cpython/Lib/test/support/os_helper.py

759 lines
24 KiB
Python

import collections.abc
import contextlib
import errno
import os
import re
import stat
import string
import sys
import time
import unittest
import warnings
from test import support
# Filename used for testing
TESTFN_ASCII = '@test'
# Disambiguate TESTFN for parallel testing, while letting it remain a valid
# module name.
TESTFN_ASCII = "{}_{}_tmp".format(TESTFN_ASCII, os.getpid())
# TESTFN_UNICODE is a non-ascii filename
TESTFN_UNICODE = TESTFN_ASCII + "-\xe0\xf2\u0258\u0141\u011f"
if sys.platform == 'darwin':
# In Mac OS X's VFS API file names are, by definition, canonically
# decomposed Unicode, encoded using UTF-8. See QA1173:
# http://developer.apple.com/mac/library/qa/qa2001/qa1173.html
import unicodedata
TESTFN_UNICODE = unicodedata.normalize('NFD', TESTFN_UNICODE)
# TESTFN_UNENCODABLE is a filename (str type) that should *not* be able to be
# encoded by the filesystem encoding (in strict mode). It can be None if we
# cannot generate such filename.
TESTFN_UNENCODABLE = None
if os.name == 'nt':
# skip win32s (0) or Windows 9x/ME (1)
if sys.getwindowsversion().platform >= 2:
# Different kinds of characters from various languages to minimize the
# probability that the whole name is encodable to MBCS (issue #9819)
TESTFN_UNENCODABLE = TESTFN_ASCII + "-\u5171\u0141\u2661\u0363\uDC80"
try:
TESTFN_UNENCODABLE.encode(sys.getfilesystemencoding())
except UnicodeEncodeError:
pass
else:
print('WARNING: The filename %r CAN be encoded by the filesystem '
'encoding (%s). Unicode filename tests may not be effective'
% (TESTFN_UNENCODABLE, sys.getfilesystemencoding()))
TESTFN_UNENCODABLE = None
# macOS and Emscripten deny unencodable filenames (invalid utf-8)
elif sys.platform not in {'darwin', 'emscripten', 'wasi'}:
try:
# ascii and utf-8 cannot encode the byte 0xff
b'\xff'.decode(sys.getfilesystemencoding())
except UnicodeDecodeError:
# 0xff will be encoded using the surrogate character u+DCFF
TESTFN_UNENCODABLE = TESTFN_ASCII \
+ b'-\xff'.decode(sys.getfilesystemencoding(), 'surrogateescape')
else:
# File system encoding (eg. ISO-8859-* encodings) can encode
# the byte 0xff. Skip some unicode filename tests.
pass
# FS_NONASCII: non-ASCII character encodable by os.fsencode(),
# or an empty string if there is no such character.
FS_NONASCII = ''
for character in (
# First try printable and common characters to have a readable filename.
# For each character, the encoding list are just example of encodings able
# to encode the character (the list is not exhaustive).
# U+00E6 (Latin Small Letter Ae): cp1252, iso-8859-1
'\u00E6',
# U+0130 (Latin Capital Letter I With Dot Above): cp1254, iso8859_3
'\u0130',
# U+0141 (Latin Capital Letter L With Stroke): cp1250, cp1257
'\u0141',
# U+03C6 (Greek Small Letter Phi): cp1253
'\u03C6',
# U+041A (Cyrillic Capital Letter Ka): cp1251
'\u041A',
# U+05D0 (Hebrew Letter Alef): Encodable to cp424
'\u05D0',
# U+060C (Arabic Comma): cp864, cp1006, iso8859_6, mac_arabic
'\u060C',
# U+062A (Arabic Letter Teh): cp720
'\u062A',
# U+0E01 (Thai Character Ko Kai): cp874
'\u0E01',
# Then try more "special" characters. "special" because they may be
# interpreted or displayed differently depending on the exact locale
# encoding and the font.
# U+00A0 (No-Break Space)
'\u00A0',
# U+20AC (Euro Sign)
'\u20AC',
):
try:
# If Python is set up to use the legacy 'mbcs' in Windows,
# 'replace' error mode is used, and encode() returns b'?'
# for characters missing in the ANSI codepage
if os.fsdecode(os.fsencode(character)) != character:
raise UnicodeError
except UnicodeError:
pass
else:
FS_NONASCII = character
break
# Save the initial cwd
SAVEDCWD = os.getcwd()
# TESTFN_UNDECODABLE is a filename (bytes type) that should *not* be able to be
# decoded from the filesystem encoding (in strict mode). It can be None if we
# cannot generate such filename (ex: the latin1 encoding can decode any byte
# sequence). On UNIX, TESTFN_UNDECODABLE can be decoded by os.fsdecode() thanks
# to the surrogateescape error handler (PEP 383), but not from the filesystem
# encoding in strict mode.
TESTFN_UNDECODABLE = None
for name in (
# b'\xff' is not decodable by os.fsdecode() with code page 932. Windows
# accepts it to create a file or a directory, or don't accept to enter to
# such directory (when the bytes name is used). So test b'\xe7' first:
# it is not decodable from cp932.
b'\xe7w\xf0',
# undecodable from ASCII, UTF-8
b'\xff',
# undecodable from iso8859-3, iso8859-6, iso8859-7, cp424, iso8859-8, cp856
# and cp857
b'\xae\xd5'
# undecodable from UTF-8 (UNIX and Mac OS X)
b'\xed\xb2\x80', b'\xed\xb4\x80',
# undecodable from shift_jis, cp869, cp874, cp932, cp1250, cp1251, cp1252,
# cp1253, cp1254, cp1255, cp1257, cp1258
b'\x81\x98',
):
try:
name.decode(sys.getfilesystemencoding())
except UnicodeDecodeError:
try:
name.decode(sys.getfilesystemencoding(),
sys.getfilesystemencodeerrors())
except UnicodeDecodeError:
continue
TESTFN_UNDECODABLE = os.fsencode(TESTFN_ASCII) + name
break
if FS_NONASCII:
TESTFN_NONASCII = TESTFN_ASCII + FS_NONASCII
else:
TESTFN_NONASCII = None
TESTFN = TESTFN_NONASCII or TESTFN_ASCII
def make_bad_fd():
"""
Create an invalid file descriptor by opening and closing a file and return
its fd.
"""
file = open(TESTFN, "wb")
try:
return file.fileno()
finally:
file.close()
unlink(TESTFN)
_can_symlink = None
def can_symlink():
global _can_symlink
if _can_symlink is not None:
return _can_symlink
# WASI / wasmtime prevents symlinks with absolute paths, see man
# openat2(2) RESOLVE_BENEATH. Almost all symlink tests use absolute
# paths. Skip symlink tests on WASI for now.
src = os.path.abspath(TESTFN)
symlink_path = src + "can_symlink"
try:
os.symlink(src, symlink_path)
can = True
except (OSError, NotImplementedError, AttributeError):
can = False
else:
os.remove(symlink_path)
_can_symlink = can
return can
def skip_unless_symlink(test):
"""Skip decorator for tests that require functional symlink"""
ok = can_symlink()
msg = "Requires functional symlink implementation"
return test if ok else unittest.skip(msg)(test)
_can_xattr = None
def can_xattr():
import tempfile
global _can_xattr
if _can_xattr is not None:
return _can_xattr
if not hasattr(os, "setxattr"):
can = False
else:
import platform
tmp_dir = tempfile.mkdtemp()
tmp_fp, tmp_name = tempfile.mkstemp(dir=tmp_dir)
try:
with open(TESTFN, "wb") as fp:
try:
# TESTFN & tempfile may use different file systems with
# different capabilities
os.setxattr(tmp_fp, b"user.test", b"")
os.setxattr(tmp_name, b"trusted.foo", b"42")
os.setxattr(fp.fileno(), b"user.test", b"")
# Kernels < 2.6.39 don't respect setxattr flags.
kernel_version = platform.release()
m = re.match(r"2.6.(\d{1,2})", kernel_version)
can = m is None or int(m.group(1)) >= 39
except OSError:
can = False
finally:
unlink(TESTFN)
unlink(tmp_name)
rmdir(tmp_dir)
_can_xattr = can
return can
def skip_unless_xattr(test):
"""Skip decorator for tests that require functional extended attributes"""
ok = can_xattr()
msg = "no non-broken extended attribute support"
return test if ok else unittest.skip(msg)(test)
_can_chmod = None
def can_chmod():
global _can_chmod
if _can_chmod is not None:
return _can_chmod
if not hasattr(os, "chown"):
_can_chmod = False
return _can_chmod
try:
with open(TESTFN, "wb") as f:
try:
os.chmod(TESTFN, 0o777)
mode1 = os.stat(TESTFN).st_mode
os.chmod(TESTFN, 0o666)
mode2 = os.stat(TESTFN).st_mode
except OSError as e:
can = False
else:
can = stat.S_IMODE(mode1) != stat.S_IMODE(mode2)
finally:
unlink(TESTFN)
_can_chmod = can
return can
def skip_unless_working_chmod(test):
"""Skip tests that require working os.chmod()
WASI SDK 15.0 cannot change file mode bits.
"""
ok = can_chmod()
msg = "requires working os.chmod()"
return test if ok else unittest.skip(msg)(test)
# Check whether the current effective user has the capability to override
# DAC (discretionary access control). Typically user root is able to
# bypass file read, write, and execute permission checks. The capability
# is independent of the effective user. See capabilities(7).
_can_dac_override = None
def can_dac_override():
global _can_dac_override
if not can_chmod():
_can_dac_override = False
if _can_dac_override is not None:
return _can_dac_override
try:
with open(TESTFN, "wb") as f:
os.chmod(TESTFN, 0o400)
try:
with open(TESTFN, "wb"):
pass
except OSError:
_can_dac_override = False
else:
_can_dac_override = True
finally:
unlink(TESTFN)
return _can_dac_override
def skip_if_dac_override(test):
ok = not can_dac_override()
msg = "incompatible with CAP_DAC_OVERRIDE"
return test if ok else unittest.skip(msg)(test)
def skip_unless_dac_override(test):
ok = can_dac_override()
msg = "requires CAP_DAC_OVERRIDE"
return test if ok else unittest.skip(msg)(test)
def unlink(filename):
try:
_unlink(filename)
except (FileNotFoundError, NotADirectoryError):
pass
if sys.platform.startswith("win"):
def _waitfor(func, pathname, waitall=False):
# Perform the operation
func(pathname)
# Now setup the wait loop
if waitall:
dirname = pathname
else:
dirname, name = os.path.split(pathname)
dirname = dirname or '.'
# Check for `pathname` to be removed from the filesystem.
# The exponential backoff of the timeout amounts to a total
# of ~1 second after which the deletion is probably an error
# anyway.
# Testing on an i7@4.3GHz shows that usually only 1 iteration is
# required when contention occurs.
timeout = 0.001
while timeout < 1.0:
# Note we are only testing for the existence of the file(s) in
# the contents of the directory regardless of any security or
# access rights. If we have made it this far, we have sufficient
# permissions to do that much using Python's equivalent of the
# Windows API FindFirstFile.
# Other Windows APIs can fail or give incorrect results when
# dealing with files that are pending deletion.
L = os.listdir(dirname)
if not (L if waitall else name in L):
return
# Increase the timeout and try again
time.sleep(timeout)
timeout *= 2
warnings.warn('tests may fail, delete still pending for ' + pathname,
RuntimeWarning, stacklevel=4)
def _unlink(filename):
_waitfor(os.unlink, filename)
def _rmdir(dirname):
_waitfor(os.rmdir, dirname)
def _rmtree(path):
from test.support import _force_run
def _rmtree_inner(path):
for name in _force_run(path, os.listdir, path):
fullname = os.path.join(path, name)
try:
mode = os.lstat(fullname).st_mode
except OSError as exc:
print("support.rmtree(): os.lstat(%r) failed with %s"
% (fullname, exc),
file=sys.__stderr__)
mode = 0
if stat.S_ISDIR(mode):
_waitfor(_rmtree_inner, fullname, waitall=True)
_force_run(fullname, os.rmdir, fullname)
else:
_force_run(fullname, os.unlink, fullname)
_waitfor(_rmtree_inner, path, waitall=True)
_waitfor(lambda p: _force_run(p, os.rmdir, p), path)
def _longpath(path):
try:
import ctypes
except ImportError:
# No ctypes means we can't expands paths.
pass
else:
buffer = ctypes.create_unicode_buffer(len(path) * 2)
length = ctypes.windll.kernel32.GetLongPathNameW(path, buffer,
len(buffer))
if length:
return buffer[:length]
return path
else:
_unlink = os.unlink
_rmdir = os.rmdir
def _rmtree(path):
import shutil
try:
shutil.rmtree(path)
return
except OSError:
pass
def _rmtree_inner(path):
from test.support import _force_run
for name in _force_run(path, os.listdir, path):
fullname = os.path.join(path, name)
try:
mode = os.lstat(fullname).st_mode
except OSError:
mode = 0
if stat.S_ISDIR(mode):
_rmtree_inner(fullname)
_force_run(path, os.rmdir, fullname)
else:
_force_run(path, os.unlink, fullname)
_rmtree_inner(path)
os.rmdir(path)
def _longpath(path):
return path
def rmdir(dirname):
try:
_rmdir(dirname)
except FileNotFoundError:
pass
def rmtree(path):
try:
_rmtree(path)
except FileNotFoundError:
pass
@contextlib.contextmanager
def temp_dir(path=None, quiet=False):
"""Return a context manager that creates a temporary directory.
Arguments:
path: the directory to create temporarily. If omitted or None,
defaults to creating a temporary directory using tempfile.mkdtemp.
quiet: if False (the default), the context manager raises an exception
on error. Otherwise, if the path is specified and cannot be
created, only a warning is issued.
"""
import tempfile
dir_created = False
if path is None:
path = tempfile.mkdtemp()
dir_created = True
path = os.path.realpath(path)
else:
try:
os.mkdir(path)
dir_created = True
except OSError as exc:
if not quiet:
raise
warnings.warn(f'tests may fail, unable to create '
f'temporary directory {path!r}: {exc}',
RuntimeWarning, stacklevel=3)
if dir_created:
pid = os.getpid()
try:
yield path
finally:
# In case the process forks, let only the parent remove the
# directory. The child has a different process id. (bpo-30028)
if dir_created and pid == os.getpid():
rmtree(path)
@contextlib.contextmanager
def change_cwd(path, quiet=False):
"""Return a context manager that changes the current working directory.
Arguments:
path: the directory to use as the temporary current working directory.
quiet: if False (the default), the context manager raises an exception
on error. Otherwise, it issues only a warning and keeps the current
working directory the same.
"""
saved_dir = os.getcwd()
try:
os.chdir(os.path.realpath(path))
except OSError as exc:
if not quiet:
raise
warnings.warn(f'tests may fail, unable to change the current working '
f'directory to {path!r}: {exc}',
RuntimeWarning, stacklevel=3)
try:
yield os.getcwd()
finally:
os.chdir(saved_dir)
@contextlib.contextmanager
def temp_cwd(name='tempcwd', quiet=False):
"""
Context manager that temporarily creates and changes the CWD.
The function temporarily changes the current working directory
after creating a temporary directory in the current directory with
name *name*. If *name* is None, the temporary directory is
created using tempfile.mkdtemp.
If *quiet* is False (default) and it is not possible to
create or change the CWD, an error is raised. If *quiet* is True,
only a warning is raised and the original CWD is used.
"""
with temp_dir(path=name, quiet=quiet) as temp_path:
with change_cwd(temp_path, quiet=quiet) as cwd_dir:
yield cwd_dir
def create_empty_file(filename):
"""Create an empty file. If the file already exists, truncate it."""
fd = os.open(filename, os.O_WRONLY | os.O_CREAT | os.O_TRUNC)
os.close(fd)
@contextlib.contextmanager
def open_dir_fd(path):
"""Open a file descriptor to a directory."""
assert os.path.isdir(path)
flags = os.O_RDONLY
if hasattr(os, "O_DIRECTORY"):
flags |= os.O_DIRECTORY
dir_fd = os.open(path, flags)
try:
yield dir_fd
finally:
os.close(dir_fd)
def fs_is_case_insensitive(directory):
"""Detects if the file system for the specified directory
is case-insensitive."""
import tempfile
with tempfile.NamedTemporaryFile(dir=directory) as base:
base_path = base.name
case_path = base_path.upper()
if case_path == base_path:
case_path = base_path.lower()
try:
return os.path.samefile(base_path, case_path)
except FileNotFoundError:
return False
class FakePath:
"""Simple implementation of the path protocol.
"""
def __init__(self, path):
self.path = path
def __repr__(self):
return f'<FakePath {self.path!r}>'
def __fspath__(self):
if (isinstance(self.path, BaseException) or
isinstance(self.path, type) and
issubclass(self.path, BaseException)):
raise self.path
else:
return self.path
def fd_count():
"""Count the number of open file descriptors.
"""
if sys.platform.startswith(('linux', 'freebsd', 'emscripten')):
try:
names = os.listdir("/proc/self/fd")
# Subtract one because listdir() internally opens a file
# descriptor to list the content of the /proc/self/fd/ directory.
return len(names) - 1
except FileNotFoundError:
pass
MAXFD = 256
if hasattr(os, 'sysconf'):
try:
MAXFD = os.sysconf("SC_OPEN_MAX")
except OSError:
pass
old_modes = None
if sys.platform == 'win32':
# bpo-25306, bpo-31009: Call CrtSetReportMode() to not kill the process
# on invalid file descriptor if Python is compiled in debug mode
try:
import msvcrt
msvcrt.CrtSetReportMode
except (AttributeError, ImportError):
# no msvcrt or a release build
pass
else:
old_modes = {}
for report_type in (msvcrt.CRT_WARN,
msvcrt.CRT_ERROR,
msvcrt.CRT_ASSERT):
old_modes[report_type] = msvcrt.CrtSetReportMode(report_type,
0)
try:
count = 0
for fd in range(MAXFD):
try:
# Prefer dup() over fstat(). fstat() can require input/output
# whereas dup() doesn't.
fd2 = os.dup(fd)
except OSError as e:
if e.errno != errno.EBADF:
raise
else:
os.close(fd2)
count += 1
finally:
if old_modes is not None:
for report_type in (msvcrt.CRT_WARN,
msvcrt.CRT_ERROR,
msvcrt.CRT_ASSERT):
msvcrt.CrtSetReportMode(report_type, old_modes[report_type])
return count
if hasattr(os, "umask"):
@contextlib.contextmanager
def temp_umask(umask):
"""Context manager that temporarily sets the process umask."""
oldmask = os.umask(umask)
try:
yield
finally:
os.umask(oldmask)
else:
@contextlib.contextmanager
def temp_umask(umask):
"""no-op on platforms without umask()"""
yield
class EnvironmentVarGuard(collections.abc.MutableMapping):
"""Class to help protect the environment variable properly. Can be used as
a context manager."""
def __init__(self):
self._environ = os.environ
self._changed = {}
def __getitem__(self, envvar):
return self._environ[envvar]
def __setitem__(self, envvar, value):
# Remember the initial value on the first access
if envvar not in self._changed:
self._changed[envvar] = self._environ.get(envvar)
self._environ[envvar] = value
def __delitem__(self, envvar):
# Remember the initial value on the first access
if envvar not in self._changed:
self._changed[envvar] = self._environ.get(envvar)
if envvar in self._environ:
del self._environ[envvar]
def keys(self):
return self._environ.keys()
def __iter__(self):
return iter(self._environ)
def __len__(self):
return len(self._environ)
def set(self, envvar, value):
self[envvar] = value
def unset(self, envvar):
del self[envvar]
def copy(self):
# We do what os.environ.copy() does.
return dict(self)
def __enter__(self):
return self
def __exit__(self, *ignore_exc):
for (k, v) in self._changed.items():
if v is None:
if k in self._environ:
del self._environ[k]
else:
self._environ[k] = v
os.environ = self._environ
try:
if support.MS_WINDOWS:
import ctypes
kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)
ERROR_FILE_NOT_FOUND = 2
DDD_REMOVE_DEFINITION = 2
DDD_EXACT_MATCH_ON_REMOVE = 4
DDD_NO_BROADCAST_SYSTEM = 8
else:
raise AttributeError
except (ImportError, AttributeError):
def subst_drive(path):
raise unittest.SkipTest('ctypes or kernel32 is not available')
else:
@contextlib.contextmanager
def subst_drive(path):
"""Temporarily yield a substitute drive for a given path."""
for c in reversed(string.ascii_uppercase):
drive = f'{c}:'
if (not kernel32.QueryDosDeviceW(drive, None, 0) and
ctypes.get_last_error() == ERROR_FILE_NOT_FOUND):
break
else:
raise unittest.SkipTest('no available logical drive')
if not kernel32.DefineDosDeviceW(
DDD_NO_BROADCAST_SYSTEM, drive, path):
raise ctypes.WinError(ctypes.get_last_error())
try:
yield drive
finally:
if not kernel32.DefineDosDeviceW(
DDD_REMOVE_DEFINITION | DDD_EXACT_MATCH_ON_REMOVE,
drive, path):
raise ctypes.WinError(ctypes.get_last_error())