AMiRo-OS

################################################################################

# AMiRo-BLT is an bootloader and toolchain designed for the Autonomous Mini    #

# Robot (AMiRo) platform.                                                      #

# Copyright (C) 2016..2017  Thomas Schöpping et al.                            #

#                                                                              #

# 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/>.        #

#                                                                              #

# This research/work was supported by the Cluster of Excellence Cognitive      #

# Interaction Technology 'CITEC' (EXC 277) at Bielefeld University, which is   #

# funded by the German Research Foundation (DFG).                              #

################################################################################

#!/bin/bash

################################################################################

# GENERIC FUNCTIONS                                                            #

################################################################################

### print an error message #####################################################

# Prints a error <message> to standard output.

#If variable 'LOG_FILE' is specified, the message is also appended to the given file.

#

# usage:      printError <message>

# arguments:  <message>

#                 Message string to print.

# return:     n/a

#

function printError {

  local string="ERROR:   $1"

  # if a log file is specified

  if [ -n "$LOG_FILE" ]; then

    printf "[$(date '+%Y-%m-%d %H:%M:%S')] $string" >> $LOG_FILE

  fi

  printf "$(tput setaf 1)>>> $string$(tput sgr 0)" 1>&2

}

### print a warning message ####################################################

# Prints a warning <message> to standard output.

#If variable 'LOG_FILE' is specified, the message is also appended to the given file.

#

# usage:      printMessage <message>

# arguments:  <message>

#                 Message string to print.

# return:     n/a

#

function printWarning {

  local string="WARNING: $1"

  # if a log file is specified

  if [ -n "$LOG_FILE" ]; then

    printf "[$(date '+%Y-%m-%d %H:%M:%S')] $string" >> $LOG_FILE

  fi

  printf "$(tput setaf 3)>>> $string$(tput sgr 0)"

}

### print an information message ###############################################

# Prints an information <message> to standard output.

#If variable 'LOG_FILE' is specified, the message is also appended to the given file.

#

# usage:      printInfo <message>

# arguments:  <message>

#                 Message string to print.

# return:     n/a

#

function printInfo {

  local string="INFO:    $1"

  # if a log file is specified

  if [ -n "$LOG_FILE" ]; then

    printf "[$(date '+%Y-%m-%d %H:%M:%S')] $string" >> $LOG_FILE

  fi

  printf "$(tput setaf 2)>>> $string$(tput sgr 0)"

}

### print a message to file ####################################################

# Appends a <message> to a log file, specified by the variable 'LOG_FILE'.

#

# usage       printLog <message>

# arguments:  <message>

#                 Message string to print.

# return:     n/a

#

function printLog {

  local string="LOG:     $1"

  # if a log file is specified

  if [ -n "$LOG_FILE" ]; then

    printf "[$(date '+%Y-%m-%d %H:%M:%S')] $string" >> $LOG_FILE

  fi

}

### exit the script normally ###################################################

# Prints a delimiter and exits the script normally (returns 0).

#

# usage:      quitScript

# arguments:  n/a

# return:     0

#                 No error or warning occurred.

#

function quitScript {

  printLog "exiting $(realpath ${BASH_SOURCE[0]})\n"

  printf "######################################################################\n"

  exit 0

}

### read a user input ##########################################################

# Reads a single character user input from a set up <options> and stores it in

# a given <return> variable.

#

# usage:      readUserInput <options> <return>

# arguments:  <options>

#                 String definiing the set of valid characters.

#                 If the string is empty, the user can input any character.

#             <return>

#                 Variable to store the selected character to.

# return:     n/a

#

function readUserInput {

  local input=""

  # read user input

  while [ -z $input ] || ( [ -n "$1" ] && [[ ! $input =~ ^[$1]$ ]] ); do

    read -p "your selection: " -n 1 -e input

    if [ -z $input ] || ( [ -n "$1" ] && [[ ! $input =~ ^[$1]$ ]] ); then

      printWarning "[$input] is no valid action\n"

    fi

  done

  printLog "[$input] has been selected\n"

  eval $2="$input"

}

### check whether argument is an option ########################################

# Checks a <string> whether it is an option.

# Options are defined to either start with '--' followed by any string, or

# to start with a single '-' followed by a single character, or

# to start with a single '-' followed by a single character, a '=' and any string.

# Examples: '--option', '--option=arg', '-o', '-o=arg', '--'

#

# usage:      parseIsOption <string>

# arguments:  <string>

#                 A string to check whether it is an option.

# return:     0

#                 <string> is an option.

#             -1

#                 <string> is not an option.

#

function parseIsOption {

  if [[ "$1" =~ ^-(.$|.=.*) ]] || [[ "$1" =~ ^--.* ]]; then

    return 0

  else

    return -1

  fi

}

### set the log file ###########################################################

# Sets a specified <infile> as log file and checks whether it already exists.

# If so, the log may either be appended to the file, its content can be cleared,

# or no log is generated at all.

# The resulting path is stored in <outvar>.

#

# usage:      setLogFile [--option=<option>] [--quiet] <infile> <outvar>

# arguments:  --option=<option>

#                 Select what to do if <file> already exists.

#                 Possible values are 'a', 'r' and 'n'.

#                 - a: append

#                 - r: delete and restart

#                 - n: no log

#                 If no option is secified but <file> exists, an interactive selection is provided.

#             --quiet

#                 Suppress all messages.

#             <infile>

#                 Path of the wanted log file.

#             <outvar>

#                 Variable to store the path of the log file to.

# return:     0

#                 No error or warning occurred.

#             -1

#                 Error: invalid input

#

function setLogFile {

  local filepath=""

  local option=""

  local quiet=false

  # parse arguments

  local otherargs=()

  while [ $# -gt 0 ]; do

    if ( parseIsOption $1 ); then

      case "$1" in

        -o=*|--option=*)

          option=${1#*=}; shift 1;;

        -o*|--option*)

          option="$2"; shift 2;;

        -q|--quiet)

          quiet=true; shift 1;;

        *)

          printError "invalid option: $1\n"; shift 1;;

      esac

    else

      otherargs+=("$1")

      shift 1

    fi

  done

  filepath=$(realpath ${otherargs[0]})

  # if file already exists

  if [ -e $filepath ]; then

    # if no option was specified, ask what to do

    if [ -z "$option" ]; then

      printWarning "log file $filepath already esists\n"

      local userinput=""

      printf "Select what to do:\n"

      printf "  [A] - append log\n"

      printf "  [R] - restart log (delete existing file)\n"

      printf "  [N] - no log\n"

      readUserInput "AaRrNn" userinput

      option=${userinput,,}

    fi

    # evaluate option

    case "$option" in

      a)

        if [ $quiet = false ]; then

          printInfo "appending log to $filepath\n"

        fi

        printf "\n" >> $filepath

        printf "######################################################################\n" >> $filepath

        printf "\n" >> $filepath

        ;;

      r)

        echo -n "" > $filepath

        if [ $quiet = false ]; then

          printInfo "content of $filepath wiped\n"

        fi

        ;;

      n)

        if [ $quiet = false ]; then

          printInfo "no log file will be generated\n"

        fi

        filepath=""

        ;;

      *) # sanity check (return error)

        printError "unexpected argument: $option\n"; return -1;;

    esac

  else

    if [ $quiet = false ]; then

      printInfo "log file set to $filepath\n"

    fi

  fi

  eval ${otherargs[1]}="$filepath"

  return 0

}

################################################################################

# SPECIFIC FUNCTIONS                                                           #

################################################################################

### print welcome text #########################################################

# Prints a welcome message to standard out.

#

# usage:      printWelcomeText

# arguments:  n/a

# return:     n/a

#

function printWelcomeText {

  printf "######################################################################\n"

  printf "#                                                                    #\n"

  printf "#                     Welcome to the GCC setup!                      #\n"

  printf "#                                                                    #\n"

  printf "######################################################################\n"

  printf "#                                                                    #\n"

  printf "# Copyright (c) 2016..2017  Thomas Schöpping                         #\n"

  printf "#                                                                    #\n"

  printf "# This is free software; see the source for copying conditions.      #\n"

  printf "# There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR  #\n"

  printf "# A PARTICULAR PURPOSE. The development of this software was         #\n"

  printf "# supported by the Excellence Cluster EXC 227 Cognitive Interaction  #\n"

  printf "# Technology. The Excellence Cluster EXC 227 is a grant of the       #\n"

  printf "# Deutsche Forschungsgemeinschaft (DFG) in the context of the German #\n"

  printf "# Excellence Initiative.                                             #\n"

  printf "#                                                                    #\n"

  printf "######################################################################\n"

}

### print help #################################################################

# Prints a help text to standard out.

#

# usage:      printHelp

# arguments:  n/a

# return:     n/a

#

function printHelp {

  printInfo "printing help text\n"

  printf "usage:    $(basename ${BASH_SOURCE[0]}) [-h|--help] [-i|--install] [-c|--change] [-q|--quit] [--log=<file>]\n"

  printf "\n"

  printf "options:  -h, --help\n"

  printf "              Print this help text.\n"

  printf "          -i, --install\n"

  printf "              Install another version.\n"

  printf "          -c, --change\n"

  printf "              Change the default version.\n"

  printf "          -q, --quit\n"

  printf "              Quit the script.\n"

  printf "          --log=<file>\n"

  printf "              Specify a log file.\n"

}

### detect installed versions ##################################################

# Detect all installed version of arm-none-eabi-gcc, if any.

#

# usage:      detectInstalledVersions <binarray> <current>

# arguments:  <binarray>

#                 Array variable to store all detected binary paths to. 

#             <current>

#                 Variable to store the currently active binary to.

# return:     n/a

#

function detectInstalledVersions {

  local armgcc_command=$(command -v arm-none-eabi-gcc)

  local armgcc_commanddir=${HOME}/gcc-none-eabi

  local armgcc_currentbin=""

  local armgcc_installdir=${HOME}/gcc-none-eabi

  local armgcc_bins=()

  local armgcc_bincnt=0

  # check for already installed versions

  if [ -n "$armgcc_command" ]; then

    # follow the link to the actual binary

    armgcc_commanddir=$(dirname $armgcc_command)

    armgcc_currentbin=$armgcc_command

    while [ -L $armgcc_currentbin ]; do

      armgcc_currentbin=$(readlink $armgcc_currentbin)

    done

    # the installation location is assumed to be two directories up

    armgcc_installdir=$(realpath $(dirname ${armgcc_currentbin})/../../)

    # list all detected instalations

    for dir in $(ls -d ${armgcc_installdir}/*/); do

      if [ -f ${dir}/bin/arm-none-eabi-gcc ]; then

        armgcc_bins[$armgcc_bincnt]=${dir}bin/arm-none-eabi-gcc

        armgcc_bincnt=$((armgcc_bincnt + 1))

      fi

    done

  fi

  eval "$1=(${armgcc_bins[*]})"

  eval $2="$armgcc_currentbin"

}

### install new version ########################################################

# Fetches an installation package from the internet, installs it and expands

# the $PATH environment variable (via .bashrc) if required.

#

# usage:      installNewVersion [-i|--install=<path>] [-l|--link=<path>]

# argumenst:  -i, --install <path>

#                 Path where to install the new version to.

#             -l, --link <path>

#                 Path where to create according links.

# return:     0

#                 No error or warnign occurred.

#             1

#                 Warning: Installation aborted by user.

#

function installNewVersion {

  local installbasedir=${HOME}/gcc-arm-embedded

  local linkdir="/usr/bin"

  # parse arguments

  local otherargs=()

  while [ $# -gt 0 ]; do

    if ( parseIsOption $1 ); then

      case "$1" in

        -i=*|--install=*)

          installbasedir=$(realpath "${1#*=}"); shift 1;;

        -i|--install)

          installbasedir="$2"; shift 2;;

        -l=*|--link=*)

          linkdir=$(realpath "${1#*=}"); shift 1;;

        -l|--link)

          linkdir="$2"; shift 2;;

        *) # sanity check (exit with error)

          printError "invalid option: $1\n"; shift 1;;

      esac

    else

      otherargs+=("$1")

      shift 1

    fi

  done

  # read download URL form user

  printLog "read installation url from user\n"

  local armgcc_downloadurl=""

  while [[ "$armgcc_downloadurl" != *".tar.bz2" ]]; do

    read -p "Download link for the installation file: " -e armgcc_downloadurl

    if [[ $armgcc_downloadurl != *".tar.bz2" ]]; then

      printWarning "please specify a .tar.bz2 file\n"

    fi

  done

  printLog "user selected $armgcc_downloadurl\n"

  # if the file already exists, ask the user if it should be downloaded again

  local armgcc_tarball=$(basename "$armgcc_downloadurl")

  if [ -e "$armgcc_tarball" ]; then

    printWarning "$armgcc_tarball already exists. Delete and redownload? [y/n]\n"

    local userinput=""

    readUserInput "YyNn" userinput

    case "$userinput" in

      Y|y)

        rm "$armgcc_tarball"

        wget "$armgcc_downloadurl" | tee -a $LOG_FILE

        ;;

      N|n)

        ;;

      *) # sanity check (exit with error)

        printError "unexpected argument: $userinput\n";;

    esac

  else

    wget "$armgcc_downloadurl" | tee -a $LOG_FILE

  fi

  # extract tarball

  printInfo "extracting ${armgcc_tarball}...\n"

  tar -jxf "$armgcc_tarball" | tee -a $LOG_FILE

  local compilerdir=`tar --bzip2 -tf ${armgcc_tarball} | sed -e 's@/.*@@' | uniq`

  # install gcc arm mebedded

  printLog "read installation directory from user\n"

  local installdir=""

  read -p "Installation directory: " -i ${installbasedir}/${compilerdir} -e installdir

  printLog "user selected $installdir\n"

  printLog "read link directory\n"

  read -p "Link directory: " -i $linkdir -e linkdir

  printLog "user selected $linkdir\n"

  # if the installation path already exists, ask user to overwrite

  if [ -d "$installdir" ]; then

    printWarning "$installdir already exists. Overwrite? [y/n]\n"

    local userinput=""

    readUserInput "YyNn" userinput

    case "$userinput" in

      Y|y)

        ;;

      N|n)

        printWarning "installation aborted by user\n"

        return 1

        ;;

      *) # sanity check (exit with error)

        printError "invalid option: $userinput\n";;

    esac

  # make sure the whole ínstallation path exists

  else

    echo "$installdir path not exist"

    while [ ! -d $(dirname "$installdir") ]; do

      local dir=$(dirname "$installdir") 

      while [ ! -d $(dirname "$dir") ]; do

        dir=$(dirname "$dir")

      done

      echo "mkdir $dir"

      mkdir "$dir"

    done

  fi

  # copy the extracted compiler folder

  cp -fR "$compilerdir" "$installdir"

  # make sure whole link path exists

  while [ ! -d "$linkdir" ]; do

    local dir="$linkdir"

    while [ ! -d $(dirname "$linkdir") ]; do

      dir=$(dirname "$dir")

    done

    mkdir "$dir"

  done

  # create / overwrite links

  ls ${installdir}/bin/ | xargs -i ln -sf ${installdir}/bin/{} ${linkdir}/{}

  printInfo "default version set to $(arm-none-eabi-gcc -dumpversion)\n"

  read -p "bashrc stuff"

  # append the link directory to the PATH environment variable if required

  if [[ ! "$linkdir" = *"$PATH"* ]]; then

    local bashrc_file=${HOME}/.bashrc

    local bashrc_identifier="##### AMiRo ENVIRONMENT CONFIGURATION #####"

    local bashrc_note="# DO NOT EDIT THESE LINES MANUALLY!"

    local bashrc_entry="export PATH=\$PATH:$linkdir"

    # find and edit old entry, or append a new one to the file

    local bashrc_idlines=$(grep -x -n "$bashrc_identifier" "$bashrc_file" | cut -f1 -d:) # string of line numbers

    bashrc_idlines=(${bashrc_idlines//"\n"/" "}) # array of line numbers

    case ${#bashrc_idlines[@]} in

      # append a new entry to the BASHRC_FILE

      0)

        # make sure the last line is empty

        if [[ ! $(tail -1 $bashrc_file) =~ ^[\ \t]*$ ]]; then

          printf "\n" >> $bashrc_file

        fi

        # append text to file

        sed -i '$a'"$bashrc_identifier\n$bashrc_note\n$bashrc_entry\n$bashrc_identifier\n" $bashrc_file

        # print note

        printInfo "Your $bashrc_file has been updated. You need to source it to apply the changes in your environment.\n"

        read -p "  Understood!"

        ;;

      # extend the old entry

      2)

        # don't do anything if the line is already present

        local bashrc_entrylines=$(grep -x -n "$bashrc_entry" $bashrc_file | cut -f1 -d:) # string of line numbers

        bashrc_entrylines=(${bashrc_entrylines//"\n"/" "}) # array of line numbers

        printf "$bashrc_entrylines\n"

        if [[ ${#bashrc_entrylines[@]} = 0 ]]; then

          # insert the entry before the closing identifier

          sed -i "${bashrc_idlines[1]}"'i'"$bashrc_entry" $bashrc_file

          # print note

          printInfo "Your $bashrc_file has been updated. You need to source it to apply the changes in your environment.\n"

          read -p "  Understood!"

        elif [[ ${#bashrc_entrylines[@]} -eq 1 && ( ${bashrc_entrylines[0]} -lt ${bashrc_idlines[0]} || ${bashrc_entrylines[0]} -gt ${bashrc_idlines[1]} ) ]]; then

          # print an error that there is an entry at the wrong place

          printError "corrupted entry in your $bashrc_file detected\n"

          printf "The following entry was found at the wrong place:\n"

          printf "\n"

          printf "$bashrc_entry\n"

          printf "\n"

          printf "To fix this, delete the line and rerun this setup.\n"

          read -p "  Understood!"

        elif [[ ${#bashrc_entrylines[@]} -gt 1 ]]; then

          # print an error that there are multiple entries

          printError "corrupted entry in your $bashrc_file detected\n"

          printf "There are multiple identical entries in your $bashrc_file file.\n"

          printf "To fix it, make sure that it contains the following line exactly once:\n"

          printf "\n"

          printf "$bashrc_entry\n"

          printf "\n"

          read -p "  Understood!"

        fi

        ;;

      # error state (corrupted entry detected)

      *)

        printError "unable to append link directory to \$PATH variable\n"

        printf "There seems to be a broken entry in your $bashrc_file file.\n"

        printf "To fix it, make sure that the following line appears exactly twice and encloses your AMiRo related settings:\n"

        printf "\n"

        printf "$bashrc_identifier\n"

        printf "\n"

        read -p "  Understood!"

        ;;

    esac

  fi

  # clean up the current directory

  rm "$armgcc_tarball"

  rm -rf "$compilerdir"

  return 0

}

### change default version #####################################################

# Change the default arm-none-eabi-gcc version.

#

# usage:      installNewVersion <versions> <linkdir>

# argumenst:  <versions>

#                 Array of available versions (full path to binary).

#             <linkdir>

#                 Path where to delete old and create new links.

# return:     0

#                 No error or warnign occurred.

#             -1

#                 Error: no installation detected.

#

function changeDefaultVersion {

  local versions=("${!1}")

  local linkdir="$2"

  # check whether an installation was detected

  if [ ${#versions[@]} -eq 0 ]; then

    printError "no installation detected\n"

    return -1

  else

    # print all available versions

    printInfo "choose the installation to switch to or type 'A' to abort:\n"

    for (( cnt=0; cnt<${#versions[@]}; ++cnt )); do

      printf "  %2u: %s\n" $(($cnt + 1)) ${versions[$cnt]}

    done

    # read user selection

    printLog "read user slection\n"

    local userinput=""

    while [[ ! "$userinput" =~ ^[0-9]+$ ]] || [ ! "$userinput" -gt 0 ] || [ ! "$userinput" -le ${#versions[@]} ] && [[ ! "$userinput" =~ ^[Aa]$ ]]; do

      read -p "your selection: " -e userinput

      printLog "user selection: $userinput\n"

      if [[ ! "$userinput" =~ ^[0-9]+$ ]] || [ ! "$userinput" -gt 0 ] || [ ! "$userinput" -le ${#versions[@]} ] && [[ ! "$userinput" =~ ^[Aa]$ ]]; then

        printWarning "Please enter an integer between 1 and ${#versions[@]} or 'A' to abort.\n"

      fi

    done

    if [[ "$userinput" =~ ^[Aa]$ ]]; then

      printWarning "aborted by user\n"

    else

      local idx=$((userinput - 1))

      # find and delete old links

      rm `find $linkdir -maxdepth 1 -type l | grep -Ev "*[0-9]\.[0-9]\.[0-9]"`

      # create new links

      local bindir=$(dirname ${versions[$idx]})

      ls $bindir | xargs -i ln -sf $bindir/{} $linkdir/{}

      printInfo "default version set to $(arm-none-eabi-gcc -dumpversion)\n"

    fi

  fi

  return 0

}

### main function of this script ###############################################

# The IDE setup lets the user select an IDE of choice.

# As of now, only QtCreator is supported.

#

# usage:      see function printHelp

# arguments:  see function printHelp

# return:     0

#                 No error or warning occurred.

#

function main {

  # print welcome/info text if not suppressed

  if [[ $@ != *"--noinfo"* ]]; then

    printWelcomeText

  else

    printf "######################################################################\n"

  fi

  printf "\n"

  # set log file if specified

  if [[ $@ == *"--log"* ]] || [[ $@ == *"--LOG"* ]]; then

    # get the parameter (file name)

    local cmdidx=1

    while [[ ! "${!cmdidx}" = "--log"* ]] && [[ ! "${!cmdidx}" = "--LOG"* ]]; do

      cmdidx=$[cmdidx + 1]

    done

    local cmd="${!cmdidx}"

    local logfile=""

    if [[ "$cmd" = "--log="* ]] || [[ "$cmd" = "--LOG="* ]]; then

      logfile=${cmd#*=}

    else

      local filenameidx=$((cmdidx + 1))

      logfile="${!filenameidx}"

    fi

    # optionally force silent appending

    if [[ "$cmd" = "--LOG"* ]]; then

      setLogFile --option=a --quiet "$logfile" LOG_FILE

    else

      setLogFile "$logfile" LOG_FILE

      printf "\n"

    fi

  fi

  # log script name

  printLog "this is $(realpath ${BASH_SOURCE[0]})\n"

  # if --help or -h was specified, print the help text and exit

  if [[ $@ == *"--help"* || $@ == *"-h"* ]]; then

    printHelp

    printf "\n"

    quitScript

  fi

  # detect installed versions and inform user

  local installedversions=()

  local currentversion=""

  detectInstalledVersions installedversions currentversion

  case "${#installedversions[@]}" in

    0)

      printInfo "no installation has been detected\n";;

    1)

      printInfo "1 installation has been detected:\n";;

    *)

      printInfo "${#installedversions[@]} installations have been detected:\n";;

  esac

  for (( idx=0; idx<${#installedversions[@]}; ++idx )); do

    if [ ${installedversions[$idx]} = "$currentversion" ]; then

      printInfo "  * ${installedversions[$idx]}\n"

    else

      printInfo "    ${installedversions[$idx]}\n"

    fi

  done

  printf "\n"

  # parse arguments

  local otherargs=()

  while [ $# -gt 0 ]; do

    if ( parseIsOption $1 ); then

      case "$1" in

        -h|--help) # already handled; ignore

          shift 1;;

        -i|--init)

          if [ -z "$currentversion" ]; then

            installNewVersion

          else

            installNewVersion --install=$(realpath $(dirname "$currentversion")/../../) --link=$(realpath $(dirname "$currentversion")/../../)

          fi

          printf "\n"; shift 1;;

        -c|--change)

          changeDefaultVersion installedversions[@] $(realpath $(dirname "$currentversion")/../../); printf "\n"; shift 1;;

        -q|--quit)

          quitScript; shift 1;;

        --log=*|--LOG=*) # already handled; ignore

          shift 1;;

        --log|--LOG) # already handled; ignore

          shift 2;;

        --noinfo) # already handled; ignore

          shift 1;;

        *)

          printError "invalid option: $1\n"; shift 1;;

      esac

    else

      otherargs+=("$1")

      shift 1

    fi

  done

  # interactive menu

  while ( true ); do

    # main menu info prompt and selection

    printInfo "GCC setup main menu\n"

    printf "Please select one of the following actions:\n"

    printf "  [I] - install another version\n"

    printf "  [C] - change default version\n"

    printf "  [Q] - quit this setup\n"

    local userinput=""

    readUserInput "IiCcQq" userinput

    printf "\n"

    # evaluate user selection

    case "$userinput" in

      I|i)

        if [ -z "$currentversion" ]; then

          installNewVersion

        else

          installNewVersion --install=$(realpath $(dirname "$currentversion")/../../) --link=$(realpath $(dirname "$currentversion")/../../)

        fi

        printf "\n";;

      C|c)

        changeDefaultVersion installedversions[@] $(realpath $(dirname "$currentversion")/../../); printf "\n";;

      Q|q)

        quitScript;;

      *) # sanity check (exit with error)

        printError "unexpected argument: $userinput\n";;

    esac

  done

  exit 0

}

################################################################################

# SCRIPT ENTRY POINT                                                           #

################################################################################

main "$@"