lightning-launcher

#!/bin/bash

###############################################################################################
##                                                                                           ##
##                       Universidad Carlos III de Madrid (UC3M)                             ##
##                                                                                           ##
##    Lightning - The simple and lightweight network simulator based on Docker containers    ##
##                                                                                           ##
##    author:         Pablo Toribio (under supervision of professor C.J. Bernardos Cano)     ##
##                                                                                           ##
##    project site:   https://github.com/ptoribi/lightning                                   ##
##                                                                                           ##
##    file description:  ensures that lightning is executed with proper user privileges      ##
##                       and launchs the application                                         ##
##                                                                                           ##
##    usage:             ./lightning-launcher                                                ##
##                                                                                           ##
###############################################################################################

# ptoribi: differences between the output of the commands logname and whoami depending on how the script was launched:
# 1.- as a regular user (user)
# 2.- using the command sudo (sudo)
# 3.- directly as root: logged in the session as root directly, not using su -l or similar (root)
#
#      | logname | whoami |
# -------------------------
# user | "user"  | "user" |
# sudo | "user"  | "root" |
# root | "root"  | "root" |

#echo "lightning-launcher --> logname: $(logname)"
#echo "lightning-launcher --> whoami:  $(whoami)"
# work_around
function log_name() {
    [ -n "$SUDO_USER" ] && echo $SUDO_USER
    [ -z "$SUDO_USER" ] && id -un
}

# ptoribi: "which" will find in the path the full location of the executable, "readlink -f" will resolve all possible symbolic links and "dirname" will remove the last component (file name).
# In the default case: /usr/local/bin/lightning -> /usr/local/lightning/lightning-launcher -> /usr/local/lightning
LIGHTNING_INSTALLATION_PATH=$(dirname $(readlink -f $(which lightning)))
USER_BEHIND_SUDO=$(log_name)
USER_BEHIND_SUDO_HOME_PATH=$(getent passwd $USER_BEHIND_SUDO | cut -d : -f 6)
source $LIGHTNING_INSTALLATION_PATH/variables.conf

if [[ $SHARED_FOLDER_LOCATION == "TMP" ]]
then
  SHARED_FOLDER=/tmp/$USER_BEHIND_SUDO/$SHARED_FOLDER_NAME
  mkdir -p $SHARED_FOLDER
  chmod 770 /tmp/$USER_BEHIND_SUDO
else
  SHARED_FOLDER=$USER_BEHIND_SUDO_HOME_PATH/$SHARED_FOLDER_NAME
fi

# paaguti: When REMOTE=1, cleanup the file holding the docker commands
if [ $REMOTE -eq 1 ]
then
  for f in commands description.txt
  do
    [ -f $USER_BEHIND_SUDO_HOME_PATH/$f ] && rm -f $USER_BEHIND_SUDO_HOME_PATH/$f
  done
fi

# ptoribi: configure the console to use 256 colors
export TERM=xterm-256color

# ptoribi: the purpose of "lightning-launcher" is to ensure that the main program
# is executed by a regular user with "sudo" command. If sudo has already been used
# for executing lightning-launcher, it just proceeds to execute the main one.
# Execution of the program directly as root is not supported.

# ptoribi: execution sequence
# lightning (symlink) ----> lightning-launcher ----> sudo lightning (main program)

if [ $# -eq 0 ]
then
  $LIGHTNING_INSTALLATION_PATH/lightning
  exit
fi

if [ -n "$1" -a "$1" == "update" ]
then
  if [ $(whoami) != "root" ]
  then
    sudo $LIGHTNING_INSTALLATION_PATH/update
  else
    $LIGHTNING_INSTALLATION_PATH/update
  fi

  exit
fi

if [ $(log_name) != "root" -a $(whoami) != "root" ]
then
  # ptoribi: the program was executed as a regular user
  # I use "$@" for propagating all the arguments among scripts.
  mkdir -p $SHARED_FOLDER
  sudo $LIGHTNING_INSTALLATION_PATH/lightning "$@"

elif [ $(log_name) != "root" -a $(whoami) == "root" ]
then
  # ptoribi: the program was executed as a regular user with sudo
  # I use "$@" for propagating all the arguments among scripts.
  mkdir -p $SHARED_FOLDER
  $LIGHTNING_INSTALLATION_PATH/lightning "$@"

elif [ $(log_name) == "root" -a $(whoami) == "root" ]
then
  # ptoribi: the program was executed as root directly
  echo $(tput setaf 220)[lightning-launcher]:$(tput sgr 0) $(tput setaf 0)$(tput setab 1) Execution of this program directly as root is not supported. $(tput sgr 0)
fi