mobile-nixos/bin/kernel-normalize-config

#!/usr/bin/env nix-shell
#!nix-shell -p ruby -i ruby

# This script is expected to be used to copy back the `kernel-builder` built
# linux configuration to the kernel's source directory.
#
# Use this to normalize the configuration after:
#
#  - Changing configuration options
#  - Changing the kernel version

require "shellwords"
ROOT = File.join(__dir__, "..")

def usage()
  puts "Usage: bin/kernel-normalize-config [--file=config.path] <device_name>"
  puts ""
  puts " --file=path/to/kernel/config.file -- detected automatically if not present."
end

# Poor approximation to arguments parsing.
params, other_args = ARGV.partition { |s| s.match(/^--/) }

if other_args.empty?
  $stderr.puts "Device name required."
  usage
  exit 1
end

# Somewhat embarassing parameter parsing
params = params.map do |param|
  k, v = param.split("=", 2)
  v = true unless v
  k = k.sub(/^--/, "")
  [k, v]
end.to_h

DEVICE = other_args.shift

@file =
  # Is the device a path?
  if DEVICE.match(%r{/})
    Dir.glob(File.join(DEVICE, "kernel", "config.*")).sort.first
  else
    Dir.glob(File.join(Dir.pwd, "devices", DEVICE, "kernel", "config.*")).sort.first
  end

if params["file"]
  @file = params.delete("file")
end

unless @file and File.exists?(@file)
  $stderr.puts "Kernel config file not found."
  $stderr.puts "Please provide path to the config file with `--file=...`."
  $stderr.puts
  usage
  exit 1
end

unless params.empty?
  $stderr.puts "Unknown parameters #{params.join(", ")}."
  usage
  exit 1
end

unless other_args.empty?
  $stderr.puts "Unexpected arguments #{other_args.join(", ")}."
  usage
  exit 1
end

unless @file
  $stderr.puts "Could not find kernel configuration file for #{DEVICE}."
  usage
  exit 1
end

arg =
  # Is the device a path?
  if DEVICE.match(%r{/})
    ["--arg", "device", DEVICE]
  else
    ["--argstr", "device", DEVICE]
  end

Dir.chdir(ROOT) do
  result = `#{[
    "nix-build",
    "--no-out-link",
    *arg,
    "-A", "config.mobile.boot.stage-1.kernel.package.normalizedConfig"
  ].shelljoin}`.strip

  # We "cat" into the file to ensure we don't copy the store path access rights.
  File.write(@file, File.read(result))
end

# vim: ft=ruby