Rubygems sandboxer for Merb.

rubygems.rb

local_rubygems = !!($:[0] == '.')
$:.shift if local_rubygems # Takes off the extra '.' put on the beginning. Now the next line will require the real rubygems
# Now require the REAL rubygems.
#   (we're going to FREEZE it next)
load 'rubygems.rb'
  $:.unshift('.') if local_rubygems

module Gem
  Sandbox = {
    'merb-core' => '=0.9.7',
    'dm-core' => '=0.9.8',
    'merb_datamapper' => '=0.9.7',
    'json' => '=1.1.2',
  }

  class SourceIndex
    def load_gems_in(*spec_dirs)
      @gems.clear
      spec_dirs.reverse_each do |spec_dir|
        spec_files = Dir.glob File.join(spec_dir, '*.gemspec')
        spec_files.each do |spec_file|
          if gemspec = self.class.load_specification(spec_file.untaint)
            if Gem::Sandbox.include?(gemspec.name)
              version_requirement = Gem::Requirement.create Gem::Sandbox[gemspec.name]
              add_spec gemspec if version_requirement.satisfied_by? gemspec.version
            else
              add_spec gemspec
            end
         end
        end
      end
      self
    end
  end

  def self.activate(agem, *version_requirements)
    $INDENT ||= ''

    if version_requirements.empty? then
      version_requirements = Gem::Requirement.default
    end

    unless agem.respond_to?(:name) and
           agem.respond_to?(:version_requirements) then
      agem = Gem::Dependency.new(agem, version_requirements)
    end
    # puts "#{$INDENT}Loading gem #{agem.name} #{agem.version_requirements}"

    matches = Gem.source_index.find_name(agem.name, agem.version_requirements)
    report_activate_error(agem) if matches.empty?

    if @loaded_specs[agem.name] then
      # This gem is already loaded.  If the currently loaded gem is not in the
      # list of candidate gems, then we have a version conflict.
      existing_spec = @loaded_specs[agem.name]

      unless matches.any? { |spec| spec.version == existing_spec.version } then
        raise Gem::Exception,
              "can't activate #{agem}, already activated #{existing_spec.full_name}"
      end

      return false
    end

    # new load
    spec = matches.last
    return false if spec.loaded?
    # puts "  '#{spec.name}' => '=#{spec.version}',"
    spec.loaded = true
    @loaded_specs[spec.name] = spec

    # Load dependent gems first
    spec.runtime_dependencies.each do |dep_gem|
      $INDENT += "\t"
      activate dep_gem
      $INDENT.chop!
    end

    # bin directory must come before library directories
    spec.require_paths.unshift spec.bindir if spec.bindir

    require_paths = spec.require_paths.map do |path|
      File.join spec.full_gem_path, path
    end

    sitelibdir = ConfigMap[:sitelibdir]

    # gem directories must come after -I and ENV['RUBYLIB']
    insert_index = load_path_insert_index

    if insert_index then
      # gem directories must come after -I and ENV['RUBYLIB']
      $LOAD_PATH.insert(insert_index, *require_paths)
    else
      # we are probably testing in core, -I and RUBYLIB don't apply
      $LOAD_PATH.unshift(*require_paths)
    end

    return true
  end
end

if $0 == 'rubygems.rb'
  def sandbox_merb
    puts "Making merb freezable..."
    merb_sh = `whereis merb`.chomp
    merb_script = File.read(merb_sh)
    new_merb_script = ''
    # Put in the comments at the top
    merb_script.each_line do |line|
      break if line =~ /require\s+.rubygems./ || line =~ /\$:\.unshift\('\.'\)/
      new_merb_script << line
    end
    # Put in the one new custom line
    new_merb_script << "$:.unshift('.')\n"
    # Put in the rest of the script
    hit = false
    merb_script.each_line do |line|
      next if line =~ /\$:\.shift/
      if line =~ /require\s+.rubygems./
        line << "$:.shift\n"
        hit = true
      end
      new_merb_script << line if hit
    end
    File.open(merb_sh, 'w') {|f| f.puts new_merb_script }
    puts `cat #{merb_sh}`
    puts "Done."
  end

  case ARGV[0]
  when 'sandbox_merb'
    sandbox_merb
  when 'list_dependencies'
    puts "Dependencies:"
    Gem::Sandbox.each do |name,version|
      version = version[/[\d\.]+/]
      puts "#{name}-#{version}"
    end
  when 'install_dependencies'
    puts "Installing Dependencies..."
    Gem::Sandbox.each do |name,version|
      version = version[/[\d\.]+/]
      has = `gem list #{name}`
      if has =~ /#{name} \(.*#{version}.*\)/
        puts "Already have #{name} #{version}"
      else
        puts "gem install #{name} --version #{version}"
        system("gem install #{name} --version #{version}")
      end
    end
    sandbox_merb
  else
    puts "Usage: ./rubygems.rb (sandbox_merb | list_dependencies | install_dependencies)"
  end
end