def load_sd_salt() -> Optional[bytearray]:
salt_auth_key = storage.device.get_sd_salt_auth_key()
if salt_auth_key is None:
return None
salt_path = _get_salt_path()
new_salt_path = _get_salt_path(new=True)
salt = _load_salt(salt_auth_key, salt_path)
if salt is not None:
return salt
# Check if there is a new salt.
salt = _load_salt(salt_auth_key, new_salt_path)
if salt is None:
# No valid salt file on this SD card.
raise WrongSdCard
# Normal salt file does not exist, but new salt file exists. That means that
# SD salt regeneration was interrupted earlier. Bring into consistent state.
# TODO Possibly overwrite salt file with random data.
try:
fatfs.unlink(salt_path)
except fatfs.FatFSError:
pass
# fatfs.rename can fail with a write error, which falls through as an FatFSError.
# This should be handled in calling code, by allowing the user to retry.
fatfs.rename(new_salt_path, salt_path)
return salt
def commit_sd_salt() -> None:
salt_path = _get_salt_path(new=False)
new_salt_path = _get_salt_path(new=True)
try:
fatfs.unlink(salt_path)
except fatfs.FatFSError:
pass
fatfs.rename(new_salt_path, salt_path)