#!/bin/sh
#
# rebuildiso 0.1
#
# USE AT YOUR OWN RISK!
# It works fine for me, in it's present form, but I suggest you look it over 
# thoroughly before using it.
#
# This script will rebuild an ISO from a current ISO or CDROM, allowing you to make
# modifications in between, without ever actually coping the files from the ISO/CDROM
# to hard disk. It does this by setting up a replica of the ISO/CDROMs's directory
# tree using links vs actual files. This saves time and space. It can also be used to 
# combine multiple ISO/CDROMs into a single ISO, for say a DVD iso. Since it mounts
# the ISO/CDROMs on a loop device, you either need to run it as root or make fstab 
# entries to allow a regular user to do it, which is a security risk in and of itself.
#
# NOTE: In order to combine multiple CDROMs you WILL need to have multiple CDROM drives
#       available, since all ISO/CDROMs MUST stay mounted until the new ISO has been
#       built. If you have a minimum of 2 CDROM drives, then you could use this script
#       to combine those 2 into 1, then use that new ISO to build upon and so on, thereby
#       combining as many as you want eventually into a single ISO. Hope that makes sense. :)
#
#
APPID="Slackware Install"        # Default Application ID Name
VOLID="Slackware Install DVD"    # Default Volume ID Name
NAME="slackware-dvd.iso"         # Default filename of new ISO
#
# DO NOT SET THESE 2 VARIABLES TO ANYTHING YOU VALUE, AS THEY ARE REMOVED AT COMPLETION!!!!!!
MNTDIR="/mnt/rebuildiso"         # Directory where the original ISO/CDROMs will be mounted
REPDIR="/tmp/rebuildiso"         # Directory to build the replica in

EXITSTAT=0
# Codes:
# 1 -- mkisofs failed
# 2 -- $MNTDIR exists & we have no idea what is there (safe play is to abort)
# 3 -- $REPDIR exists & we have no idea what is there (safe play is to abort)
# 4 -- mkdir failed
# 5 -- mount -o loop failed
# 6 -- user abort

create_iso ()
{
  cd $REPDIR
  if [ -h isolinux/isolinux.bin ]; then
    # mkisofs modifies isolinux.bin, so we need to remove the link to it
    #  and copy the actual file into the new tree
    cp -H isolinux/isolinux.bin /tmp
    rm isolinux/isolinux.bin
    cp /tmp/isolinux.bin isolinux/
    rm /tmp/isolinux.bin
  fi
  if [ -e isolinux/isolinux.boot ]; then
    # mkisofs creates isolinux.boot, so just remove it if present
    rm -f isolinux/isolinux.boot
  fi
  
  if [ -d isolinux ]; then
    mkisofs -o $NAME -R -J -V "$APPID" -hide-rr-moved \
    -v -d -N -no-emul-boot -boot-load-size 4 -boot-info-table \
    -sort isolinux/iso.sort -b isolinux/isolinux.bin \
    -c isolinux/isolinux.boot -A "$VOLID" -f .
    if [ ! "$?" = "0" ]; then
      EXITSTAT=1
      echo "mkisofs failed!!!"
    fi
  else
    echo
    echo "There is no isolinux directory present. The ISO will not"
    echo "be bootable! Not a problem if you'll be adding isolinux"
    echo "later or don't care if it's bootable or not."
    echo -n "Continue anyway? (y/n): "
    read ANSWER
    if [ "$ANSWER" = "y" ]; then
      mkisofs -o $NAME -R -J -V "$APPID" -hide-rr-moved \
      -v -d -N -A "$VOLID" -f .
      if [ ! "$?" = "0" ]; then
        EXITSTAT=1
        echo "mkisofs failed!!!"
      fi
    else
      echo "Aborted..."
      exit 6
    fi
  fi
}

cleanup ()
{
  cd /
  for ((a=1; a <= NUM ; a++))
  do
    umount $MNTDIR/loop$a
    rmdir $MNTDIR/loop$a
  done
  rm -rf $REPDIR
  rm -f /tmp/.rebuildiso-save
  rmdir $MNTDIR
}

if [ -f /tmp/.rebuildiso-save ]; then
  # Get the settings from the saved build, if present
  . /tmp/.rebuildiso-save
  echo "Found a saved session at $REPDIR"
  echo -n "Create the ISO from it? (y/n): "
  read ANSWER
  if [ "$ANSWER" = "y" ]; then
    create_iso
    cleanup
    echo
    if [ "$EXITSTAT" = "0" ]; then
      echo "ISO $NAME build is complete..."
    else
      echo "ISO $NAME build failed!!!"
    fi
  else
    rm /tmp/.rebuildiso-save
  fi
  exit $EXITSTAT
fi

while [ "$GOTALL" != "y" ]
do
  # Here we collect all the information we need
  echo
  echo -n "How many ISO/CDROMs do you want to include?: "
  read NUM

  if (( NUM )); then
    ((a = 1))
    while (( a <= NUM ))
    do
      echo
      echo "What is the full path to ISO/CDROM #$a?" 
      echo -n "(ie /home/gomer/slack.iso, /dev/cdrom): "
      read ISOS[$a]
      if [ -f ${ISOS[$a]} ] || [ -b ${ISOS[$a]} ]; then
        ((a += 1))
      else
        echo
        echo "${ISOS[$a]} either does not exist or is not a regular file or device!"
      fi
    done

    ((a = 1))
    while (( a ))
    do
      echo
      echo -n "What shall I name the new ISO? [`basename $NAME`]: "
      read TMP
      if [ -n "$TMP" ]; then
         NAME=$TMP
      fi
      # Force it into /tmp/filename so we don't end up writing the new ISO inside $REPDIR
      # when using the -o option to mkisofs
      NAME="/tmp/`basename $NAME`"
      if [ -e $NAME ]; then
        echo
        echo -n "$NAME already exists. Overwrite it? (y/n): "
        read ANSWER
        if [ "$ANSWER" = "y" ]; then
          (( a = 0 ))
        fi
      else
        (( a = 0 ))
      fi
    done

  echo
  echo -n "What should I use for the Application ID? [$APPID]: "
  read TMP
  if [ -n "$TMP" ]; then
    APPID=$TMP
  fi
  echo
  echo -n "What should I use for the Volume ID? [$VOLID]: "
  read TMP
  if [ -n "$TMP" ]; then
    VOLID=$TMP
  fi

  echo "About to generate $NAME from the following ISO/CDROMs:"
  for ((a=1; a <= NUM ; a++))
  do
    echo "    ${ISOS[$a]}"
  done
  echo
  echo -n "Proceed? (y/n): "
  read GOTALL
  fi
done

if [ -e $MNTDIR/loop1 ]; then
  echo
  echo "I can not proceed until you unmount anything in $MNTDIR"
  echo "and remove the directory, since I have no way of knowing"
  echo "for sure what is there."
  exit 2
fi

if [ -e $REPDIR ]; then
  echo
  echo "I can not proceed until you remove $REPDIR, since I have"
  echo "no way of knowing for sure what is there."
  exit 3
fi
mkdir -p $REPDIR
if [ ! "$?" = "0" ]; then
  echo "Failed to create $REPDIR"
  exit 4
fi

for ((a=1; a <= NUM ; a++))
do
  mkdir -p $MNTDIR/loop$a
  if [ ! "$?" = "0" ]; then
    echo "Failed to create $MNTDIR/loop$a"
    exit 4
  fi
  mount -o loop ${ISOS[$a]} $MNTDIR/loop$a
  if [ ! "$?" = "0" ]; then
    echo "Could not mount ${ISOS[$a]}"
    exit 5
  fi
  cd $MNTDIR/loop$a
  (( x=1 ))
  echo
  echo -n "Adding ISO/CDROM #$a to $REPDIR ... "
  for file in `find . | cut -c 3-`
  do
    if [ -d "$file" ]; then
      mkdir -p $REPDIR/$file
    else
      ln -sf $MNTDIR/loop$a/$file $REPDIR/$file
    fi
    # Print progress
    case $x in
      1)
        printf "\b|";;
      2)
        printf "\b/";;
      3)
        printf "\b-";;
      *)
        printf "\b\\"
        x=1;;
    esac
    (( x++ ))
  done
  printf "\bDone!"
done

echo
cat << EOF 
The directory tree for the new ISO is ready at $REPDIR.
If you would like to make some custom modifications to it
then you can exit this script now, make your mods, and then
rerun this script to build the ISO.

NOTE: Before you can modify any file, you will need to replace
      the link with the actual file from the ISO/CDROM. All of 
      the ISO/CDROMs are mounted at $MNTDIR.
EOF
echo
echo -n "Proceed now? (y/n): "
read ANSWER
if [ "$ANSWER" = "n" ]; then
  # Save the variables for later
  cat << EOF > /tmp/.rebuildiso-save
# DO NOT MODIFY THIS FILE! IT'S INTEGRITY IS ASSUMED!"
NUM=$NUM
REPDIR="$REPDIR"
MNTDIR="$MNTDIR"
NAME="$NAME"
APPID="$APPID"
VOLID="$VOLID"
GOTALL="y"
EOF
  exit 0
fi

create_iso
cleanup
echo
if [ "$EXITSTAT" = "0" ]; then
  echo "ISO $NAME build is complete..."
else
  echo "ISO $NAME build failed!!!"
fi
exit $EXITSTAT
# End of script