code: def sys_access(self, buf, mode):
          
          filename = b''
          for i in range(0, 255):
              c = Operators.CHR(self.current.read_int(buf + i, 8))
              if c == b'\x00':
                  break
              filename += c
  
          if os.access(filename, mode):
              return 0
          else:
              return -1
docs: Checks real user's permissions for a file
          :rtype: int
  
          :param buf: a buffer containing the pathname to the file to check its permissions.
          :param mode: the access permissions to check.
          :return:
              -  C{0} if the calling process can access the file in the desired mode.
              - C{-1} if the calling process can not access the file in the desired mode.