"[^\#]+@href=\"@;
        print HTML $line;
        }
        close TOC;

        # rest of html src
        while (<HTMLSRC>) {
        print HTML $_;
        }
        close HTMLSRC;
        close HTML;

        &util::rm("${output_filestem}_ToC.html");
        &util::rm("${output_filestem}.src");
    }
    # we don't yet do anything with footnotes ($output_filestem_fn.html) :(
    return 1; # success
    }

    if (-e "$output_filestem.err") {
    if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile")))
    {
        print FAILLOG "Error - rtftohtml - couldn't extract text\n";
        #print FAILLOG "Error - rtf-converter - couldn't extract text\n";
        print FAILLOG " (rtf file might be too recent):\n";
        open (ERRLOG, "$output_filestem.err");
        while (<ERRLOG>) {print FAILLOG $_;}
        close ERRLOG;
        close FAILLOG;
    }
    &util::rm("$output_filestem.err");
    }

    &util::rm("$output_filestem.html") if (-e "$output_filestem.html");

    return 0;
}


# Convert a pdf file to html with the pdftohtml command

sub pdf_to_html {
    my ($dirname, $input_filename, $output_filestem) = @_;

    $cmd = "";
    if ($timeout) {$cmd = "ulimit -t $timeout;";}
    $cmd .= "perl -S pdftohtml.pl -zoom $pdf_zoom";
    $cmd .= " -c" if ($pdf_complex);
    $cmd .= " -i" if ($pdf_ignore_images);
    $cmd .= " -a" if ($pdf_allow_images_only);
    $cmd .= " -hidden" unless ($pdf_nohidden);
    $cmd .= " \"$input_filename\" \"$output_filestem\"";
    
    if ($ENV{'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000) {
    $cmd .= " > \"$output_filestem.out\" 2> \"$output_filestem.err\"";
    } else {
    $cmd .= " > \"$output_filestem.err\"";
    }

    $!=0;

    my $retval=system($cmd);
    if ($retval!=0)
    {
    print STDERR "Error executing pdftohtml.pl";
    if ($!) {print STDERR ": $!";} 
    print STDERR "\n";
    }

    # make sure the converter made something
    if ($retval!=0 || ! -s "$output_filestem.html")
    {
    &util::rm("$output_filestem.out") if (-e "$output_filestem.out");
    # print out the converter's std err, if any
    if (-s "$output_filestem.err") {
        open (ERRLOG, "$output_filestem.err") || die "$!";
        print STDERR "pdftohtml error log:\n";
        while (<ERRLOG>) {
        print STDERR "$_";
        }
        close ERRLOG;
    }
    &util::rm("$output_filestem.html") if (-e "$output_filestem.html");
    if (-e "$output_filestem.err") {
        if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile")))
        {
        open (ERRLOG, "$output_filestem.err");
        while (<ERRLOG>) {print FAILLOG $_;}
        close ERRLOG;
        close FAILLOG;
        }   
        &util::rm("$output_filestem.err");
    }
    return 0;
    }

    &util::rm("$output_filestem.err") if (-e "$output_filestem.err");
    &util::rm("$output_filestem.out") if (-e "$output_filestem.out");
    return 1;
}

# Convert a pdf file to various types of image with the convert command

sub pdfps_to_img {
    my ($dirname, $input_filename, $output_filestem, $output_type) = @_;

    # Check that ImageMagick is installed and available on the path (except for Windows 95/98)
    if (!($ENV{'GSDLOS'} eq "windows" && !Win32::IsWinNT())) {
    my $result = `identify 2>&1`;
    if ($? == -1 || $? == 256) {  # Linux and Windows return different values for "program not found"
        #ImageMagick is not installed, thus the convert utility is not available. 
        print STDERR "*** ImageMagick is not installed, the convert utility is not available. Unable to convert PDF/PS to images\n";
        return 0;
    }
    }

    $cmd = "";
    if ($timeout) {$cmd = "ulimit -t $timeout;";}
    $output_type =~ s/.*\_(.*)/$1/i;
    $cmd .= "perl -S pdfpstoimg.pl -convert_to $output_type \"$input_filename\" \"$output_filestem\"";
    if ($ENV{'GSDLOS'} !~ m/^windows$/i || $is_winnt_2000) {
    $cmd .= " > \"$output_filestem.out\" 2> \"$output_filestem.err\"";
    } else {
    $cmd .= " > \"$output_filestem.err\"";
    }

    # don't include path on windows (to avoid having to play about
    # with quoting when GSDLHOME might contain spaces) but assume
    # that the PATH is set up correctly
    $!=0;
    my $retval=system($cmd);
    if ($retval!=0)
    {
    print STDERR "Error executing pdftoimg.pl";
    if ($!) {print STDERR ": $!";} 
    print STDERR "\n";
    }

    #make sure the converter made something
    #if ($retval !=0) || ! -s "$output_filestem")
    if ($retval !=0) 
    {
    &util::rm("$output_filestem.out") if (-e "$output_filestem.out");
    #print out the converter's std err, if any
    if (-s "$output_filestem.err") {
        open (ERRLOG, "$output_filestem.err") || die "$!";
        print STDERR "pdfpstoimg error log:\n";
        while (<ERRLOG>) {
        print STDERR "$_";
        }
        close ERRLOG;
    }
    #&util::rm("$output_filestem.html") if (-e "$output_filestem.html");
    if (-e "$output_filestem.err") {
        if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile")))
        {
        open (ERRLOG, "$output_filestem.err");
        while (<ERRLOG>) {print FAILLOG $_;}
        close ERRLOG;
        close FAILLOG;
       }    
        &util::rm("$output_filestem.err");
    }
    return 0;
    }
    &util::rm("$output_filestem.err") if (-e "$output_filestem.err");
    &util::rm("$output_filestem.out") if (-e "$output_filestem.out");
    return 1;
}

# Convert a PDF file to text with the pdftotext command

sub pdf_to_text {
    my ($dirname, $input_filename, $output_filestem) = @_;

    my $cmd = "pdftotext \"$input_filename\" \"$output_filestem.text\"";

    if ($ENV{'GSDLOS'} !~ m/^windows$/i) {
    $cmd .= " > \"$output_filestem.out\" 2> \"$output_filestem.err\"";
    } else {
    $cmd .= " > \"$output_filestem.err\"";
    }
    
    if (system($cmd)!=0)
    {
    print STDERR "Error executing $cmd: $!\n";
    &util::rm("$output_filestem.text") if (-e "$output_filestem.text");
    }

    # make sure there is some extracted text.
    if (-e "$output_filestem.text") {
    open (EXTR_TEXT, "$output_filestem.text") || warn "open: $!";
    binmode(EXTR_TEXT); # just in case...
    my $line="";
    my $seen_text=0;
    while (($seen_text==0) && ($line=<EXTR_TEXT>)) {
        if ($line=~ m/\w/) {$seen_text=1;}
    }
    close EXTR_TEXT;
    if ($seen_text==0) { # no text was extracted
        print STDERR "Error: pdftotext found no text\n";
        &util::rm("$output_filestem.text");
    }
    }

    # make sure the converter made something
    if (! -s "$output_filestem.text")
    {
    # print out the converters std err, if any
    if (-s "$output_filestem.err") {
        open (ERRLOG, "$output_filestem.err") || die "$!";
        print STDERR "pdftotext error log:\n";
        while (<ERRLOG>) {
        print STDERR "$_";
        }
        close ERRLOG;
    }
    # does this converter create a .out file?
    &util::rm("$output_filestem.out") if (-e "$output_filestem.out");
    &util::rm("$output_filestem.text") if (-e "$output_filestem.text");
    if (-e "$output_filestem.err") {
        if ($faillogfile ne "" && defined(open(FAILLOG,">>$faillogfile")))
        {
        open (ERRLOG,"$output_filestem.err");
        while (<ERRLOG>) {print FAILLOG $_;}
        close ERRLOG;
        close FAILLOG;
        }
        &util::rm("$output_filestem.err");
    }
    return 0;
    }
    &util::rm("$output_filestem.err") if (-e "$output_filestem.err");
    return 1;
}

# Convert a PostScript document to text
# note - just using "ps2ascii" isn't good enough, as it
# returns 0 for a postscript interpreter error. ps2ascii is just
# a wrapper to "gs" anyway, so we use that cmd here.

sub ps_to_text {
    my ($input_filename, $output_filestem) = @_;

    my $error = "";

    # if we're on windows we'll fall straight through without attempting
    # to use gs
    if ($ENV{'GSDLOS'} =~ m/^windows$/i) {
    $error = "Windows does not support gs";

    } else {
    my $cmd = "";
    if ($timeout) {$cmd = "ulimit -t $timeout; ";}
    $cmd .= "gs -q -dNODISPLAY -dNOBIND -dWRITESYSTEMDICT -dSIMPLE -c save ";
    $cmd .= "-f ps2ascii.ps \"$input_filename\" -c quit > \"$output_filestem.text\"";
    #$cmd .= "pstotext -output \"$output_filestem.text\" $input_filename\"";
    $cmd .= " 2> $output_filestem.err";
    $!=0;

    my $retcode=system($cmd);
    $retcode = $? >> 8;  # see man perlfunc - system for this...
    # if system returns -1 | 127 (couldn't start program), look at $! for message

    if ($retcode!=0) {if ($!) {$error=$!;} else {$error="couldn't run.\n";}}
    elsif (! -e "$output_filestem.text") {
        $error="did not create output file.\n";
    }
    else 
    {   # make sure the interpreter didn't get an error. It is technically
        # possible for the actual text to start with this, but....
        open PSOUT, "$output_filestem.text";
        if (<PSOUT> =~ m/^Error: (.*)/) {
        $error="interpreter error - \"$1\"";
        }
        close PSOUT;
    }
    }

    if ($error ne "")
    {
    print STDERR "Warning: Error executing gs: $error\n";
    &util::rm("$output_filestem.text") if (-e "$output_filestem.text");

    if ("$faillogfile" ne "" && defined(open (FAILLOG, ">>$faillogfile")))
    {
        print FAILLOG "gs - $error\n";
        if (-e "$output_filestem.err") {
        open(ERRLOG, "$output_filestem.err");
        while (<ERRLOG>) {print FAILLOG $_;}
        close ERRLOG;
        }
        close FAILLOG;
    }
    &util::rm("$output_filestem.err") if (-e "$output_filestem.err");


    # Fine then. We'll just do a lousy job by ourselves...
    # Based on 5-line regexp sed script found at:
    # http://snark.ptc.spbu.ru/mail-archives/lout/brown/msg00003.html
    # 
    print STDERR "Stripping text from postscript\n";
    my $errorcode=0;
    open (IN, "$input_filename") 
        ||  ($errorcode=1, warn "Couldn't read file: $!");
    open (OUT, ">$output_filestem.text") 
        ||  ($errorcode=1, warn "Couldn't write file: $!");
    if ($errorcode) {print STDERR "errors\n";return 0;}
    
    my $text="";  # this is for whole .ps file...
    $text = join('', <IN>); # see man perlport, under "System Resources"
    close IN;

    # Make sure this is a ps file...
    if ($text !~ m/^%!/) {
        print STDERR "Bad postscript header: not '%!'\n";
        if ($faillogfile ne "" && defined(open(FAILLOG, ">>$faillogfile")))
        {
        print FAILLOG "Bad postscript header: not '%!'\n";
        close FAILLOG;
        }
        return 0;
    }

    # if ps has Page data, then use it to delete all stuff before it.
    $text =~ s/^.*?%%Page:.*?\n//s; # treat string as single line
    
    # remove all leading non-data stuff
    $text =~ s/^.*?\(//s;

    # remove all newline chars for easier processing
    $text =~ s/\n//g;
    
    # Big assumption here - assume that if any co-ordinates are
    # given, then we are at the end of a sentence.
    $text =~ s/\)-?\d+\ -?\d+/\) \(\n\)/g;

    # special characters--
    $text =~ s/\(\|\)/\(\ - \)/g; # j -> em-dash?

    # ? ps text formatting (eg italics?) ?
    $text =~ s/Fn\(f\)/\(\{\)/g; # f -> {
    $text =~ s/Fn\(g\)/\(\}\)/g; # g -> }
    $text =~ s/Fn\(j\)/\(\|\)/g; # j -> |
    # default - remove the rest
    $text =~ s/\ ?F.\((.+?)\)/\($1\)/g;

    # attempt to add whitespace between words... 
    # this is based purely on observation, and may be completely wrong...
    $text =~ s/([^F])[defghijkuy]\(/$1 \( /g;
    # eg I notice "b(" is sometimes NOT a space if preceded by a 
    # negative number.
    $text =~ s/\)\d+ ?b\(/\) \( /g;

    # change quoted braces to brackets
    $text =~ s/([^\\])\\\(/$1\{/g;
    $text =~ s/([^\\])\\\)/$1\}/g ;

    # remove everything that is not between braces
    $text =~ s/\)([^\(\)])+?\(//sg ;
    
    # remove any Trailer eof stuff.
    $text =~ s/\)[^\)]*$//sg;

    ### ligatures have special characters...
    $text =~ s/\\013/ff/g;
    $text =~ s/\\014/fi/g;
    $text =~ s/\\015/fl/g;
    $text =~ s/\\016/ffi/g;
    $text =~ s/\\214/fi/g;
    $text =~ s/\\215/fl/g;
    $text =~ s/\\017/\n\* /g; # asterisk?
    $text =~ s/\\023/\023/g;  # e acute ('e)
    $text =~ s/\\177/\252/g;  # u"
#   $text =~ s/ ?? /\344/g;  # a"

    print OUT "$text";
    close OUT;
    }
    # wrap the text - use a minimum length. ie, first space after this length.
    my $wrap_length=72;
    &util::mv("$output_filestem.text", "$output_filestem.text.tmp");
    open INFILE, "$output_filestem.text.tmp" ||
    die "Couldn't open file: $!";
    open OUTFILE, ">$output_filestem.text" ||
    die "Couldn't open file for writing: $!";
    my $line="";
    while ($line=<INFILE>) {
    while (length($line)>0) {
        if (length($line)>$wrap_length) {
        $line =~ s/^(.{$wrap_length}[^\s]*)\s*//;
        print OUTFILE "$1\n";
        } else {
        print OUTFILE "$line";
        $line="";
        }
    }
    }
    close INFILE;
    close OUTFILE;
    &util::rm("$output_filestem.text.tmp");

    &util::rm("$output_filestem.err") if (-e "$output_filestem.err");
    return 1;
}


# Convert any file to HTML with a crude perl implementation of the
# UNIX strings command.

sub any_to_html {
    ($input_filename, $output_filestem) = @_;

    # First generate a text file
    return 0 unless (&any_to_text($input_filename, $output_filestem));

    # create an HTML file from the text file
    open(TEXT, "<$output_filestem.text");
    open(HTML, ">$output_filestem.html");

    print HTML "<html><head>\n";
    print HTML "<META HTTP-EQUIV=\"Content-Type\" CONTENT=\"text/html\">\n";
    print HTML "<META NAME=\"GENERATOR\" CONTENT=\"Greenstone any_to_html\">\n";
    print HTML "</head><body>\n\n";

    my $line;
    while ($line=<TEXT>) { 
    $line =~ s/</&lt;/g;
    $line =~ s/>/&gt;/g;
    if ($line =~ m/^\s*$/) {
        print HTML "<p>";
    } else {
        print HTML "<br> ", $line;
    }
    }
    print HTML "\n</body></html>\n";

    close HTML;
    close TEXT;

    &util::rm("$output_filestem.text") if (-e "$output_filestem.text");
    return 1;
}

# Convert any file to TEXT with a crude perl implementation of the
# UNIX strings command.
# Note - this assumes ascii charsets :(     (jrm21)

sub any_to_text {
    ($input_filename, $output_filestem) = @_;

    if (!$use_strings) {
      return 0;
    }

    print STDERR "\n**** In any to text****\n\n";
    open(IN, "<$input_filename") || return 0;
    binmode(IN);
    open(OUT, ">$output_filestem.text") || return 0;

    my ($line);
    my $output_line_count = 0;
    while (<IN>) { 
    $line = $_;

    # delete anything that isn't a printable character
    $line =~ s/[^\040-\176]+/\n/sg;

    # delete any string less than 10 characters long
    $line =~ s/^.{0,9}$/\n/mg;
    while ($line =~ m/^.{1,9}$/m) {
        $line =~ s/^.{0,9}$/\n/mg;
        $line =~ s/\n+/\n/sg;
    }

    # remove extraneous whitespace
    $line =~ s/\n+/\n/gs;
    $line =~ s/^\n//gs;

    # output whatever is left
    if ($line =~ m/[^\n ]/) {
        print OUT $line;
        ++$output_line_count;
    }
    }

    close OUT;
    close IN;

    if ($output_line_count) { # try to protect against binary only formats
    return 1;
    }

    &util::rm("$output_filestem.text");
    return 0;

}