# File lib/rack/utils.rb, line 259
      def self.parse_multipart(env)
        unless env['CONTENT_TYPE'] =~
            %r|\Amultipart/form-data.*boundary=\"?([^\";,]+)\"?|n
          nil
        else
          boundary = "--#{$1}"

          params = {}
          buf = ""
          content_length = env['CONTENT_LENGTH'].to_i
          input = env['rack.input']

          boundary_size = boundary.size + EOL.size
          bufsize = 16384

          content_length -= boundary_size

          status = input.read(boundary_size)
          raise EOFError, "bad content body"  unless status == boundary + EOL

          rx = /(?:#{EOL})?#{Regexp.quote boundary}(#{EOL}|--)/

          loop {
            head = nil
            body = ''
            filename = content_type = name = nil

            until head && buf =~ rx
              if !head && i = buf.index("\r\n\r\n")
                head = buf.slice!(0, i+2) # First \r\n
                buf.slice!(0, 2)          # Second \r\n

                filename = head[/Content-Disposition:.* filename="?([^\";]*)"?/ni, 1]
                content_type = head[/Content-Type: (.*)\r\n/ni, 1]
                name = head[/Content-Disposition:.* name="?([^\";]*)"?/ni, 1]

                if filename
                  body = Tempfile.new("RackMultipart")
                  body.binmode  if body.respond_to?(:binmode)
                end

                next
              end

              # Save the read body part.
              if head && (boundary_size+4 < buf.size)
                body << buf.slice!(0, buf.size - (boundary_size+4))
              end

              c = input.read(bufsize < content_length ? bufsize : content_length)
              raise EOFError, "bad content body"  if c.nil? || c.empty?
              buf << c
              content_length -= c.size
            end

            # Save the rest.
            if i = buf.index(rx)
              body << buf.slice!(0, i)
              buf.slice!(0, boundary_size+2)

              content_length = -1  if $1 == "--"
            end

            if filename
              body.rewind
              data = {:filename => filename, :type => content_type,
                      :name => name, :tempfile => body, :head => head}
            else
              data = body
            end

            if name
              if name =~ /\[\]\z/
                params[name] ||= []
                params[name] << data
              else
                params[name] = data
              end
            end

            break  if buf.empty? || content_length == -1
          }

          params
        end
      end