unless Fog.mocking?

  module Fog
    module AWS
      class S3

        # Get headers for an object from S3
        #
        # ==== Parameters
        # * bucket_name<~String> - Name of bucket to read from
        # * object_name<~String> - Name of object to read
        # * options<~Hash>:
        #   * 'If-Match'<~String> - Returns object only if its etag matches this value, otherwise returns 412 (Precondition Failed).
        #   * 'If-Modified-Since'<~Time> - Returns object only if it has been modified since this time, otherwise returns 304 (Not Modified).
        #   * 'If-None-Match'<~String> - Returns object only if its etag differs from this value, otherwise returns 304 (Not Modified)
        #   * 'If-Unmodified-Since'<~Time> - Returns object only if it has not been modified since this time, otherwise returns 412 (Precodition Failed).
        #   * 'Range'<~String> - Range of object to download
        #
        # ==== Returns
        # * response<~Fog::AWS::Response>:
        #   * body<~String> - Contents of object
        #   * headers<~Hash>:
        #     * 'Content-Length'<~String> - Size of object contents
        #     * 'Content-Type'<~String> - MIME type of object
        #     * 'ETag'<~String> - Etag of object
        #     * 'Last-Modified'<~String> - Last modified timestamp for object
        def head_object(bucket_name, object_name, options={})
          headers = {}
          headers['If-Modified-Since'] = options['If-Modified-Since'].utc.strftime("%a, %d %b %Y %H:%M:%S +0000") if options['If-Modified-Since']
          headers['If-Unmodified-Since'] = options['If-Unmodified-Since'].utc.strftime("%a, %d %b %Y %H:%M:%S +0000") if options['If-Modified-Since']
          headers.merge!(options)
          request({
            :expects  => 200,
            :headers  => headers,
            :host     => "#{bucket_name}.#{@host}",
            :method   => 'HEAD',
            :path     => CGI.escape(object_name)
          })
        end

      end
    end
  end

else

  module Fog
    module AWS
      class S3

        def head_object(bucket_name, object_name, options = {})
          response = get_object(bucket_name, object_name, options)
          response.body = nil
          response
        end

      end
    end
  end

end