mkbimage

Linux启动程序grub的源码分析与实现；

#!/bin/sh
# MaKe a Bootable IMAGE --- 1.44, 2.88 and El Torito no-emulation mode
# C) 2001,2002,2003 Thierry Laronde <[e-mail]>
# C) 2001,2002,2003 Robert Millan <[e-mail]>


# 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, 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 can either send email to this
# program's maintainer or write to: The Free Software Foundation,
# Inc.; 59 Temple Place, Suite 330; Boston, MA 02111-1307, USA.

# $Id: mkbimage,v 1.19 2004/07/21 14:43:04 robertmh Exp $

# Global variables
tarfile=
dir=
fs= #file system type
decompress=
image_type=
uname=`uname -s`
PATH=/sbin:$PATH

# You can set GRUB_PATH  if you need to use a specially located GRUB.
# This MUST end by a '/'!


#----------------------------DON'T CHANGE: INTERNALS

block_size=512
cylinders=
heads=
sectors=
cyl_size=
type_option=
geo_option=
image=
bk_120=$((2 * 15 * 80))
bk_144=$((2 * 18 * 80))
bk_288=$((2 * 36 * 80))
bk_160=$((2 * 20 * 80))
bk_168=$((2 * 21 * 80))
bk_174=$((2 * 21 * 83))
lo_options=
device_map=
mkfs_options=
debug=
stage2_os_name=

# Name by which this script was invoked.
program=`echo "$0" | sed -e 's/[^\/]*\///g'`
version_number='$Revision: 1.19 $'

usage="
Usage: $program [-hVF] [-t TYPE] [-d DIRECTORY] [-s FS_TYPE] -f TAR_FILE
Make a Bootable IMAGE using GRUB as a bootloader

Options:
 Actions:
 -d DIRECTORY [default CWD]
	    Directory where the boot.image and the partition subdirectories
	    are/will be created
 -f TAR_FILE
	    Name of the tar file containing the filesystem to install. Can
	    be a pure tar file [.tar] or a compressed tar file
	    [.tar.gz|.tar.bz2]
 -s FS_TYPE
	    Type of the file system to create on the virtual disk. Choices 
	    are:
		ext2 on GNU [default is ext2]
		ext2, minix or msdos on GNU/Linux [default is ext2]

 -t TYPE
	    Type of the image to create. Choices are '1.20', '1.44', '1.60',
	    '1.68', '1.74', '2.88' or 'hd' [default is hd]
 -F
	    Force to set the set_dpt flag (unnecessary 99% of the time! Be
	    careful! 
 Informations:
 -D     
	    turn Debugging on [xtrace]
 -h|--help	
	    display this Help and exit
 -V|--version	
	    display Version information and exit

Copyright (c) 2001,2002,2003 Thierry Laronde <[e-mail]>. 
Copyright (c) 2001,2002 Robert Millan <[e-mail]>.
GPLed."

version="mkbimage $version_number

Written by Thierry Laronde and Robert Millan.

Copyright (c) 2001,2002,2003 Thierry Laronde <[e-mail]>.
Copyright (c) 2001,2002,2003 Robert Millan <[e-mail]>.

This is free software under the GPL version 2 or later; see the source for 
copying conditions.  There is NO warranty, not even for MERCHANTABILITY or 
FITNESS FOR A PARTICULAR PURPOSE."

# Functions

error ()
{
	case $1 in
	bug) echo "This is a bug!";
		echo "$usage";;
	option) echo "Unknow option"; echo "$usage";;
	missing_argument) echo "You must give an argument to the option!";
		echo "$usage";;
	missing_option) echo "You must indicate at least one option!";
		echo "$usage";;
	must_be_root) echo "You must be root! (or install e2tools/mtools)";;
	unknown_fs)	if [ $uname = Linux ];
				then echo "The GNU/Linux supported fs are: ext2, minix or msdos!";
			elif [ $uname = GNU ];
				then echo "The GNU supported fs is ext2!";
			fi;;
	unknown_format) echo "The tar file must be .tar|.tar.gz|.tar.bz2!";;
	wont_fit) echo "The files won't fit on the selected type of media!";;
	wrong_directory) echo "Directory inexistant or not given!";
		echo "$usage";;
	wrong_file) echo "File inexistant or empty!";
		echo "$usage";;
	wrong_type) echo "The type specified is not a valid one!";
		echo "$usage";;
	esac	
	exit 1
}

# create a filesystem of type $fs in $image with offset $offset
mkbimage_mkfs ()
{
  case $offset in
    0)  lo_options="";;
    *) lo_options="-o $offset";;
  esac

  if [ "$offset" = "0" ] ; then
    mkfs.$fs -F $image
  elif [ `id -u` = "0" ] ; then
    losetup $lo_options /dev/loop1 $image
    mkfs.$fs /dev/loop1
    losetup -d /dev/loop1
  else
    error must_be_root
  fi
}

# copy ${image}1/* to ${image}:/, assuming ${image} contains a filesystem
# of type $fs in offset $offset
mkbimage_cp ()
{
  case $offset in
    0)  lo_options="";;
    *)  lo_options="-o $offset";;
  esac
  case $fs in
    ext2)
      cp="e2cp";
      mkdir="e2mkdir";;
    vfat)
      cp="mcopy";
      mkdir="mmd";;
    *)
      cp="";
      mkdir="";;
  esac

  if [ "$offset" = 0 ] && which $cp > /dev/null ; then
    for dir in $(cd ${image}1 && find -type d) ; do
	$mkdir ${image}:$dir
    done
    for file in $(cd ${image}1 && find -type f) ; do
	$cp ${image}1/$file ${image}:$file
    done
  elif [ "`id -u`" = "0" ] ; then
    losetup $lo_options /dev/loop1 $image
    mkdir ${image}.mnt
    mount -t $fs /dev/loop1 ${image}.mnt
    cp -a ${image}1/* ${image}.mnt/ && sync
    umount ${image}.mnt
    rmdir ${image}.mnt
    losetup -d /dev/loop1
  else
    error must_be_root
  fi
}

#**********************************************************************
#                          MAIN PROGRAM                               *
#**********************************************************************

#---------------------- Getting the options

[ $# -eq 0 ] && error missing_option;

while [ $# -gt 0 ]; do
	case "$1" in
		-d) shift;
			dir="$1";
			[ ! -d "$1" ] && error wrong_directory;;
		-f) shift;
			tarfile="$1";
			[ -z "$tarfile" ] && error missing_argument;;
		-s) shift;
			fs="$1";;
		-t) shift;
			image_type="$1";;
		-F) geo_option="-F";;
		-D) debug="-v";
		    set -x;;
		-h|--help) echo "$usage"; exit 0;;
		-V|--version) echo "$version"; exit 0;;
	 	*) error option ;;
	esac
shift	
done
#---------------------- Sanity checks
[ ! "$tarfile" ] && error missing_argument;
[ ! -s "$tarfile" ] && error wrong_file;

if [ ! "$image_type" ]; then
	image_type=hd;
elif [ "$image_type" != "1.20" ] && [ "$image_type" != "1.44" ] \
  && [ "$image_type" != "1.60" ] && [ "$image_type" != "1.68" ] \
  && [ "$image_type" != "2.88" ] && [ "$image_type" != "1.74" ] \
  && [ "$image_type" != "hd" ] && [ "$image_type" != "1.60" ] ; then
  error wrong_type ;
fi

[ ! "$fs" ] && fs=ext2

# Carlo Contavalli reported that I [TL] have forgotten to specify the
# partition ID for sfdisk to correctly fill the partition table (ext2 is the
# default on Linux, so this worked in this case...). This is fixed below.
case "$fs" in
	ext2) mkfs_options="-m 0";
		  part_id="83";; # This is the default
#	ufs)	if [ $uname = Linux ];
#		then error unknown_fs;
#		fi;;
	minix)	if [ $uname = GNU ];
		then error unknown_fs;
		else 
			mkfs_options="-v"; # Minix version 2
			part_id="81";
		fi;;
	msdos)	if [ $uname = GNU ];
		then error unknown_fs;
		else 
			mkfs_options="-f 1 -F 12"; # the smallest...
			part_id="1"; 
		fi;;
	*) error unknown_fs;;
esac

# What type of tar file has been given ?

suffix=`echo "$tarfile" | sed -n 's/^.*\.\([targbz2]\{2,3\}\)$/\1/p'`
case "$suffix" in
	tar) decompress="cat";;
	gz) decompress="gunzip -c";;
	bz2) decompress="bunzip2 -c";;
	*) error unknown_format;;
esac
#---------------------- Initializations

[ ! "$dir" ] && dir=`pwd`

image=$dir/$image_type.image
device_map=$dir/device.map

# First, find the size of the tar file in block_size.
file_size=`$decompress $tarfile | wc -c | tr -d ' '`
file_size=$(($file_size / $block_size + 1))

# Increase in order to be sure that with a fs there will be enough
# room (trying 110%)
file_size=$(($file_size + $file_size / 10))

case "$image_type" in
  hd) heads=16;
    sectors=63;
    cyl_size=$((16 * 63));
    # Create the minimum number of cylinders. At the moment, we leave
    # some space by rounding everything up by adding 1 cylinder, plus
    # another one for MBR + reserved track.
    cylinders=$(($file_size / $cyl_size + 2));; 
  1.20) [ $file_size -ge $bk_120 ] && error wont_fit; 
    heads=2;
    sectors=15;
    cyl_size=$((2 * 15));
    cylinders=80;;
  1.44) [ $file_size -ge $bk_144 ] && error wont_fit; 
    heads=2;
    sectors=18;
    cyl_size=$((2 * 18));
    cylinders=80;;
  1.60) [ $file_size -ge $bk_160 ] && error wont_fit; 
    heads=2;
    sectors=20;
    cyl_size=$((2 * 20));
    cylinders=80;
    geo_option="-F";;
  1.68) [ $file_size -ge $bk_168 ] && error wont_fit; 
    heads=2;
    sectors=21;
    cyl_size=$((2 * 21));
    cylinders=80;;
  1.74) [ $file_size -ge $bk_174 ] && error wont_fit; 
    heads=2;
    sectors=21;
    cyl_size=$((2 * 21));
    cylinders=83;;
  2.88) [ $file_size -ge $bk_288 ] && error wont_fit;
    heads=2;
    sectors=36;
    cyl_size=$((2 * 36));
    cylinders=80;;
  *) error bug;;
esac

type_option="-t $image_type"

# We start by creating a virtual disk which size is the number of
# cylinders of $cyl_size mandatory to put the files stocked in the $tarfile
# Create the empty virtual disk
dd if=/dev/zero of=$image bs=$block_size count=$(($cyl_size * $cylinders))

# We then format the virtual disk
# NOTE: the El Torito specification wants only one partition. So we
# create the first, and the remaining 3 entries are empty.

if [ "$image_type" = "hd" ]; then
  sfdisk -C $cylinders -H $heads -S $sectors -D $image<<EOT
,,$part_id,*,0,1,1


EOT
  offset="$(($sectors * $block_size))" 
  type_option=
else
  offset="0"
fi

# It's time now to create the filesystem on the first partition.
mkbimage_mkfs

# then untar the files
[ ! -e ${image}1 ] || { echo "${image}1 exists, please remove it first"; exit 1;}
mkdir -p ${image}1
$decompress $tarfile | tar -C ${image}1 $debug -xf -

# copy the untarred files into the filesystem image
mkbimage_cp

#We verify that the stage2 exists and we search the name
stage2_os_name=`find ${image}1 -name stage2 -type f`

[ -r "$stage2_os_name" ] || { echo "I can't find stage2!"; exit 1;}

#------------------------- GRUB stuff
if [ "$image_type" = "hd" ]; then
	device='(hd0)'
	root='(hd0,0)'
else
	device='(fd0)'
	root='(fd0)'
fi

cat<<EOT >$device_map
$device	${image}
EOT

${GRUB_PATH}grub --device-map=$device_map --batch<<EOT
geometry $device $cylinders $heads $sectors
root $root
setup $device
geometry $geo_option -w $type_option $device $cylinders $heads $sectors
EOT

echo "-------------------WHAT'S NEXT?-------------------------------------"
echo

cat <<EOF
If you have created an image aimed to a floppy, then something like:

dd if=<type>.image of=/dev/fd0[u<size>] bs=512

will be more than enough... if you have formated the floppy correctly
using \`superformat' to be found in \`fdutils' package.

For El Torito floppy emulation :

mkisofs -b <image> -c boot.catalog -o raw.iso <dir>

And for El Torito Hard Disk emulation:

mkisofs -b <image> -hard-disk-boot -c boot.catalog -o raw.iso <dir> 

Enjoy!
EOF

rm -rf ${image}1

exit 0