#! /bin/sh
#
# Copyright © 2011, 2012, 2014 Richard Kettlewell.
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
set -e

action=mount
act=""
keyfile=""

while [ $# -gt 0 ]; do
  case "$1" in
  --unmount | -u )
    shift
    action=unmount
    ;;
  --check | -c )
    shift
    action=check
    ;;
  --dry-run | -n )
    shift
    act="echo"
    ;;
  --key-file | -k )
    shift
    keyfile="$1"
    shift
    ;;
  --help | -h )
    cat <<EOF
Usage:
  rsbackup-mount [OPTIONS] [--] [DEVICES]

Options:
  --unmount, -u        Unmount instead of mount
  --check, -c          Check for devices that are attached but not mounted
  --dry-run, -n        Display commands but do nothing
  --key-file, -k PATH  Path to encryption key
  --help, -h           Display usage message
  --version, -V        Display version string
EOF
    exit 0
    ;;
  -V | --version )
    echo "rsbackup-mount _version_"
    exit 0
    ;;
  -- )
    shift
    break
    ;;
  -* )
    echo "ERROR: unknown option '$1'" >&2
    exit 1
    ;;
  * )
    break
    ;;
  esac
done

. /etc/rsbackup/devices

if [ $# = 0 ]; then
  set $devices
  auto=true
else
  auto=false
fi

# Set the parameters for the device as follows:
#
#   uuid=<uuid of physical device>
#   encrypted=<true|false>
#   luks_device=<path to encrypted container>    (if encrypted=true)
#   luks_device_attached=<true|false>
#   luks_device_open=<true|false>
device_parameters() {
  dev="$1"
  uuid=$(eval echo \$${dev}_uuid)
  plain=$(eval echo \$${dev}_plain)
  if [ -z "$plain" ]; then
    encrypted=true
    luks_device=/dev/disk/by-uuid/$uuid
    if [ -e ${luks_device} ]; then
      luks_device_attached=true
      if [ -e /dev/mapper/$device ]; then
        luks_device_open=true
      else
        luks_device_open=false
      fi
    else
      luks_device_attached=false
    fi
  else
    encrypted=false
  fi
}

case $action in
mount )
  for device; do
    device_parameters $device
    if $encrypted && ! $luks_device_attached && $auto; then
      echo >&2 "WARNING: $device not attached, skipping"
      continue
    fi
    if $encrypted && ! $luks_device_open; then
      if $luks_device_attached; then
        echo "Decrypting $device:"
        if [ -n "$keyfile" ]; then
          $act cryptsetup luksOpen --key-file "$keyfile" "${luks_device}" $device
        else
          $act cryptsetup luksOpen "${luks_device}" $device
        fi
      else
        echo >&2 "ERROR: $device not attached"
        exit 1
      fi
    fi
    if [ -r /$device ] && [ -x /$device ]; then
      if [ ! -e /$device/device-id ]; then
        $act mount /$device
      else
        if ! $auto; then
          echo >&2 "WARNING: /$device/device-id already exists"
        fi
      fi
    else
      echo >&2 "ERROR: /$device is not accessible"
      exit 1
    fi
  done
  ;;
unmount )
  for device; do
    if [ -e /$device/device-id ]; then
      $act umount /$device
    fi
    if [ -e /dev/mapper/$device ]; then
      $act cryptsetup luksClose $device
    fi
  done
  ;;
check )
  for device; do
    device_parameters $device
    if $encrypted && $luks_device_attached; then
      if ! $luks_device_open; then
        echo "$device is attached but not decrypted"
      elif [ ! -e /$device/device-id ]; then
        echo "$device is attached and open, but does not seem to be mounted"
      fi
    fi
  done
  ;;
esac
