#!/bin/bash 
#
# Randy - Copy a RedHat Initial Ram Disk 
#
# The point of this script is to make a copy of an initial RAM disk (initrd) 
# from one of the RedHat installation bootdisks while making it possible
# to remove unneeded modules to make space on the disk for a Kickstart
# configuration file.
# 
# Note:  This is not an automatic tool, it just provides a lot of 
# assistance.  You still have to know what the hell you are doing.
#
# Eric Myers <myers@umich.edu>  - 9 April 2001
# @(#) $Id: Randy,v 1.2 2001/04/10 15:03:36 myers Exp myers $
######################################################################

compress=1			# compress the final target?  YES!
IMAGESIZE=1250			# smaller is better
MODDIR=/tmp/2.2.14-5.0BOOT
MODULES=/tmp/modules.cgz 
BOOTDIR=`pwd`/bootnet

IMAGE0=/tmp/initrd.img.orig
IMAGE1=/tmp/initrd.img.new
target=initrd.img
/bin/rm -f $target

INITRD=$BOOTDIR/initrd.img
if [ $# -gt 0 ]; then
  INITRD=$1
  shift
fi
echo "initrd is $INITRD"

/bin/cp $INITRD  ${IMAGE0}.gz
gunzip --force  ${IMAGE0}.gz

if [ ! -f $IMAGE0 ]; then
  echo "Cannot unpack image initrd."
  exit 2
fi

# First mount original intrd on loop device

for devnum in 0 1 2 3 4 5 6 7 8; do
    if losetup /dev/loop$devnum $IMAGE0 2>/dev/null ; then break; fi
done

if [ "$devnum" = "8" ]; then
    echo "Cannot get loopback device for Original initrd!" >&2
    exit 1
fi

LODEV0=/dev/loop$devnum
MNTPOINT0=/tmp/mnt$devnum
echo "Using loopback device $LODEV0 for Original initrd:"
losetup $LODEV0

clean0 () {
  umount $MNTPOINT0
  losetup -d $LODEV0
  rm $IMAGE0
}
trap "clean0; exit" 2 3 15

mkdir -p $MNTPOINT0
mount -t ext2 $LODEV0 $MNTPOINT0 || {
	echo "Cannot mount loopback device $LODEV0"
	exit 1
}

ORIG=$MNTPOINT0

if [ -d $ORIG ]; then
  echo "=============== ="
  echo "$ORIG:"
  ls $ORIG
  echo "=============== ="
else
  echo "Cannot find $ORIG"
  exit 2
fi

echo " "
echo "Original initrd now mounted on $ORIG  (press return to continue)"
read JUNK

##################
# Extract the modules from original 

MODCGZ=$ORIG/modules/modules.cgz

if [ -f $MODCGZ ]; then
  gunzip < $MODCGZ > /tmp/modules.cpio
  ( cd /tmp; cpio -idv < modules.cpio )
else
  echo "Cannot find $MODCGZ"
fi

################
# Now mount new empty filesystem on next loop device

/bin/rm -f $IMAGE1
dd if=/dev/zero of=$IMAGE1  bs=1k count=$IMAGESIZE 2> /dev/null
ls -s $IMAGE1

for devnum in 0 1 2 3 4 5 6 7 8; do
    if losetup /dev/loop$devnum $IMAGE1 2>/dev/null ; then break; fi
done

if [ "$devnum" = "8" ]; then
    echo "Cannot get loopback device for NEW!" >&2
    clean0; exit 1
fi

LODEV1=/dev/loop$devnum
MNTPOINT1=/tmp/mnt$devnum
echo "Using loopback device $LODEV1 for new initrd."
losetup $LODEV1

clean1 () {
  umount $MNTPOINT1
  losetup -d $LODEV1
  rm $IMAGE1
}
trap "clean0; clean1; exit " 2 3 15


# make a filesystem on new file
# We have to "echo y |" so that it doesn't complain about $IMAGE not
# being a block device
echo y | mke2fs $LODEV1 $IMAGESIZE >/dev/null 2>/dev/null
echo "Made ext2 filesystem on $LODEV1"

mkdir -p $MNTPOINT1
mount -t ext2 $LODEV1 $MNTPOINT1 || {
	echo "Cannot mount loopback device $LODEV1"
	clean 0; clean1; exit 1
}

NEW=$MNTPOINT1

############
# copy the original initrd

/bin/cp -a $ORIG/*  $NEW

if [ -d $NEW ]; then
  echo "=============== "
  ls $NEW
  echo "=============== "
else
  echo "Cannot find $NEW"
  exit 2
fi

echo " "
echo "New initrd is now mounted on $NEW "
echo "Edit modules etc as you like and then press Enter."
read JUNK


# Now collect modules from module dir and replace

find $MODDIR -print | cpio -H crc -ov | gzip -9 > $MODULES

/bin/cp -i $MODULES $NEW/modules/


####################
# Compress target and clean up 

if [ -n "$compress" ]; then
    echo "compressing the image..."
    gzip -9 < $IMAGE1 > $target
else
    cp -a $IMAGE1 $target
fi

echo "Final result is $target"

clean0
clean1

exit 0