"""Common operations on Posix pathnames.

Instead of importing this module directly, import os and refer to

this module as os.path. The "os.path" name is an alias for this

module on Posix systems; on other systems (e.g. Mac, Windows),

os.path provides the same operations in a manner specific to that

platform, and is an alias to another module (e.g. macpath, ntpath).

Some of this can actually be useful on non-Posix systems too, e.g.

for manipulation of the pathname component of URLs.

"""

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",

"samefile","sameopenfile","samestat",

"curdir","pardir","sep","pathsep","defpath","altsep","extsep",

"devnull","realpath","supports_unicode_filenames","relpath",

"commonpath"]

# Strings representing various path-related bits and pieces.

# These are primarily for export; internally, they are hardcoded.

curdir = '.'

pardir = '..'

extsep = '.'

sep = '/'

pathsep = ':'

defpath = ':/bin:/usr/bin'

altsep = None

devnull = '/dev/null'

def _get_sep(path):

if isinstance(path, bytes):

return b'/'

else:

return '/'

# Normalize the case of a pathname. Trivial in Posix, string.lower on Mac.

# On MS-DOS this may also turn slashes into backslashes; however, other

# normalizations (such as optimizing '../' away) are not allowed

# (another function should be defined to do that).

def normcase(s):

"""Normalize case of pathname. Has no effect under Posix"""

if not isinstance(s, (bytes, str)):

raise TypeError("normcase() argument must be str or bytes, "

"not '{}'".format(s.__class__.__name__))

return s

# Return whether a path is absolute.

# Trivial in Posix, harder on the Mac or MS-DOS.

def isabs(s):

"""Test whether a path is absolute"""

sep = _get_sep(s)

return s.startswith(sep)

# Join pathnames.

# Ignore the previous parts if a part is absolute.

# Insert a '/' unless the first part is empty or already ends in '/'.

def join(a, *p):

"""Join two or more pathname components, inserting '/' as needed.

If any component is an absolute path, all previous path components

will be discarded. An empty last part will result in a path that

ends with a separator."""

sep = _get_sep(a)

path = a

try:

if not p:

path[:0] + sep #23780: Ensure compatible data type even if p is null.

for b in p:

if b.startswith(sep):

path = b

elif not path or path.endswith(sep):

path += b

else:

path += sep + b

except (TypeError, AttributeError, BytesWarning):

genericpath._check_arg_types('join', a, *p)

raise

return path

# Split a path in head (everything up to the last '/') and tail (the

# rest). If the path ends in '/', tail will be empty. If there is no

# '/' in the path, head will be empty.

# Trailing '/'es are stripped from head unless it is the root.

def split(p):

"""Split a pathname. Returns tuple "(head, tail)" where "tail" is

everything after the final slash. Either part may be empty."""

sep = _get_sep(p)

i = p.rfind(sep) + 1

head, tail = p[:i], p[i:]

if head and head != sep*len(head):

head = head.rstrip(sep)

return 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):

if isinstance(p, bytes):

sep = b'/'

extsep = b'.'

else:

sep = '/'

extsep = '.'

return genericpath._splitext(p, sep, None, extsep)

splitext.__doc__ = genericpath._splitext.__doc__

# Split a pathname into a drive specification and the rest of the

# path. Useful on DOS/Windows/NT; on Unix, the drive is always empty.

def splitdrive(p):

"""Split a pathname into drive and path. On Posix, drive is always

empty."""

return p[:0], p

# Return the tail (basename) part of a path, same as split(path)[1].

def basename(p):

"""Returns the final component of a pathname"""

sep = _get_sep(p)

i = p.rfind(sep) + 1

return p[i:]

# Return the head (dirname) part of a path, same as split(path)[0].

def dirname(p):

"""Returns the directory component of a pathname"""

sep = _get_sep(p)

i = p.rfind(sep) + 1

head = p[:i]

if head and head != sep*len(head):

head = head.rstrip(sep)

return head

# 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"""

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:

os.lstat(path)

except OSError:

return False

return True

# Is a path a mount point?

# (Does this work for all UNIXes? Is it even guaranteed to work by Posix?)

def ismount(path):

"""Test whether a path is a mount point"""

try:

s1 = os.lstat(path)

except OSError:

# It doesn't exist -- so not a mount point. :-)

return False

else:

# A symlink can never be a mount point

if stat.S_ISLNK(s1.st_mode):

return False

if isinstance(path, bytes):

parent = join(path, b'..')

else:

parent = join(path, '..')

parent = realpath(parent)

try:

s2 = os.lstat(parent)

except OSError:

return False

dev1 = s1.st_dev

dev2 = s2.st_dev

if dev1 != dev2:

return True # path/.. on a different device as path

ino1 = s1.st_ino

ino2 = s2.st_ino

if ino1 == ino2:

return True # path/.. is the same i-node as path

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 constructions. If user or $HOME is unknown,

do nothing."""

if isinstance(path, bytes):

tilde = b'~'

else:

tilde = '~'

if not path.startswith(tilde):

return path

sep = _get_sep(path)

i = path.find(sep, 1)

if i < 0:

i = len(path)

if i == 1:

if 'HOME' not in os.environ:

import pwd

userhome = pwd.getpwuid(os.getuid()).pw_dir

else:

userhome = os.environ['HOME']

else:

import pwd

name = path[1:i]

if isinstance(name, bytes):

name = str(name, 'ASCII')

try:

pwent = pwd.getpwnam(name)

except KeyError:

return path

userhome = pwent.pw_dir

if isinstance(path, bytes):

userhome = os.fsencode(userhome)

root = b'/'

else:

root = '/'

userhome = userhome.rstrip(root)

return (userhome + path[i:]) or root

# Expand paths containing shell variable substitutions.

# This expands the forms $variable and ${variable} only.

# Non-existent variables are left unchanged.

_varprog = None

_varprogb = None

def expandvars(path):

"""Expand shell variables of form $var and ${var}. Unknown variables

are left unchanged."""

global _varprog, _varprogb

if isinstance(path, bytes):

if b'$' not in path:

return path

if not _varprogb:

import re

_varprogb = re.compile(br'\$(\w+|\{[^}]*\})', re.ASCII)

search = _varprogb.search

start = b'{'

end = b'}'

environ = getattr(os, 'environb', None)

else:

if '$' not in path:

return path

if not _varprog:

import re

_varprog = re.compile(r'\$(\w+|\{[^}]*\})', re.ASCII)

search = _varprog.search

start = '{'

end = '}'

environ = os.environ

i = 0

while True:

m = search(path, i)

if not m:

break

i, j = m.span(0)

name = m.group(1)

if name.startswith(start) and name.endswith(end):

name = name[1:-1]

try:

if environ is None:

value = os.fsencode(os.environ[os.fsdecode(name)])

else:

value = environ[name]

except KeyError:

i = j

else:

tail = path[j:]

path = path[:i] + value

i = len(path)

path += tail

return path

# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.

# It should be understood that this may change the meaning of the path

# if it contains symbolic links!

def normpath(path):

"""Normalize path, eliminating double slashes, etc."""

if isinstance(path, bytes):

sep = b'/'

empty = b''

dot = b'.'

dotdot = b'..'

else:

sep = '/'

empty = ''

dot = '.'

dotdot = '..'

if path == empty:

return dot

initial_slashes = path.startswith(sep)

# POSIX allows one or two initial slashes, but treats three or more

# as single slash.

if (initial_slashes and

path.startswith(sep*2) and not path.startswith(sep*3)):

initial_slashes = 2

comps = path.split(sep)

new_comps = []

for comp in comps:

if comp in (empty, dot):

continue

if (comp != dotdot or (not initial_slashes and not new_comps) or

(new_comps and new_comps[-1] == dotdot)):

new_comps.append(comp)

elif new_comps:

new_comps.pop()

comps = new_comps

path = sep.join(comps)

if initial_slashes:

path = sep*initial_slashes + path

return path or dot

def abspath(path):

"""Return an absolute path."""

if not isabs(path):

if isinstance(path, bytes):

cwd = os.getcwdb()

else:

cwd = os.getcwd()

path = join(cwd, path)

return normpath(path)

# Return a canonical path (i.e. the absolute location of a file on the

# filesystem).

def realpath(filename):

"""Return the canonical path of the specified filename, eliminating any

symbolic links encountered in the path."""

path, ok = _joinrealpath(filename[:0], filename, {})

return abspath(path)

# Join two paths, normalizing and eliminating any symbolic links

# encountered in the second path.

def _joinrealpath(path, rest, seen):

if isinstance(path, bytes):

sep = b'/'

curdir = b'.'

pardir = b'..'

else:

sep = '/'

curdir = '.'

pardir = '..'

if isabs(rest):

rest = rest[1:]

path = sep

while rest:

name, _, rest = rest.partition(sep)

if not name or name == curdir:

# current dir

continue

if name == pardir:

# parent dir

if path:

path, name = split(path)

if name == pardir:

path = join(path, pardir, pardir)

else:

path = pardir

continue

newpath = join(path, name)

if not islink(newpath):

path = newpath

continue

# Resolve the symbolic link

if newpath in seen:

# Already seen this path

path = seen[newpath]

if path is not None:

# use cached value

continue

# The symlink is not resolved, so we must have a symlink loop.

# Return already resolved part + rest of the path unchanged.

return join(newpath, rest), False

seen[newpath] = None # not resolved symlink

path, ok = _joinrealpath(path, os.readlink(newpath), seen)

if not ok:

return join(path, rest), False

seen[newpath] = path # resolved symlink

return path, True

supports_unicode_filenames = (sys.platform == 'darwin')

def relpath(path, start=None):

"""Return a relative version of a path"""

if not path:

raise ValueError("no path specified")

if isinstance(path, bytes):

curdir = b'.'

sep = b'/'

pardir = b'..'

else:

curdir = '.'

sep = '/'

pardir = '..'

if start is None:

start = curdir

try:

start_list = [x for x in abspath(start).split(sep) if x]

path_list = [x for x in abspath(path).split(sep) if x]

# Work out how much of the filepath is shared by start and path.

i = len(commonprefix([start_list, path_list]))

rel_list = [pardir] * (len(start_list)-i) + path_list[i:]

if not rel_list:

return curdir

return join(*rel_list)

except (TypeError, 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 paths are not normalized before comparing them (this is the

# responsibility of the caller). 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')

if isinstance(paths[0], bytes):

sep = b'/'

curdir = b'.'

else:

sep = '/'

curdir = '.'

try:

split_paths = [path.split(sep) for path in paths]

try:

isabs, = set(p[:1] == sep for p in paths)

except ValueError:

raise ValueError("Can't mix absolute and relative paths") from None

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)

common = s1

for i, c in enumerate(s1):

if c != s2[i]:

common = s1[:i]

break

prefix = sep if isabs else sep[:0]

return prefix + sep.join(common)

except (TypeError, AttributeError):

genericpath._check_arg_types('commonpath', *paths)

raise