src/starboard/tools/environment.py

#
# Copyright 2017 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License."""
"""Sets up a Starboard environment for use by the host application.

Applications that use Starboard should contain a Python file, called
"starboard_configuration.py", somewhere in the ancestor path of their
"starboard" directory.

The file should contain a variable, called PORT_ROOTS. Assign to it a
list of paths to directories in which Starboard ports are located.
Each path should be represented as a list of directory names whose locations
are relative to the configuration file.  Example:

PORT_ROOTS = [
    ["some_directory", "starboard"]
    ["somewhere_else", "starboard"]
]

IF YOU ARE GOING TO USE STARBOARD FILES OUTSIDE OF STARBOARD, YOU NEED TO IMPORT
THIS MODULE FIRST.  Otherwise, sys.path will not be configured properly, none of
your code will work, and you'll be sad.
"""

import importlib
import os
import sys

PATHS = [
    # Necessary because the gyp_configuration for linux-x64x11 imports
    # directly from "starboard/".
    os.path.abspath(os.path.join(
        os.path.dirname(__file__), os.pardir, os.pardir)),

    # Necessary because gyp_configuration modules use relative imports.
    # "cobalt/build" needs to be in sys.path to keep the imports working
    os.path.abspath(os.path.join(
        os.path.dirname(__file__), os.pardir, os.pardir,
        "cobalt", "build"))
]

# This module should only add the above paths to sys.path when they are not
# present in the list already.
for new_path in PATHS:
  if new_path not in sys.path:
    sys.path.append(new_path)


def _GetStarboardConfigPath():
  """Gets the path to the "starboard_configuration.py" file from the host app.

  Returns:
    Path to the "starboard_configuration.py" file from the host app

  Raises:
    RuntimeError: There is no configuration file.
  """
  current_path = os.path.normpath(os.path.dirname(__file__))
  while not os.path.exists(os.path.join(current_path,
                                        "starboard_configuration.py")):
    next_path = os.path.dirname(current_path)
    if next_path == current_path:
      current_path = None
      break
    current_path = next_path
  config_path = current_path

  if not config_path:
    raise RuntimeError("No starboard configuration declared.")

  return config_path


def GetStarboardPortRoots():
  """Gets paths to the host app's Starboard port directories."""
  config_path = _GetStarboardConfigPath()
  sys.path.append(config_path)
  config_module = importlib.import_module("starboard_configuration")
  port_roots = config_module.PORT_ROOTS
  port_root_paths = [os.path.abspath(os.path.join(
      config_path, os.sep.join(root))) for root in port_roots]
  return port_root_paths