model.py 文件源码

def fix_header(self):
    """
    Repairs the header values.
    """
    # Update magic
    self.header.magic = self.header._MAGIC

    # Update system_data_size
    system_raw = self.system.dumps()
    self.header.system_data_size = len(system_raw)

    # Update user_data_size
    user_raw = self._user_raw
    self.header.user_data_size = len(user_raw)

    # Update crc32
    header_raw = self.header.dumps(False)
    checksum = 0
    checksum = crc32(header_raw, checksum)
    checksum = crc32(system_raw, checksum)
    checksum = crc32(user_raw, checksum)

    # Convert the checksum into 32-bit unsigned integer (for Python 2/3 compatibility)
    self.header.crc32 = (checksum & 0xffffffff)