lib/paygen/utils.py

# -*- coding: utf-8 -*-
# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Common python commands used by various internal build scripts."""

from __future__ import print_function

import os


def ListdirFullpath(directory):
  """Return all files in a directory with full pathnames.

  Args:
    directory: directory to find files for.

  Returns:
    Full paths to every file in that directory.
  """
  return [os.path.join(directory, f) for f in os.listdir(directory)]


class RestrictedAttrDict(dict):
  """Define a dictionary which is also a struct.

  The keys will belong to a restricted list of values.
  """

  _slots = ()

  def __init__(self, *args, **kwargs):
    """Ensure that only the expected keys are added during initialization."""
    dict.__init__(self, *args, **kwargs)

    # Ensure all slots are at least populated with None.
    for key in self._slots:
      self.setdefault(key)

    for key in self.keys():
      assert key in self._slots, 'Unexpected key %s in %s' % (key, self._slots)

  def __setattr__(self, name, val):
    """Setting an attribute, actually sets a dictionary value."""
    if name not in self._slots:
      raise AttributeError("'%s' may not have attribute '%s'" %
                           (self.__class__.__name__, name))
    self[name] = val

  def __getattr__(self, name):
    """Fetching an attribute, actually fetches a dictionary value."""
    if name not in self:
      raise AttributeError("'%s' has no attribute '%s'" %
                           (self.__class__.__name__, name))
    return self[name]

  def __setitem__(self, name, val):
    """Restrict which keys can be stored in this dictionary."""
    if name not in self._slots:
      raise KeyError(name)
    dict.__setitem__(self, name, val)

  def __str__(self):
    """Default stringification behavior."""
    name = self._name if hasattr(self, '_name') else self.__class__.__name__
    return '%s (%s)' % (name, self._GetAttrString())

  def _GetAttrString(self, delim=', ', equal='='):
    """Return string showing all non-None values of self._slots.

    The ordering of attributes in self._slots is honored in string.

    Args:
      delim: String for separating key/value elements in result.
      equal: String to put between key and associated value in result.

    Returns:
      A string like "a='foo', b=12".
    """
    slots = [s for s in self._slots if self[s] is not None]
    elems = ['%s%s%r' % (s, equal, self[s]) for s in slots]
    return delim.join(elems)

  def _clear_if_default(self, key, default):
    """Helper for constructors.

    If they key value is set to the default value, set it to None.

    Args:
      key: Key value to check and possibly clear.
      default: Default value to compare the key value against.
    """
    if self[key] == default:
      self[key] = None


def ReadLsbRelease(sysroot):
  """Reads the /etc/lsb-release file out of the given sysroot.

  Args:
    sysroot: The path to sysroot of an image to read sysroot/etc/lsb-release.

  Returns:
    The lsb-release file content in a dictionary of key/values.
  """
  lsb_release_file = os.path.join(sysroot, 'etc', 'lsb-release')
  lsb_release = {}
  with open(lsb_release_file, 'r') as f:
    for line in f:
      tokens = line.strip().split('=')
      lsb_release[tokens[0]] = tokens[1]

  return lsb_release