# class Gem::Validator

`Validator` performs various gem file and gem database validation

### Public Instance Methods

alien (gems=[])
Source

    # File lib/rubygems/validator.rb, line 62
    def alien(gems=[])
      errors = Hash.new {|h,k| h[k] = {} }

      Gem::Specification.each do |spec|
        unless gems.empty?
          next unless gems.include? spec.name
        end
        next if spec.default_gem?

        gem_name      = spec.file_name
        gem_path      = spec.cache_file
        spec_path     = spec.spec_file
        gem_directory = spec.full_gem_path

        unless File.directory? gem_directory
          errors[gem_name][spec.full_name] =
            "Gem registered but doesn't exist at #{gem_directory}"
          next
        end

        unless File.exist? spec_path
          errors[gem_name][spec_path] = "Spec file missing for installed gem"
        end

        begin
          unless File.readable?(gem_path)
            raise Gem::VerificationError, "missing gem file #{gem_path}"
          end

          good, gone, unreadable = nil, nil, nil, nil

          File.open gem_path, Gem.binary_mode do |_file|
            package = Gem::Package.new gem_path

            good, gone = package.contents.partition do |file_name|
              File.exist? File.join(gem_directory, file_name)
            end

            gone.sort.each do |path|
              errors[gem_name][path] = "Missing file"
            end

            good, unreadable = good.partition do |file_name|
              File.readable? File.join(gem_directory, file_name)
            end

            unreadable.sort.each do |path|
              errors[gem_name][path] = "Unreadable file"
            end

            good.each do |entry, data|
              next unless data # HACK: `gem check -a mkrf`

              source = File.join gem_directory, entry["path"]

              File.open source, Gem.binary_mode do |f|
                unless f.read == data
                  errors[gem_name][entry["path"]] = "Modified from original"
                end
              end
            end
          end

          installed_files = find_files_for_gem(gem_directory)
          extras = installed_files - good - unreadable

          extras.each do |extra|
            errors[gem_name][extra] = "Extra file"
          end
        rescue Gem::VerificationError => e
          errors[gem_name][gem_path] = e.message
        end
      end

      errors.each do |name, subhash|
        errors[name] = subhash.map do |path, msg|
          ErrorData.new path, msg
        end.sort
      end

      errors
    end

Checks the gem directory for the following potential inconsistencies/problems:

- Checksum gem itself

- For each file in each gem, check consistency of installed versions

- Check for files that aren’t part of the gem but are in the gems directory

- 1 cache - 1 spec - 1 directory.

returns a hash of ErrorData objects, keyed on the problem gem’s name.

### Private Instance Methods

find_files_for_gem (gem_directory)
Source

    # File lib/rubygems/validator.rb, line 24
    def find_files_for_gem(gem_directory)
      installed_files = []

      Find.find gem_directory do |file_name|
        fn = file_name[gem_directory.size..file_name.size - 1].sub(%r{^/}, "")
        installed_files << fn unless
          fn.empty? || fn.include?("CVS") || File.directory?(file_name)
      end

      installed_files
    end