lib/paygen/paygen_stateful_payload_lib.py

# Copyright 2019 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Library for handling Chrome OS partition."""

import logging
import os

from chromite.lib import constants
from chromite.lib import cros_build_lib
from chromite.lib import image_lib
from chromite.lib import osutils


STATEFUL_FILE = "stateful.tgz"


def GenerateStatefulPayload(image_path, output):
    """Generates a stateful update payload given a full path to an image.

    Args:
      image_path: Full path to the image.
      output: Can be either the path to the directory to leave the resulting
        payload or a file descriptor to write the payload into.

    Returns:
      str: The full path to the generated file.
    """
    logging.info("Generating stateful update file.")

    if isinstance(output, int):
        output_gz = output
    else:
        output_gz = os.path.join(output, STATEFUL_FILE)

    # Mount the image to pull out the important directories.
    with osutils.TempDir() as stateful_mnt, image_lib.LoopbackPartitions(
        image_path, stateful_mnt
    ) as image:
        stateful_dir = image.Mount((constants.PART_STATE,))[0]

        try:
            logging.info("Tarring up /usr/local and /var!")
            inputs = ["dev_image", "var_overlay"]
            if os.path.exists(os.path.join(stateful_dir, "unencrypted")):
                inputs += ["unencrypted"]
            cros_build_lib.CreateTarball(
                output_gz,
                ".",
                sudo=True,
                compression=cros_build_lib.CompressionType.GZIP,
                inputs=inputs,
                extra_args=[
                    "--selinux",
                    "--directory=%s" % stateful_dir,
                    "--transform=s,^dev_image,dev_image_new,",
                    "--transform=s,^var_overlay,var_new,",
                ],
            )
        except:
            logging.error("Failed to create stateful update file")
            raise

    logging.info("Successfully generated %s", output_gz)

    return output_gz