Merge postinstall config during merge target files

# The sorting algorithm for apexkeys.txt and apkcerts.txt does not include the

# ".apex" or ".apk" suffix, so we use the following pattern to extract a key.

def LoadKeyValueText(path):

  keyvalue_store = {}

  if os.path.exists(path):

    with open(path) as fp:

      for line in fp.readlines():

        components = line.strip().split("=", 1)

        if len(components) == 2:

          keyvalue_store[components[0]] = components[1]

  return keyvalue_store

MODULE_KEY_PATTERN = re.compile(r'name="(.+)\.(apex|apk)"')

def MergePostinstallConfig(framework_meta_dir, vendor_meta_dir,

                            merged_meta_dir):

  _CONFIG_NAME = 'postinstall_config.txt'

  _SYSTEM_PARTITIONS = ["system", "system_ext", "product", "init_boot"]

  _SYSTEM_PARTITIONS_PREFIXED = [ "_" + p for p in _SYSTEM_PARTITIONS ]

  framework_config_path = os.path.join(framework_meta_dir, _CONFIG_NAME)

  vendor_config_path = os.path.join(vendor_meta_dir, _CONFIG_NAME)

  merged_config_path = os.path.join(merged_meta_dir, _CONFIG_NAME)

  framework_config = LoadKeyValueText(framework_config_path)

  vendor_config = LoadKeyValueText(vendor_config_path)

  merged_config = {}

  merged_config.update(framework_config)

  key: str

  for (key, val) in vendor_config.items():

    # only allow vendor postinstall config to override non-system postinstall

    # configs

    if not key.endswith(tuple(_SYSTEM_PARTITIONS_PREFIXED)):

      merged_config[key] = val

  # TODO: might want to consider sorting according to suffix to group per partition

  merge_utils.WriteSortedData(merged_config, merged_config_path)

def MergeUpdateEngineConfig(framework_meta_dir, vendor_meta_dir,

                            merged_meta_dir):

  if OPTIONS.merged_misc_info.get('ab_update') == 'true':

    MergeUpdateEngineConfig(

        framework_meta_dir, vendor_meta_dir, merged_meta_dir)

    MergePostinstallConfig(framework_meta_dir, vendor_meta_dir, merged_meta_dir)

  # Write the now-finalized OPTIONS.merged_misc_info.

  merge_utils.WriteSortedData(