rlink.sh

#!/bin/bash
#
# title         : rlink.sh
# description   : A shell script to mount TOMTOM.xxx files from a TomTom
#                 SD card to browse/modify its content.
# author        : JV conseil – Internet Consulting
# credits       : JV-conseil
# copyright     : Copyright (c) 2021, JV conseil – Internet Consulting,
#                 All rights reserved.
# usage         : bash ./rlink.sh
# requirements  : VirtualBox, VM VirtualBox Extension Pack and one Linux
#                 distribution like Ubuntu.
# date          : 20210525
# version       : 1.0
# bash_version  : 5.1.8(1)-release
#
#===============================================================================

__TOMTOM_PATH="./"

__rlink_help() {
  cat <<EOF

R-Link Evolution Missing Explorer
---------------------------------

Place this file in the same folder where your TOMTOM.000 ... files are, ideally
on the SD card:

/Volumes/SDCARD
├── TOMTOM.000
├── TOMTOM.001
├── TOMTOM.002
├── TOMTOM.003
└── rlink.sh

options:
h   Help.

A TomTom R-Link SD card is made of multiple TOMTOM.xxx (000, 001, ...) files.

These files contain a splitted Lunux filesystem. The scripts will:
- Attach each file to a virtual block device, called a loopback device : /dev/loopX
- Aggregate all these devices as a big "linear" one: /dev/md/tomtom_vfs, seen a a real disk
- Mount this new device to the /mnt/tomtom_vfs directory.

Once done, you can modify the content, to add, for example, POIs.

EOF
}

# Output to stderr
__rlink_echoerr() {
  echo "$@" 1>&2
}

# Find first available /dev/loopX
__rlink_loopback_dev() {

  typeset -i num
  num=0
  while [[ ${num} -le 255 ]]; do
    if ! losetup /dev/loop${num} >/dev/null 2>&1; then
      break
    fi
    num=$((num + 2))
  done

  echo "/dev/loop${num}"

}

# Count the number of TOMTOM.xxx files
__rlink_count_tomtom_vfs_files() {

  typeset -i count_vfs_files
  count_vfs_files=0

  while [[ -e ${__TOMTOM_PATH}TOMTOM.$(printf "%03d" ${count_vfs_files}) ]]; do
    count_vfs_files+=1
  done

  echo ${count_vfs_files}

}

# Associate all TOMTOM.xxx files to a loopback device
__rlink_init_loopback_devs() {

  typeset -gi COUNT_VFS_FILES
  LOOPBACK_DEV_LIST=""

  COUNT_VFS_FILES=$(__rlink_count_tomtom_vfs_files ${__TOMTOM_PATH})
  echo "${COUNT_VFS_FILES} tomtom files found."

  echo "Creating loopback devices."

  for ((i = 0; i < COUNT_VFS_FILES; i++)); do
    VFS_FILE=${__TOMTOM_PATH}TOMTOM.$(printf "%03d" "$i")
    LOOPBACK_DEV=$(__rlink_loopback_dev)
    LOOPBACK_DEV_LIST="${LOOPBACK_DEV_LIST} ${LOOPBACK_DEV}"

    # associate file to loopback device
    if ! sudo losetup "${LOOPBACK_DEV}" "${VFS_FILE}"; then
      __rlink_echoerr "Error while creating loopback device ${LOOPBACK_DEV} from ${VFS_FILE}. Cancel."
      __rlink_remove_loopback_devs
      exit 1
    fi

    echo "${VFS_FILE} is now associated to ${LOOPBACK_DEV}."
  done

}

# Delete all loopback devices
__rlink_remove_loopback_devs() {

  echo "Removing all loopback devices."
  # shellcheck disable=SC2086
  if ! sudo losetup -d $LOOPBACK_DEV_LIST; then
    __rlink_echoerr "Error while removing one or multiple loopback devices. Please check with losetp and dmesg."
    exit 1
  fi
  return 0

}

# Build the linear raid device from all loopback devices (TOMTOM.xxx files)
__rlink_build_linear_raid() {

  echo "Build linear raid device."
  COMMAND="mdadm --build --auto=part --verbose /dev/md/tomtom_vfs --rounding=32 --level=linear -n${COUNT_VFS_FILES} ${LOOPBACK_DEV_LIST}"
  # shellcheck disable=SC2086
  if ! sudo $COMMAND; then
    __rlink_echoerr "Error during raid device creation. Trying to cancel. Check /proc/mdstat, mdadm and dmesg."
    __rlink_remove_loopback_devs
    exit 1
  fi
  return 0

}

# Delete the /dev/md/tomtom_vfs raid device
__rlink_delete_linear_raid() {

  echo "Stopping linear raid device."
  if ! sudo mdadm -S /dev/md/tomtom_vfs; then
    __rlink_echoerr "Error during raid device deletion. Please check /proc/mdstat, mdadm and dmesg. Loopback devices won't be removed."
    exit 1
  fi
  return 0

}

# wait for a carriage return
__press_enter_to_continue() {

  # shellcheck disable=SC2162
  read -p "Please press enter to continue:"
  echo "Thank you."
  return 0

}

# Mount the TOMTOM.xxx linear raid ex3 filesystem in /mnt/tomtom_vfs
__rlink_mount_vfs() {

  # Ensure it's not already mounted
  mount | grep "on /mnt/tomtom_vfs " >/dev/null 2>&1
  # shellcheck disable=SC2181
  if [[ $? -eq 0 ]]; then
    echo "Mountpoint already in use. Cancel."
  else
    echo "Creating mount point and mount tomtom filesystem."
    sudo mkdir -p /mnt/tomtom_vfs 2>/dev/null
    sudo mount /dev/md/tomtom_vfs /mnt/tomtom_vfs
    if [[ $? -eq 0 ]]; then
      vfs_user=$(stat -c "%u" /mnt/tomtom_vfs/common)
      vfs_group=$(stat -c "%g" /mnt/tomtom_vfs/common)
      current_group=$(id -gn)

      # bind to
      mkdir -p "$HOME/tomtom_vfs"
      sudo bindfs -u "$USER" -g "${current_group}" --create-for-user="${vfs_user}" --create-for-group="${vfs_group}" /mnt/tomtom_vfs/ "$HOME/tomtom_vfs"
      echo "Filesystem is now available in /mnt/tomtom_vfs as root and $HOME/tomtom_vfs as $USER."
      sleep 1
    else
      __rlink_echoerr "Something is wrong. Corrupted files ? Trying to cancel."
      __rlink_umount_vfs
      __rlink_delete_linear_raid
      __rlink_remove_loopback_devs
      exit 1
    fi
  fi
  return 0
}

# unmount /mnt/tomtom_vfs (TOMTOM.xxx linear raid ext3 filesystem)
__rlink_umount_vfs() {

  # Ensure it's mounted
  mount | grep "on /mnt/tomtom_vfs " >/dev/null 2>&1
  # shellcheck disable=SC2181
  if [[ $? -ne 0 ]]; then
    echo "Nothing to do, /mnt/tomtom_vfs Not mounted."
    return 0
  fi

  # synchronise files
  sync

  # check if there's something to kill
  fuserkill=0
  lsof "$HOME/tomtom_vfs" >/dev/null 2>&1
  [[ $? -ne 1 ]] && fuserkill=1
  lsof /mnt/tomtom_vfs >/dev/null 2>&1
  [[ $? -ne 1 ]] && fuserkill=1

  if [[ ${fuserkill} -eq 1 ]]; then
    # Killing local users
    echo "Killing remaining processus using the mountpoints."
    sudo fuser -k "$HOME/tomtom_vfs"

    # First kill everything that is related to the mountpoint
    sudo fuser -k /mnt/tomtom_vfs

    echo "Waiting 5 seconds."
    sleep 5
  fi

  # Then, umount
  echo "Unmounting tomtom filesystem and remove mount point."
  sudo fusermount -u "$HOME/tomtom_vfs"
  if ! sudo umount /mnt/tomtom_vfs; then
    __rlink_echoerr "Cannot unmount /mnt/tomtom_vfs. Please check dmesg, fuser and dmesg. raid and loopback devices left untouched."
    exit 1
  fi
  sudo rmdir /mnt/tomtom_vfs
  sudo rmdir "$HOME/tomtom_vfs"
  return 0

}

# If on X, open default file manager
__rlink_open_default_file_manager() {

  if xhost >&/dev/null; then
    echo "Launching default file manager."
    xdg-open "$HOME/tomtom_vfs"
  fi
  return 0

}

# Check if prerequires are installed
__rlink_check_prerequires() {

  ERR=0
  PREREQUIRES="mdadm losetup bindfs"
  for prerequire in $PREREQUIRES; do
    if ! which "$prerequire" >/dev/null 2>&1; then
      __rlink_echoerr "$prerequire command is missing."
      echo "Please install it (the method depends of your Linux distribution)."
      echo "For Ubuntu: apt-get install $prerequire"
      ERR=1
    fi
  done
  return $ERR

}

__rlink_search_cards() {

  typeset -i COUNT_CARDS
  COUNT_CARDS=0

  # shellcheck disable=SC2044
  for card in $(find "$HOME/tomtom_vfs" -name "*.pna"); do
    echo "Found $card card."
    COUNT_CARDS+=1
  done

  echo "Found ${COUNT_CARDS} card(s)."
  return 0

}

rlink() {

  if ! __rlink_check_prerequires; then
    exit 1
  fi

  echo "Starting."

  __rlink_init_loopback_devs
  __rlink_build_linear_raid
  __rlink_mount_vfs
  __rlink_search_cards
  __rlink_open_default_file_manager
  __press_enter_to_continue
  __rlink_umount_vfs
  __rlink_delete_linear_raid
  __rlink_remove_loopback_devs

  echo "End."
  return 0

}

# Tree
if [[ -z "$1" ]]; then
  __rlink_help
  echo
  read -p "Do you want to assemble your TOMTOM files? [y/N] " -n 1 -r
  echo
  if [[ $REPLY =~ ^[Yy]$ ]]; then
    rlink "$@"
  fi
else
  while getopts ":h" option; do
    case $option in
    h) # display Help
      __rlink_help
      ;;

    \?) # incorrect option
      __rlink_echoerr "Error: Invalid option."
      __rlink_help
      ;;
    esac
  done
fi