Basic EFI KCL editor

Author: zdykstra

bin/zbm-efi-kcl

@@ -0,0 +1,139 @@
+#!/bin/bash
+# vim: softtabstop=2 shiftwidth=2 expandtab
+
+cleanup() {
+  if [[ -f "${TEMP_EFI}" && -z "${PRESERVE_TEMP_EFI}" ]]; then
+    rm "${TEMP_EFI}"
+  fi
+  [ -f "${TEMP_KCL}" ] && rm "${TEMP_KCL}"
+}
+
+usage() {
+  cat <<-EOF
+    USAGE: $0 [-e <arg>] [-f <arg>] [-k <arg>] [-o <arg>]
+    
+    -e <arg>  ZFSBootMenu EFI file
+    -f <arg>  Replace kernel command line with contents of file
+    -k <arg>  Replace kernel command line with quoted arguments
+    -o <arg>  Output file; if undefined the input file will be replaced
+
+    If neither -f or -k are provided, the command line from the
+    input EFI will be opened in \$EDITOR.
+	EOF
+}
+
+INPUT_EFI=
+OUTPUT_EFI=
+ARG_FILE=
+ARG_VAR=
+
+while getopts "e:f:k:o:" opt; do
+  case "${opt}" in
+    e)
+      INPUT_EFI="${OPTARG}"
+      if [ ! -f "${INPUT_EFI}" ]; then
+        echo "Unable to open ${INPUT_EFI}"
+        exit 1
+      fi
+      # Set OUTPUT_EFI to the input by default
+      [ -z "${OUTPUT_EFI}" ] && OUTPUT_EFI="${INPUT_EFI}"
+      ;;
+    o)
+      # Override the output file
+      OUTPUT_EFI="${OPTARG}"
+      ;;
+    f)
+      ARG_FILE="${OPTARG}"
+      ARG_VAR=
+      if [ ! -f "${ARG_FILE}" ]; then
+        echo "Unable to open ${ARG_FILE}"
+        exit 1
+      fi
+      ;;
+    k)
+      ARG_VAR="${OPTARG}"
+      ARG_FILE=
+      ;;
+    *)
+      usage
+      exit 1
+      ;;
+  esac
+done
+
+if [ -z "${INPUT_EFI}" ]; then
+  usage
+  exit 1
+fi
+
+if ! command -v objcopy > /dev/null 2>&1 ; then
+  echo "Missing required binary 'objcopy'"
+  exit 1
+fi
+
+trap cleanup EXIT INT TERM
+
+TEMP_EFI="$(mktemp)"
+if ! objout="$( objcopy --remove-section .cmdline "${INPUT_EFI}" "${TEMP_EFI}" 2>&1 )"; then
+  echo "Unable to remove .cmdline from '${INPUT_EFI}'"
+  echo "${objout}"
+  exit 1
+fi
+
+TEMP_KCL="$(mktemp)"
+if [ -n "${ARG_VAR}" ]; then
+  echo -n "${ARG_VAR}" > "${TEMP_KCL}"
+elif [ -n "${ARG_FILE}" ]; then
+  cp "${ARG_FILE}" "${TEMP_KCL}" || exit 1
+else
+  if ! objout="$( objcopy --dump-section .cmdline="${TEMP_KCL}" "${INPUT_EFI}" 2>&1 )"; then
+    echo "Unable to extract cmdline from '${INPUT_EFI}'"
+    echo "${objout}"
+    exit 1
+  fi
+
+  # Remove null terminators
+  sed -i 's/\x0//g' "${TEMP_KCL}"
+
+  # Strip leading and trailing spaces
+  sed -i 's/^[[:space:]]*//g;s/[[:space:]]*$//g' "${TEMP_KCL}"
+
+  if ! command -v "${EDITOR:=vi}" >/dev/null 2>&1 ; then
+    echo "define \$EDITOR to edit"
+    exit 1
+  fi
+
+  if ! "${EDITOR}" "${TEMP_KCL}"; then
+    echo "failed to edit KCL for ${INPUT_EFI}"
+    exit 1
+  fi
+fi
+
+# Strip leading and trailing spaces
+sed -i 's/^[[:space:]]*//g;s/[[:space:]]*$//g' "${TEMP_KCL}"
+
+# Remove existing null terminators
+sed -i 's/\x0//g' "${TEMP_KCL}"
+
+# Collapse multiple lines into one
+sed -i -z 's/\n/ /g' "${TEMP_KCL}"
+
+# Pad with a space; replicating Dracut behavior.
+# FIXME: Is this strictly needed?
+sed -i 's/^/ /' "${TEMP_KCL}"
+
+# Add a null terminator for the efi stub; replicating Dracut behavior
+echo -ne "\x00" >> "${TEMP_KCL}"
+
+if objout="$( objcopy --add-section .cmdline="${TEMP_KCL}" --change-section-vma .cmdline=0x30000 "${TEMP_EFI}" 2>&1 )"; then
+  if ! cp "${TEMP_EFI}" "${OUTPUT_EFI}" ; then
+    echo "Unable to copy ${TEMP_EFI} to ${OUTPUT}"
+    echo "Preserving '${TEMP_EFI}'"
+    PRESERVE_TEMP_EFI=1
+    exit 1
+  fi
+else
+  echo "Unable to add commandline to ${TEMP_KCL}"
+  echo "${objout}"
+  exit 1
+fi