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bpo-38453: Ensure ntpath.realpath correctly resolves relative paths (GH-16967) 

Ensure isabs() is always True for \\?\ prefixed paths
Avoid unnecessary usage of readlink() to avoid resolving broken links incorrectly
Ensure shutil tests run in test directory
This commit is contained in:
Steve Dower 2019-11-15 15:25:03 -08:00 committed by GitHub
parent e963c57cfb
commit 66c0f01f98
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 91 additions and 23 deletions
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49
Lib/ntpath.py
View File

@ -61,6 +61,14 @@ def normcase(s):
def isabs(s):
"""Test whether a path is absolute"""
s = os.fspath(s)
# Paths beginning with \\?\ are always absolute, but do not
# necessarily contain a drive.
if isinstance(s, bytes):
if s.replace(b'/', b'\\').startswith(b'\\\\?\\'):
return True
else:
if s.replace('/', '\\').startswith('\\\\?\\'):
return True
s = splitdrive(s)[1]
return len(s) > 0 and s[0] in _get_bothseps(s)
@ -526,10 +534,7 @@ except ImportError:
# realpath is a no-op on systems without _getfinalpathname support.
realpath = abspath
else:
def _readlink_deep(path, seen=None):
if seen is None:
seen = set()
def _readlink_deep(path):
# These error codes indicate that we should stop reading links and
# return the path we currently have.
# 1: ERROR_INVALID_FUNCTION
@ -546,10 +551,22 @@ else:
# 4393: ERROR_REPARSE_TAG_INVALID
allowed_winerror = 1, 2, 3, 5, 21, 32, 50, 67, 87, 4390, 4392, 4393
seen = set()
while normcase(path) not in seen:
seen.add(normcase(path))
try:
old_path = path
path = _nt_readlink(path)
# Links may be relative, so resolve them against their
# own location
if not isabs(path):
# If it's something other than a symlink, we don't know
# what it's actually going to be resolved against, so
# just return the old path.
if not islink(old_path):
path = old_path
break
path = normpath(join(dirname(old_path), path))
except OSError as ex:
if ex.winerror in allowed_winerror:
break
@ -579,23 +596,31 @@ else:
# Non-strict algorithm is to find as much of the target directory
# as we can and join the rest.
tail = ''
seen = set()
while path:
try:
path = _readlink_deep(path, seen)
path = _getfinalpathname(path)
return join(path, tail) if tail else path
except OSError as ex:
if ex.winerror not in allowed_winerror:
raise
try:
# The OS could not resolve this path fully, so we attempt
# to follow the link ourselves. If we succeed, join the tail
# and return.
new_path = _readlink_deep(path)
if new_path != path:
return join(new_path, tail) if tail else new_path
except OSError:
# If we fail to readlink(), let's keep traversing
pass
path, name = split(path)
# TODO (bpo-38186): Request the real file name from the directory
# entry using FindFirstFileW. For now, we will return the path
# as best we have it
if path and not name:
return abspath(path + tail)
return path + tail
tail = join(name, tail) if tail else name
return abspath(tail)
return tail
def realpath(path):
path = normpath(path)
@ -604,12 +629,20 @@ else:
unc_prefix = b'\\\\?\\UNC\\'
new_unc_prefix = b'\\\\'
cwd = os.getcwdb()
# bpo-38081: Special case for realpath(b'nul')
if normcase(path) == normcase(os.fsencode(devnull)):
return b'\\\\.\\NUL'
else:
prefix = '\\\\?\\'
unc_prefix = '\\\\?\\UNC\\'
new_unc_prefix = '\\\\'
cwd = os.getcwd()
# bpo-38081: Special case for realpath('nul')
if normcase(path) == normcase(devnull):
return '\\\\.\\NUL'
had_prefix = path.startswith(prefix)
if not had_prefix and not isabs(path):
path = join(cwd, path)
try:
path = _getfinalpathname(path)
initial_winerror = 0

52
Lib/test/test_ntpath.py
View File

@ -286,14 +286,16 @@ class TestNtpath(NtpathTestCase):
ABSTFN + r"\missing")
self.assertPathEqual(ntpath.realpath(r"broken\foo"),
ABSTFN + r"\missing\foo")
# bpo-38453: We no longer recursively resolve segments of relative
# symlinks that the OS cannot resolve.
self.assertPathEqual(ntpath.realpath(r"broken1"),
ABSTFN + r"\missing\bar")
ABSTFN + r"\broken\bar")
self.assertPathEqual(ntpath.realpath(r"broken1\baz"),
ABSTFN + r"\missing\bar\baz")
ABSTFN + r"\broken\bar\baz")
self.assertPathEqual(ntpath.realpath("broken2"),
ABSTFN + r"\missing")
ABSTFN + r"\self\self\missing")
self.assertPathEqual(ntpath.realpath("broken3"),
ABSTFN + r"\missing")
ABSTFN + r"\subdir\parent\subdir\parent\missing")
self.assertPathEqual(ntpath.realpath("broken4"),
ABSTFN + r"\missing")
self.assertPathEqual(ntpath.realpath("broken5"),
@ -304,13 +306,13 @@ class TestNtpath(NtpathTestCase):
self.assertPathEqual(ntpath.realpath(rb"broken\foo"),
os.fsencode(ABSTFN + r"\missing\foo"))
self.assertPathEqual(ntpath.realpath(rb"broken1"),
os.fsencode(ABSTFN + r"\missing\bar"))
os.fsencode(ABSTFN + r"\broken\bar"))
self.assertPathEqual(ntpath.realpath(rb"broken1\baz"),
os.fsencode(ABSTFN + r"\missing\bar\baz"))
os.fsencode(ABSTFN + r"\broken\bar\baz"))
self.assertPathEqual(ntpath.realpath(b"broken2"),
os.fsencode(ABSTFN + r"\missing"))
os.fsencode(ABSTFN + r"\self\self\missing"))
self.assertPathEqual(ntpath.realpath(rb"broken3"),
os.fsencode(ABSTFN + r"\missing"))
os.fsencode(ABSTFN + r"\subdir\parent\subdir\parent\missing"))
self.assertPathEqual(ntpath.realpath(b"broken4"),
os.fsencode(ABSTFN + r"\missing"))
self.assertPathEqual(ntpath.realpath(b"broken5"),
@ -319,8 +321,8 @@ class TestNtpath(NtpathTestCase):
@support.skip_unless_symlink
@unittest.skipUnless(HAVE_GETFINALPATHNAME, 'need _getfinalpathname')
def test_realpath_symlink_loops(self):
# Bug #930024, return the path unchanged if we get into an infinite
# symlink loop.
# Symlink loops are non-deterministic as to which path is returned, but
# it will always be the fully resolved path of one member of the cycle
ABSTFN = ntpath.abspath(support.TESTFN)
self.addCleanup(support.unlink, ABSTFN)
self.addCleanup(support.unlink, ABSTFN + "1")
@ -332,8 +334,6 @@ class TestNtpath(NtpathTestCase):
os.symlink(ABSTFN, ABSTFN)
self.assertPathEqual(ntpath.realpath(ABSTFN), ABSTFN)
# cycles are non-deterministic as to which path is returned, but
# it will always be the fully resolved path of one member of the cycle
os.symlink(ABSTFN + "1", ABSTFN + "2")
os.symlink(ABSTFN + "2", ABSTFN + "1")
expected = (ABSTFN + "1", ABSTFN + "2")
@ -402,6 +402,34 @@ class TestNtpath(NtpathTestCase):
def test_realpath_nul(self):
tester("ntpath.realpath('NUL')", r'\\.\NUL')
@unittest.skipUnless(HAVE_GETFINALPATHNAME, 'need _getfinalpathname')
def test_realpath_cwd(self):
ABSTFN = ntpath.abspath(support.TESTFN)
support.unlink(ABSTFN)
support.rmtree(ABSTFN)
os.mkdir(ABSTFN)
self.addCleanup(support.rmtree, ABSTFN)
test_dir_long = ntpath.join(ABSTFN, "MyVeryLongDirectoryName")
test_dir_short = ntpath.join(ABSTFN, "MYVERY~1")
test_file_long = ntpath.join(test_dir_long, "file.txt")
test_file_short = ntpath.join(test_dir_short, "file.txt")
os.mkdir(test_dir_long)
with open(test_file_long, "wb") as f:
f.write(b"content")
self.assertPathEqual(test_file_long, ntpath.realpath(test_file_short))
with support.change_cwd(test_dir_long):
self.assertPathEqual(test_file_long, ntpath.realpath("file.txt"))
with support.change_cwd(test_dir_long.lower()):
self.assertPathEqual(test_file_long, ntpath.realpath("file.txt"))
with support.change_cwd(test_dir_short):
self.assertPathEqual(test_file_long, ntpath.realpath("file.txt"))
def test_expandvars(self):
with support.EnvironmentVarGuard() as env:
env.clear()

12
Lib/test/test_shutil.py
View File

@ -177,7 +177,10 @@ class TestShutil(unittest.TestCase):
Returns the path of the directory.
"""
d = tempfile.mkdtemp()
basedir = None
if sys.platform == "win32":
basedir = os.path.realpath(os.getcwd())
d = tempfile.mkdtemp(dir=basedir)
self.tempdirs.append(d)
return d
@ -1788,8 +1791,11 @@ class TestMove(unittest.TestCase):
def setUp(self):
filename = "foo"
self.src_dir = tempfile.mkdtemp()
self.dst_dir = tempfile.mkdtemp()
basedir = None
if sys.platform == "win32":
basedir = os.path.realpath(os.getcwd())
self.src_dir = tempfile.mkdtemp(dir=basedir)
self.dst_dir = tempfile.mkdtemp(dir=basedir)
self.src_file = os.path.join(self.src_dir, filename)
self.dst_file = os.path.join(self.dst_dir, filename)
with open(self.src_file, "wb") as f:

1
Misc/NEWS.d/next/Windows/2019-10-28-10-32-43.bpo-38453.NwwatW.rst Normal file
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@ -0,0 +1 @@
Ensure ntpath.realpath() correctly resolves relative paths.