build_dlc: Split build_dlc script into a library and script

Split the build_dlc script and move anything reusable to the new
library build_dlc_lib to improve the organization of the code, so
chromite libraries don't have to import chromite scripts.

BUG=chromium:1066214
TEST=./run_tests #chromite unit tests.
TEST=emerge dummy dlc and cros deploy

Change-Id: I57b33c300b9d47cef7993577b7b980c4f663d3e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2248498
Reviewed-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Commit-Queue: Andrew Lassalle <andrewlassalle@chromium.org>
Tested-by: Andrew Lassalle <andrewlassalle@chromium.org>
diff --git a/scripts/build_dlc.py b/scripts/build_dlc.py
index e0478d8..4b7598b 100644
--- a/scripts/build_dlc.py
+++ b/scripts/build_dlc.py
@@ -4,639 +4,23 @@
 # found in the LICENSE file.
 """Script to generate a DLC (Downloadable Content) artifact."""
 
-from __future__ import division
 from __future__ import print_function
 
-import hashlib
-import json
-import math
-import os
-import re
-import shutil
 import sys
 
+from chromite.lib import dlc_lib
 from chromite.lib import commandline
-from chromite.lib import cros_build_lib
 from chromite.lib import cros_logging as logging
-from chromite.lib import osutils
-from chromite.lib import pformat
 
-from chromite.licensing  import licenses_lib
-from chromite.scripts import cros_set_lsb_release
 
 assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
 
-DLC_META_DIR = 'opt/google/dlc/'
-DLC_TMP_META_DIR = 'meta'
-DLC_BUILD_DIR = 'build/rootfs/dlc/'
-LICENSE = 'LICENSE'
-LSB_RELEASE = 'etc/lsb-release'
-DLC_IMAGE = 'dlc.img'
-IMAGELOADER_JSON = 'imageloader.json'
-EBUILD_PARAMETERS = 'ebuild_parameters.json'
-
-# This file has major and minor version numbers that the update_engine client
-# supports. These values are needed for generating a delta/full payload.
-UPDATE_ENGINE_CONF = 'etc/update_engine.conf'
-
-_EXTRA_RESOURCES = (UPDATE_ENGINE_CONF,)
-
-DLC_ID_KEY = 'DLC_ID'
-DLC_PACKAGE_KEY = 'DLC_PACKAGE'
-DLC_NAME_KEY = 'DLC_NAME'
-DLC_APPID_KEY = 'DLC_RELEASE_APPID'
-
-_SQUASHFS_TYPE = 'squashfs'
-_EXT4_TYPE = 'ext4'
-
-_USED_BY_USER = 'user'
-_USED_BY_SYSTEM = 'system'
-
-MAX_ID_NAME = 40
-
-
-def HashFile(file_path):
-  """Calculate the sha256 hash of a file.
-
-  Args:
-    file_path: (str) path to the file.
-
-  Returns:
-    [str]: The sha256 hash of the file.
-  """
-  sha256 = hashlib.sha256()
-  with open(file_path, 'rb') as f:
-    for b in iter(lambda: f.read(2048), b''):
-      sha256.update(b)
-  return sha256.hexdigest()
-
-
-def GetValueInJsonFile(json_path, key, default_value=None):
-  """Reads file containing JSON and returns value or default_value for key.
-
-  Args:
-    json_path: (str) File containing JSON.
-    key: (str) The desired key to lookup.
-    default_value: (default:None) The default value returned in case of missing
-      key.
-  """
-  with open(json_path) as fd:
-    return json.load(fd).get(key, default_value)
-
-
-class EbuildParams(object):
-  """Object to store and retrieve DLC ebuild parameters.
-
-  Attributes:
-    dlc_id: (str) DLC ID.
-    dlc_package: (str) DLC package.
-    fs_type: (str) file system type.
-    pre_allocated_blocks: (int) number of blocks pre-allocated on device.
-    version: (str) DLC version.
-    name: (str) DLC name.
-    description: (str) DLC description.
-    preload: (bool) allow for preloading DLC.
-    used_by: (str) The user of this DLC, e.g. "system" or "user"
-    fullnamerev: (str) The full package & version name.
-  """
-
-  def __init__(self, dlc_id, dlc_package, fs_type, pre_allocated_blocks,
-               version, name, description, preload, used_by, fullnamerev):
-    self.dlc_id = dlc_id
-    self.dlc_package = dlc_package
-    self.fs_type = fs_type
-    self.pre_allocated_blocks = pre_allocated_blocks
-    self.version = version
-    self.name = name
-    self.description = description
-    self.preload = preload
-    self.used_by = used_by
-    self.fullnamerev = fullnamerev
-
-  def StoreDlcParameters(self, install_root_dir, sudo):
-    """Store DLC parameters defined in the ebuild.
-
-    Store DLC parameters defined in the ebuild in a temporary file so they can
-    be retrieved in the build_image phase.
-
-    Args:
-      install_root_dir: (str) The path to the root installation directory.
-      sudo: (bool) Use sudo to write the file.
-    """
-    ebuild_params_path = EbuildParams.GetParamsPath(install_root_dir,
-                                                    self.dlc_id,
-                                                    self.dlc_package)
-    osutils.WriteFile(ebuild_params_path,
-                      json.dumps(self.__dict__),
-                      makedirs=True, sudo=sudo)
-
-  @staticmethod
-  def GetParamsPath(install_root_dir, dlc_id, dlc_package):
-    """Get the path to the file storing the ebuild parameters.
-
-    Args:
-      install_root_dir: (str) The path to the root installation directory.
-      dlc_id: (str) DLC ID.
-      dlc_package: (str) DLC package.
-
-    Returns:
-      [str]: Path to |EBUILD_PARAMETERS|.
-    """
-    return os.path.join(install_root_dir, DLC_BUILD_DIR, dlc_id, dlc_package,
-                        EBUILD_PARAMETERS)
-
-  @classmethod
-  def LoadEbuildParams(cls, sysroot, dlc_id, dlc_package):
-    """Read the stored ebuild parameters file and return a class instance.
-
-    Args:
-      dlc_id: (str) DLC ID.
-      dlc_package: (str) DLC package.
-      sysroot: (str) The path to the build root directory.
-
-    Returns:
-      [bool] : True if |ebuild_params_path| exists, False otherwise.
-    """
-    path = cls.GetParamsPath(sysroot, dlc_id, dlc_package)
-    if not os.path.exists(path):
-      return None
-
-    with open(path, 'rb') as fp:
-      return cls(**json.load(fp))
-
-  def __str__(self):
-    return str(self.__dict__)
-
-
-class DlcGenerator(object):
-  """Object to generate DLC artifacts."""
-  # Block size for the DLC image.
-  # We use 4K for various reasons:
-  # 1. it's what imageloader (linux kernel) supports.
-  # 2. it's what verity supports.
-  _BLOCK_SIZE = 4096
-  # Blocks in the initial sparse image.
-  _BLOCKS = 500000
-  # Version of manifest file.
-  _MANIFEST_VERSION = 1
-
-  # The DLC root path inside the DLC module.
-  _DLC_ROOT_DIR = 'root'
-
-  def __init__(self, ebuild_params, sysroot, install_root_dir, board,
-               src_dir=None):
-    """Object initializer.
-
-    Args:
-      sysroot: (str) The path to the build root directory.
-      install_root_dir: (str) The path to the root installation directory.
-      ebuild_params: (EbuildParams) Ebuild variables.
-      board: (str) The target board we are building for.
-      src_dir: (str) Optional path to the DLC source root directory. When None,
-               the default directory in |DLC_BUILD_DIR| is used.
-    """
-    # Use a temporary directory to avoid having to use sudo every time we write
-    # into the build directory.
-    self.temp_root = osutils.TempDir(prefix='dlc', sudo_rm=True)
-    self.src_dir = src_dir
-    self.sysroot = sysroot
-    self.install_root_dir = install_root_dir
-    self.board = board
-    self.ebuild_params = ebuild_params
-    # If the client is not overriding the src_dir, use the default one.
-    if not self.src_dir:
-      self.src_dir = os.path.join(self.sysroot, DLC_BUILD_DIR,
-                                  self.ebuild_params.dlc_id,
-                                  self.ebuild_params.dlc_package,
-                                  self._DLC_ROOT_DIR)
-
-    self.image_dir = os.path.join(self.temp_root.tempdir,
-                                  DLC_BUILD_DIR,
-                                  self.ebuild_params.dlc_id,
-                                  self.ebuild_params.dlc_package)
-
-    self.meta_dir = os.path.join(self.image_dir, DLC_TMP_META_DIR)
-
-    # Create path for all final artifacts.
-    self.dest_image = os.path.join(self.image_dir, DLC_IMAGE)
-    self.dest_table = os.path.join(self.meta_dir, 'table')
-    self.dest_imageloader_json = os.path.join(self.meta_dir, IMAGELOADER_JSON)
-
-    # Log out the member variable values initially set.
-    logging.debug('Initial internal values of DlcGenerator: %s',
-                  repr({k:str(i) for k, i in self.__dict__.items()}))
-
-  def CopyTempContentsToBuildDir(self):
-    """Copy the temp files to the build directory using sudo."""
-    src = self.temp_root.tempdir.rstrip('/') + '/.'
-    dst = self.install_root_dir
-    logging.info(
-        'Copy files from temporary directory (%s) to build directory (%s).',
-        src, dst)
-    cros_build_lib.sudo_run(['cp', '-dR', src, dst])
-
-  def SquashOwnerships(self, path):
-    """Squash the owernships & permissions for files.
-
-    Args:
-      path: (str) path that contains all files to be processed.
-    """
-    cros_build_lib.sudo_run(['chown', '-R', '0:0', path])
-    cros_build_lib.sudo_run([
-        'find', path, '-exec', 'touch', '-h', '-t', '197001010000.00', '{}', '+'
-    ])
-
-  def CreateExt4Image(self):
-    """Create an ext4 image."""
-    with osutils.TempDir(prefix='dlc_') as temp_dir:
-      mount_point = os.path.join(temp_dir, 'mount_point')
-      # Create the directory where the image is located if it doesn't exist.
-      osutils.SafeMakedirs(os.path.split(self.dest_image)[0])
-      # Create a raw image file.
-      with open(self.dest_image, 'w') as f:
-        f.truncate(self._BLOCKS * self._BLOCK_SIZE)
-      # Create an ext4 file system on the raw image.
-      cros_build_lib.run([
-          '/sbin/mkfs.ext4', '-b',
-          str(self._BLOCK_SIZE), '-O', '^has_journal', self.dest_image
-      ],
-                         capture_output=True)
-      # Create the mount_point directory.
-      osutils.SafeMakedirs(mount_point)
-      # Mount the ext4 image.
-      osutils.MountDir(self.dest_image, mount_point, mount_opts=('loop', 'rw'))
-
-      try:
-        self.SetupDlcImageFiles(mount_point)
-      finally:
-        # Unmount the ext4 image.
-        osutils.UmountDir(mount_point)
-      # Shrink to minimum size.
-      cros_build_lib.run(['/sbin/e2fsck', '-y', '-f', self.dest_image],
-                         capture_output=True)
-      cros_build_lib.run(['/sbin/resize2fs', '-M', self.dest_image],
-                         capture_output=True)
-
-  def CreateSquashfsImage(self):
-    """Create a squashfs image."""
-    with osutils.TempDir(prefix='dlc_') as temp_dir:
-      squashfs_root = os.path.join(temp_dir, 'squashfs-root')
-      self.SetupDlcImageFiles(squashfs_root)
-
-      cros_build_lib.run([
-          'mksquashfs', squashfs_root, self.dest_image, '-4k-align', '-noappend'
-      ],
-                         capture_output=True)
-
-      # We changed the ownership and permissions of the squashfs_root
-      # directory. Now we need to remove it manually.
-      osutils.RmDir(squashfs_root, sudo=True)
-
-  def SetupDlcImageFiles(self, dlc_dir):
-    """Prepares the directory dlc_dir with all the files a DLC needs.
-
-    Args:
-      dlc_dir: (str) The path to where to setup files inside the DLC.
-    """
-    dlc_root_dir = os.path.join(dlc_dir, self._DLC_ROOT_DIR)
-    osutils.SafeMakedirs(dlc_root_dir)
-    osutils.CopyDirContents(self.src_dir, dlc_root_dir, symlinks=True)
-    self.PrepareLsbRelease(dlc_dir)
-    self.AddLicensingFile(dlc_dir)
-    self.CollectExtraResources(dlc_dir)
-    self.SquashOwnerships(dlc_dir)
-
-  def PrepareLsbRelease(self, dlc_dir):
-    """Prepare the file /etc/lsb-release in the DLC module.
-
-    This file is used dropping some identification parameters for the DLC.
-
-    Args:
-      dlc_dir: (str) The path to the mounted point during image creation.
-    """
-    # Reading the platform APPID and creating the DLC APPID.
-    platform_lsb_release = osutils.ReadFile(
-        os.path.join(self.sysroot, LSB_RELEASE))
-    app_id = None
-    for line in platform_lsb_release.split('\n'):
-      if line.startswith(cros_set_lsb_release.LSB_KEY_APPID_RELEASE):
-        app_id = line.split('=')[1]
-    if app_id is None:
-      raise Exception(
-          '%s does not have a valid key %s' %
-          (platform_lsb_release, cros_set_lsb_release.LSB_KEY_APPID_RELEASE))
-
-    fields = (
-        (DLC_ID_KEY, self.ebuild_params.dlc_id),
-        (DLC_PACKAGE_KEY, self.ebuild_params.dlc_package),
-        (DLC_NAME_KEY, self.ebuild_params.name),
-        # The DLC appid is generated by concatenating the platform appid with
-        # the DLC ID using an underscore. This pattern should never be changed
-        # once set otherwise it can break a lot of things!
-        (DLC_APPID_KEY, '%s_%s' % (app_id, self.ebuild_params.dlc_id)),
-    )
-
-    lsb_release = os.path.join(dlc_dir, LSB_RELEASE)
-    osutils.SafeMakedirs(os.path.dirname(lsb_release))
-    content = ''.join('%s=%s\n' % (k, v) for k, v in fields)
-    osutils.WriteFile(lsb_release, content)
-
-  def AddLicensingFile(self, dlc_dir):
-    """Add the licensing file for this DLC.
-
-    Args:
-      dlc_dir: (str) The path to the mounted point during image creation.
-    """
-    if not self.ebuild_params.fullnamerev:
-      return
-
-    licensing = licenses_lib.Licensing(self.board,
-                                       [self.ebuild_params.fullnamerev], True)
-    licensing.LoadPackageInfo()
-    licensing.ProcessPackageLicenses()
-    license_path = os.path.join(dlc_dir, LICENSE)
-    # The first (and only) item contains the values for |self.fullnamerev|.
-    _, license_txt = next(iter(licensing.GenerateLicenseText().items()))
-    osutils.WriteFile(license_path, license_txt)
-
-  def CollectExtraResources(self, dlc_dir):
-    """Collect the extra resources needed by the DLC module.
-
-    Look at the documentation around _EXTRA_RESOURCES.
-
-    Args:
-      dlc_dir: (str) The path to the mounted point during image creation.
-    """
-    for r in _EXTRA_RESOURCES:
-      source_path = os.path.join(self.sysroot, r)
-      target_path = os.path.join(dlc_dir, r)
-      osutils.SafeMakedirs(os.path.dirname(target_path))
-      shutil.copyfile(source_path, target_path)
-
-  def CreateImage(self):
-    """Create the image and copy the DLC files to it."""
-    logging.info('Creating the DLC image.')
-    if self.ebuild_params.fs_type == _EXT4_TYPE:
-      self.CreateExt4Image()
-    elif self.ebuild_params.fs_type == _SQUASHFS_TYPE:
-      self.CreateSquashfsImage()
-    else:
-      raise ValueError('Wrong fs type: %s used:' % self.ebuild_params.fs_type)
-
-  def VerifyImageSize(self):
-    """Verify the image can fit to the reserved file."""
-    logging.info('Verifying the DLC image size.')
-    image_bytes = os.path.getsize(self.dest_image)
-    preallocated_bytes = (self.ebuild_params.pre_allocated_blocks *
-                          self._BLOCK_SIZE)
-    # Verifies the actual size of the DLC image is NOT smaller than the
-    # preallocated space.
-    if preallocated_bytes < image_bytes:
-      raise ValueError(
-          'The DLC_PREALLOC_BLOCKS (%s) value set in DLC ebuild resulted in a '
-          'max size of DLC_PREALLOC_BLOCKS * 4K (%s) bytes the DLC image is '
-          'allowed to occupy. The value is smaller than the actual image size '
-          '(%s) required. Increase DLC_PREALLOC_BLOCKS in your ebuild to at '
-          'least %d.' %
-          (self.ebuild_params.pre_allocated_blocks, preallocated_bytes,
-           image_bytes, self.GetOptimalImageBlockSize(image_bytes)))
-
-  def GetOptimalImageBlockSize(self, image_bytes):
-    """Given the image bytes, get the least amount of blocks required."""
-    return int(math.ceil(image_bytes / self._BLOCK_SIZE))
-
-  def GetImageloaderJsonContent(self, image_hash, table_hash, blocks):
-    """Return the content of imageloader.json file.
-
-    Args:
-      image_hash: (str) sha256 hash of the DLC image.
-      table_hash: (str) sha256 hash of the DLC table file.
-      blocks: (int) number of blocks in the DLC image.
-
-    Returns:
-      [str]: content of imageloader.json file.
-    """
-    return {
-        'fs-type': self.ebuild_params.fs_type,
-        'id': self.ebuild_params.dlc_id,
-        'package': self.ebuild_params.dlc_package,
-        'image-sha256-hash': image_hash,
-        'image-type': 'dlc',
-        'is-removable': True,
-        'manifest-version': self._MANIFEST_VERSION,
-        'name': self.ebuild_params.name,
-        'description': self.ebuild_params.description,
-        'pre-allocated-size':
-            str(self.ebuild_params.pre_allocated_blocks * self._BLOCK_SIZE),
-        'size': str(blocks * self._BLOCK_SIZE),
-        'table-sha256-hash': table_hash,
-        'version': self.ebuild_params.version,
-        'preload-allowed': self.ebuild_params.preload,
-        'used-by': self.ebuild_params.used_by,
-    }
-
-  def GenerateVerity(self):
-    """Generate verity parameters and hashes for the image."""
-    logging.info('Generating DLC image verity.')
-    with osutils.TempDir(prefix='dlc_') as temp_dir:
-      hash_tree = os.path.join(temp_dir, 'hash_tree')
-      # Get blocks in the image.
-      blocks = math.ceil(os.path.getsize(self.dest_image) / self._BLOCK_SIZE)
-      result = cros_build_lib.run([
-          'verity', 'mode=create', 'alg=sha256', 'payload=' + self.dest_image,
-          'payload_blocks=' + str(blocks), 'hashtree=' + hash_tree,
-          'salt=random'
-      ],
-                                  capture_output=True)
-      table = result.output
-
-      # Append the merkle tree to the image.
-      osutils.WriteFile(
-          self.dest_image, osutils.ReadFile(hash_tree, mode='rb'), mode='a+b')
-
-      # Write verity parameter to table file.
-      osutils.WriteFile(self.dest_table, table, mode='wb')
-
-      # Compute image hash.
-      image_hash = HashFile(self.dest_image)
-      table_hash = HashFile(self.dest_table)
-      # Write image hash to imageloader.json file.
-      blocks = math.ceil(os.path.getsize(self.dest_image) / self._BLOCK_SIZE)
-      imageloader_json_content = self.GetImageloaderJsonContent(
-          image_hash, table_hash, int(blocks))
-      pformat.json(imageloader_json_content, fp=self.dest_imageloader_json)
-
-  def GenerateDLC(self):
-    """Generate a DLC artifact."""
-    # Create directories.
-    osutils.SafeMakedirs(self.image_dir)
-    osutils.SafeMakedirs(self.meta_dir)
-
-    # Create the image into |self.temp_root| and copy the DLC files to it.
-    self.CreateImage()
-    # Verify the image created is within pre-allocated size.
-    self.VerifyImageSize()
-    # Generate hash tree and other metadata and save them under
-    # |self.temp_root|.
-    self.GenerateVerity()
-    # Copy the files from |self.temp_root| into the build directory.
-    self.CopyTempContentsToBuildDir()
-
-    # Now that the image was successfully generated, delete |ebuild_params_path|
-    # to indicate that the image in the build directory is in sync with the
-    # files installed during the build_package phase.
-    ebuild_params_path = EbuildParams.GetParamsPath(
-        self.sysroot, self.ebuild_params.dlc_id, self.ebuild_params.dlc_package)
-    osutils.SafeUnlink(ebuild_params_path, sudo=True)
-
-
-def IsDlcPreloadingAllowed(dlc_id, dlc_build_dir):
-  """Validates that DLC and it's packages all were built with DLC_PRELOAD=true.
-
-  Args:
-    dlc_id: (str) DLC ID.
-    dlc_build_dir: (str) the root path where DLC build files reside.
-  """
-
-  dlc_id_meta_dir = os.path.join(dlc_build_dir, dlc_id)
-  if not os.path.exists(dlc_id_meta_dir):
-    logging.error('DLC build directory (%s) does not exist for preloading '
-                  'check, will not preload', dlc_id_meta_dir)
-    return False
-
-  packages = os.listdir(dlc_id_meta_dir)
-  if not packages:
-    logging.error('DLC ID build directory (%s) does not have any '
-                  'packages, will not preload.', dlc_id_meta_dir)
-    return False
-
-  for package in packages:
-    image_loader_json = os.path.join(dlc_id_meta_dir, package, DLC_TMP_META_DIR,
-                                     IMAGELOADER_JSON)
-    if not os.path.exists(image_loader_json):
-      logging.error('DLC metadata file (%s) does not exist, will not preload.',
-                    image_loader_json)
-      return False
-    if not GetValueInJsonFile(json_path=image_loader_json,
-                              key='preload-allowed', default_value=False):
-      return False
-  # All packages support preload.
-  return True
-
-
-def InstallDlcImages(sysroot, board, dlc_id=None, install_root_dir=None,
-                     preload=False, rootfs=None, src_dir=None):
-  """Copies all DLC image files into the images directory.
-
-  Copies the DLC image files in the given build directory into the given DLC
-  image directory. If the DLC build directory does not exist, or there is no DLC
-  for that board, this function does nothing.
-
-  Args:
-    sysroot: Path to directory containing DLC images, e.g /build/<board>.
-    board: The target board we are building for.
-    dlc_id: (str) DLC ID. If None, all the DLCs will be installed.
-    install_root_dir: Path to DLC output directory, e.g.
-      src/build/images/<board>/<version>. If None, the image will be generated
-      but will not be copied to a destination.
-    preload: When true, only copies DLC(s) if built with DLC_PRELOAD=true.
-    rootfs: (str) Path to the platform rootfs.
-    src_dir: (str) Path to the DLC source root directory.
-  """
-  dlc_build_dir = os.path.join(sysroot, DLC_BUILD_DIR)
-  if not os.path.exists(dlc_build_dir):
-    logging.info('DLC build directory (%s) does not exist, ignoring.',
-                 dlc_build_dir)
-    return
-
-  if dlc_id is not None:
-    if not os.path.exists(os.path.join(dlc_build_dir, dlc_id)):
-      raise Exception(
-          'DLC "%s" does not exist in the build directory %s.' %
-          (dlc_id, dlc_build_dir))
-    dlc_ids = [dlc_id]
-  else:
-    # Process all DLCs.
-    dlc_ids = os.listdir(dlc_build_dir)
-    if not dlc_ids:
-      logging.info('There are no DLC(s) to copy to output, ignoring.')
-      return
-
-    logging.info('Detected the following DLCs: %s', ', '.join(dlc_ids))
-
-  for d_id in dlc_ids:
-    dlc_id_path = os.path.join(dlc_build_dir, d_id)
-    dlc_packages = [direct for direct in os.listdir(dlc_id_path)
-                    if os.path.isdir(os.path.join(dlc_id_path, direct))]
-    for d_package in dlc_packages:
-      logging.info('Building image: DLC %s', d_id)
-      params = EbuildParams.LoadEbuildParams(sysroot=sysroot, dlc_id=d_id,
-                                             dlc_package=d_package)
-      # Because portage sandboxes every ebuild package during build_packages
-      # phase, we cannot delete the old image during that phase, but we can use
-      # the existence of the file |EBUILD_PARAMETERS| to know if the image
-      # has to be generated or not.
-      if not params:
-        logging.info('The ebuild parameters file (%s) for DLC (%s) does not '
-                     'exist. This means that the image was already '
-                     'generated and there is no need to create it again.',
-                     EbuildParams.GetParamsPath(sysroot, d_id, d_package), d_id)
-      else:
-        dlc_generator = DlcGenerator(
-            src_dir=src_dir,
-            sysroot=sysroot,
-            install_root_dir=sysroot,
-            board=board,
-            ebuild_params=params)
-        dlc_generator.GenerateDLC()
-
-      # Copy the dlc images to install_root_dir.
-      if install_root_dir:
-        if preload and not IsDlcPreloadingAllowed(d_id, dlc_build_dir):
-          logging.info('Skipping installation of DLC %s because the preload '
-                       'flag is set and the DLC does not support preloading.',
-                       d_id)
-        else:
-          osutils.SafeMakedirsNonRoot(install_root_dir)
-          install_dlc_dir = os.path.join(install_root_dir, d_id, d_package)
-          osutils.SafeMakedirsNonRoot(install_dlc_dir)
-          source_dlc_dir = os.path.join(dlc_build_dir, d_id, d_package)
-          for filepath in (os.path.join(source_dlc_dir, fname) for fname in
-                           os.listdir(source_dlc_dir) if
-                           fname.endswith('.img')):
-            logging.info('Copying DLC(%s) image from %s to %s: ', d_id,
-                         filepath, install_dlc_dir)
-            shutil.copy(filepath, install_dlc_dir)
-            logging.info('Done copying DLC to %s.', install_dlc_dir)
-      else:
-        logging.info('install_root_dir value was not provided. Copying dlc'
-                     ' image skipped.')
-
-      # Create metadata directory in rootfs.
-      if rootfs:
-        meta_rootfs = os.path.join(rootfs, DLC_META_DIR, d_id, d_package)
-        osutils.SafeMakedirs(meta_rootfs, sudo=True)
-        # Copy the metadata files to rootfs.
-        meta_dir_src = os.path.join(dlc_build_dir, d_id, d_package,
-                                    DLC_TMP_META_DIR)
-        logging.info('Copying DLC(%s) metadata from %s to %s: ', d_id,
-                     meta_dir_src, meta_rootfs)
-        # Use sudo_run since osutils.CopyDirContents doesn't support sudo.
-        cros_build_lib.sudo_run(['cp', '-dR',
-                                 meta_dir_src.rstrip('/') + '/.',
-                                 meta_rootfs], print_cmd=False, stderr=True)
-
-      else:
-        logging.info('rootfs value was not provided. Copying metadata skipped.')
-
-  logging.info('Done installing DLCs.')
-
 
 def GetParser():
   """Creates an argument parser and returns it."""
   parser = commandline.ArgumentParser(description=__doc__)
   # This script is used both for building an individual DLC or copying all final
-  # DLCs images to their final destination nearby chromiumsos_test_image.bin,
+  # DLCs images to their final destination nearby chromiumos_test_image.bin,
   # etc. These two arguments are required in both cases.
   parser.add_argument(
       '--sysroot',
@@ -659,7 +43,8 @@
       ' install DLC images (%s) and metadata (%s). Otherwise it'
       ' is the target directory where the Chrome OS images gets'
       ' dropped in build_image, e.g. '
-      'src/build/images/<board>/latest.' % (DLC_BUILD_DIR, DLC_META_DIR))
+      'src/build/images/<board>/latest.' % (dlc_lib.DLC_BUILD_DIR,
+                                            dlc_lib.DLC_META_DIR))
 
   one_dlc = parser.add_argument_group('Arguments required for building only '
                                       'one DLC')
@@ -693,8 +78,8 @@
   one_dlc.add_argument(
       '--fs-type',
       metavar='FS_TYPE',
-      default=_SQUASHFS_TYPE,
-      choices=(_SQUASHFS_TYPE, _EXT4_TYPE),
+      default=dlc_lib.SQUASHFS_TYPE,
+      choices=(dlc_lib.SQUASHFS_TYPE, dlc_lib.EXT4_TYPE),
       help='File system type of the image.')
   one_dlc.add_argument(
       '--preload',
@@ -702,8 +87,8 @@
       action='store_true',
       help='Allow preloading of DLC.')
   one_dlc.add_argument(
-      '--used-by', default=_USED_BY_SYSTEM,
-      choices=(_USED_BY_USER, _USED_BY_SYSTEM),
+      '--used-by', default=dlc_lib.USED_BY_SYSTEM,
+      choices=(dlc_lib.USED_BY_USER, dlc_lib.USED_BY_SYSTEM),
       help='Defines how this DLC will be used so dlcservice can take proper '
       'actions based on the type of usage. For example, if "user" is passed, '
       'dlcservice does ref counting when DLC is installed/uninstalled. For '
@@ -717,37 +102,6 @@
   return parser
 
 
-def ValidateDlcIdentifier(parser, name):
-  """Validates the DLC identifiers like ID and package names.
-
-  The name specifications are:
-    - No underscore.
-    - First character should be only alphanumeric.
-    - Other characters can be alphanumeric and '-' (dash).
-    - Maximum length of 40 (MAX_ID_NAME) characters.
-
-  For more info see:
-  https://chromium.googlesource.com/chromiumos/platform2/+/master/dlcservice/docs/developer.md#create-a-dlc-module
-
-  Args:
-    parser: Arguments parser.
-    name: The value of the string to be validated.
-  """
-  errors = []
-  if not name:
-    errors.append('Must not be empty.')
-  if not name[0].isalnum():
-    errors.append('Must start with alphanumeric character.')
-  if not re.match(r'^[a-zA-Z0-9][a-zA-Z0-9-]*$', name):
-    errors.append('Must only use alphanumeric and - (dash).')
-  if len(name) > MAX_ID_NAME:
-    errors.append('Must be within %d characters.' % MAX_ID_NAME)
-
-  if errors:
-    msg = '%s is invalid:\n%s' % (name, '\n'.join(errors))
-    parser.error(msg)
-
-
 def ValidateArguments(parser, opts, req_flags, invalid_flags):
   """Validates the correctness of the passed arguments.
 
@@ -769,13 +123,13 @@
                    '%s should be passed in the build_packages phase, not in '
                    'the build_image phase.' % invalid_flags)
 
-  if opts.fs_type == _EXT4_TYPE:
+  if opts.fs_type == dlc_lib.EXT4_TYPE:
     parser.error('ext4 unsupported for DLC, see https://crbug.com/890060')
 
   if opts.id:
-    ValidateDlcIdentifier(parser, opts.id)
+    dlc_lib.ValidateDlcIdentifier(opts.id)
   if opts.package:
-    ValidateDlcIdentifier(parser, opts.package)
+    dlc_lib.ValidateDlcIdentifier(opts.package)
 
 
 def main(argv):
@@ -797,7 +151,7 @@
 
   if opts.build_package:
     logging.info('Building package: DLC %s', opts.id)
-    params = EbuildParams(
+    params = dlc_lib.EbuildParams(
         dlc_id=opts.id,
         dlc_package=opts.package,
         fs_type=opts.fs_type,
@@ -811,7 +165,7 @@
     params.StoreDlcParameters(install_root_dir=opts.install_root_dir, sudo=True)
 
   else:
-    InstallDlcImages(
+    dlc_lib.InstallDlcImages(
         sysroot=opts.sysroot,
         dlc_id=opts.id,
         install_root_dir=opts.install_root_dir,