code: function(raw) {
          var result = {}
          var md = raw.split(protocol.FDFS_RECORD_SEPERATOR)
          md.forEach(function(item) {
              var arr = item.split(protocol.FDFS_FIELD_SEPERATOR)
              var key = helpers.trim(arr[0])
              var value = helpers.trim(arr[1])
              result[key] = value
          })
  
          return result
      }
docs: raw meta data to structure
  @param raw