#! /bin/bash
#
# usbboot_grub
#
# Author: Michael Towers <gradgrind[at]online[dot]de>

# This file is part of the larch project.
#
#    larch 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.
#
#    larch 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 larch; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
#----------------------------------------------------------------------------
# 2008.06.22

APP="$( basename $0 )"

usage () {
    echo
    echo "Usage:"
    echo "  ${APP} [<Arch installation root directory>]"
    echo
    echo "   Prepare a bootable USB-stick from a larch build."
    echo "   If no Arch directory is given, '/' is assumed."
    exit 1
}

if [ -n "$1" ]; then
    AINSTALL="$( readlink -f $1 )"
    if [ ! -x ${AINSTALL}/sbin/grub ]; then
        echo "ERROR: ${AINSTALL}/sbin/grub not found"
        exit 1
    fi
else
    AINSTALL=""
    if ! which grub &>/dev/null; then
        echo "ERROR: grub not found"
        exit 1
    fi
fi
CDDATA=${AINSTALL}/.larch/cd

if [ ! -f ${CDDATA}/system.sqf ]; then
    echo "ERROR: ${CDDATA} does not contain larch cd data"
    usage
fi
if [ ! -f ${CDDATA}/boot/grub/stage1 ]; then
    echo "ERROR: grub data not in ${CDDATA}/boot/grub"
    exit 1
fi

echo "//"
echo "// **********************************************************"
echo "//"
echo "// ${APP} will prepare a bootable USB stick with your"
echo "// previously prepared larch data from ${CDDATA}"
echo "//"
echo "// As an alternative it might render your system unbootable."
echo "// If that thought disturbs you please don't continue."
echo "//"
echo "// This program is DANGEROUS - you have been warned!!!"
echo "//"
echo "// If you are too cool to be concerned about the warnings,"
echo "// please insert your USB stick, which should already be"
echo "// appropriately partitioned."
echo "//"
echo "// **********************************************************"
echo "//"

# test if the script is started by root user. If not, exit
if [ $UID -ne 0 ]; then
    echo "Only root can run ${APP}"; exit 1
fi

echo "//"
echo "// Enter the number of the partition you wish to use (0 to quit):"

devices=/tmp/devices$$
:> ${devices}
i=0
sfdisk -d | grep "/dev/sd[a-z][1-4] " | grep -v "Id= [05]" | \
        sed "s|\(.*\):.*size=\( *[0-9]*\).*|\1 \2|" | while read device sectors; do

    i=$(( ${i} + 1 ))
    echo "${device}" >>${devices}
    echo "// ${i}: ${device} $(( ${sectors} / 2048 )) MiB"
done

while true; do
    read -p "// Device: " d
    if [ "${d}" -eq "0" ]; then exit 1; fi
    i=0
    { while read device; do
        i=$(( ${i} + 1 ))
        if [ "${d}" -eq "${i}" ]; then break 2; fi
    done } <${devices}
done

rm ${devices}

echo "//"
read -p "// \"${device}\" will now be prepared. Continue? [y/N]: " ans
if [ -z "`echo ${ans} | grep '^ *[yY]'`" ]; then exit 1; fi

echo "//"
echo "// Formatting ${device} (ext2)"
dev=${device:0:8}
part=${device:8}
sfdisk ${dev} -N${part} <<EOF
,,L,*
EOF

mke2fs ${device}

echo "// Copying the files"
stick=/tmp/mnt
mkdir -p ${stick}
umount ${device} &>/dev/null
mount ${device} ${stick}
if [ $? != 0 ]; then
  echo "ERROR: Failed to mount device, quitting"
  exit 3
fi
cp -a ${CDDATA}/* ${stick}
umount ${stick}

# Convert the device and partion to grub syntax
grubdevice ()
{
## The contents of device.map look something like this:
#(fd0)   /dev/fd0
#(hd0)   /dev/hda
#(hd1)   /dev/sda
gdev="$( cat ${AINSTALL}${dmap} | grep "${dev}" | cut -f1  | tr -d "()" )"
gpart=$(( ${part} - 1 ))
echo "// Installing GRUB to (${gdev}), root (${gdev},${gpart})"
}

dmap=/tmp/device.map
rm -f ${AINSTALL}${dmap}
if [ -n "${AINSTALL}" ]; then
    # First try to get a device mapping
    mount --bind /dev ${AINSTALL}/dev
    echo "quit" | chroot ${AINSTALL} grub --no-floppy --device-map=${dmap} --batch
    grubdevice
    # Now actually install grub
    # As far as I can tell, the extra options to grub are not needed here
    chroot ${AINSTALL} grub --batch <<EOT
root (${gdev},${gpart})
setup (${gdev})
quit
EOT
    umount ${AINSTALL}/dev
else
    # First try to get a device mapping
    echo "quit" | grub --no-floppy --device-map=${dmap} --batch
    grubdevice
    # Now actually install grub
    # As far as I can tell, the extra options to grub are not needed here
    grub --batch <<EOT
root (${gdev},${gpart})
setup (${gdev})
quit
EOT
fi
rm -f ${AINSTALL}${dmap}

echo "//"
echo "// Done!"
echo "// If all went well your usb stick should now be a bootable larch system"