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229 lines
6.4 KiB
Perl
229 lines
6.4 KiB
Perl
#!/usr/bin/perl
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use Getopt::Std;
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#
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# geteltorito.pl: a bootimage extractor
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# Script that will extract the first El Torito bootimage from a
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# bootable CD image
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# R. Krienke 08/2001
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# krienke@uni-koblenz.de
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# License: GPL
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#
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# Get latest version from:
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# http://userpages.uni-koblenz.de/~krienke/ftp/noarch/geteltorito
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#
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$utilVersion="0.6";
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#
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# Version 0.6
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# 2015/02/25
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# I included a patch by Daniel Kekez, daniel.kekez@utoronto.ca to make geteltorito
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# better compatible with windows:
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# "To run this Perl script using using Strawberry Perl under Windows, I
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# found it was necessary to explicitly open the files in binary mode since
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# Windows will default to text mode when open() is called."
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# Version 0.5
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# 2009/06/22
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# A patch for harddisk emulation images from <colimit@gmail.com>.
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# For BootMediaType=4 (harddisk emulation) SectorCount is always 1, and geteltorito.pl
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# returns just MBR. This patch guesses the correct bootimage size
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# from MBR (offset+size of the first partitition).
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# Version 0.4
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# 2007/02/01
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# A patch from Santiago Garcia <manty@debian.org> to use a virtual sector
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# size (vSecSize) of 512 bytes, as defined on "El Torito" specs and change
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# unpack of the sector count from n to v to get the correct sector count.
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# Version 0.3
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# 2006/02/21
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# A patch from Ben Collins <bcollins@ubuntu.com> to make the
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# utility work on PPC machines (change from 'L'-encoding in pack to 'V')
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# Version 0.2
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# Several patches included from Nathan Stratton Treadway(nathant@ontko.com)
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# to adjust the platform output as well as fixes for other minor bugs
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# Version 0.1
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# Initial release
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#
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# For information on El Torito see
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# http://en.wikipedia.org/wiki/El_torito
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$vSecSize=512;
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$secSize=2048;
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$ret=undef;$version=undef;$opt_h=undef;$loadSegment=undef;$systemType=undef;
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#
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# Read a particular sector from a file
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# sector counting starts at 0, not 1
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#
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sub getSector{
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my ($secNum, $secCount, $file)=@_;
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my ($sec, $count);
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open(FILE, "<:raw", $file) || die "Cannot open \"$file\" \n";
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seek(FILE, $secNum*$secSize, 0);
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$count=read(FILE, $sec, $vSecSize*$secCount, 0) ;
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if( $count != $vSecSize*$secCount ){
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warn "Error reading from file \"$file\"\n";
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}
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close(FILE);
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return($sec);
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}
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#
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# Write eltorito data into a file
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#
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sub writeOutputFile{
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my($name)=shift;
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my($value)=shift;
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open(OUT, ">:raw", $name)|| die "$0: Cannot open outputfile \"$name\" for writing. Stop.";
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print OUT $value;
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close(OUT);
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}
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#
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# Usage
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#
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sub usage{
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warn "\n$0 [-hv] [-o outputfilename] cd-image \n",
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"Script will try to extract an El Torito image from a \n",
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"bootable CD (or cd-image) given by <cd-image> and write \n",
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"the data extracted to STDOUT or to a file.\n",
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" -h: This help. \n",
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" -v: Print version of script and exit.\n",
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" -o <file>: Write extracted data to file <file> instead of STDOUT.\n",
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"\n\n";
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exit 0;
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}
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# ---------------------------------------------------------------------
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$ret=getopts('hvo:');
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if( defined($opt_v) ){
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warn "Version: $utilVersion \n";
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exit 0;
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}
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if( defined($opt_h) || $#ARGV <0 ){
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usage(0);
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}
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if( defined($opt_o) ){
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$outputFilename="$opt_o";
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}
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$imageFile=$ARGV[0];
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if( ! -r $imageFile ){
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die "Cannot read image/device \"$imageFile\". Aborting\n";
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}
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#
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# Read Sector 17 from CD which should contain a Boot Record Volume
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# descriptor. This descriptor contains at its start the text ($isoIdent)
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# CD001 and ($toritoSpec)
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# EL TORITO SPECIFICATION
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# see http://www.cdpage.com/Compact_Disc_Variations/eltoritoi.html
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# for details
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#
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$sector=getSector(17, 1, $imageFile );
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($boot, $isoIdent, $version, $toritoSpec,
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$unUsed, $bootP)= unpack( "Ca5CA32A32V", $sector );
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if( $isoIdent ne "CD001" || $toritoSpec ne "EL TORITO SPECIFICATION" ){
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die "This data image does not seem to be a bootable CD-image\n";
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}
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#
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# Now fetch the sector of the booting catalog
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#
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$sector=getSector($bootP, 1, $imageFile );
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print STDERR "Booting catalog starts at sector: $bootP \n";
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# The first 32 bytes of this sector contains the validation entry for a
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# boot. The first byte has to be 01, the next byte determines the
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# architecture the image is designed for, where 00 is i86, 01 is PowerPC
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# and 02 is Mac. More data give info about manufacturer, etc. The
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# final two bytes must contain 0x55 and 0xAA respectively (as
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# defined by the El Torito standard).
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$validateEntry=substr($sector, 0, 32);
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($header, $platform, $unUsed, $manufact, $unUsed, $five, $aa)=
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unpack( "CCvA24vCC", $validateEntry);
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if( $header != 1 || $five != 0x55 || $aa != 0xaa ){
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die "Invalid Validation Entry on image \n";
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}
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print STDERR "Manufacturer of CD: $manufact\n";
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print STDERR "Image architecture: ";
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print STDERR "x86" if( $platform == 0 );
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print STDERR "PowerPC" if( $platform == 1 );
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print STDERR "Mac" if( $platform == 2 );
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print STDERR "unknown ($platform)" if( $platform > 2 );
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print STDERR "\n";
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#
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# Now we examine the initial/defaultentry which follows the validate
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# entry and has a size of 32 bytes.
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$initialEntry=substr($sector, 32, 32);
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($boot, $media, $loadSegment, $systemType, $unUsed,
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$sCount, $imgStart, $unUsed)=unpack( "CCvCCvVC", $initialEntry);
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if( $boot != 0x88 ){
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die "Boot indicator in Initial/Default-Entry is not 0x88. CD is not bootable. \n";
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}
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print STDERR "Boot media type is: ";
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if( $media == 0 ){
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print STDERR "no emulation";
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$count=0;
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}
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if( $media == 1 ){
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print STDERR "1.2meg floppy";
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$count=1200*1024/$vSecSize;
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}
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if( $media == 2 ){
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print STDERR "1.44meg floppy";
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$count=1440*1024/$vSecSize;
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}
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if( $media == 3 ){
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print STDERR "2.88meg floppy";
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$count=2880*1024/$vSecSize;
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}
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if( $media == 4 ){
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print STDERR "harddisk";
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$MBR=getSector($imgStart, 1, $imageFile );
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$partition1=substr($MBR, 446, 16);
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($unUsed, $firstSector, $partitionSize) = unpack( "A8VV", $partition1);
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$count=$firstSector + $partitionSize;
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}
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print STDERR "\n";
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# Only use the internal sector counter if the real size is unknown
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# ($count==0)
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$cnt=$count==0?$sCount:$count;
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print STDERR "El Torito image starts at sector $imgStart and has $cnt sector(s) of $vSecSize Bytes\n";
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# We are there:
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# Now read the bootimage to stdout
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$image=getSector($imgStart, $cnt, $imageFile);
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if( length($outputFilename) ){
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writeOutputFile($outputFilename, $image);
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print STDERR "\nImage has been written to file \"$outputFilename\".\n";
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}else{
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print "$image";
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print STDERR "Image has been written to stdout ....\n";
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}
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