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
diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index d4ecff9..6f77177 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -61,6 +61,14 @@
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 @@
# 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 @@
# 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 @@
# 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 @@
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