From bd3ae47ba7d37ed3691abac6113ea94fa1f448d0 Mon Sep 17 00:00:00 2001
From: jbjohnso <jbjohnso@8638fb3e-16cb-4fca-ae20-7b5d299a9bcd>
Date: Tue, 11 Oct 2011 19:10:08 +0000
Subject: [PATCH] Script to extract EFI el torito image (e.g. needed to get
 ISO9660 efi driver from vmware media)

git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/trunk@10747 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd
---
 .../share/xcat/scripts/extractefiboot.pl      | 96 +++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100755 xCAT-server/share/xcat/scripts/extractefiboot.pl

diff --git a/xCAT-server/share/xcat/scripts/extractefiboot.pl b/xCAT-server/share/xcat/scripts/extractefiboot.pl
new file mode 100755
index 000000000..ea7124b8d
--- /dev/null
+++ b/xCAT-server/share/xcat/scripts/extractefiboot.pl
@@ -0,0 +1,96 @@
+#!/usr/bin/env perl
+#This is a utility to scrape out the EFI boot image from an el torito enabled disk
+use strict;
+use Fcntl qw/SEEK_SET/;
+my $iso;
+my $outfile;
+GetOptions("out=s" => \$outfile,
+	   "iso=s" => \$iso);
+my $emul;
+my $blksize=2048;
+my $istream;
+use Getopt::Long;
+sub grabimage {
+	my $bootcat = shift;
+	my $image;
+	my @recdata = unpack("C2vC2vV",$bootcat);
+	unless ($recdata[0] == 0x88) { printf "Error: EFI torito record not bootable\n"; exit; }
+	$emul=$recdata[1];
+	#for now, ignore load segment, system type
+	seek($istream,$recdata[6]*$blksize,SEEK_SET);
+	my $size=$recdata[5];
+	if ($size==0) { $size = 1; } #if 0/1, it's auto-detect time
+	my $readbytes=read($istream,$image,$size*512);
+	if ($size == 1) { #we have to interpret the FAT header to get the real size
+		seek($istream,$recdata[6]*$blksize,SEEK_SET); # go back to beginning
+		my @fatheader = unpack("C11vCvC3vC11V",$image);
+		my $secsize=$fatheader[11];
+		if ($fatheader[17]) {
+			$size=$secsize*($fatheader[17]);
+		} else {
+			die "Unsupported FAT header, requires test of commented code segment";
+		}
+#		} elsif ($fatheader[-1]) {
+#			$size=$secsize*$fatheader[-1];
+#		}
+		$readbytes=read($istream,$image,$size);
+	}
+	my $outh;
+	open($outh,">",$outfile);
+	print $outh $image;
+	close($outh);
+}
+if (! -r $iso) { 
+	printf "Error, $iso does not seem to exist or is not readable";
+	exit 1;
+}
+open($istream,"<",$iso) || die "Error opening $iso";
+my $bootsect;
+seek($istream,17*$blksize,SEEK_SET);
+my $readbytes = read($istream,$bootsect,0x4b);
+unless ($readbytes == 0x4b) {
+	printf "Error reading boot record volume from $iso\n";
+	exit 1;
+}
+my @recdata;
+@recdata = unpack("CA5CA32C32V",$bootsect); #it would have been nice if the el torito actually said little endian on it..
+unless ($recdata[0] == 0 and $recdata[1] eq 'CD001'
+	and $recdata[2] == 1 and $recdata[3] eq "EL TORITO SPECIFICATION") { 
+	printf "Error: Boot record volume format invalid\n";
+	exit 1;
+}
+my $bootcatidx=$recdata[-1];
+my $bootcat;
+seek($istream,$bootcatidx*$blksize,SEEK_SET);
+$readbytes = read($istream,$bootcat,0x20);
+unless ($readbytes == 0x20) { printf "Error reading boot catalog at $bootcatidx\n"; exit 1; }
+@recdata = unpack("C*",$bootcat);
+unless ($recdata[0] == 1 and $recdata[0x1e] == 0x55 and $recdata[0x1f] == 0xaa) {
+	printf "Boot catalog has invalid header\n"; exit 1; 
+}
+$readbytes = read($istream,$bootcat,0x20);
+my $image;
+unless ($readbytes == 0x20) { printf "Error reading default El torito record\n"; exit; }
+if ($recdata[1] == 0xef) { #wow, the efi record came first, actually interpret that first record
+	grabimage($bootcat);
+} else { # keep looking for an *EFI* record
+	#read in first header
+	read($istream,$bootcat,0x20);
+	@recdata = unpack("CCv",$bootcat);
+	while ($recdata[0] == 0x90 and $recdata[1] != 0xef) { 	
+		my $additionalrecords=$recdata[2];
+		while ($additionalrecords) {
+		 	read($istream,$bootcat,0x20); #throw away irrelevant sectors
+			$additionalrecords -= 1;
+		}
+		read($istream,$bootcat,0x20); #throw away irrelevant sectors
+		@recdata = unpack("CCv",$bootcat);
+	}
+	if ($recdata[1] != 0xef) {
+		printf "No EFI boot image found\n";
+		exit 1;
+	}
+	$readbytes=read($istream,$bootcat,0x20);
+	grabimage($bootcat);
+}
+