init_image.sh

#!/usr/bin/env bash
# Initialize an .img file with a single partition and formated with a
# filesystem.

# Defaults #
# Filesystem to use. At this time, only ext4 is supported
FS_TYPE="ext4"
# Image Size, in Megabytes
IMG_SIZE=20480 # 20GB
# bytestream to use for initial creation. Defaults to all zeros
FILL_SRC=/dev/zero

#moved to main loop, this needs ROOT
#LOOP_DEV=$(losetup -f)
LOOP_DEV="INVALID"
PART_N=1
MOUNT_POINT="$(mktemp -d)"
ROOT_METHOD="sudo"
# /Defaults #

help_and_exit() {
  cat 1>&2 << EOF
init_image.sh:

Create an disk .img file, with a single parition and a file system. Creates a
file of an arbitrary size, formats it with the ext4 filesystem. Takes one
parameter, filename.

Default file size is 20GB.

USAGE:
	
	init_image [-s <size>] <filename.img>
	
OPTIONS:
	
	-s,--size	Size of image, in Megabytes, defaults to 20GB

EOF
  exit 4
}
message() {
  echo "init_image.sh: ${@}"
}

submsg() {
  echo "==>	${@}"
}

exit_with_error() {
  echo 1>&2 "init_image.sh: ERROR: ${2}"
  exit ${1}
}

warn() {
  echo 1>&2 "init_image.sh: WARN: ${@}"
}

as_root() {
  # execute a command as root.
  case $ROOT_METHOD in
   sudo)
    sudo ${@}
    ;;
   pkexec)
    pkexec ${@}
    ;;
   uid)
    ${@}
    ;;
  esac
}

switch_checker() {
  while [ ! -z "$1" ];do
   case "$1" in
    --help|-\?)
     help_and_exit
     ;;
    -s|--size)
     IMG_SIZE="${2}"
     shift
     ;;
    *)
     PARMS+="${1}"
     ;;
   esac
   shift
  done
}

abort_cleanup() {
  # If this fails or is aborted, cleanup before we exit
  rm "${OUTFILE}"
  as_root losetup -d ${LOOP_DEV} &> /dev/null
  rmdir "${MOUNT_POINT}"
  exit_with_error 2 "INTERRUPT: ABORT!"
}

_setup-loop() {
  local -i local_exit=0
  submsg "Setting up loop: ${OUT_FILE} on ${LOOP_DEV}"
  as_root losetup -P ${LOOP_DEV} "${OUT_FILE}" || local_exit+=1
  return ${local_exit}
}

_destroy-loop() {
  local -i local_exit=0
  submsg "Destroying ${LOOP_DEV}"
  as_root losetup -d ${LOOP_DEV} &> /dev/null || local_exit+=1
  return ${local_exit}
}

_create_blank_file() {
  # Generate a blank file of arbitrary size
  local -i local_exit=0
  local blocksize="1024k" # 1 Megabyte
  
  submsg "Generating Blank file ${IMG_SIZE}M long"
  dd if="${FILL_SRC}" of="${OUT_FILE}" bs=${blocksize} count=${IMG_SIZE} status=progress || local_exit+=1
  sync
  return ${local_exit}
}

_partition() {
  # Create partition
  local -i local_exit=0
  #local label="msdos"
  #local -i offset=2048 #first 2048 sectors
  
  submsg "Partitioning image"
  # parted
  #as_root parted --script ${LOOP_DEV} mklabel ${label} || local_exit+=1
  #as_root parted --script ${LOOP_DEV} mkpart primary ${FS_TYPE} ${offset}S -- -1 || local_exit+=1
  # sfdisk
  as_root sfdisk ${LOOP_DEV} > /dev/null << EOF
;
EOF
  [ $? -ne 0 ] && local_exit+=1
  return ${local_exit}
}

_format() {
  # format with filesystem
  local -i local_exit=0

  submsg "Foramting with ${FS_TYPE}"
  as_root mkfs -t ${FS_TYPE} ${LOOP_DEV}p${PART_N} &> /dev/null|| local_exit+=1
  
  return ${local_exit}
}

main() {
  OUT_FILE="${@}"
  local -i errors=0
  [ -z ${OUT_FILE} ] && help_and_exit
  trap "abort_cleanup" 1 2 3 9 15

  message "Making ${IMG_SIZE}M image file ${OUT_FILE}"
  as_root true # get root
  
  LOOP_DEV=$(as_root losetup -f)

  _create_blank_file || exit_with_error 1 "Could Not Generate Blank File, Exiting"
  
  _setup-loop || exit_with_error 1 "Could Not Set Up Loop Device, Exiting"
  
  _partition || exit_with_error 1 "Could Not Generate Paritions in ${OUT_FILE}, Exiting"
  
  _format || exit_with_error 1 "Formatting Failed, Exiting"
  
  _destroy-loop
  if [ ${?} -ne 0 ];then
    "Couldn't remove loop device. Clean up mantually" 
    errors+=1
  fi
  
  # Clean up last random mount point
  rmdir "${MOUNT_POINT}"
  if [ ${?} -ne 0 ];then
    warn "couldn't delete ${MOUNT_POINT}, clean up manually"
    errors+=1
  fi
  
  if [ $errors -gt 0 ];then
    message "Done, but with ${errors} errors"
    exit 1
   else
    message "Done"
    exit 0
  fi
}

PARMS=""
switch_checker "${@}"
main "${PARMS}"