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cpython/Lib/ntpath.py
Tim Graham d03b775781 bpo-31047: Fix ntpath.abspath to trim ending separator (GH-10082) 
Regression in b0bf51b322.
2018-10-25 11:26:37 -04:00

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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)
try:
if isinstance(s, bytes):
return s.replace(b'/', b'\\').lower()
else:
return s.replace('/', '\\').lower()
except (TypeError, AttributeError):
if not isinstance(s, (bytes, str)):
raise TypeError("normcase() argument must be str or bytes, "
"not %r" % s.__class__.__name__) from None
raise
# 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)
s = splitdrive(s)[1]
return len(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 in seps:
return True
if _getvolumepathname:
return path.rstrip(seps) == _getvolumepathname(path).rstrip(seps)
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 'HOME' in os.environ:
userhome = os.environ['HOME']
elif '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 isinstance(path, bytes):
userhome = os.fsencode(userhome)
if i != 1: #~user
userhome = join(dirname(userhome), path[1:i])
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!
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
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)
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)
# realpath is a no-op on systems without islink support
realpath = abspath
# 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
# determine if two files are in fact the same file
try:
# GetFinalPathNameByHandle is available starting with Windows 6.0.
# Windows XP and non-Windows OS'es will mock _getfinalpathname.
if sys.getwindowsversion()[:2] >= (6, 0):
from nt import _getfinalpathname
else:
raise ImportError
except (AttributeError, ImportError):
# On Windows XP and earlier, two files are the same if their absolute
# pathnames are the same.
# Non-Windows operating systems fake this method with an XP
# approximation.
def _getfinalpathname(f):
return normcase(abspath(f))
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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