#!/bin/bash
# Copyright 2018 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.
#
# This script creates a symlink using udev to the stateful device.
#
# Positional arguments: symlink device_path
# symlink is a relative path in /dev to the desired location of the output
#     symlink.
# device_path is an absolute file path or absolute file path prefix. It is
#     interpreted as an absolute file path prefix if and only if it ends with
#     a * character.

set -o errexit
set -o pipefail

get_device() {
  local -r dev="$1"
  udevadm settle
  if [[ "${dev: -1}" != "*" ]]; then
    echo "${dev}"
    return
  fi
  echo "${dev::-1}"* | tr " " "\n" | sort -V | tail -n 1
}

main() {
  local -r symlink="$1"
  local -r input_dev="$2"
  local -r dev="$(get_device "${input_dev}")"
  local real_dev
  if [[ -b "${dev}" ]]; then
    real_dev="$(realpath "${dev}")"
    echo "KERNEL==\"${real_dev#/dev/}\", SYMLINK+=\"${symlink}\"" > \
      /etc/udev/rules.d/00-stateful-dev.rules
    udevadm control -R
    udevadm trigger "${real_dev}"
  else
    echo "not a valid device: ${dev}"
    return 1
  fi
}

main "$@"