#!/bin/bash
#
#    Copyright (C) 2012-2020  Ruben Rodriguez <ruben@trisquel.info>
#    Copyright (C) 2020       Andrew Engelbrecht <andrew@fsf.org>
#
#    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 of the License, 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, write to the Free Software
#    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
#

set -e

usage(){
echo
echo You need to run this script as root
echo Usage: sudo $0 distro.iso /dev/sdX
echo Example: sudo $0 trisquel_11.0-fsf_amd64.iso /dev/sdb
echo
echo WARNING!: this script will delete all data on the whole disk you pass as the second parameter. Make sure it is your USB drive and not your internal hard drive!
echo ANOTHER WARNING!: This script can bite your dog. Use it with care, backup your data.
echo
exit 1
}

[ $(id -u) != 0 ] && usage
[ $# != 2 ] && usage

ISO=$1
DEV=$2
PERSISTENCESIZE=4096 # Size of the persistence file, in MB

ISOTMP=$(mktemp -d)
DEVTMP=$(mktemp -d)

umount $DEV* || true
mount -o loop $ISO $ISOTMP

# Create FAT32 LBA partition taking all disk
echo 'start=2048, type=c' | sfdisk $DEV
mkfs.vfat -I -F32 ${DEV}1 -n FSF-LIVE

# Copy the data
mount ${DEV}1 $DEVTMP
cp -vr $ISOTMP/* $ISOTMP/.disk $DEVTMP || true

cp -vr $DEVTMP/isolinux $DEVTMP/syslinux
mv $DEVTMP/syslinux/isolinux.cfg $DEVTMP/syslinux/syslinux.cfg

# apparently running syslinux command when /syslinux/ and /isolinux/ both exist
# leads to GRUB not detecting the isolinux directory.
mv $DEVTMP/isolinux $DEVTMP/isolinux.bak

# Create persistency file
# dd if=/dev/zero of=$DEVTMP/casper-rw bs=1M count=$PERSISTENCESIZE oflag=sync status=progress
# mkfs.ext4 -L casper-rw -F $DEVTMP/casper-rw
# sed -i 's/noprompt --/noprompt persistent --/' $DEVTMP/syslinux/txt.cfg $DEVTMP/isolinux/txt.cfg

umount $DEVTMP
umount $ISOTMP

# Set up bootloader, requires syslinux. version 6.04 has been tested.
syslinux --directory /syslinux/ --install ${DEV}1
sudo dd if=/usr/lib/SYSLINUX/mbr.bin of=${DEV}
parted $DEV set 1 boot on

mount ${DEV}1 $DEVTMP
mv $DEVTMP/isolinux.bak $DEVTMP/isolinux
umount $DEVTMP

rmdir $DEVTMP
rmdir $ISOTMP

#eject $DEV
sync