file.py 文件源码

def seek(self, offset, whence=os.SEEK_SET):
    """Set the file's current position.

    Args:
      offset: seek offset as number.
      whence: seek mode. Supported modes are os.SEEK_SET (absolute seek),
        os.SEEK_CUR (seek relative to the current position), and os.SEEK_END
        (seek relative to the end, offset should be negative).
    """
    if whence == os.SEEK_SET:
      self._position = offset
    elif whence == os.SEEK_CUR:
      self._position += offset
    elif whence == os.SEEK_END:
      file_stat = stat(self._filename)
      self._position = file_stat.st_size + offset
    else:
      raise InvalidArgumentError('Whence mode %d is not supported', whence)
    self._buffer = ''
    self._buffer_pos = 0
    self._eof = False