"""Utilities for dealing with the operating system."""
from __future__ import absolute_import
import contextlib
import logging
import os

@contextlib.contextmanager
def change_cwd(path):
  old_path = os.path.abspath('.')
  os.chdir(path)
  logging.debug(
      "Changed directory from %s to %s", old_path, os.path.abspath('.'))
  yield
  os.chdir(old_path)
  logging.debug("Changed directory back to %s", old_path)


def find_files(root, filename):
  matching_paths = []
  for base, _, files in os.walk(root):
    if filename in files:
      matching_paths.append(os.path.join(base, filename))
  return matching_paths