#!/bin/sh
#
# Copyright 2017 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
# Determines whether a TPM firmware update is available and prints the name of
# the file that contains the firmware binary.

: "${TPM_FIRMWARE_DIR:=/lib/firmware/tpm}"

# Parse key-value pairs and assign corresponding shell variables. Keys and
# values are sanitized before assigning.
read_key_value_pairs() {
  local prefix="$1"
  local field_separator="$2"
  local input="$3"
  local key
  local value
  while IFS="${field_separator}" read -r key value; do
    local sanitized_key=$(
      echo "${key}" | tr '[:upper:] ' '[:lower:]_' | tr -cd '[:alnum:]_-')
    local sanitized_value=$(
      echo "${value}" | tr '[:upper:]' '[:lower:]' | tr -cd '[:alnum:]._-')
    export "${prefix}_${sanitized_key}=${sanitized_value}"
  done <<EOF
${input}
EOF
}

usage() {
  cat 1>&2 <<EOL
Usage: $0 <tpm-version-info> <ifx-update-info>

Checks TPM version information to determine whether there's a TPM firmware
update available that can be installed. The necessary <tpm-version-info> and
<ifx-update-info> parameters can be retrieved via tpmc or tpm-manager.
EOL
  exit 1
}

main() {
  local tpm_version_info="$1"
  local ifx_upgrade_info="$2"

  read_key_value_pairs tpm_version " " "${tpm_version_info}"
  read_key_value_pairs ifx_upgrade " " "${ifx_upgrade_info}"

  # This script can only handle Infineon TPMs.
  if [ "${tpm_version_vendor}" != "49465800" ]; then
    return 1
  fi

  # Determine firmware package ID and current build number.
  local package_id
  local build_number
  if [ "${ifx_upgrade_fw0_stale_version}" != "ffffeeee" ]; then
    package_id="${ifx_upgrade_fw0_package_id}"
    build_number="${ifx_upgrade_fw0_version}"
  else
    package_id="${ifx_upgrade_fw1_package_id}"
    build_number="${ifx_upgrade_fw1_version}"
  fi

  local pattern
  if [ "${ifx_upgrade_status}" = "5a3c" ]; then
    # For bootloader mode, append the target build number.
    pattern="${package_id}_${build_number}_${ifx_upgrade_process_fw_version}"
  else
    # For non-bootloader mode, attempt to get the current build number
    # from 'tpmc getver' instead. 'getver' provides more reliable information
    # about the current version than 'ifxfui'.
    if [ "${tpm_version_vendor_specific}" != "" ]; then
      build_number="0000$(echo "${tpm_version_vendor_specific}" | cut -c5-8)"
    fi
    pattern="${package_id}_${build_number}_*"
  fi

  # Consider all firmware images with the correct source version and sort them
  # to pick the one with the latest target version.
  local path="$(ls "${TPM_FIRMWARE_DIR}"/ifx/${pattern}.bin 2>/dev/null |
                sort -r | head -n 1)"

  if [ -f "${path}" ]; then
    echo "${path}"
    return 0
  fi

  return 1
}

if [ "$(basename "$0")" = "tpm-firmware-locate-update" ]; then
  main "$@"
fi