post-run

#!/bin/sh -u
# -u: Treat unset variables as an error when performing parameter expansion.
# If expansion is attempted on an unset interactive, exits with a non-zero status.
#
# Process executed after application manager execution
#
# Author: Loan Lassalle <https://github.com/lassalleloan>

# Working directory
WORKING_DIRECTORY="$(sed -En 's/^WORKING_DIRECTORY=(\/[^ #]+)(( |#)?.*)$/\1/p' .conf)"
WORKING_DIRECTORY="${WORKING_DIRECTORY%/}"

# Source file for creating hard link
# Note: After each execution, the inode of "$SRC_FILE" changes
# "$HARD_LINK_SRC_FILE" exists to keep the hardlink fonctional by keeping the same inode
SRC_FILE="$WORKING_DIRECTORY/src/etc/hosts"
HARD_LINK_SRC_FILE="$WORKING_DIRECTORY/src/etc/hosts.hardlink"

# Current and latest version of StevenBlack/hosts source files
CURRENT_VERSION="$(sed -En 's/^CURRENT_VERSION=([0-9]+([.][0-9]+)*)(( |#).*)?$/\1/p' .conf)"
LATEST_VERSION="$(sed -En 's/^LATEST_VERSION=([0-9]+([.][0-9]+)*)(( |#).*)?$/\1/p' .conf)"

# Default verbosity level
VERBOSITY="$(sed -En 's/^VERBOSITY=([0-9]{1})(( |#).*)?$/\1/p' .conf)"

# Display a banner
banner() {
  printf "Post-run script\n"
}

# Usage of the script
usage() {
  printf "Usage: post-run [--verbosity (0 | 1 | 2)]\n"
  printf "\n"
  printf "Process executed after run-app execution\n"
  printf "\n"
  printf "Version: 1.0.0, build deadbeef\n"
  printf "\n"
  printf "Author:\n"
  printf "  Loan Lassalle - <https://github.com/lassalleloan>\n"
  printf "\n"
  printf "Options:\n"
  printf "  -v, --verbosity (0 | 1 | 2)     Level of verbosity: no ouput, step information (default), all information\n"
  printf "  -h, --help                      Help on how to use this script\n"
}

# Create a hard link between /etc/hosts and $hard_link_src_file
hard_link() {
  local src_file="$1"
  local hard_link_src_file="$2"
  local verbosity="$3"
  
  local is_hard_link=$(stat -f "%l" /etc/hosts)

  if [ "$verbosity" -ne 0 ]; then
    printf "Creation of hard link between /etc/hosts and %s\n" "$hard_link_src_file"
  fi
 
  # Copy of the source file to keep the hardlink fonctional
  # Note: After each execution, the inode of "$SRC_FILE" changes
  # "$HARD_LINK_SRC_FILE" exists to keep the hardlink fonctional by keeping the same inode
  \cp "$SRC_FILE" "$HARD_LINK_SRC_FILE"

  if [ "$is_hard_link" -le 1 ]; then
    printf "sudo command is required to create the hard link, please run the following command:\n"
    printf "sudo ln -f %s /etc/hosts\n" "$hard_link_src_file"
  fi
}

# Flush the local DNS cache
flush_dns_cache() {
  local verbosity="$1"

  if [ "$verbosity" -ne 0 ]; then
    printf "Flushing of local DNS cache\n"
  fi

  if [ "$verbosity" -eq 2 ]; then
    killall -HUP mDNSResponder
  else 
    killall -HUP mDNSResponder >/dev/null 2>&1
  fi
}

# Check if it is an integer
exit_if_not_integer() {
  local variable="$1"

  if ! echo "$variable" | grep -Eq  "^[0-9]{1}$"; then
    printf "%s: not a integer\n" "$variable"
    usage
    exit 1
  fi
}

# Main
for arg in "$@"; do
  shift
  case "$arg" in
    "--verbosity")
      set -- "$@" "-v"
      ;;
    "--help")
      set -- "$@" "-h"
      ;;
    "--"*)
      set -- "$@" "-?"
      ;;
    *)
      set -- "$@" "$arg"
  esac
done

while getopts ":v:h" option; do
  case $option in
    v)
      VERBOSITY=$OPTARG
      exit_if_not_integer "$VERBOSITY"
      ;;
    h)
      usage
      exit
      ;;
    :)
      printf "%s: required argument\n" "$OPTARG"
      exit 1
      ;;
    \?)
      printf "%s: invalid option\n" "$OPTARG"
      usage
      exit 1
      ;;
  esac
done

if [ "$VERBOSITY" -ne 0 ]; then
  banner
fi

# Create a hard link to /etc/hosts of local machine
hard_link "$SRC_FILE" "$HARD_LINK_SRC_FILE" "$VERBOSITY"

# Flush the local DNS cache
flush_dns_cache "$VERBOSITY"

# Update the current version in .conf file
sed -i '' -E "/^CURRENT_VERSION=$CURRENT_VERSION(( |#).*)?$/ s/$CURRENT_VERSION/$LATEST_VERSION/" \
  .conf

# Audit system
if [ "$VERBOSITY" -eq 0 ]; then
  printf "%s\tinfo\tupgrade\t%s\t%s\t\"Upgrade completed\"\n" \
    "$(date -u +%FT%TZ)" "$LATEST_VERSION" "$LATEST_VERSION" >> .log
fi

# To avoid exit 1 of the DNS cache flushing
exit 0