zfsbootmenu/bin/zbm-kcl

#!/bin/bash
# vim: softtabstop=2 shiftwidth=2 expandtab

zbm_load_lib() {
  lib="${1?no library specified for load}"

  : "${ZBM_MODULEDIR:=/usr/share/zfsbootmenu}"

  if [ -r "${ZBM_MODULEDIR}/lib/${lib}" ]; then
    # shellcheck disable=SC1090
    source "${ZBM_MODULEDIR}/lib/${lib}"
  else
    echo "ERROR: ${ZBM_MODULEDIR}/lib/${lib} not found" >&2
    echo "Set ZBM_MODULEDIR to the root of the ZBM module" >&2
    exit 1
  fi
}

usage() {
  cat <<-EOF
	USAGE: $0 [-a <arg>] [-r <arg>] [-e] [-d] [-v] [bootenv]
        Review or update kernel command line (KCL) associated with <bootenv>
        When the boot environment is unspecified, the current root will be used

	-a <arg>: Append an argument
	-r <arg>: Remove an argument
	-e: Open the KCL for editing in \$EDITOR
	-d: Remove entire command line
	-v: Enable verbose output
	EOF
}

strip_kcl() {
  awk '
  BEGIN { first = 1; }

  /^$/ { exit; }

  {
    gsub("[[:space:]]*#.*", "");

    if (length == 0) next;

    if (first == 1) {
      first = 0;
    } else {
      printf " ";
    }

    printf "%s", $0;
  }
  '
}

delete() {
  local bootenv="${1}"

  if ! zfs list -o name -H "${bootenv}" >/dev/null 2>&1; then
    zerror "no boot environment specified"
    usage
    return 1
  fi

  if ! zfs inherit org.zfsbootmenu:commandline "${bootenv}"; then
    zerror "failed to remove KCL from ${bootenv}"
    return 1
  fi
}

raw_kcl() {
  local bootenv="${1}"
  local kcl

  kcl="$(zfs get -H -o value org.zfsbootmenu:commandline "${bootenv}")" || return 1
  [ "${kcl}" = "-" ] && return

  echo "${kcl}"
}

review() {
  local bootenv="${1}"
  local kcl

  kcl="$(raw_kcl "${bootenv}")"
  echo "${kcl}"

  if [[ "${kcl}" =~ "%{parent}" ]]; then
    echo "# With parent references, KCL expands to"
    echo "#  $(read_kcl_prop "${bootenv}")"
  fi

  return 0
}

edit() {
  local bootenv kclfile oldsum newkcl newsum

  bootenv="${1}"

  if ! command -v "${EDITOR:=vi}" >/dev/null 2>&1; then
    zerror "define \$EDITOR to edit"
    return 1
  fi

  if ! kclfile="$(mktemp)"; then
    zerror "failed to create temporary file"
    return 1
  fi

  trap 'rm -f "${kclfile}"' RETURN

  if ! review "${bootenv}" > "${kclfile}"; then
    zerror "unable to read KCL for ${bootenv}"
    return 1
  fi

  cat >> "${kclfile}" <<-EOF
	
	# KCL processing ends with the first line that contains no text.
	# Anything starting with # is considered a comment and will be ignored.
	# Multiple lines will be concatenated with spaces to form a single line.
	EOF

  if ! oldsum="$(strip_kcl < "${kclfile}" | md5sum | awk '{print $1}')"; then
    zerror "unable to compute checksum for existing KCL"
    return 1
  fi

  if ! "${EDITOR}" "${kclfile}"; then
    zerror "failed to edit KCL for ${bootenv}"
    return 1
  fi

  if ! newkcl="$(strip_kcl < "${kclfile}")"; then
    zerror "failed to parse new KCL for ${bootenv}"
    return 1
  fi

  if ! newsum="$(echo -n "${newkcl}" | md5sum | awk '{print $1}')"; then
    zerror "failed to compute checksum for new KCL"
    return 1
  fi

  if  [ "${newsum}" = "${oldsum}" ]; then
    znotice "modified KCL appears the same as original, will not change"
    return 0
  fi

  if ! zfs set org.zfsbootmenu:commandline="${newkcl}" "${bootenv}"; then
    zerror "failed to set ZBM KCL"
    return 1
  fi
}

getbootenv() {
  local dev mntpt fs opts

  # shellcheck disable=SC2034
  while read -r dev mntpt fs opts; do
    [ "${mntpt}" = "/" ] || continue

    if [ "${fs}" != "zfs" ]; then
      return 1
    fi

    echo "${dev}"
    return 0
  done < /proc/mounts
}


delkcl=
editkcl=
havemods=
appends=()
removes=()
loglevel=4

while getopts "ha:r:edv" opt; do
  case "${opt}" in
    a)
      appends+=( "${OPTARG}" )
      ;;
    r)
      removes+=( "${OPTARG}" )
      ;;
    e)
      editkcl="yes"
      ;;
    d)
      delkcl="yes"
      ;;
    v)
      loglevel="$((loglevel + 1))"
      ;;
    h)
      usage
      exit
      ;;
    *)
      usage
      exit 1
      ;;
  esac
done

shift $((OPTIND-1))

zbm_load_lib "zfsbootmenu-kcl.sh"
zbm_load_lib "echo-log-lib.sh"

bootenv="${1}"
if [ -z "${bootenv}" ]; then
  if ! bootenv="$(getbootenv)"; then
    zerror "root does not appear to be ZFS" >&2
    exit 1
  fi
fi

if ! zfs list -o name -H "${bootenv}" >/dev/null 2>&1; then
  zerror "boot environment ${bootenv} does not exist"
  exit 1
fi

if [ "${editkcl}" = "yes" ]; then
  edit "${bootenv}"
  exit
fi

if (( ${#removes[@]} != 0 || ${#appends[@]} != 0 )); then
  havemods="yes"
fi

if [ "${delkcl}" ]; then
  if [ "${havemods}" = "yes" ]; then
    zerror "-d is incompatible with -a or -r"
    exit 1
  fi

  delete "${bootenv}"
  exit
fi

if [ "${havemods}" != "yes" ]; then
  review "${bootenv}"
  exit 0
fi

# Act on raw KCL argument for append/remove operations
if ! kcl="$(raw_kcl "${bootenv}" | kcl_tokenize )"; then
  zerror "failed to read KCL for ${bootenv}"
  exit 1
fi

# Strip and append arguments
kcl="$( kcl_suppress "${removes[@]}" <<< "${kcl}" | kcl_append "${appends[@]}" | kcl_assemble )"

if ! zfs set org.zfsbootmenu:commandline="${kcl}" "${bootenv}"; then
  zerror "failed to set ZBM KCL"
  exit 1
fi