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cpython/Lib/ntpath.py
Steve Dower 99fcf15052
bpo-45582: Port getpath[p].c to Python (GH-29041) 
The getpath.py file is frozen at build time and executed as code over a namespace. It is never imported, nor is it meant to be importable or reusable. However, it should be easier to read, modify, and patch than the previous code.

This commit attempts to preserve every previously tested quirk, but these may be changed in the future to better align platforms.
2021-12-03 00:08:42 +00:00

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# Module 'ntpath' -- common operations on WinNT/Win95 pathnames
"""Common pathname manipulations, WindowsNT/95 version.
Instead of importing this module directly, import os and refer to this
module as os.path.
"""
# strings representing various path-related bits and pieces
# These are primarily for export; internally, they are hardcoded.
# Should be set before imports for resolving cyclic dependency.
curdir = '.'
pardir = '..'
extsep = '.'
sep = '\\'
pathsep = ';'
altsep = '/'
defpath = '.;C:\\bin'
devnull = 'nul'
import os
import sys
import stat
import genericpath
from genericpath import *
__all__ = ["normcase","isabs","join","splitdrive","split","splitext",
"basename","dirname","commonprefix","getsize","getmtime",
"getatime","getctime", "islink","exists","lexists","isdir","isfile",
"ismount", "expanduser","expandvars","normpath","abspath",
"curdir","pardir","sep","pathsep","defpath","altsep",
"extsep","devnull","realpath","supports_unicode_filenames","relpath",
"samefile", "sameopenfile", "samestat", "commonpath"]
def _get_bothseps(path):
if isinstance(path, bytes):
return b'\\/'
else:
return '\\/'
# Normalize the case of a pathname and map slashes to backslashes.
# Other normalizations (such as optimizing '../' away) are not done
# (this is done by normpath).
def normcase(s):
"""Normalize case of pathname.
Makes all characters lowercase and all slashes into backslashes."""
s = os.fspath(s)
if isinstance(s, bytes):
return s.replace(b'/', b'\\').lower()
else:
return s.replace('/', '\\').lower()
# Return whether a path is absolute.
# Trivial in Posix, harder on Windows.
# For Windows it is absolute if it starts with a slash or backslash (current
# volume), or if a pathname after the volume-letter-and-colon or UNC-resource
# starts with a slash or backslash.
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] and s[0] in _get_bothseps(s)
# Join two (or more) paths.
def join(path, *paths):
path = os.fspath(path)
if isinstance(path, bytes):
sep = b'\\'
seps = b'\\/'
colon = b':'
else:
sep = '\\'
seps = '\\/'
colon = ':'
try:
if not paths:
path[:0] + sep #23780: Ensure compatible data type even if p is null.
result_drive, result_path = splitdrive(path)
for p in map(os.fspath, paths):
p_drive, p_path = splitdrive(p)
if p_path and p_path[0] in seps:
# Second path is absolute
if p_drive or not result_drive:
result_drive = p_drive
result_path = p_path
continue
elif p_drive and p_drive != result_drive:
if p_drive.lower() != result_drive.lower():
# Different drives => ignore the first path entirely
result_drive = p_drive
result_path = p_path
continue
# Same drive in different case
result_drive = p_drive
# Second path is relative to the first
if result_path and result_path[-1] not in seps:
result_path = result_path + sep
result_path = result_path + p_path
## add separator between UNC and non-absolute path
if (result_path and result_path[0] not in seps and
result_drive and result_drive[-1:] != colon):
return result_drive + sep + result_path
return result_drive + result_path
except (TypeError, AttributeError, BytesWarning):
genericpath._check_arg_types('join', path, *paths)
raise
# Split a path in a drive specification (a drive letter followed by a
# colon) and the path specification.
# It is always true that drivespec + pathspec == p
def splitdrive(p):
"""Split a pathname into drive/UNC sharepoint and relative path specifiers.
Returns a 2-tuple (drive_or_unc, path); either part may be empty.
If you assign
result = splitdrive(p)
It is always true that:
result[0] + result[1] == p
If the path contained a drive letter, drive_or_unc will contain everything
up to and including the colon. e.g. splitdrive("c:/dir") returns ("c:", "/dir")
If the path contained a UNC path, the drive_or_unc will contain the host name
and share up to but not including the fourth directory separator character.
e.g. splitdrive("//host/computer/dir") returns ("//host/computer", "/dir")
Paths cannot contain both a drive letter and a UNC path.
"""
p = os.fspath(p)
if len(p) >= 2:
if isinstance(p, bytes):
sep = b'\\'
altsep = b'/'
colon = b':'
else:
sep = '\\'
altsep = '/'
colon = ':'
normp = p.replace(altsep, sep)
if (normp[0:2] == sep*2) and (normp[2:3] != sep):
# is a UNC path:
# vvvvvvvvvvvvvvvvvvvv drive letter or UNC path
# \\machine\mountpoint\directory\etc\...
# directory ^^^^^^^^^^^^^^^
index = normp.find(sep, 2)
if index == -1:
return p[:0], p
index2 = normp.find(sep, index + 1)
# a UNC path can't have two slashes in a row
# (after the initial two)
if index2 == index + 1:
return p[:0], p
if index2 == -1:
index2 = len(p)
return p[:index2], p[index2:]
if normp[1:2] == colon:
return p[:2], p[2:]
return p[:0], p
# Split a path in head (everything up to the last '/') and tail (the
# rest). After the trailing '/' is stripped, the invariant
# join(head, tail) == p holds.
# The resulting head won't end in '/' unless it is the root.
def split(p):
"""Split a pathname.
Return tuple (head, tail) where tail is everything after the final slash.
Either part may be empty."""
p = os.fspath(p)
seps = _get_bothseps(p)
d, p = splitdrive(p)
# set i to index beyond p's last slash
i = len(p)
while i and p[i-1] not in seps:
i -= 1
head, tail = p[:i], p[i:] # now tail has no slashes
# remove trailing slashes from head, unless it's all slashes
head = head.rstrip(seps) or head
return d + head, tail
# Split a path in root and extension.
# The extension is everything starting at the last dot in the last
# pathname component; the root is everything before that.
# It is always true that root + ext == p.
def splitext(p):
p = os.fspath(p)
if isinstance(p, bytes):
return genericpath._splitext(p, b'\\', b'/', b'.')
else:
return genericpath._splitext(p, '\\', '/', '.')
splitext.__doc__ = genericpath._splitext.__doc__
# Return the tail (basename) part of a path.
def basename(p):
"""Returns the final component of a pathname"""
return split(p)[1]
# Return the head (dirname) part of a path.
def dirname(p):
"""Returns the directory component of a pathname"""
return split(p)[0]
# Is a path a symbolic link?
# This will always return false on systems where os.lstat doesn't exist.
def islink(path):
"""Test whether a path is a symbolic link.
This will always return false for Windows prior to 6.0.
"""
try:
st = os.lstat(path)
except (OSError, ValueError, AttributeError):
return False
return stat.S_ISLNK(st.st_mode)
# Being true for dangling symbolic links is also useful.
def lexists(path):
"""Test whether a path exists. Returns True for broken symbolic links"""
try:
st = os.lstat(path)
except (OSError, ValueError):
return False
return True
# Is a path a mount point?
# Any drive letter root (eg c:\)
# Any share UNC (eg \\server\share)
# Any volume mounted on a filesystem folder
#
# No one method detects all three situations. Historically we've lexically
# detected drive letter roots and share UNCs. The canonical approach to
# detecting mounted volumes (querying the reparse tag) fails for the most
# common case: drive letter roots. The alternative which uses GetVolumePathName
# fails if the drive letter is the result of a SUBST.
try:
from nt import _getvolumepathname
except ImportError:
_getvolumepathname = None
def ismount(path):
"""Test whether a path is a mount point (a drive root, the root of a
share, or a mounted volume)"""
path = os.fspath(path)
seps = _get_bothseps(path)
path = abspath(path)
root, rest = splitdrive(path)
if root and root[0] in seps:
return (not rest) or (rest in seps)
if rest and rest in seps:
return True
if _getvolumepathname:
x = path.rstrip(seps)
y =_getvolumepathname(path).rstrip(seps)
return x.casefold() == y.casefold()
else:
return False
# Expand paths beginning with '~' or '~user'.
# '~' means $HOME; '~user' means that user's home directory.
# If the path doesn't begin with '~', or if the user or $HOME is unknown,
# the path is returned unchanged (leaving error reporting to whatever
# function is called with the expanded path as argument).
# See also module 'glob' for expansion of *, ? and [...] in pathnames.
# (A function should also be defined to do full *sh-style environment
# variable expansion.)
def expanduser(path):
"""Expand ~ and ~user constructs.
If user or $HOME is unknown, do nothing."""
path = os.fspath(path)
if isinstance(path, bytes):
tilde = b'~'
else:
tilde = '~'
if not path.startswith(tilde):
return path
i, n = 1, len(path)
while i < n and path[i] not in _get_bothseps(path):
i += 1
if 'USERPROFILE' in os.environ:
userhome = os.environ['USERPROFILE']
elif not 'HOMEPATH' in os.environ:
return path
else:
try:
drive = os.environ['HOMEDRIVE']
except KeyError:
drive = ''
userhome = join(drive, os.environ['HOMEPATH'])
if i != 1: #~user
target_user = path[1:i]
if isinstance(target_user, bytes):
target_user = os.fsdecode(target_user)
current_user = os.environ.get('USERNAME')
if target_user != current_user:
# Try to guess user home directory. By default all user
# profile directories are located in the same place and are
# named by corresponding usernames. If userhome isn't a
# normal profile directory, this guess is likely wrong,
# so we bail out.
if current_user != basename(userhome):
return path
userhome = join(dirname(userhome), target_user)
if isinstance(path, bytes):
userhome = os.fsencode(userhome)
return userhome + path[i:]
# Expand paths containing shell variable substitutions.
# The following rules apply:
# - no expansion within single quotes
# - '$$' is translated into '$'
# - '%%' is translated into '%' if '%%' are not seen in %var1%%var2%
# - ${varname} is accepted.
# - $varname is accepted.
# - %varname% is accepted.
# - varnames can be made out of letters, digits and the characters '_-'
# (though is not verified in the ${varname} and %varname% cases)
# XXX With COMMAND.COM you can use any characters in a variable name,
# XXX except '^|<>='.
def expandvars(path):
"""Expand shell variables of the forms $var, ${var} and %var%.
Unknown variables are left unchanged."""
path = os.fspath(path)
if isinstance(path, bytes):
if b'$' not in path and b'%' not in path:
return path
import string
varchars = bytes(string.ascii_letters + string.digits + '_-', 'ascii')
quote = b'\''
percent = b'%'
brace = b'{'
rbrace = b'}'
dollar = b'$'
environ = getattr(os, 'environb', None)
else:
if '$' not in path and '%' not in path:
return path
import string
varchars = string.ascii_letters + string.digits + '_-'
quote = '\''
percent = '%'
brace = '{'
rbrace = '}'
dollar = '$'
environ = os.environ
res = path[:0]
index = 0
pathlen = len(path)
while index < pathlen:
c = path[index:index+1]
if c == quote: # no expansion within single quotes
path = path[index + 1:]
pathlen = len(path)
try:
index = path.index(c)
res += c + path[:index + 1]
except ValueError:
res += c + path
index = pathlen - 1
elif c == percent: # variable or '%'
if path[index + 1:index + 2] == percent:
res += c
index += 1
else:
path = path[index+1:]
pathlen = len(path)
try:
index = path.index(percent)
except ValueError:
res += percent + path
index = pathlen - 1
else:
var = path[:index]
try:
if environ is None:
value = os.fsencode(os.environ[os.fsdecode(var)])
else:
value = environ[var]
except KeyError:
value = percent + var + percent
res += value
elif c == dollar: # variable or '$$'
if path[index + 1:index + 2] == dollar:
res += c
index += 1
elif path[index + 1:index + 2] == brace:
path = path[index+2:]
pathlen = len(path)
try:
index = path.index(rbrace)
except ValueError:
res += dollar + brace + path
index = pathlen - 1
else:
var = path[:index]
try:
if environ is None:
value = os.fsencode(os.environ[os.fsdecode(var)])
else:
value = environ[var]
except KeyError:
value = dollar + brace + var + rbrace
res += value
else:
var = path[:0]
index += 1
c = path[index:index + 1]
while c and c in varchars:
var += c
index += 1
c = path[index:index + 1]
try:
if environ is None:
value = os.fsencode(os.environ[os.fsdecode(var)])
else:
value = environ[var]
except KeyError:
value = dollar + var
res += value
if c:
index -= 1
else:
res += c
index += 1
return res
# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A\B.
# Previously, this function also truncated pathnames to 8+3 format,
# but as this module is called "ntpath", that's obviously wrong!
try:
from nt import _path_normpath
except ImportError:
def normpath(path):
"""Normalize path, eliminating double slashes, etc."""
path = os.fspath(path)
if isinstance(path, bytes):
sep = b'\\'
altsep = b'/'
curdir = b'.'
pardir = b'..'
special_prefixes = (b'\\\\.\\', b'\\\\?\\')
else:
sep = '\\'
altsep = '/'
curdir = '.'
pardir = '..'
special_prefixes = ('\\\\.\\', '\\\\?\\')
if path.startswith(special_prefixes):
# in the case of paths with these prefixes:
# \\.\ -> device names
# \\?\ -> literal paths
# do not do any normalization, but return the path
# unchanged apart from the call to os.fspath()
return path
path = path.replace(altsep, sep)
prefix, path = splitdrive(path)
# collapse initial backslashes
if path.startswith(sep):
prefix += sep
path = path.lstrip(sep)
comps = path.split(sep)
i = 0
while i < len(comps):
if not comps[i] or comps[i] == curdir:
del comps[i]
elif comps[i] == pardir:
if i > 0 and comps[i-1] != pardir:
del comps[i-1:i+1]
i -= 1
elif i == 0 and prefix.endswith(sep):
del comps[i]
else:
i += 1
else:
i += 1
# If the path is now empty, substitute '.'
if not prefix and not comps:
comps.append(curdir)
return prefix + sep.join(comps)
else:
def normpath(path):
"""Normalize path, eliminating double slashes, etc."""
path = os.fspath(path)
if isinstance(path, bytes):
return os.fsencode(_path_normpath(os.fsdecode(path))) or b"."
return _path_normpath(path) or "."
def _abspath_fallback(path):
"""Return the absolute version of a path as a fallback function in case
`nt._getfullpathname` is not available or raises OSError. See bpo-31047 for
more.
"""
path = os.fspath(path)
if not isabs(path):
if isinstance(path, bytes):
cwd = os.getcwdb()
else:
cwd = os.getcwd()
path = join(cwd, path)
return normpath(path)
# Return an absolute path.
try:
from nt import _getfullpathname
except ImportError: # not running on Windows - mock up something sensible
abspath = _abspath_fallback
else: # use native Windows method on Windows
def abspath(path):
"""Return the absolute version of a path."""
try:
return normpath(_getfullpathname(path))
except (OSError, ValueError):
return _abspath_fallback(path)
try:
from nt import _getfinalpathname, readlink as _nt_readlink
except ImportError:
# realpath is a no-op on systems without _getfinalpathname support.
realpath = abspath
else:
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
# 2: ERROR_FILE_NOT_FOUND
# 3: ERROR_DIRECTORY_NOT_FOUND
# 5: ERROR_ACCESS_DENIED
# 21: ERROR_NOT_READY (implies drive with no media)
# 32: ERROR_SHARING_VIOLATION (probably an NTFS paging file)
# 50: ERROR_NOT_SUPPORTED (implies no support for reparse points)
# 67: ERROR_BAD_NET_NAME (implies remote server unavailable)
# 87: ERROR_INVALID_PARAMETER
# 4390: ERROR_NOT_A_REPARSE_POINT
# 4392: ERROR_INVALID_REPARSE_DATA
# 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
raise
except ValueError:
# Stop on reparse points that are not symlinks
break
return path
def _getfinalpathname_nonstrict(path):
# These error codes indicate that we should stop resolving the path
# and return the value we currently have.
# 1: ERROR_INVALID_FUNCTION
# 2: ERROR_FILE_NOT_FOUND
# 3: ERROR_DIRECTORY_NOT_FOUND
# 5: ERROR_ACCESS_DENIED
# 21: ERROR_NOT_READY (implies drive with no media)
# 32: ERROR_SHARING_VIOLATION (probably an NTFS paging file)
# 50: ERROR_NOT_SUPPORTED
# 67: ERROR_BAD_NET_NAME (implies remote server unavailable)
# 87: ERROR_INVALID_PARAMETER
# 123: ERROR_INVALID_NAME
# 1920: ERROR_CANT_ACCESS_FILE
# 1921: ERROR_CANT_RESOLVE_FILENAME (implies unfollowable symlink)
allowed_winerror = 1, 2, 3, 5, 21, 32, 50, 67, 87, 123, 1920, 1921
# Non-strict algorithm is to find as much of the target directory
# as we can and join the rest.
tail = ''
while path:
try:
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 path + tail
tail = join(name, tail) if tail else name
return tail
def realpath(path, *, strict=False):
path = normpath(path)
if isinstance(path, bytes):
prefix = b'\\\\?\\'
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
except OSError as ex:
if strict:
raise
initial_winerror = ex.winerror
path = _getfinalpathname_nonstrict(path)
# The path returned by _getfinalpathname will always start with \\?\ -
# strip off that prefix unless it was already provided on the original
# path.
if not had_prefix and path.startswith(prefix):
# For UNC paths, the prefix will actually be \\?\UNC\
# Handle that case as well.
if path.startswith(unc_prefix):
spath = new_unc_prefix + path[len(unc_prefix):]
else:
spath = path[len(prefix):]
# Ensure that the non-prefixed path resolves to the same path
try:
if _getfinalpathname(spath) == path:
path = spath
except OSError as ex:
# If the path does not exist and originally did not exist, then
# strip the prefix anyway.
if ex.winerror == initial_winerror:
path = spath
return path
# Win9x family and earlier have no Unicode filename support.
supports_unicode_filenames = (hasattr(sys, "getwindowsversion") and
sys.getwindowsversion()[3] >= 2)
def relpath(path, start=None):
"""Return a relative version of a path"""
path = os.fspath(path)
if isinstance(path, bytes):
sep = b'\\'
curdir = b'.'
pardir = b'..'
else:
sep = '\\'
curdir = '.'
pardir = '..'
if start is None:
start = curdir
if not path:
raise ValueError("no path specified")
start = os.fspath(start)
try:
start_abs = abspath(normpath(start))
path_abs = abspath(normpath(path))
start_drive, start_rest = splitdrive(start_abs)
path_drive, path_rest = splitdrive(path_abs)
if normcase(start_drive) != normcase(path_drive):
raise ValueError("path is on mount %r, start on mount %r" % (
path_drive, start_drive))
start_list = [x for x in start_rest.split(sep) if x]
path_list = [x for x in path_rest.split(sep) if x]
# Work out how much of the filepath is shared by start and path.
i = 0
for e1, e2 in zip(start_list, path_list):
if normcase(e1) != normcase(e2):
break
i += 1
rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
if not rel_list:
return curdir
return join(*rel_list)
except (TypeError, ValueError, AttributeError, BytesWarning, DeprecationWarning):
genericpath._check_arg_types('relpath', path, start)
raise
# Return the longest common sub-path of the sequence of paths given as input.
# The function is case-insensitive and 'separator-insensitive', i.e. if the
# only difference between two paths is the use of '\' versus '/' as separator,
# they are deemed to be equal.
#
# However, the returned path will have the standard '\' separator (even if the
# given paths had the alternative '/' separator) and will have the case of the
# first path given in the sequence. Additionally, any trailing separator is
# stripped from the returned path.
def commonpath(paths):
"""Given a sequence of path names, returns the longest common sub-path."""
if not paths:
raise ValueError('commonpath() arg is an empty sequence')
paths = tuple(map(os.fspath, paths))
if isinstance(paths[0], bytes):
sep = b'\\'
altsep = b'/'
curdir = b'.'
else:
sep = '\\'
altsep = '/'
curdir = '.'
try:
drivesplits = [splitdrive(p.replace(altsep, sep).lower()) for p in paths]
split_paths = [p.split(sep) for d, p in drivesplits]
try:
isabs, = set(p[:1] == sep for d, p in drivesplits)
except ValueError:
raise ValueError("Can't mix absolute and relative paths") from None
# Check that all drive letters or UNC paths match. The check is made only
# now otherwise type errors for mixing strings and bytes would not be
# caught.
if len(set(d for d, p in drivesplits)) != 1:
raise ValueError("Paths don't have the same drive")
drive, path = splitdrive(paths[0].replace(altsep, sep))
common = path.split(sep)
common = [c for c in common if c and c != curdir]
split_paths = [[c for c in s if c and c != curdir] for s in split_paths]
s1 = min(split_paths)
s2 = max(split_paths)
for i, c in enumerate(s1):
if c != s2[i]:
common = common[:i]
break
else:
common = common[:len(s1)]
prefix = drive + sep if isabs else drive
return prefix + sep.join(common)
except (TypeError, AttributeError):
genericpath._check_arg_types('commonpath', *paths)
raise
try:
# The genericpath.isdir implementation uses os.stat and checks the mode
# attribute to tell whether or not the path is a directory.
# This is overkill on Windows - just pass the path to GetFileAttributes
# and check the attribute from there.
from nt import _isdir as isdir
except ImportError:
# Use genericpath.isdir as imported above.
pass
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