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cpython/Lib/ntpath.py
Serhiy Storchaka 7dfaa27fdd Issue #6815: os.path.expandvars() now supports non-ASCII environment 
variables names and values.
2014-02-13 10:14:48 +02:00

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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.
"""
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",
"splitunc","curdir","pardir","sep","pathsep","defpath","altsep",
"extsep","devnull","realpath","supports_unicode_filenames","relpath",
"samefile", "sameopenfile", "samestat",]
# strings representing various path-related bits and pieces
# These are primarily for export; internally, they are hardcoded.
curdir = '.'
pardir = '..'
extsep = '.'
sep = '\\'
pathsep = ';'
altsep = '/'
defpath = '.;C:\\bin'
if 'ce' in sys.builtin_module_names:
defpath = '\\Windows'
devnull = 'nul'
def _get_empty(path):
if isinstance(path, bytes):
return b''
else:
return ''
def _get_sep(path):
if isinstance(path, bytes):
return b'\\'
else:
return '\\'
def _get_altsep(path):
if isinstance(path, bytes):
return b'/'
else:
return '/'
def _get_bothseps(path):
if isinstance(path, bytes):
return b'\\/'
else:
return '\\/'
def _get_dot(path):
if isinstance(path, bytes):
return b'.'
else:
return '.'
def _get_colon(path):
if isinstance(path, bytes):
return b':'
else:
return ':'
def _get_special(path):
if isinstance(path, bytes):
return (b'\\\\.\\', 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."""
if not isinstance(s, (bytes, str)):
raise TypeError("normcase() argument must be str or bytes, "
"not '{}'".format(s.__class__.__name__))
return s.replace(_get_altsep(s), _get_sep(s)).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 = splitdrive(s)[1]
return len(s) > 0 and s[:1] in _get_bothseps(s)
# Join two (or more) paths.
def join(path, *paths):
sep = _get_sep(path)
seps = _get_bothseps(path)
colon = _get_colon(path)
result_drive, result_path = splitdrive(path)
for p in 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
# 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.
"""
empty = _get_empty(p)
if len(p) > 1:
sep = _get_sep(p)
normp = p.replace(_get_altsep(p), 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 empty, 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 empty, p
if index2 == -1:
index2 = len(p)
return p[:index2], p[index2:]
if normp[1:2] == _get_colon(p):
return p[:2], p[2:]
return empty, p
# Parse UNC paths
def splitunc(p):
"""Deprecated since Python 3.1. Please use splitdrive() instead;
it now handles UNC paths.
Split a pathname into UNC mount point and relative path specifiers.
Return a 2-tuple (unc, rest); either part may be empty.
If unc is not empty, it has the form '//host/mount' (or similar
using backslashes). unc+rest is always the input path.
Paths containing drive letters never have an UNC part.
"""
import warnings
warnings.warn("ntpath.splitunc is deprecated, use ntpath.splitdrive instead",
DeprecationWarning, 2)
drive, path = splitdrive(p)
if len(drive) == 2:
# Drive letter present
return p[:0], p
return drive, path
# 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."""
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
head2 = head
while head2 and head2[-1:] in seps:
head2 = head2[:-1]
head = head2 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):
return genericpath._splitext(p, _get_sep(p), _get_altsep(p),
_get_dot(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, 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:
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)"""
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."""
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 = userhome.encode(sys.getfilesystemencoding())
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
# - '$$' is translated into '$'
# - '%%' is translated into '%' if '%%' are not seen in %var1%%var2%
# - ${varname} is accepted.
# - $varname is accepted.
# - %varname% is accepted.
# - varnames can be made out of letters, digits and the characters '_-'
# (though is not verified in the ${varname} and %varname% cases)
# XXX With COMMAND.COM you can use any characters in a variable name,
# XXX except '^|<>='.
def expandvars(path):
"""Expand shell variables of the forms $var, ${var} and %var%.
Unknown variables are left unchanged."""
if isinstance(path, bytes):
if ord('$') not in path and ord('%') not in path:
return path
import string
varchars = bytes(string.ascii_letters + string.digits + '_-', 'ascii')
quote = b'\''
percent = b'%'
brace = b'{'
dollar = b'$'
environ = getattr(os, 'environb', None)
else:
if '$' not in path and '%' not in path:
return path
import string
varchars = string.ascii_letters + string.digits + '_-'
quote = '\''
percent = '%'
brace = '{'
dollar = '$'
environ = os.environ
res = path[:0]
index = 0
pathlen = len(path)
while index < pathlen:
c = path[index:index+1]
if c == quote: # no expansion within single quotes
path = path[index + 1:]
pathlen = len(path)
try:
index = path.index(c)
res += c + path[:index + 1]
except ValueError:
res += path
index = pathlen - 1
elif c == percent: # variable or '%'
if path[index + 1:index + 2] == percent:
res += c
index += 1
else:
path = path[index+1:]
pathlen = len(path)
try:
index = path.index(percent)
except ValueError:
res += percent + path
index = pathlen - 1
else:
var = path[:index]
try:
if environ is None:
value = os.fsencode(os.environ[os.fsdecode(var)])
else:
value = environ[var]
except KeyError:
value = percent + var + percent
res += value
elif c == dollar: # variable or '$$'
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:
if isinstance(path, bytes):
index = path.index(b'}')
else:
index = path.index('}')
except ValueError:
if isinstance(path, bytes):
res += b'${' + path
else:
res += '${' + 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:
if isinstance(path, bytes):
value = b'${' + var + b'}'
else:
value = '${' + var + '}'
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."""
sep = _get_sep(path)
dotdot = _get_dot(path) * 2
special_prefixes = _get_special(path)
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(_get_altsep(path), 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] == _get_dot(path):
del comps[i]
elif comps[i] == dotdot:
if i > 0 and comps[i-1] != dotdot:
del comps[i-1:i+1]
i -= 1
elif i == 0 and prefix.endswith(_get_sep(path)):
del comps[i]
else:
i += 1
else:
i += 1
# If the path is now empty, substitute '.'
if not prefix and not comps:
comps.append(_get_dot(path))
return prefix + sep.join(comps)
# Return an absolute path.
try:
from nt import _getfullpathname
except ImportError: # not running on Windows - mock up something sensible
def abspath(path):
"""Return the absolute version of a path."""
if not isabs(path):
if isinstance(path, bytes):
cwd = os.getcwdb()
else:
cwd = os.getcwd()
path = join(cwd, path)
return normpath(path)
else: # use native Windows method on Windows
def abspath(path):
"""Return the absolute version of a path."""
if path: # Empty path must return current working directory.
try:
path = _getfullpathname(path)
except OSError:
pass # Bad path - return unchanged.
elif isinstance(path, bytes):
path = os.getcwdb()
else:
path = os.getcwd()
return normpath(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=curdir):
"""Return a relative version of a path"""
sep = _get_sep(path)
if start is curdir:
start = _get_dot(path)
if not path:
raise ValueError("no path specified")
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):
error = "path is on mount '{0}', start on mount '{1}'".format(
path_drive, start_drive)
raise ValueError(error)
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
if isinstance(path, bytes):
pardir = b'..'
else:
pardir = '..'
rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
if not rel_list:
return _get_dot(path)
return join(*rel_list)
# 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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