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),
        and os.SEEK_CUR (seek relative to the current position) and os.SEEK_END
        (seek relative to the end, offset should be negative).
    """
    self._verify_read_mode()
    if whence == os.SEEK_SET:
      self._offset = offset
    elif whence == os.SEEK_CUR:
      self._offset += offset
    elif whence == os.SEEK_END:
      file_stat = self.stat()
      self._offset = file_stat.st_size + offset
    else:
      raise InvalidArgumentError('Whence mode %d is not supported', whence)