text: # As a test suite for the os module, this is woefully inadequate, but this
  # does add tests for a few functions which have been determined to be more
  # portable than they had been thought to be.
  
  import os
  import errno
  import unittest
  import warnings
  import sys
  import signal
  import subprocess
  import time
  import shutil
  from test import support
  import contextlib
  import mmap
  import platform
  import re
  import uuid
  import asyncore
  import asynchat
  import socket
  import itertools
  import stat
  import locale
  import codecs
  try:
      import threading
  except ImportError:
      threading = None
  from test.script_helper import assert_python_ok
  
  with warnings.catch_warnings():
      warnings.simplefilter("ignore", DeprecationWarning)
      os.stat_float_times(True)
  st = os.stat(__file__)
  stat_supports_subsecond = (
      # check if float and int timestamps are different
      (st.st_atime != st[7])
      or (st.st_mtime != st[8])
      or (st.st_ctime != st[9]))
  
  # Detect whether we're on a Linux system that uses the (now outdated
  # and unmaintained) linuxthreads threading library.  There's an issue
  # when combining linuxthreads with a failed execv call: see
  # http://bugs.python.org/issue4970.
  if hasattr(sys, 'thread_info') and sys.thread_info.version:
      USING_LINUXTHREADS = sys.thread_info.version.startswith("linuxthreads")
  else:
      USING_LINUXTHREADS = False
  
  # Tests creating TESTFN
  class FileTests(unittest.TestCase):
      def setUp(self):
          if os.path.exists(support.TESTFN):
              os.unlink(support.TESTFN)
      tearDown = setUp
  
      def test_access(self):
          f = os.open(support.TESTFN, os.O_CREAT|os.O_RDWR)
          os.close(f)
          self.assertTrue(os.access(support.TESTFN, os.W_OK))
  
      def test_closerange(self):
          first = os.open(support.TESTFN, os.O_CREAT|os.O_RDWR)
          # We must allocate two consecutive file descriptors, otherwise
          # it will mess up other file descriptors (perhaps even the three
          # standard ones).
          second = os.dup(first)
          try:
              retries = 0
              while second != first + 1:
                  os.close(first)
                  retries += 1
                  if retries > 10:
                      # XXX test skipped
                      self.skipTest("couldn't allocate two consecutive fds")
                  first, second = second, os.dup(second)
          finally:
              os.close(second)
          # close a fd that is open, and one that isn't
          os.closerange(first, first + 2)
          self.assertRaises(OSError, os.write, first, b"a")
  
      @support.cpython_only
      def test_rename(self):
          path = support.TESTFN
          old = sys.getrefcount(path)
          self.assertRaises(TypeError, os.rename, path, 0)
          new = sys.getrefcount(path)
          self.assertEqual(old, new)
  
      def test_read(self):
          with open(support.TESTFN, "w+b") as fobj:
              fobj.write(b"spam")
              fobj.flush()
              fd = fobj.fileno()
              os.lseek(fd, 0, 0)
              s = os.read(fd, 4)
              self.assertEqual(type(s), bytes)
              self.assertEqual(s, b"spam")
  
      def test_write(self):
          # os.write() accepts bytes- and buffer-like objects but not strings
          fd = os.open(support.TESTFN, os.O_CREAT | os.O_WRONLY)
          self.assertRaises(TypeError, os.write, fd, "beans")
          os.write(fd, b"bacon\n")
          os.write(fd, bytearray(b"eggs\n"))
          os.write(fd, memoryview(b"spam\n"))
          os.close(fd)
          with open(support.TESTFN, "rb") as fobj:
              self.assertEqual(fobj.read().splitlines(),
                  [b"bacon", b"eggs", b"spam"])
  
      def write_windows_console(self, *args):
          retcode = subprocess.call(args,
              # use a new console to not flood the test output
              creationflags=subprocess.CREATE_NEW_CONSOLE,
              # use a shell to hide the console window (SW_HIDE)
              shell=True)
          self.assertEqual(retcode, 0)
  
      @unittest.skipUnless(sys.platform == 'win32',
                           'test specific to the Windows console')
      def test_write_windows_console(self):
          # Issue #11395: the Windows console returns an error (12: not enough
          # space error) on writing into stdout if stdout mode is binary and the
          # length is greater than 66,000 bytes (or less, depending on heap
          # usage).
          code = "print('x' * 100000)"
          self.write_windows_console(sys.executable, "-c", code)
          self.write_windows_console(sys.executable, "-u", "-c", code)
  
      def fdopen_helper(self, *args):
          fd = os.open(support.TESTFN, os.O_RDONLY)
          f = os.fdopen(fd, *args)
          f.close()
  
      def test_fdopen(self):
          fd = os.open(support.TESTFN, os.O_CREAT|os.O_RDWR)
          os.close(fd)
  
          self.fdopen_helper()
          self.fdopen_helper('r')
          self.fdopen_helper('r', 100)
  
      def test_replace(self):
          TESTFN2 = support.TESTFN + ".2"
          with open(support.TESTFN, 'w') as f:
              f.write("1")
          with open(TESTFN2, 'w') as f:
              f.write("2")
          self.addCleanup(os.unlink, TESTFN2)
          os.replace(support.TESTFN, TESTFN2)
          self.assertRaises(FileNotFoundError, os.stat, support.TESTFN)
          with open(TESTFN2, 'r') as f:
              self.assertEqual(f.read(), "1")
  
  
  # Test attributes on return values from os.*stat* family.
  class StatAttributeTests(unittest.TestCase):
      def setUp(self):
          os.mkdir(support.TESTFN)
          self.fname = os.path.join(support.TESTFN, "f1")
          f = open(self.fname, 'wb')
          f.write(b"ABC")
          f.close()
  
      def tearDown(self):
          os.unlink(self.fname)
          os.rmdir(support.TESTFN)
  
      def check_stat_attributes(self, fname):
          if not hasattr(os, "stat"):
              return
  
          result = os.stat(fname)
  
          # Make sure direct access works
          self.assertEqual(result[stat.ST_SIZE], 3)
          self.assertEqual(result.st_size, 3)
  
          # Make sure all the attributes are there
          members = dir(result)
          for name in dir(stat):
              if name[:3] == 'ST_':
                  attr = name.lower()
                  if name.endswith("TIME"):
                      def trunc(x): return int(x)
                  else:
                      def trunc(x): return x
                  self.assertEqual(trunc(getattr(result, attr)),
                                    result[getattr(stat, name)])
                  self.assertIn(attr, members)
  
          # Make sure that the st_?time and st_?time_ns fields roughly agree
          # (they should always agree up to around tens-of-microseconds)
          for name in 'st_atime st_mtime st_ctime'.split():
              floaty = int(getattr(result, name) * 100000)
              nanosecondy = getattr(result, name + "_ns") // 10000
              self.assertAlmostEqual(floaty, nanosecondy, delta=2)
  
          try:
              result[200]
              self.fail("No exception thrown")
          except IndexError:
              pass
  
          # Make sure that assignment fails
          try:
              result.st_mode = 1
              self.fail("No exception thrown")
          except AttributeError:
              pass
  
          try:
              result.st_rdev = 1
              self.fail("No exception thrown")
          except (AttributeError, TypeError):
              pass
  
          try:
              result.parrot = 1
              self.fail("No exception thrown")
          except AttributeError:
              pass
  
          # Use the stat_result constructor with a too-short tuple.
          try:
              result2 = os.stat_result((10,))
              self.fail("No exception thrown")
          except TypeError:
              pass
  
          # Use the constructor with a too-long tuple.
          try:
              result2 = os.stat_result((0,1,2,3,4,5,6,7,8,9,10,11,12,13,14))
          except TypeError:
              pass
  
      def test_stat_attributes(self):
          self.check_stat_attributes(self.fname)
  
      def test_stat_attributes_bytes(self):
          try:
              fname = self.fname.encode(sys.getfilesystemencoding())
          except UnicodeEncodeError:
              self.skipTest("cannot encode %a for the filesystem" % self.fname)
          with warnings.catch_warnings():
              warnings.simplefilter("ignore", DeprecationWarning)
              self.check_stat_attributes(fname)
  
      def test_statvfs_attributes(self):
          if not hasattr(os, "statvfs"):
              return
  
          try:
              result = os.statvfs(self.fname)
          except OSError as e:
              # On AtheOS, glibc always returns ENOSYS
              if e.errno == errno.ENOSYS:
                  return
  
          # Make sure direct access works
          self.assertEqual(result.f_bfree, result[3])
  
          # Make sure all the attributes are there.
          members = ('bsize', 'frsize', 'blocks', 'bfree', 'bavail', 'files',
                      'ffree', 'favail', 'flag', 'namemax')
          for value, member in enumerate(members):
              self.assertEqual(getattr(result, 'f_' + member), result[value])
  
          # Make sure that assignment really fails
          try:
              result.f_bfree = 1
              self.fail("No exception thrown")
          except AttributeError:
              pass
  
          try:
              result.parrot = 1
              self.fail("No exception thrown")
          except AttributeError:
              pass
  
          # Use the constructor with a too-short tuple.
          try:
              result2 = os.statvfs_result((10,))
              self.fail("No exception thrown")
          except TypeError:
              pass
  
          # Use the constructor with a too-long tuple.
          try:
              result2 = os.statvfs_result((0,1,2,3,4,5,6,7,8,9,10,11,12,13,14))
          except TypeError:
              pass
  
      def test_utime_dir(self):
          delta = 1000000
          st = os.stat(support.TESTFN)
          # round to int, because some systems may support sub-second
          # time stamps in stat, but not in utime.
          os.utime(support.TESTFN, (st.st_atime, int(st.st_mtime-delta)))
          st2 = os.stat(support.TESTFN)
          self.assertEqual(st2.st_mtime, int(st.st_mtime-delta))
  
      def _test_utime(self, filename, attr, utime, delta):
          # Issue #13327 removed the requirement to pass None as the
          # second argument. Check that the previous methods of passing
          # a time tuple or None work in addition to no argument.
          st0 = os.stat(filename)
          # Doesn't set anything new, but sets the time tuple way
          utime(filename, (attr(st0, "st_atime"), attr(st0, "st_mtime")))
          # Setting the time to the time you just read, then reading again,
          # should always return exactly the same times.
          st1 = os.stat(filename)
          self.assertEqual(attr(st0, "st_mtime"), attr(st1, "st_mtime"))
          self.assertEqual(attr(st0, "st_atime"), attr(st1, "st_atime"))
          # Set to the current time in the old explicit way.
          os.utime(filename, None)
          st2 = os.stat(support.TESTFN)
          # Set to the current time in the new way
          os.utime(filename)
          st3 = os.stat(filename)
          self.assertAlmostEqual(attr(st2, "st_mtime"), attr(st3, "st_mtime"), delta=delta)
  
      def test_utime(self):
          def utime(file, times):
              return os.utime(file, times)
          self._test_utime(self.fname, getattr, utime, 10)
          self._test_utime(support.TESTFN, getattr, utime, 10)
  
  
      def _test_utime_ns(self, set_times_ns, test_dir=True):
          def getattr_ns(o, attr):
              return getattr(o, attr + "_ns")
          ten_s = 10 * 1000 * 1000 * 1000
          self._test_utime(self.fname, getattr_ns, set_times_ns, ten_s)
          if test_dir:
              self._test_utime(support.TESTFN, getattr_ns, set_times_ns, ten_s)
  
      def test_utime_ns(self):
          def utime_ns(file, times):
              return os.utime(file, ns=times)
          self._test_utime_ns(utime_ns)
  
      requires_utime_dir_fd = unittest.skipUnless(
                                  os.utime in os.supports_dir_fd,
                                  "dir_fd support for utime required for this test.")
      requires_utime_fd = unittest.skipUnless(
                                  os.utime in os.supports_fd,
                                  "fd support for utime required for this test.")
      requires_utime_nofollow_symlinks = unittest.skipUnless(
                                  os.utime in os.supports_follow_symlinks,
                                  "follow_symlinks support for utime required for this test.")
  
      @requires_utime_nofollow_symlinks
      def test_lutimes_ns(self):
          def lutimes_ns(file, times):
              return os.utime(file, ns=times, follow_symlinks=False)
          self._test_utime_ns(lutimes_ns)
  
      @requires_utime_fd
      def test_futimes_ns(self):
          def futimes_ns(file, times):
              with open(file, "wb") as f:
                  os.utime(f.fileno(), ns=times)
          self._test_utime_ns(futimes_ns, test_dir=False)
  
      def _utime_invalid_arguments(self, name, arg):
          with self.assertRaises(ValueError):
              getattr(os, name)(arg, (5, 5), ns=(5, 5))
  
      def test_utime_invalid_arguments(self):
          self._utime_invalid_arguments('utime', self.fname)
  
  
      @unittest.skipUnless(stat_supports_subsecond,
                           "os.stat() doesn't has a subsecond resolution")
      def _test_utime_subsecond(self, set_time_func):
          asec, amsec = 1, 901
          atime = asec + amsec * 1e-3
          msec, mmsec = 2, 901
          mtime = msec + mmsec * 1e-3
          filename = self.fname
          os.utime(filename, (0, 0))
          set_time_func(filename, atime, mtime)
          with warnings.catch_warnings():
              warnings.simplefilter("ignore", DeprecationWarning)
              os.stat_float_times(True)
          st = os.stat(filename)
          self.assertAlmostEqual(st.st_atime, atime, places=3)
          self.assertAlmostEqual(st.st_mtime, mtime, places=3)
  
      def test_utime_subsecond(self):
          def set_time(filename, atime, mtime):
              os.utime(filename, (atime, mtime))
          self._test_utime_subsecond(set_time)
  
      @requires_utime_fd
      def test_futimes_subsecond(self):
          def set_time(filename, atime, mtime):
              with open(filename, "wb") as f:
                  os.utime(f.fileno(), times=(atime, mtime))
          self._test_utime_subsecond(set_time)
  
      @requires_utime_fd
      def test_futimens_subsecond(self):
          def set_time(filename, atime, mtime):
              with open(filename, "wb") as f:
                  os.utime(f.fileno(), times=(atime, mtime))
          self._test_utime_subsecond(set_time)
  
      @requires_utime_dir_fd
      def test_futimesat_subsecond(self):
          def set_time(filename, atime, mtime):
              dirname = os.path.dirname(filename)
              dirfd = os.open(dirname, os.O_RDONLY)
              try:
                  os.utime(os.path.basename(filename), dir_fd=dirfd,
                               times=(atime, mtime))
              finally:
                  os.close(dirfd)
          self._test_utime_subsecond(set_time)
  
      @requires_utime_nofollow_symlinks
      def test_lutimes_subsecond(self):
          def set_time(filename, atime, mtime):
              os.utime(filename, (atime, mtime), follow_symlinks=False)
          self._test_utime_subsecond(set_time)
  
      @requires_utime_dir_fd
      def test_utimensat_subsecond(self):
          def set_time(filename, atime, mtime):
              dirname = os.path.dirname(filename)
              dirfd = os.open(dirname, os.O_RDONLY)
              try:
                  os.utime(os.path.basename(filename), dir_fd=dirfd,
                               times=(atime, mtime))
              finally:
                  os.close(dirfd)
          self._test_utime_subsecond(set_time)
  
      # Restrict test to Win32, since there is no guarantee other
      # systems support centiseconds
      if sys.platform == 'win32':
          def get_file_system(path):
              root = os.path.splitdrive(os.path.abspath(path))[0] + '\\'
              import ctypes
              kernel32 = ctypes.windll.kernel32
              buf = ctypes.create_unicode_buffer("", 100)
              if kernel32.GetVolumeInformationW(root, None, 0, None, None, None, buf, len(buf)):
                  return buf.value
  
          if get_file_system(support.TESTFN) == "NTFS":
              def test_1565150(self):
                  t1 = 1159195039.25
                  os.utime(self.fname, (t1, t1))
                  self.assertEqual(os.stat(self.fname).st_mtime, t1)
  
              def test_large_time(self):
                  t1 = 5000000000 # some day in 2128
                  os.utime(self.fname, (t1, t1))
                  self.assertEqual(os.stat(self.fname).st_mtime, t1)
  
          def test_1686475(self):
              # Verify that an open file can be stat'ed
              try:
                  os.stat(r"c:\pagefile.sys")
              except WindowsError as e:
                  if e.errno == 2: # file does not exist; cannot run test
                      return
                  self.fail("Could not stat pagefile.sys")
  
  from test import mapping_tests
  
  class EnvironTests(mapping_tests.BasicTestMappingProtocol):
      """check that os.environ object conform to mapping protocol"""
      type2test = None
  
      def setUp(self):
          self.__save = dict(os.environ)
          if os.supports_bytes_environ:
              self.__saveb = dict(os.environb)
          for key, value in self._reference().items():
              os.environ[key] = value
  
      def tearDown(self):
          os.environ.clear()
          os.environ.update(self.__save)
          if os.supports_bytes_environ:
              os.environb.clear()
              os.environb.update(self.__saveb)
  
      def _reference(self):
          return {"KEY1":"VALUE1", "KEY2":"VALUE2", "KEY3":"VALUE3"}
  
      def _empty_mapping(self):
          os.environ.clear()
          return os.environ
  
      # Bug 1110478
      def test_update2(self):
          os.environ.clear()
          if os.path.exists("/bin/sh"):
              os.environ.update(HELLO="World")
              with os.popen("/bin/sh -c 'echo $HELLO'") as popen:
                  value = popen.read().strip()
                  self.assertEqual(value, "World")
  
      def test_os_popen_iter(self):
          if os.path.exists("/bin/sh"):
              with os.popen(
                  "/bin/sh -c 'echo \"line1\nline2\nline3\"'") as popen:
                  it = iter(popen)
                  self.assertEqual(next(it), "line1\n")
                  self.assertEqual(next(it), "line2\n")
                  self.assertEqual(next(it), "line3\n")
                  self.assertRaises(StopIteration, next, it)
  
      # Verify environ keys and values from the OS are of the
      # correct str type.
      def test_keyvalue_types(self):
          for key, val in os.environ.items():
              self.assertEqual(type(key), str)
              self.assertEqual(type(val), str)
  
      def test_items(self):
          for key, value in self._reference().items():
              self.assertEqual(os.environ.get(key), value)
  
      # Issue 7310
      def test___repr__(self):
          """Check that the repr() of os.environ looks like environ({...})."""
          env = os.environ
          self.assertEqual(repr(env), 'environ({{{}}})'.format(', '.join(
              '{!r}: {!r}'.format(key, value)
              for key, value in env.items())))
  
      def test_get_exec_path(self):
          defpath_list = os.defpath.split(os.pathsep)
          test_path = ['/monty', '/python', '', '/flying/circus']
          test_env = {'PATH': os.pathsep.join(test_path)}
  
          saved_environ = os.environ
          try:
              os.environ = dict(test_env)
              # Test that defaulting to os.environ works.
              self.assertSequenceEqual(test_path, os.get_exec_path())
              self.assertSequenceEqual(test_path, os.get_exec_path(env=None))
          finally:
              os.environ = saved_environ
  
          # No PATH environment variable
          self.assertSequenceEqual(defpath_list, os.get_exec_path({}))
          # Empty PATH environment variable
          self.assertSequenceEqual(('',), os.get_exec_path({'PATH':''}))
          # Supplied PATH environment variable
          self.assertSequenceEqual(test_path, os.get_exec_path(test_env))
  
          if os.supports_bytes_environ:
              # env cannot contain 'PATH' and b'PATH' keys
              try:
                  # ignore BytesWarning warning
                  with warnings.catch_warnings(record=True):
                      mixed_env = {'PATH': '1', b'PATH': b'2'}
              except BytesWarning:
                  # mixed_env cannot be created with python -bb
                  pass
              else:
                  self.assertRaises(ValueError, os.get_exec_path, mixed_env)
  
              # bytes key and/or value
              self.assertSequenceEqual(os.get_exec_path({b'PATH': b'abc'}),
                  ['abc'])
              self.assertSequenceEqual(os.get_exec_path({b'PATH': 'abc'}),
                  ['abc'])
              self.assertSequenceEqual(os.get_exec_path({'PATH': b'abc'}),
                  ['abc'])
  
      @unittest.skipUnless(os.supports_bytes_environ,
                           "os.environb required for this test.")
      def test_environb(self):
          # os.environ -> os.environb
          value = 'euro\u20ac'
          try:
              value_bytes = value.encode(sys.getfilesystemencoding(),
                                         'surrogateescape')
          except UnicodeEncodeError:
              msg = "U+20AC character is not encodable to %s" % (
                  sys.getfilesystemencoding(),)
              self.skipTest(msg)
          os.environ['unicode'] = value
          self.assertEqual(os.environ['unicode'], value)
          self.assertEqual(os.environb[b'unicode'], value_bytes)
  
          # os.environb -> os.environ
          value = b'\xff'
          os.environb[b'bytes'] = value
          self.assertEqual(os.environb[b'bytes'], value)
          value_str = value.decode(sys.getfilesystemencoding(), 'surrogateescape')
          self.assertEqual(os.environ['bytes'], value_str)
  
      # On FreeBSD < 7 and OS X < 10.6, unsetenv() doesn't return a value (issue
      # #13415).
      @support.requires_freebsd_version(7)
      @support.requires_mac_ver(10, 6)
      def test_unset_error(self):
          if sys.platform == "win32":
              # an environment variable is limited to 32,767 characters
              key = 'x' * 50000
              self.assertRaises(ValueError, os.environ.__delitem__, key)
          else:
              # "=" is not allowed in a variable name
              key = 'key='
              self.assertRaises(OSError, os.environ.__delitem__, key)
  
  class WalkTests(unittest.TestCase):
      """Tests for os.walk()."""
  
      def setUp(self):
          import os
          from os.path import join
  
          # Build:
          #     TESTFN/
          #       TEST1/              a file kid and two directory kids
          #         tmp1
          #         SUB1/             a file kid and a directory kid
          #           tmp2
          #           SUB11/          no kids
          #         SUB2/             a file kid and a dirsymlink kid
          #           tmp3
          #           link/           a symlink to TESTFN.2
          #           broken_link
          #       TEST2/
          #         tmp4              a lone file
          walk_path = join(support.TESTFN, "TEST1")
          sub1_path = join(walk_path, "SUB1")
          sub11_path = join(sub1_path, "SUB11")
          sub2_path = join(walk_path, "SUB2")
          tmp1_path = join(walk_path, "tmp1")
          tmp2_path = join(sub1_path, "tmp2")
          tmp3_path = join(sub2_path, "tmp3")
          link_path = join(sub2_path, "link")
          t2_path = join(support.TESTFN, "TEST2")
          tmp4_path = join(support.TESTFN, "TEST2", "tmp4")
          link_path = join(sub2_path, "link")
          broken_link_path = join(sub2_path, "broken_link")
  
          # Create stuff.
          os.makedirs(sub11_path)
          os.makedirs(sub2_path)
          os.makedirs(t2_path)
          for path in tmp1_path, tmp2_path, tmp3_path, tmp4_path:
              f = open(path, "w")
              f.write("I'm " + path + " and proud of it.  Blame test_os.\n")
              f.close()
          if support.can_symlink():
              if os.name == 'nt':
                  def symlink_to_dir(src, dest):
                      os.symlink(src, dest, True)
              else:
                  symlink_to_dir = os.symlink
              symlink_to_dir(os.path.abspath(t2_path), link_path)
              symlink_to_dir('broken', broken_link_path)
              sub2_tree = (sub2_path, ["link"], ["broken_link", "tmp3"])
          else:
              sub2_tree = (sub2_path, [], ["tmp3"])
  
          # Walk top-down.
          all = list(os.walk(walk_path))
          self.assertEqual(len(all), 4)
          # We can't know which order SUB1 and SUB2 will appear in.
          # Not flipped:  TESTFN, SUB1, SUB11, SUB2
          #     flipped:  TESTFN, SUB2, SUB1, SUB11
          flipped = all[0][1][0] != "SUB1"
          all[0][1].sort()
          all[3 - 2 * flipped][-1].sort()
          self.assertEqual(all[0], (walk_path, ["SUB1", "SUB2"], ["tmp1"]))
          self.assertEqual(all[1 + flipped], (sub1_path, ["SUB11"], ["tmp2"]))
          self.assertEqual(all[2 + flipped], (sub11_path, [], []))
          self.assertEqual(all[3 - 2 * flipped], sub2_tree)
  
          # Prune the search.
          all = []
          for root, dirs, files in os.walk(walk_path):
              all.append((root, dirs, files))
              # Don't descend into SUB1.
              if 'SUB1' in dirs:
                  # Note that this also mutates the dirs we appended to all!
                  dirs.remove('SUB1')
          self.assertEqual(len(all), 2)
          self.assertEqual(all[0], (walk_path, ["SUB2"], ["tmp1"]))
          all[1][-1].sort()
          self.assertEqual(all[1], sub2_tree)
  
          # Walk bottom-up.
          all = list(os.walk(walk_path, topdown=False))
          self.assertEqual(len(all), 4)
          # We can't know which order SUB1 and SUB2 will appear in.
          # Not flipped:  SUB11, SUB1, SUB2, TESTFN
          #     flipped:  SUB2, SUB11, SUB1, TESTFN
          flipped = all[3][1][0] != "SUB1"
          all[3][1].sort()
          all[2 - 2 * flipped][-1].sort()
          self.assertEqual(all[3], (walk_path, ["SUB1", "SUB2"], ["tmp1"]))
          self.assertEqual(all[flipped], (sub11_path, [], []))
          self.assertEqual(all[flipped + 1], (sub1_path, ["SUB11"], ["tmp2"]))
          self.assertEqual(all[2 - 2 * flipped], sub2_tree)
  
          if support.can_symlink():
              # Walk, following symlinks.
              for root, dirs, files in os.walk(walk_path, followlinks=True):
                  if root == link_path:
                      self.assertEqual(dirs, [])
                      self.assertEqual(files, ["tmp4"])
                      break
              else:
                  self.fail("Didn't follow symlink with followlinks=True")
  
      def tearDown(self):
          # Tear everything down.  This is a decent use for bottom-up on
          # Windows, which doesn't have a recursive delete command.  The
          # (not so) subtlety is that rmdir will fail unless the dir's
          # kids are removed first, so bottom up is essential.
          for root, dirs, files in os.walk(support.TESTFN, topdown=False):
              for name in files:
                  os.remove(os.path.join(root, name))
              for name in dirs:
                  dirname = os.path.join(root, name)
                  if not os.path.islink(dirname):
                      os.rmdir(dirname)
                  else:
                      os.remove(dirname)
          os.rmdir(support.TESTFN)
  
  
  @unittest.skipUnless(hasattr(os, 'fwalk'), "Test needs os.fwalk()")
  class FwalkTests(WalkTests):
      """Tests for os.fwalk()."""
  
      def _compare_to_walk(self, walk_kwargs, fwalk_kwargs):
          """
          compare with walk() results.
          """
          for topdown, followlinks in itertools.product((True, False), repeat=2):
              d = {'topdown': topdown, 'followlinks': followlinks}
              walk_kwargs.update(d)
              fwalk_kwargs.update(d)
  
              expected = {}
              for root, dirs, files in os.walk(**walk_kwargs):
                  expected[root] = (set(dirs), set(files))
  
              for root, dirs, files, rootfd in os.fwalk(**fwalk_kwargs):
                  self.assertIn(root, expected)
                  self.assertEqual(expected[root], (set(dirs), set(files)))
  
      def test_compare_to_walk(self):
          kwargs = {'top': support.TESTFN}
          self._compare_to_walk(kwargs, kwargs)
  
      def test_dir_fd(self):
          try:
              fd = os.open(".", os.O_RDONLY)
              walk_kwargs = {'top': support.TESTFN}
              fwalk_kwargs = walk_kwargs.copy()
              fwalk_kwargs['dir_fd'] = fd
              self._compare_to_walk(walk_kwargs, fwalk_kwargs)
          finally:
              os.close(fd)
  
      def test_yields_correct_dir_fd(self):
          # check returned file descriptors
          for topdown, followlinks in itertools.product((True, False), repeat=2):
              args = support.TESTFN, topdown, None, followlinks
              for root, dirs, files, rootfd in os.fwalk(*args):
                  # check that the FD is valid
                  os.fstat(rootfd)
                  # redundant check
                  os.stat(rootfd)
                  # check that listdir() returns consistent information
                  self.assertEqual(set(os.listdir(rootfd)), set(dirs) | set(files))
  
      def test_fd_leak(self):
          # Since we're opening a lot of FDs, we must be careful to avoid leaks:
          # we both check that calling fwalk() a large number of times doesn't
          # yield EMFILE, and that the minimum allocated FD hasn't changed.
          minfd = os.dup(1)
          os.close(minfd)
          for i in range(256):
              for x in os.fwalk(support.TESTFN):
                  pass
          newfd = os.dup(1)
          self.addCleanup(os.close, newfd)
          self.assertEqual(newfd, minfd)
  
      def tearDown(self):
          # cleanup
          for root, dirs, files, rootfd in os.fwalk(support.TESTFN, topdown=False):
              for name in files:
                  os.unlink(name, dir_fd=rootfd)
              for name in dirs:
                  st = os.stat(name, dir_fd=rootfd, follow_symlinks=False)
                  if stat.S_ISDIR(st.st_mode):
                      os.rmdir(name, dir_fd=rootfd)
                  else:
                      os.unlink(name, dir_fd=rootfd)
          os.rmdir(support.TESTFN)
  
  
  class MakedirTests(unittest.TestCase):
      def setUp(self):
          os.mkdir(support.TESTFN)
  
      def test_makedir(self):
          base = support.TESTFN
          path = os.path.join(base, 'dir1', 'dir2', 'dir3')
          os.makedirs(path)             # Should work
          path = os.path.join(base, 'dir1', 'dir2', 'dir3', 'dir4')
          os.makedirs(path)
  
          # Try paths with a '.' in them
          self.assertRaises(OSError, os.makedirs, os.curdir)
          path = os.path.join(base, 'dir1', 'dir2', 'dir3', 'dir4', 'dir5', os.curdir)
          os.makedirs(path)
          path = os.path.join(base, 'dir1', os.curdir, 'dir2', 'dir3', 'dir4',
                              'dir5', 'dir6')
          os.makedirs(path)
  
      def test_exist_ok_existing_directory(self):
          path = os.path.join(support.TESTFN, 'dir1')
          mode = 0o777
          old_mask = os.umask(0o022)
          os.makedirs(path, mode)
          self.assertRaises(OSError, os.makedirs, path, mode)
          self.assertRaises(OSError, os.makedirs, path, mode, exist_ok=False)
          self.assertRaises(OSError, os.makedirs, path, 0o776, exist_ok=True)
          os.makedirs(path, mode=mode, exist_ok=True)
          os.umask(old_mask)
  
      def test_exist_ok_s_isgid_directory(self):
          path = os.path.join(support.TESTFN, 'dir1')
          S_ISGID = stat.S_ISGID
          mode = 0o777
          old_mask = os.umask(0o022)
          try:
              existing_testfn_mode = stat.S_IMODE(
                      os.lstat(support.TESTFN).st_mode)
              os.chmod(support.TESTFN, existing_testfn_mode | S_ISGID)
              if (os.lstat(support.TESTFN).st_mode & S_ISGID != S_ISGID):
                  raise unittest.SkipTest('No support for S_ISGID dir mode.')
              # The os should apply S_ISGID from the parent dir for us, but
              # this test need not depend on that behavior.  Be explicit.
              os.makedirs(path, mode | S_ISGID)
              # http://bugs.python.org/issue14992
              # Should not fail when the bit is already set.
              os.makedirs(path, mode, exist_ok=True)
              # remove the bit.
              os.chmod(path, stat.S_IMODE(os.lstat(path).st_mode) & ~S_ISGID)
              with self.assertRaises(OSError):
                  # Should fail when the bit is not already set when demanded.
                  os.makedirs(path, mode | S_ISGID, exist_ok=True)
          finally:
              os.umask(old_mask)
  
      def test_exist_ok_existing_regular_file(self):
          base = support.TESTFN
          path = os.path.join(support.TESTFN, 'dir1')
          f = open(path, 'w')
          f.write('abc')
          f.close()
          self.assertRaises(OSError, os.makedirs, path)
          self.assertRaises(OSError, os.makedirs, path, exist_ok=False)
          self.assertRaises(OSError, os.makedirs, path, exist_ok=True)
          os.remove(path)
  
      def tearDown(self):
          path = os.path.join(support.TESTFN, 'dir1', 'dir2', 'dir3',
                              'dir4', 'dir5', 'dir6')
          # If the tests failed, the bottom-most directory ('../dir6')
          # may not have been created, so we look for the outermost directory
          # that exists.
          while not os.path.exists(path) and path != support.TESTFN:
              path = os.path.dirname(path)
  
          os.removedirs(path)
  
  class DevNullTests(unittest.TestCase):
      def test_devnull(self):
          with open(os.devnull, 'wb') as f:
              f.write(b'hello')
              f.close()
          with open(os.devnull, 'rb') as f:
              self.assertEqual(f.read(), b'')
  
  class URandomTests(unittest.TestCase):
      def test_urandom_length(self):
          self.assertEqual(len(os.urandom(0)), 0)
          self.assertEqual(len(os.urandom(1)), 1)
          self.assertEqual(len(os.urandom(10)), 10)
          self.assertEqual(len(os.urandom(100)), 100)
          self.assertEqual(len(os.urandom(1000)), 1000)
  
      def test_urandom_value(self):
          data1 = os.urandom(16)
          data2 = os.urandom(16)
          self.assertNotEqual(data1, data2)
  
      def get_urandom_subprocess(self, count):
          code = '\n'.join((
              'import os, sys',
              'data = os.urandom(%s)' % count,
              'sys.stdout.buffer.write(data)',
              'sys.stdout.buffer.flush()'))
          out = assert_python_ok('-c', code)
          stdout = out[1]
          self.assertEqual(len(stdout), 16)
          return stdout
  
      def test_urandom_subprocess(self):
          data1 = self.get_urandom_subprocess(16)
          data2 = self.get_urandom_subprocess(16)
          self.assertNotEqual(data1, data2)
  
  @contextlib.contextmanager
  def _execvpe_mockup(defpath=None):
      """
      Stubs out execv and execve functions when used as context manager.
      Records exec calls. The mock execv and execve functions always raise an
      exception as they would normally never return.
      """
      # A list of tuples containing (function name, first arg, args)
      # of calls to execv or execve that have been made.
      calls = []
  
      def mock_execv(name, *args):
          calls.append(('execv', name, args))
          raise RuntimeError("execv called")
  
      def mock_execve(name, *args):
          calls.append(('execve', name, args))
          raise OSError(errno.ENOTDIR, "execve called")
  
      try:
          orig_execv = os.execv
          orig_execve = os.execve
          orig_defpath = os.defpath
          os.execv = mock_execv
          os.execve = mock_execve
          if defpath is not None:
              os.defpath = defpath
          yield calls
      finally:
          os.execv = orig_execv
          os.execve = orig_execve
          os.defpath = orig_defpath
  
  class ExecTests(unittest.TestCase):
      @unittest.skipIf(USING_LINUXTHREADS,
                       "avoid triggering a linuxthreads bug: see issue #4970")
      def test_execvpe_with_bad_program(self):
          self.assertRaises(OSError, os.execvpe, 'no such app-',
                            ['no such app-'], None)
  
      def test_execvpe_with_bad_arglist(self):
          self.assertRaises(ValueError, os.execvpe, 'notepad', [], None)
  
      @unittest.skipUnless(hasattr(os, '_execvpe'),
                           "No internal os._execvpe function to test.")
      def _test_internal_execvpe(self, test_type):
          program_path = os.sep + 'absolutepath'
          if test_type is bytes:
              program = b'executable'
              fullpath = os.path.join(os.fsencode(program_path), program)
              native_fullpath = fullpath
              arguments = [b'progname', 'arg1', 'arg2']
          else:
              program = 'executable'
              arguments = ['progname', 'arg1', 'arg2']
              fullpath = os.path.join(program_path, program)
              if os.name != "nt":
                  native_fullpath = os.fsencode(fullpath)
              else:
                  native_fullpath = fullpath
          env = {'spam': 'beans'}
  
          # test os._execvpe() with an absolute path
          with _execvpe_mockup() as calls:
              self.assertRaises(RuntimeError,
                  os._execvpe, fullpath, arguments)
              self.assertEqual(len(calls), 1)
              self.assertEqual(calls[0], ('execv', fullpath, (arguments,)))
  
          # test os._execvpe() with a relative path:
          # os.get_exec_path() returns defpath
          with _execvpe_mockup(defpath=program_path) as calls:
              self.assertRaises(OSError,
                  os._execvpe, program, arguments, env=env)
              self.assertEqual(len(calls), 1)
              self.assertSequenceEqual(calls[0],
                  ('execve', native_fullpath, (arguments, env)))
  
          # test os._execvpe() with a relative path:
          # os.get_exec_path() reads the 'PATH' variable
          with _execvpe_mockup() as calls:
              env_path = env.copy()
              if test_type is bytes:
                  env_path[b'PATH'] = program_path
              else:
                  env_path['PATH'] = program_path
              self.assertRaises(OSError,
                  os._execvpe, program, arguments, env=env_path)
              self.assertEqual(len(calls), 1)
              self.assertSequenceEqual(calls[0],
                  ('execve', native_fullpath, (arguments, env_path)))
  
      def test_internal_execvpe_str(self):
          self._test_internal_execvpe(str)
          if os.name != "nt":
              self._test_internal_execvpe(bytes)
  
  
  class Win32ErrorTests(unittest.TestCase):
      def test_rename(self):
          self.assertRaises(WindowsError, os.rename, support.TESTFN, support.TESTFN+".bak")
  
      def test_remove(self):
          self.assertRaises(WindowsError, os.remove, support.TESTFN)
  
      def test_chdir(self):
          self.assertRaises(WindowsError, os.chdir, support.TESTFN)
  
      def test_mkdir(self):
          f = open(support.TESTFN, "w")
          try:
              self.assertRaises(WindowsError, os.mkdir, support.TESTFN)
          finally:
              f.close()
              os.unlink(support.TESTFN)
  
      def test_utime(self):
          self.assertRaises(WindowsError, os.utime, support.TESTFN, None)
  
      def test_chmod(self):
          self.assertRaises(WindowsError, os.chmod, support.TESTFN, 0)
  
  class TestInvalidFD(unittest.TestCase):
      singles = ["fchdir", "dup", "fdopen", "fdatasync", "fstat",
                 "fstatvfs", "fsync", "tcgetpgrp", "ttyname"]
      #singles.append("close")
      #We omit close because it doesn'r raise an exception on some platforms
      def get_single(f):
          def helper(self):
              if  hasattr(os, f):
                  self.check(getattr(os, f))
          return helper
      for f in singles:
          locals()["test_"+f] = get_single(f)
  
      def check(self, f, *args):
          try:
              f(support.make_bad_fd(), *args)
          except OSError as e:
              self.assertEqual(e.errno, errno.EBADF)
          else:
              self.fail("%r didn't raise a OSError with a bad file descriptor"
                        % f)
  
      def test_isatty(self):
          if hasattr(os, "isatty"):
              self.assertEqual(os.isatty(support.make_bad_fd()), False)
  
      def test_closerange(self):
          if hasattr(os, "closerange"):
              fd = support.make_bad_fd()
              # Make sure none of the descriptors we are about to close are
              # currently valid (issue 6542).
              for i in range(10):
                  try: os.fstat(fd+i)
                  except OSError:
                      pass
                  else:
                      break
              if i < 2:
                  raise unittest.SkipTest(
                      "Unable to acquire a range of invalid file descriptors")
              self.assertEqual(os.closerange(fd, fd + i-1), None)
  
      def test_dup2(self):
          if hasattr(os, "dup2"):
              self.check(os.dup2, 20)
  
      def test_fchmod(self):
          if hasattr(os, "fchmod"):
              self.check(os.fchmod, 0)
  
      def test_fchown(self):
          if hasattr(os, "fchown"):
              self.check(os.fchown, -1, -1)
  
      def test_fpathconf(self):
          if hasattr(os, "fpathconf"):
              self.check(os.pathconf, "PC_NAME_MAX")
              self.check(os.fpathconf, "PC_NAME_MAX")
  
      def test_ftruncate(self):
          if hasattr(os, "ftruncate"):
              self.check(os.truncate, 0)
              self.check(os.ftruncate, 0)
  
      def test_lseek(self):
          if hasattr(os, "lseek"):
              self.check(os.lseek, 0, 0)
  
      def test_read(self):
          if hasattr(os, "read"):
              self.check(os.read, 1)
  
      def test_tcsetpgrpt(self):
          if hasattr(os, "tcsetpgrp"):
              self.check(os.tcsetpgrp, 0)
  
      def test_write(self):
          if hasattr(os, "write"):
              self.check(os.write, b" ")
  
  
  class LinkTests(unittest.TestCase):
      def setUp(self):
          self.file1 = support.TESTFN
          self.file2 = os.path.join(support.TESTFN + "2")
  
      def tearDown(self):
          for file in (self.file1, self.file2):
              if os.path.exists(file):
                  os.unlink(file)
  
      def _test_link(self, file1, file2):
          with open(file1, "w") as f1:
              f1.write("test")
  
          with warnings.catch_warnings():
              warnings.simplefilter("ignore", DeprecationWarning)
              os.link(file1, file2)
          with open(file1, "r") as f1, open(file2, "r") as f2:
              self.assertTrue(os.path.sameopenfile(f1.fileno(), f2.fileno()))
  
      def test_link(self):
          self._test_link(self.file1, self.file2)
  
      def test_link_bytes(self):
          self._test_link(bytes(self.file1, sys.getfilesystemencoding()),
                          bytes(self.file2, sys.getfilesystemencoding()))
  
      def test_unicode_name(self):
          try:
              os.fsencode("\xf1")
          except UnicodeError:
              raise unittest.SkipTest("Unable to encode for this platform.")
  
          self.file1 += "\xf1"
          self.file2 = self.file1 + "2"
          self._test_link(self.file1, self.file2)
  
  if sys.platform != 'win32':
      class Win32ErrorTests(unittest.TestCase):
          pass
  
      class PosixUidGidTests(unittest.TestCase):
          if hasattr(os, 'setuid'):
              def test_setuid(self):
                  if os.getuid() != 0:
                      self.assertRaises(os.error, os.setuid, 0)
                  self.assertRaises(OverflowError, os.setuid, 1<<32)
  
          if hasattr(os, 'setgid'):
              def test_setgid(self):
                  if os.getuid() != 0:
                      self.assertRaises(os.error, os.setgid, 0)
                  self.assertRaises(OverflowError, os.setgid, 1<<32)
  
          if hasattr(os, 'seteuid'):
              def test_seteuid(self):
                  if os.getuid() != 0:
                      self.assertRaises(os.error, os.seteuid, 0)
                  self.assertRaises(OverflowError, os.seteuid, 1<<32)
  
          if hasattr(os, 'setegid'):
              def test_setegid(self):
                  if os.getuid() != 0:
                      self.assertRaises(os.error, os.setegid, 0)
                  self.assertRaises(OverflowError, os.setegid, 1<<32)
  
          if hasattr(os, 'setreuid'):
              def test_setreuid(self):
                  if os.getuid() != 0:
                      self.assertRaises(os.error, os.setreuid, 0, 0)
                  self.assertRaises(OverflowError, os.setreuid, 1<<32, 0)
                  self.assertRaises(OverflowError, os.setreuid, 0, 1<<32)
  
              def test_setreuid_neg1(self):
                  # Needs to accept -1.  We run this in a subprocess to avoid
                  # altering the test runner's process state (issue8045).
                  subprocess.check_call([
                          sys.executable, '-c',
                          'import os,sys;os.setreuid(-1,-1);sys.exit(0)'])
  
          if hasattr(os, 'setregid'):
              def test_setregid(self):
                  if os.getuid() != 0:
                      self.assertRaises(os.error, os.setregid, 0, 0)
                  self.assertRaises(OverflowError, os.setregid, 1<<32, 0)
                  self.assertRaises(OverflowError, os.setregid, 0, 1<<32)
  
              def test_setregid_neg1(self):
                  # Needs to accept -1.  We run this in a subprocess to avoid
                  # altering the test runner's process state (issue8045).
                  subprocess.check_call([
                          sys.executable, '-c',
                          'import os,sys;os.setregid(-1,-1);sys.exit(0)'])
  
      class Pep383Tests(unittest.TestCase):
          def setUp(self):
              if support.TESTFN_UNENCODABLE:
                  self.dir = support.TESTFN_UNENCODABLE
              else:
                  self.dir = support.TESTFN
              self.bdir = os.fsencode(self.dir)
  
              bytesfn = []
              def add_filename(fn):
                  try:
                      fn = os.fsencode(fn)
                  except UnicodeEncodeError:
                      return
                  bytesfn.append(fn)
              add_filename(support.TESTFN_UNICODE)
              if support.TESTFN_UNENCODABLE:
                  add_filename(support.TESTFN_UNENCODABLE)
              if not bytesfn:
                  self.skipTest("couldn't create any non-ascii filename")
  
              self.unicodefn = set()
              os.mkdir(self.dir)
              try:
                  for fn in bytesfn:
                      support.create_empty_file(os.path.join(self.bdir, fn))
                      fn = os.fsdecode(fn)
                      if fn in self.unicodefn:
                          raise ValueError("duplicate filename")
                      self.unicodefn.add(fn)
              except:
                  shutil.rmtree(self.dir)
                  raise
  
          def tearDown(self):
              shutil.rmtree(self.dir)
  
          def test_listdir(self):
              expected = self.unicodefn
              found = set(os.listdir(self.dir))
              self.assertEqual(found, expected)
              # test listdir without arguments
              current_directory = os.getcwd()
              try:
                  os.chdir(os.sep)
                  self.assertEqual(set(os.listdir()), set(os.listdir(os.sep)))
              finally:
                  os.chdir(current_directory)
  
          def test_open(self):
              for fn in self.unicodefn:
                  f = open(os.path.join(self.dir, fn), 'rb')
                  f.close()
  
          def test_stat(self):
              for fn in self.unicodefn:
                  os.stat(os.path.join(self.dir, fn))
  else:
      class PosixUidGidTests(unittest.TestCase):
          pass
      class Pep383Tests(unittest.TestCase):
          pass
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  class Win32KillTests(unittest.TestCase):
      def _kill(self, sig):
          # Start sys.executable as a subprocess and communicate from the
          # subprocess to the parent that the interpreter is ready. When it
          # becomes ready, send *sig* via os.kill to the subprocess and check
          # that the return code is equal to *sig*.
          import ctypes
          from ctypes import wintypes
          import msvcrt
  
          # Since we can't access the contents of the process' stdout until the
          # process has exited, use PeekNamedPipe to see what's inside stdout
          # without waiting. This is done so we can tell that the interpreter
          # is started and running at a point where it could handle a signal.
          PeekNamedPipe = ctypes.windll.kernel32.PeekNamedPipe
          PeekNamedPipe.restype = wintypes.BOOL
          PeekNamedPipe.argtypes = (wintypes.HANDLE, # Pipe handle
                                    ctypes.POINTER(ctypes.c_char), # stdout buf
                                    wintypes.DWORD, # Buffer size
                                    ctypes.POINTER(wintypes.DWORD), # bytes read
                                    ctypes.POINTER(wintypes.DWORD), # bytes avail
                                    ctypes.POINTER(wintypes.DWORD)) # bytes left
          msg = "running"
          proc = subprocess.Popen([sys.executable, "-c",
                                   "import sys;"
                                   "sys.stdout.write('{}');"
                                   "sys.stdout.flush();"
                                   "input()".format(msg)],
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE,
                                  stdin=subprocess.PIPE)
          self.addCleanup(proc.stdout.close)
          self.addCleanup(proc.stderr.close)
          self.addCleanup(proc.stdin.close)
  
          count, max = 0, 100
          while count < max and proc.poll() is None:
              # Create a string buffer to store the result of stdout from the pipe
              buf = ctypes.create_string_buffer(len(msg))
              # Obtain the text currently in proc.stdout
              # Bytes read/avail/left are left as NULL and unused
              rslt = PeekNamedPipe(msvcrt.get_osfhandle(proc.stdout.fileno()),
                                   buf, ctypes.sizeof(buf), None, None, None)
              self.assertNotEqual(rslt, 0, "PeekNamedPipe failed")
              if buf.value:
                  self.assertEqual(msg, buf.value.decode())
                  break
              time.sleep(0.1)
              count += 1
          else:
              self.fail("Did not receive communication from the subprocess")
  
          os.kill(proc.pid, sig)
          self.assertEqual(proc.wait(), sig)
  
      def test_kill_sigterm(self):
          # SIGTERM doesn't mean anything special, but make sure it works
          self._kill(signal.SIGTERM)
  
      def test_kill_int(self):
          # os.kill on Windows can take an int which gets set as the exit code
          self._kill(100)
  
      def _kill_with_event(self, event, name):
          tagname = "test_os_%s" % uuid.uuid1()
          m = mmap.mmap(-1, 1, tagname)
          m[0] = 0
          # Run a script which has console control handling enabled.
          proc = subprocess.Popen([sys.executable,
                     os.path.join(os.path.dirname(__file__),
                                  "win_console_handler.py"), tagname],
                     creationflags=subprocess.CREATE_NEW_PROCESS_GROUP)
          # Let the interpreter startup before we send signals. See #3137.
          count, max = 0, 100
          while count < max and proc.poll() is None:
              if m[0] == 1:
                  break
              time.sleep(0.1)
              count += 1
          else:
              # Forcefully kill the process if we weren't able to signal it.
              os.kill(proc.pid, signal.SIGINT)
              self.fail("Subprocess didn't finish initialization")
          os.kill(proc.pid, event)
          # proc.send_signal(event) could also be done here.
          # Allow time for the signal to be passed and the process to exit.
          time.sleep(0.5)
          if not proc.poll():
              # Forcefully kill the process if we weren't able to signal it.
              os.kill(proc.pid, signal.SIGINT)
              self.fail("subprocess did not stop on {}".format(name))
  
      @unittest.skip("subprocesses aren't inheriting CTRL+C property")
      def test_CTRL_C_EVENT(self):
          from ctypes import wintypes
          import ctypes
  
          # Make a NULL value by creating a pointer with no argument.
          NULL = ctypes.POINTER(ctypes.c_int)()
          SetConsoleCtrlHandler = ctypes.windll.kernel32.SetConsoleCtrlHandler
          SetConsoleCtrlHandler.argtypes = (ctypes.POINTER(ctypes.c_int),
                                            wintypes.BOOL)
          SetConsoleCtrlHandler.restype = wintypes.BOOL
  
          # Calling this with NULL and FALSE causes the calling process to
          # handle CTRL+C, rather than ignore it. This property is inherited
          # by subprocesses.
          SetConsoleCtrlHandler(NULL, 0)
  
          self._kill_with_event(signal.CTRL_C_EVENT, "CTRL_C_EVENT")
  
      def test_CTRL_BREAK_EVENT(self):
          self._kill_with_event(signal.CTRL_BREAK_EVENT, "CTRL_BREAK_EVENT")
  
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  @support.skip_unless_symlink
  class Win32SymlinkTests(unittest.TestCase):
      filelink = 'filelinktest'
      filelink_target = os.path.abspath(__file__)
      dirlink = 'dirlinktest'
      dirlink_target = os.path.dirname(filelink_target)
      missing_link = 'missing link'
  
      def setUp(self):
          assert os.path.exists(self.dirlink_target)
          assert os.path.exists(self.filelink_target)
          assert not os.path.exists(self.dirlink)
          assert not os.path.exists(self.filelink)
          assert not os.path.exists(self.missing_link)
  
      def tearDown(self):
          if os.path.exists(self.filelink):
              os.remove(self.filelink)
          if os.path.exists(self.dirlink):
              os.rmdir(self.dirlink)
          if os.path.lexists(self.missing_link):
              os.remove(self.missing_link)
  
      def test_directory_link(self):
          os.symlink(self.dirlink_target, self.dirlink, True)
          self.assertTrue(os.path.exists(self.dirlink))
          self.assertTrue(os.path.isdir(self.dirlink))
          self.assertTrue(os.path.islink(self.dirlink))
          self.check_stat(self.dirlink, self.dirlink_target)
  
      def test_file_link(self):
          os.symlink(self.filelink_target, self.filelink)
          self.assertTrue(os.path.exists(self.filelink))
          self.assertTrue(os.path.isfile(self.filelink))
          self.assertTrue(os.path.islink(self.filelink))
          self.check_stat(self.filelink, self.filelink_target)
  
      def _create_missing_dir_link(self):
          'Create a "directory" link to a non-existent target'
          linkname = self.missing_link
          if os.path.lexists(linkname):
              os.remove(linkname)
          target = r'c:\\target does not exist.29r3c740'
          assert not os.path.exists(target)
          target_is_dir = True
          os.symlink(target, linkname, target_is_dir)
  
      def test_remove_directory_link_to_missing_target(self):
          self._create_missing_dir_link()
          # For compatibility with Unix, os.remove will check the
          #  directory status and call RemoveDirectory if the symlink
          #  was created with target_is_dir==True.
          os.remove(self.missing_link)
  
      @unittest.skip("currently fails; consider for improvement")
      def test_isdir_on_directory_link_to_missing_target(self):
          self._create_missing_dir_link()
          # consider having isdir return true for directory links
          self.assertTrue(os.path.isdir(self.missing_link))
  
      @unittest.skip("currently fails; consider for improvement")
      def test_rmdir_on_directory_link_to_missing_target(self):
          self._create_missing_dir_link()
          # consider allowing rmdir to remove directory links
          os.rmdir(self.missing_link)
  
      def check_stat(self, link, target):
          self.assertEqual(os.stat(link), os.stat(target))
          self.assertNotEqual(os.lstat(link), os.stat(link))
  
          bytes_link = os.fsencode(link)
          with warnings.catch_warnings():
              warnings.simplefilter("ignore", DeprecationWarning)
              self.assertEqual(os.stat(bytes_link), os.stat(target))
              self.assertNotEqual(os.lstat(bytes_link), os.stat(bytes_link))
  
      def test_12084(self):
          level1 = os.path.abspath(support.TESTFN)
          level2 = os.path.join(level1, "level2")
          level3 = os.path.join(level2, "level3")
          try:
              os.mkdir(level1)
              os.mkdir(level2)
              os.mkdir(level3)
  
              file1 = os.path.abspath(os.path.join(level1, "file1"))
  
              with open(file1, "w") as f:
                  f.write("file1")
  
              orig_dir = os.getcwd()
              try:
                  os.chdir(level2)
                  link = os.path.join(level2, "link")
                  os.symlink(os.path.relpath(file1), "link")
                  self.assertIn("link", os.listdir(os.getcwd()))
  
                  # Check os.stat calls from the same dir as the link
                  self.assertEqual(os.stat(file1), os.stat("link"))
  
                  # Check os.stat calls from a dir below the link
                  os.chdir(level1)
                  self.assertEqual(os.stat(file1),
                                   os.stat(os.path.relpath(link)))
  
                  # Check os.stat calls from a dir above the link
                  os.chdir(level3)
                  self.assertEqual(os.stat(file1),
                                   os.stat(os.path.relpath(link)))
              finally:
                  os.chdir(orig_dir)
          except OSError as err:
              self.fail(err)
          finally:
              os.remove(file1)
              shutil.rmtree(level1)
  
  
  class FSEncodingTests(unittest.TestCase):
      def test_nop(self):
          self.assertEqual(os.fsencode(b'abc\xff'), b'abc\xff')
          self.assertEqual(os.fsdecode('abc\u0141'), 'abc\u0141')
  
      def test_identity(self):
          # assert fsdecode(fsencode(x)) == x
          for fn in ('unicode\u0141', 'latin\xe9', 'ascii'):
              try:
                  bytesfn = os.fsencode(fn)
              except UnicodeEncodeError:
                  continue
              self.assertEqual(os.fsdecode(bytesfn), fn)
  
  
  
  class DeviceEncodingTests(unittest.TestCase):
  
      def test_bad_fd(self):
          # Return None when an fd doesn't actually exist.
          self.assertIsNone(os.device_encoding(123456))
  
      @unittest.skipUnless(os.isatty(0) and (sys.platform.startswith('win') or
              (hasattr(locale, 'nl_langinfo') and hasattr(locale, 'CODESET'))),
              'test requires a tty and either Windows or nl_langinfo(CODESET)')
      def test_device_encoding(self):
          encoding = os.device_encoding(0)
          self.assertIsNotNone(encoding)
          self.assertTrue(codecs.lookup(encoding))
  
  
  class PidTests(unittest.TestCase):
      @unittest.skipUnless(hasattr(os, 'getppid'), "test needs os.getppid")
      def test_getppid(self):
          p = subprocess.Popen([sys.executable, '-c',
                                'import os; print(os.getppid())'],
                               stdout=subprocess.PIPE)
          stdout, _ = p.communicate()
          # We are the parent of our subprocess
          self.assertEqual(int(stdout), os.getpid())
  
  
  # The introduction of this TestCase caused at least two different errors on
  # *nix buildbots. Temporarily skip this to let the buildbots move along.
  @unittest.skip("Skip due to platform/environment differences on *NIX buildbots")
  @unittest.skipUnless(hasattr(os, 'getlogin'), "test needs os.getlogin")
  class LoginTests(unittest.TestCase):
      def test_getlogin(self):
          user_name = os.getlogin()
          self.assertNotEqual(len(user_name), 0)
  
  
  @unittest.skipUnless(hasattr(os, 'getpriority') and hasattr(os, 'setpriority'),
                       "needs os.getpriority and os.setpriority")
  class ProgramPriorityTests(unittest.TestCase):
      """Tests for os.getpriority() and os.setpriority()."""
  
      def test_set_get_priority(self):
  
          base = os.getpriority(os.PRIO_PROCESS, os.getpid())
          os.setpriority(os.PRIO_PROCESS, os.getpid(), base + 1)
          try:
              new_prio = os.getpriority(os.PRIO_PROCESS, os.getpid())
              if base >= 19 and new_prio <= 19:
                  raise unittest.SkipTest(
        "unable to reliably test setpriority at current nice level of %s" % base)
              else:
                  self.assertEqual(new_prio, base + 1)
          finally:
              try:
                  os.setpriority(os.PRIO_PROCESS, os.getpid(), base)
              except OSError as err:
                  if err.errno != errno.EACCES:
                      raise
  
  
  if threading is not None:
      class SendfileTestServer(asyncore.dispatcher, threading.Thread):
  
          class Handler(asynchat.async_chat):
  
              def __init__(self, conn):
                  asynchat.async_chat.__init__(self, conn)
                  self.in_buffer = []
                  self.closed = False
                  self.push(b"220 ready\r\n")
  
              def handle_read(self):
                  data = self.recv(4096)
                  self.in_buffer.append(data)
  
              def get_data(self):
                  return b''.join(self.in_buffer)
  
              def handle_close(self):
                  self.close()
                  self.closed = True
  
              def handle_error(self):
                  raise
  
          def __init__(self, address):
              threading.Thread.__init__(self)
              asyncore.dispatcher.__init__(self)
              self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
              self.bind(address)
              self.listen(5)
              self.host, self.port = self.socket.getsockname()[:2]
              self.handler_instance = None
              self._active = False
              self._active_lock = threading.Lock()
  
          # --- public API
  
          @property
          def running(self):
              return self._active
  
          def start(self):
              assert not self.running
              self.__flag = threading.Event()
              threading.Thread.start(self)
              self.__flag.wait()
  
          def stop(self):
              assert self.running
              self._active = False
              self.join()
  
          def wait(self):
              # wait for handler connection to be closed, then stop the server
              while not getattr(self.handler_instance, "closed", False):
                  time.sleep(0.001)
              self.stop()
  
          # --- internals
  
          def run(self):
              self._active = True
              self.__flag.set()
              while self._active and asyncore.socket_map:
                  self._active_lock.acquire()
                  asyncore.loop(timeout=0.001, count=1)
                  self._active_lock.release()
              asyncore.close_all()
  
          def handle_accept(self):
              conn, addr = self.accept()
              self.handler_instance = self.Handler(conn)
  
          def handle_connect(self):
              self.close()
          handle_read = handle_connect
  
          def writable(self):
              return 0
  
          def handle_error(self):
              raise
  
  
  @unittest.skipUnless(threading is not None, "test needs threading module")
  @unittest.skipUnless(hasattr(os, 'sendfile'), "test needs os.sendfile()")
  class TestSendfile(unittest.TestCase):
  
      DATA = b"12345abcde" * 16 * 1024  # 160 KB
      SUPPORT_HEADERS_TRAILERS = not sys.platform.startswith("linux") and \
                                 not sys.platform.startswith("solaris") and \
                                 not sys.platform.startswith("sunos")
  
      @classmethod
      def setUpClass(cls):
          with open(support.TESTFN, "wb") as f:
              f.write(cls.DATA)
  
      @classmethod
      def tearDownClass(cls):
          support.unlink(support.TESTFN)
  
      def setUp(self):
          self.server = SendfileTestServer((support.HOST, 0))
          self.server.start()
          self.client = socket.socket()
          self.client.connect((self.server.host, self.server.port))
          self.client.settimeout(1)
          # synchronize by waiting for "220 ready" response
          self.client.recv(1024)
          self.sockno = self.client.fileno()
          self.file = open(support.TESTFN, 'rb')
          self.fileno = self.file.fileno()
  
      def tearDown(self):
          self.file.close()
          self.client.close()
          if self.server.running:
              self.server.stop()
  
      def sendfile_wrapper(self, sock, file, offset, nbytes, headers=[], trailers=[]):
          """A higher level wrapper representing how an application is
          supposed to use sendfile().
          """
          while 1:
              try:
                  if self.SUPPORT_HEADERS_TRAILERS:
                      return os.sendfile(sock, file, offset, nbytes, headers,
                                         trailers)
                  else:
                      return os.sendfile(sock, file, offset, nbytes)
              except OSError as err:
                  if err.errno == errno.ECONNRESET:
                      # disconnected
                      raise
                  elif err.errno in (errno.EAGAIN, errno.EBUSY):
                      # we have to retry send data
                      continue
                  else:
                      raise
  
      def test_send_whole_file(self):
          # normal send
          total_sent = 0
          offset = 0
          nbytes = 4096
          while total_sent < len(self.DATA):
              sent = self.sendfile_wrapper(self.sockno, self.fileno, offset, nbytes)
              if sent == 0:
                  break
              offset += sent
              total_sent += sent
              self.assertTrue(sent <= nbytes)
              self.assertEqual(offset, total_sent)
  
          self.assertEqual(total_sent, len(self.DATA))
          self.client.shutdown(socket.SHUT_RDWR)
          self.client.close()
          self.server.wait()
          data = self.server.handler_instance.get_data()
          self.assertEqual(len(data), len(self.DATA))
          self.assertEqual(data, self.DATA)
  
      def test_send_at_certain_offset(self):
          # start sending a file at a certain offset
          total_sent = 0
          offset = len(self.DATA) // 2
          must_send = len(self.DATA) - offset
          nbytes = 4096
          while total_sent < must_send:
              sent = self.sendfile_wrapper(self.sockno, self.fileno, offset, nbytes)
              if sent == 0:
                  break
              offset += sent
              total_sent += sent
              self.assertTrue(sent <= nbytes)
  
          self.client.shutdown(socket.SHUT_RDWR)
          self.client.close()
          self.server.wait()
          data = self.server.handler_instance.get_data()
          expected = self.DATA[len(self.DATA) // 2:]
          self.assertEqual(total_sent, len(expected))
          self.assertEqual(len(data), len(expected))
          self.assertEqual(data, expected)
  
      def test_offset_overflow(self):
          # specify an offset > file size
          offset = len(self.DATA) + 4096
          try:
              sent = os.sendfile(self.sockno, self.fileno, offset, 4096)
          except OSError as e:
              # Solaris can raise EINVAL if offset >= file length, ignore.
              if e.errno != errno.EINVAL:
                  raise
          else:
              self.assertEqual(sent, 0)
          self.client.shutdown(socket.SHUT_RDWR)
          self.client.close()
          self.server.wait()
          data = self.server.handler_instance.get_data()
          self.assertEqual(data, b'')
  
      def test_invalid_offset(self):
          with self.assertRaises(OSError) as cm:
              os.sendfile(self.sockno, self.fileno, -1, 4096)
          self.assertEqual(cm.exception.errno, errno.EINVAL)
  
      # --- headers / trailers tests
  
      if SUPPORT_HEADERS_TRAILERS:
  
          def test_headers(self):
              total_sent = 0
              sent = os.sendfile(self.sockno, self.fileno, 0, 4096,
                                 headers=[b"x" * 512])
              total_sent += sent
              offset = 4096
              nbytes = 4096
              while 1:
                  sent = self.sendfile_wrapper(self.sockno, self.fileno,
                                                       offset, nbytes)
                  if sent == 0:
                      break
                  total_sent += sent
                  offset += sent
  
              expected_data = b"x" * 512 + self.DATA
              self.assertEqual(total_sent, len(expected_data))
              self.client.close()
              self.server.wait()
              data = self.server.handler_instance.get_data()
              self.assertEqual(hash(data), hash(expected_data))
  
          def test_trailers(self):
              TESTFN2 = support.TESTFN + "2"
              with open(TESTFN2, 'wb') as f:
                  f.write(b"abcde")
              with open(TESTFN2, 'rb')as f:
                  self.addCleanup(os.remove, TESTFN2)
                  os.sendfile(self.sockno, f.fileno(), 0, 4096,
                              trailers=[b"12345"])
                  self.client.close()
                  self.server.wait()
                  data = self.server.handler_instance.get_data()
                  self.assertEqual(data, b"abcde12345")
  
          if hasattr(os, "SF_NODISKIO"):
              def test_flags(self):
                  try:
                      os.sendfile(self.sockno, self.fileno, 0, 4096,
                                  flags=os.SF_NODISKIO)
                  except OSError as err:
                      if err.errno not in (errno.EBUSY, errno.EAGAIN):
                          raise
  
  
  def supports_extended_attributes():
      if not hasattr(os, "setxattr"):
          return False
      try:
          with open(support.TESTFN, "wb") as fp:
              try:
                  os.setxattr(fp.fileno(), b"user.test", b"")
              except OSError:
                  return False
      finally:
          support.unlink(support.TESTFN)
      # Kernels < 2.6.39 don't respect setxattr flags.
      kernel_version = platform.release()
      m = re.match("2.6.(\d{1,2})", kernel_version)
      return m is None or int(m.group(1)) >= 39
  
  
  @unittest.skipUnless(supports_extended_attributes(),
                       "no non-broken extended attribute support")
  class ExtendedAttributeTests(unittest.TestCase):
  
      def tearDown(self):
          support.unlink(support.TESTFN)
  
      def _check_xattrs_str(self, s, getxattr, setxattr, removexattr, listxattr, **kwargs):
          fn = support.TESTFN
          open(fn, "wb").close()
          with self.assertRaises(OSError) as cm:
              getxattr(fn, s("user.test"), **kwargs)
          self.assertEqual(cm.exception.errno, errno.ENODATA)
          init_xattr = listxattr(fn)
          self.assertIsInstance(init_xattr, list)
          setxattr(fn, s("user.test"), b"", **kwargs)
          xattr = set(init_xattr)
          xattr.add("user.test")
          self.assertEqual(set(listxattr(fn)), xattr)
          self.assertEqual(getxattr(fn, b"user.test", **kwargs), b"")
          setxattr(fn, s("user.test"), b"hello", os.XATTR_REPLACE, **kwargs)
          self.assertEqual(getxattr(fn, b"user.test", **kwargs), b"hello")
          with self.assertRaises(OSError) as cm:
              setxattr(fn, s("user.test"), b"bye", os.XATTR_CREATE, **kwargs)
          self.assertEqual(cm.exception.errno, errno.EEXIST)
          with self.assertRaises(OSError) as cm:
              setxattr(fn, s("user.test2"), b"bye", os.XATTR_REPLACE, **kwargs)
          self.assertEqual(cm.exception.errno, errno.ENODATA)
          setxattr(fn, s("user.test2"), b"foo", os.XATTR_CREATE, **kwargs)
          xattr.add("user.test2")
          self.assertEqual(set(listxattr(fn)), xattr)
          removexattr(fn, s("user.test"), **kwargs)
          with self.assertRaises(OSError) as cm:
              getxattr(fn, s("user.test"), **kwargs)
          self.assertEqual(cm.exception.errno, errno.ENODATA)
          xattr.remove("user.test")
          self.assertEqual(set(listxattr(fn)), xattr)
          self.assertEqual(getxattr(fn, s("user.test2"), **kwargs), b"foo")
          setxattr(fn, s("user.test"), b"a"*1024, **kwargs)
          self.assertEqual(getxattr(fn, s("user.test"), **kwargs), b"a"*1024)
          removexattr(fn, s("user.test"), **kwargs)
          many = sorted("user.test{}".format(i) for i in range(100))
          for thing in many:
              setxattr(fn, thing, b"x", **kwargs)
          self.assertEqual(set(listxattr(fn)), set(init_xattr) | set(many))
  
      def _check_xattrs(self, *args, **kwargs):
          def make_bytes(s):
              return bytes(s, "ascii")
          self._check_xattrs_str(str, *args, **kwargs)
          support.unlink(support.TESTFN)
          self._check_xattrs_str(make_bytes, *args, **kwargs)
  
      def test_simple(self):
          self._check_xattrs(os.getxattr, os.setxattr, os.removexattr,
                             os.listxattr)
  
      def test_lpath(self):
          self._check_xattrs(os.getxattr, os.setxattr, os.removexattr,
                             os.listxattr, follow_symlinks=False)
  
      def test_fds(self):
          def getxattr(path, *args):
              with open(path, "rb") as fp:
                  return os.getxattr(fp.fileno(), *args)
          def setxattr(path, *args):
              with open(path, "wb") as fp:
                  os.setxattr(fp.fileno(), *args)
          def removexattr(path, *args):
              with open(path, "wb") as fp:
                  os.removexattr(fp.fileno(), *args)
          def listxattr(path, *args):
              with open(path, "rb") as fp:
                  return os.listxattr(fp.fileno(), *args)
          self._check_xattrs(getxattr, setxattr, removexattr, listxattr)
  
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  class Win32DeprecatedBytesAPI(unittest.TestCase):
      def test_deprecated(self):
          import nt
          filename = os.fsencode(support.TESTFN)
          with warnings.catch_warnings():
              warnings.simplefilter("error", DeprecationWarning)
              for func, *args in (
                  (nt._getfullpathname, filename),
                  (nt._isdir, filename),
                  (os.access, filename, os.R_OK),
                  (os.chdir, filename),
                  (os.chmod, filename, 0o777),
                  (os.getcwdb,),
                  (os.link, filename, filename),
                  (os.listdir, filename),
                  (os.lstat, filename),
                  (os.mkdir, filename),
                  (os.open, filename, os.O_RDONLY),
                  (os.rename, filename, filename),
                  (os.rmdir, filename),
                  (os.startfile, filename),
                  (os.stat, filename),
                  (os.unlink, filename),
                  (os.utime, filename),
              ):
                  self.assertRaises(DeprecationWarning, func, *args)
  
      @support.skip_unless_symlink
      def test_symlink(self):
          filename = os.fsencode(support.TESTFN)
          with warnings.catch_warnings():
              warnings.simplefilter("error", DeprecationWarning)
              self.assertRaises(DeprecationWarning,
                                os.symlink, filename, filename)
  
  
  @unittest.skipUnless(hasattr(os, 'get_terminal_size'), "requires os.get_terminal_size")
  class TermsizeTests(unittest.TestCase):
      def test_does_not_crash(self):
          """Check if get_terminal_size() returns a meaningful value.
  
          There's no easy portable way to actually check the size of the
          terminal, so let's check if it returns something sensible instead.
          """
          try:
              size = os.get_terminal_size()
          except OSError as e:
              if sys.platform == "win32" or e.errno in (errno.EINVAL, errno.ENOTTY):
                  # Under win32 a generic OSError can be thrown if the
                  # handle cannot be retrieved
                  self.skipTest("failed to query terminal size")
              raise
  
          self.assertGreaterEqual(size.columns, 0)
          self.assertGreaterEqual(size.lines, 0)
  
      def test_stty_match(self):
          """Check if stty returns the same results
  
          stty actually tests stdin, so get_terminal_size is invoked on
          stdin explicitly. If stty succeeded, then get_terminal_size()
          should work too.
          """
          try:
              size = subprocess.check_output(['stty', 'size']).decode().split()
          except (FileNotFoundError, subprocess.CalledProcessError):
              self.skipTest("stty invocation failed")
          expected = (int(size[1]), int(size[0])) # reversed order
  
          try:
              actual = os.get_terminal_size(sys.__stdin__.fileno())
          except OSError as e:
              if sys.platform == "win32" or e.errno in (errno.EINVAL, errno.ENOTTY):
                  # Under win32 a generic OSError can be thrown if the
                  # handle cannot be retrieved
                  self.skipTest("failed to query terminal size")
              raise
          self.assertEqual(expected, actual)
  
  
  @support.reap_threads
  def test_main():
      support.run_unittest(
          FileTests,
          StatAttributeTests,
          EnvironTests,
          WalkTests,
          FwalkTests,
          MakedirTests,
          DevNullTests,
          URandomTests,
          ExecTests,
          Win32ErrorTests,
          TestInvalidFD,
          PosixUidGidTests,
          Pep383Tests,
          Win32KillTests,
          Win32SymlinkTests,
          FSEncodingTests,
          DeviceEncodingTests,
          PidTests,
          LoginTests,
          LinkTests,
          TestSendfile,
          ProgramPriorityTests,
          ExtendedAttributeTests,
          Win32DeprecatedBytesAPI,
          TermsizeTests,
      )
  
  if __name__ == "__main__":
      test_main()
  