read_multipart

# File actionpack/lib/action_controller/request.rb, line 523
        def read_multipart(body, boundary, body_size, env)
          params = Hash.new([])
          boundary = "--" + boundary
          quoted_boundary = Regexp.quote(boundary)
          buf = ""
          bufsize = 10 * 1024
          boundary_end=""

          # start multipart/form-data
          body.binmode if defined? body.binmode
          case body
          when File
            body.set_encoding(Encoding::BINARY) if body.respond_to?(:set_encoding)
          when StringIO
            body.string.force_encoding(Encoding::BINARY) if body.string.respond_to?(:force_encoding)
          end
          boundary_size = boundary.size + EOL.size
          body_size -= boundary_size
          status = body.read(boundary_size)
          if nil == status
            raise EOFError, "no content body"
          elsif boundary + EOL != status
            raise EOFError, "bad content body"
          end

          loop do
            head = nil
            content =
              if 10240 < body_size
                UploadedTempfile.new("CGI")
              else
                UploadedStringIO.new
              end
            content.binmode if defined? content.binmode

            until head and /#{quoted_boundary}(?:#{EOL}|--)/n.match(buf)

              if (not head) and /#{EOL}#{EOL}/n.match(buf)
                buf = buf.sub(/\A((?:.|\n)*?#{EOL})#{EOL}/n) do
                  head = $1.dup
                  ""
                end
                next
              end

              if head and ( (EOL + boundary + EOL).size < buf.size )
                content.print buf[0 ... (buf.size - (EOL + boundary + EOL).size)]
                buf[0 ... (buf.size - (EOL + boundary + EOL).size)] = ""
              end

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

            buf = buf.sub(/\A((?:.|\n)*?)(?:[\r\n]{1,2})?#{quoted_boundary}([\r\n]{1,2}|--)/n) do
              content.print $1
              if "--" == $2
                body_size = -1
              end
              boundary_end = $2.dup
              ""
            end

            content.rewind

            head =~ /Content-Disposition:.* filename=(?:"((?:\\.|[^\"])*)"|([^;]*))/ni
            if filename = $1 || $2
              if /Mac/ni.match(env['HTTP_USER_AGENT']) and
                  /Mozilla/ni.match(env['HTTP_USER_AGENT']) and
                  (not /MSIE/ni.match(env['HTTP_USER_AGENT']))
                filename = CGI.unescape(filename)
              end
              content.original_path = filename.dup
            end

            head =~ /Content-Type: ([^\r]*)/ni
            content.content_type = $1.dup if $1

            head =~ /Content-Disposition:.* name="?([^\";]*)"?/ni
            name = $1.dup if $1

            if params.has_key?(name)
              params[name].push(content)
            else
              params[name] = [content]
            end
            break if body_size == -1
          end
          raise EOFError, "bad boundary end of body part" unless boundary_end=~/--/

          begin
            body.rewind if body.respond_to?(:rewind)
          rescue Errno::ESPIPE
            # Handles exceptions raised by input streams that cannot be rewound
            # such as when using plain CGI under Apache
          end

          params
        end