init/upstart/send-boot-elog-metrics.conf

# Copyright 2021 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.

description   "Report once-per-boot elog-related UMA statistics"
author        "chromium-os-dev@chromium.org"

# Because the elogtool leverages SPI driver, wait for ui.conf ready to
# ensure there is no race condition between ui and this script which
# might result in increasing the boot time.
start on started system-services and started ui

# Killable for memory leaks.
oom score -100

script
  get_elog_after_last_report() {
    local elog="$(elogtool list)"
    local filename="/var/lib/metrics/elog-last-line"
    local filesize="$(stat -c%s "${filename}")"

    local elog_last_line
    local elog_after_last_report="${elog}"

    # Try to get the last line of previous uploads.
    # Since we cannot make assumptions about the content of this file
    # which has a volatile path and could be corrupted or modified,
    # we have to ensure the file size is not suspiciously large.
    if [ "${filesize}" -lt 65536 ]; then
      elog_last_line="$(cat "${filename}" 2> /dev/null)"

      # Cut out the elog events which are already uploaded.
      if [ -n "${elog_last_line}" ]; then
        elog_after_last_report="${elog##*"${elog_last_line}"}"
      fi
    fi

    # Update the elog-last-line.
    echo "${elog_after_last_report}" | tail -1 > "${filename}"

    # Return the log string.
    echo "${elog_after_last_report}"
  }

  # MiniDiag (pre-boot diagnostics) related metrics.
  # Report the MiniDiag launch count.
  launch="$(get_elog_after_last_report | \
         grep -c "Launch Diagnostics")" || :
  metrics_client Platform.MiniDiag.Launch -e "${launch}" 50

end script