#!/bin/sh

# Copyright (C) 2015
# Thomas Schmitt <scdbackup@gmx.net>, libburnia-project.org
# Provided under BSD license: Use, modify, and distribute as you like.

echo >&2
echo "frontend/grub-mkrescue-sed.sh manipulating xorriso arguments" >&2
echo >&2

# This script may be handed by its absolute path to grub-mkrescue
# via option --xorriso= . E.g.
#
#   mkdir minimal
#   touch minimal/empty-file.txt
#   grub-mkrescue -o output.iso minimal \
#         --xorriso=/home/thomas/xorriso-1.4.3./frontend/grub-mkrescue-sed.sh
#
# It will manipulate the xorriso arguments before they get executed by a
# xorriso program. Default is the neighboring ../../xorriso/xorriso program or,
# if that neighbor cannot be found, the system-wide installed xorriso.
#
# The mode "mjg" implements an experiment which should be accompanied by a
# GNU xorriso built by
#   export CPPFLAGS="-DLibisofs_mjg_boot_for_grub2" 
#   ./configure && make clean && make
#
# The mode "mbr_only" implements an alternative fully UEFI compliant layout
# which does not produce GTP, HFS+, and APM.
# It is supposed to work with any unmodified xorriso >= 1.3.2
#

#
#                              Variation settings
#
# The environment variables MKRESCUE_SED_* override the following
# default settings:

# Manipulation mode:
#  "mjg"       =  ESP in MBR+GPT+APM, with HFS+
#  "mbr_only"  =  ESP in MBR, without HFS+
#  "original"  =  pass arguments unchanged
mode="mjg"
if test -n "$MKRESCUE_SED_MODE"
then
  mode="$MKRESCUE_SED_MODE"
fi

# First argument of -append_partition with mode "mjg". Values: 1 or 2.
partno=1
if test -n "$MKRESCUE_SED_PARTNO"
then
  partno="$MKRESCUE_SED_PARTNO"
fi

# Replacement for option --protective-msdos-label. Either itself or empty text.
# If the environment variable contains the word "no", this means empty.
protective="--protective-msdos-label"
if test -n "$MKRESCUE_SED_PROTECTIVE"
then
  if test x"$MKRESCUE_SED_PROTECTIVE" = xno
  then
    protective=""
  elif test x"$MKRESCUE_SED_PROTECTIVE" = xyes
  then
    protective="--protective-msdos-label"
  else
    protective="$MKRESCUE_SED_PROTECTIVE"
  fi
fi

# "yes" shows xorriso arguments, "extra" additionally shows all input files.
debug=no
if test -n "$MKRESCUE_SED_DEBUG"
then
  debug="$MKRESCUE_SED_DEBUG"
fi

# The path to the program that will be executed with the converted arguments.
if test -n "$MKRESCUE_SED_XORRISO"
then
  xorriso="$MKRESCUE_SED_XORRISO"
else
  # Prefer neighboring xorriso binary over system-wide installed one.
  self_dir="$(dirname $(dirname "$0") )"
  if test -x "$self_dir"/xorriso/xorriso
  then
    xorriso="$self_dir"/xorriso/xorriso
  else
    xorriso="xorriso"
  fi
fi 

# MKRESCUE_SED_XORRISO_ARGS will be used as first arguments of the xorriso run.
# (Trailing xorriso arguments may be simply added to the grub-mkrescue
#  command line.)
# Each argument must be a single word. No whitespace. No quotation marks.


#
#                               Do the work 
#

echo "frontend/grub-mkrescue-sed.sh mode:  $mode" >&2
echo >&2

if test x"$debug" = xyes -o x"$debug" = xextra
then
  # Show arguments
  echo "##### Begin of received arguments" >&2
  echo "$0" >&2
  for i in "$@"
  do
    echo "$i" >&2
  done
  echo "##### End of recived arguments" >&2
  echo >&2
fi

# Look for the name of the /tmp directory with the GRUB2 files.
# It is the next argument after -r.
next_is_dir=0
dir="."
for i in "$@"
do
  if test x"$i" = x"-r"
  then
    next_is_dir=1
  elif test $next_is_dir = 1
  then
    next_is_dir=0
    dir="$i"
  fi
done

if test x"$debug" = xextra
then
  # Show files on disk
  find "$dir"
fi

if test x"$mode" = xmjg
then
  # Exchange arguments for the experimental GRUB2 mjg layout
  x=$(echo " $*" | sed \
    -e "s/-efi-boot-part --efi-boot-image/-no-pad -append_partition $partno 0xef \/tmp\/$(basename "$dir")\/efi.img/" \
    -e "s/--efi-boot efi\.img/-eltorito-alt-boot -e efi.img -no-emul-boot -isohybrid-gpt-basdat/" \
    -e "s/--protective-msdos-label/$protective/" \
     )

elif test x"$mode" = xmbr_only
then
  # Exchange arguments for no-HFS MBR-only layout
  x=$(echo " $*" | sed \
    -e "s/-efi-boot-part --efi-boot-image/-no-pad -append_partition 2 0xef \/tmp\/$(basename "$dir")\/efi.img/" \
    -e "s/-hfsplus .*CoreServices\/boot.efi//" \
    -e "s/--protective-msdos-label/$protective/" \
     )

elif test x"$mode" = xoriginal
then
  # Pass arguments unchanged
  x=" $*"

else
  echo >&2
  echo "$0 : FATAL : Unknown manipulation mode '$mode'." >&2
  echo >&2
  exit 1
fi

if test x"$debug" = xyes -o x"$debug" = xextra
then
  echo "+ converted xorriso arguments:" >&2
  echo "  $x" >&2
  echo >&2
fi

# Run xorriso binary with the converted arguments
"$xorriso" $MKRESCUE_SED_XORRISO_ARGS $x