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