Class: Gem::Commands::RebuildCommand

# File 'lib/rubygems/commands/rebuild_command.rb', line 192

def build_gem(gem_name, source_date_epoch, output_file)
  gemspec = options[:gemspec_file] || find_gemspec("#{gem_name}.gemspec")

  if gemspec
    build_package(gemspec, source_date_epoch, output_file)
  else
    alert_error error_message(gem_name)
    terminate_interaction(1)
  end
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 203

def build_package(gemspec, source_date_epoch, output_file)
  with_source_date_epoch(source_date_epoch) do
    spec = Gem::Specification.load(gemspec)
    if spec
      Gem::Package.build(
        spec,
        options[:force],
        options[:strict],
        output_file
      )
    else
      alert_error "Error loading gemspec. Aborting."
      terminate_interaction 1
    end
  end
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 133

def compare(source_date_epoch, old_file, new_file)
  date = Time.at(source_date_epoch.to_i).strftime("%F %T %Z")

  old_hash = sha256(old_file)
  new_hash = sha256(new_file)

  say
  say "Built at: #{date} (#{source_date_epoch})"
  say "Original build saved to:   #{old_file}"
  say "Reproduced build saved to: #{new_file}"
  say "Working directory: #{options[:build_path] || Dir.pwd}"
  say
  say "Hash comparison:"
  say "  #{old_hash}\t#{old_file}"
  say "  #{new_hash}\t#{new_file}"
  say

  if old_hash == new_hash
    say "SUCCESS - original and rebuild hashes matched"
  else
    say "FAILURE - original and rebuild hashes did not match"
    say

    if options[:diff]
      if system("diffoscope", old_file, new_file).nil?
        alert_error "error: could not find `diffoscope` executable"
      end
    else
      say "Pass --diff for more details (requires diffoscope to be installed)."
    end

    terminate_interaction 1
  end
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 52

def description # :nodoc:
  <<-EOF
The rebuild command allows you to (attempt to) reproduce a build of a gem
from a ruby gemspec.

This command assumes the gemspec can be built with the `gem build` command.
If you use any of `gem build`, `rake build`, or`rake release` in the
build/release process for a gem, it is a potential candidate.

You will need to match the RubyGems version used, since this is included in
the Gem metadata.

If the gem includes lockfiles (e.g. Gemfile.lock) and similar, it will
require more effort to reproduce a build. For example, it might require
more precisely matched versions of Ruby and/or Bundler to be used.
  EOF
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 237

def download_gem(gem_name, gem_version, old_file)
  # This code was based loosely off the `gem fetch` command.
  version = "= #{gem_version}"
  dep = Gem::Dependency.new gem_name, version

  specs_and_sources, errors =
    Gem::SpecFetcher.fetcher.spec_for_dependency dep

  # There should never be more than one item in specs_and_sources,
  # since we search for an exact version.
  spec, source = specs_and_sources[0]

  if spec.nil?
    show_lookup_failure gem_name, version, errors, options[:domain]
    terminate_interaction 1
  end

  download_path = source.download spec

  FileUtils.move(download_path, old_file)

  say "Downloaded #{gem_name} version #{gem_version} as #{old_file}."
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 229

def error_message(gem_name)
  if gem_name
    "Couldn't find a gemspec file matching '#{gem_name}' in #{Dir.pwd}"
  else
    "Couldn't find a gemspec file in #{Dir.pwd}"
  end
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 74

def execute
  gem_name, gem_version = get_gem_name_and_version

  old_dir, new_dir = prep_dirs

  gem_filename = "#{gem_name}-#{gem_version}.gem"
  old_file = File.join(old_dir, gem_filename)
  new_file = File.join(new_dir, gem_filename)

  if options[:original_gem_file]
    FileUtils.copy_file(options[:original_gem_file], old_file)
  else
    download_gem(gem_name, gem_version, old_file)
  end

  rg_version = rubygems_version(old_file)
  unless rg_version == Gem::VERSION
    alert_error <<-EOF
You need to use the same RubyGems version #{gem_name} v#{gem_version} was built with.

#{gem_name} v#{gem_version} was built using RubyGems v#{rg_version}.
Gem files include the version of RubyGems used to build them.
This means in order to reproduce #{gem_filename}, you must also use RubyGems v#{rg_version}.

You're using RubyGems v#{Gem::VERSION}.

Please install RubyGems v#{rg_version} and try again.
    EOF
    terminate_interaction 1
  end

  source_date_epoch = get_timestamp(old_file).to_s

  if build_path = options[:build_path]
    Dir.chdir(build_path) { build_gem(gem_name, source_date_epoch, new_file) }
  else
    build_gem(gem_name, source_date_epoch, new_file)
  end

  compare(source_date_epoch, old_file, new_file)
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 179

def get_gem_name_and_version
  args = options[:args] || []
  if args.length == 2
    gem_name, gem_version = args
  elsif args.length > 2
    raise Gem::CommandLineError, "Too many arguments"
  else
    raise Gem::CommandLineError, "Expected GEM_NAME and GEM_VERSION arguments (gem rebuild GEM_NAME GEM_VERSION)"
  end

  [gem_name, gem_version]
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 122

def get_timestamp(file)
  mtime = nil
  File.open(file, Gem.binary_mode) do |f|
    Gem::Package::TarReader.new(f) do |tar|
      mtime = tar.seek("metadata.gz") {|tf| tf.header.mtime }
    end
  end

  mtime
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 168

def prep_dirs
  rebuild_dir = Dir.mktmpdir("gem_rebuild")
  old_dir = File.join(rebuild_dir, "old")
  new_dir = File.join(rebuild_dir, "new")

  FileUtils.mkdir_p(old_dir)
  FileUtils.mkdir_p(new_dir)

  [old_dir, new_dir]
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 261

def rubygems_version(gem_file)
  Gem::Package.new(gem_file).spec.rubygems_version
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 118

def sha256(file)
  Digest::SHA256.hexdigest(Gem.read_binary(file))
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 70

def usage # :nodoc:
  "#{program_name} GEM_NAME GEM_VERSION"
end

# File 'lib/rubygems/commands/rebuild_command.rb', line 220

def with_source_date_epoch(source_date_epoch)
  old_sde = ENV["SOURCE_DATE_EPOCH"]
  ENV["SOURCE_DATE_EPOCH"] = source_date_epoch.to_s

  yield
ensure
  ENV["SOURCE_DATE_EPOCH"] = old_sde
end