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bpo-44316: add keep_curdir and keep_pardir arguments to os.path.normpath() #26694

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ce917c0
bpo-44316: add `strict` argument to `os.path.normpath`
barneygale Jun 12, 2021
d43050e
Add support for retaining '.' entries.
barneygale Jun 13, 2021
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23 changes: 17 additions & 6 deletions Doc/library/os.path.rst
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Expand Up @@ -332,17 +332,28 @@ the :mod:`glob` module.)
Accepts a :term:`path-like object`.


.. function:: normpath(path)
.. function:: normpath(path, *, keep_curdir=False, keep_pardir=False)

Normalize a pathname by collapsing redundant separators and up-level
references so that ``A//B``, ``A/B/``, ``A/./B`` and ``A/foo/../B`` all
become ``A/B``. This string manipulation may change the meaning of a path
that contains symbolic links. On Windows, it converts forward slashes to
backward slashes. To normalize case, use :func:`normcase`.
Normalize a pathname by collapsing redundant separators so that ``A//B`` and
``A/B/`` become ``A/B``.

Unless *keep_curdir* is ``True``, references to the current directory are
collapsed so that ``./A/./B`` becomes ``A/B``. This may change how the path
is interpreted by a shell.

Unless *keep_pardir* is ``True``, references to the parent directory are
collapsed so that ``A/foo/../B`` becomes ``A/B``. This string manipulation
may change the meaning of a path that contains symbolic links.

On Windows, this function converts forward slashes to backward slashes. To
normalize case, use :func:`normcase`.

.. versionchanged:: 3.6
Accepts a :term:`path-like object`.

.. versionchanged:: 3.11
The *strict* parameter was added.


.. function:: realpath(path, *, strict=False)

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14 changes: 8 additions & 6 deletions Lib/ntpath.py
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Expand Up @@ -460,20 +460,20 @@ def expandvars(path):
# Previously, this function also truncated pathnames to 8+3 format,
# but as this module is called "ntpath", that's obviously wrong!

def normpath(path):
def normpath(path, *, keep_curdir=False, keep_pardir=False):
"""Normalize path, eliminating double slashes, etc."""
path = os.fspath(path)
if isinstance(path, bytes):
sep = b'\\'
altsep = b'/'
curdir = b'.'
pardir = b'..'
dot = b'.'
dotdot = b'..'
special_prefixes = (b'\\\\.\\', b'\\\\?\\')
else:
sep = '\\'
altsep = '/'
curdir = '.'
pardir = '..'
dot = '.'
dotdot = '..'
special_prefixes = ('\\\\.\\', '\\\\?\\')
if path.startswith(special_prefixes):
# in the case of paths with these prefixes:
Expand All @@ -482,6 +482,8 @@ def normpath(path):
# do not do any normalization, but return the path
# unchanged apart from the call to os.fspath()
return path
curdir = object() if keep_curdir else dot
pardir = object() if keep_pardir else dotdot
path = path.replace(altsep, sep)
prefix, path = splitdrive(path)

Expand All @@ -507,7 +509,7 @@ def normpath(path):
i += 1
# If the path is now empty, substitute '.'
if not prefix and not comps:
comps.append(curdir)
comps.append(dot)
return prefix + sep.join(comps)

def _abspath_fallback(path):
Expand Down
10 changes: 6 additions & 4 deletions Lib/posixpath.py
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Expand Up @@ -334,7 +334,7 @@ def expandvars(path):
# It should be understood that this may change the meaning of the path
# if it contains symbolic links!

def normpath(path):
def normpath(path, *, keep_curdir=False, keep_pardir=False):
"""Normalize path, eliminating double slashes, etc."""
path = os.fspath(path)
if isinstance(path, bytes):
Expand All @@ -349,6 +349,8 @@ def normpath(path):
dotdot = '..'
if path == empty:
return dot
curdir = object() if keep_curdir else dot
pardir = object() if keep_pardir else dotdot
initial_slashes = path.startswith(sep)
# POSIX allows one or two initial slashes, but treats three or more
# as single slash.
Expand All @@ -358,10 +360,10 @@ def normpath(path):
comps = path.split(sep)
new_comps = []
for comp in comps:
if comp in (empty, dot):
if comp in (empty, curdir):
continue
if (comp != dotdot or (not initial_slashes and not new_comps) or
(new_comps and new_comps[-1] == dotdot)):
if (comp != pardir or (not initial_slashes and not new_comps) or
(new_comps and new_comps[-1] == pardir)):
new_comps.append(comp)
elif new_comps:
new_comps.pop()
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125 changes: 125 additions & 0 deletions Lib/test/test_ntpath.py
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Expand Up @@ -236,6 +236,131 @@ def test_normpath(self):
tester("ntpath.normpath('\\\\.\\NUL')", r'\\.\NUL')
tester("ntpath.normpath('\\\\?\\D:/XY\\Z')", r'\\?\D:/XY\Z')

def test_normpath_keep_curdir(self):
tester("ntpath.normpath('A//////././//.//B', keep_curdir=True)", r'A\.\.\.\B')
tester("ntpath.normpath('A/./B', keep_curdir=True)", r'A\.\B')
tester("ntpath.normpath('A/foo/../B', keep_curdir=True)", r'A\B')
tester("ntpath.normpath('C:A//B', keep_curdir=True)", r'C:A\B')
tester("ntpath.normpath('D:A/./B', keep_curdir=True)", r'D:A\.\B')
tester("ntpath.normpath('e:A/foo/../B', keep_curdir=True)", r'e:A\B')

tester("ntpath.normpath('C:///A//B', keep_curdir=True)", r'C:\A\B')
tester("ntpath.normpath('D:///A/./B', keep_curdir=True)", r'D:\A\.\B')
tester("ntpath.normpath('e:///A/foo/../B', keep_curdir=True)", r'e:\A\B')

tester("ntpath.normpath('..', keep_curdir=True)", r'..')
tester("ntpath.normpath('.', keep_curdir=True)", r'.')
tester("ntpath.normpath('', keep_curdir=True)", r'.')
tester("ntpath.normpath('/', keep_curdir=True)", '\\')
tester("ntpath.normpath('c:/', keep_curdir=True)", 'c:\\')
tester("ntpath.normpath('/../.././..', keep_curdir=True)", '\\')
tester("ntpath.normpath('c:/../../..', keep_curdir=True)", 'c:\\')
tester("ntpath.normpath('../.././..', keep_curdir=True)", r'..\..')
tester("ntpath.normpath('K:../.././..', keep_curdir=True)", r'K:..\..')
tester("ntpath.normpath('C:////a/b', keep_curdir=True)", r'C:\a\b')
tester("ntpath.normpath('//machine/share//a/b', keep_curdir=True)", r'\\machine\share\a\b')

tester("ntpath.normpath('\\\\.\\NUL', keep_curdir=True)", r'\\.\NUL')
tester("ntpath.normpath('\\\\?\\D:/XY\\Z', keep_curdir=True)", r'\\?\D:/XY\Z')

def test_normpath_keep_pardir(self):
tester("ntpath.normpath('A//////././//.//B', keep_pardir=True)", r'A\B')
tester("ntpath.normpath('A/./B', keep_pardir=True)", r'A\B')
tester("ntpath.normpath('A/foo/../B', keep_pardir=True)", r'A\foo\..\B')
tester("ntpath.normpath('C:A//B', keep_pardir=True)", r'C:A\B')
tester("ntpath.normpath('D:A/./B', keep_pardir=True)", r'D:A\B')
tester("ntpath.normpath('e:A/foo/../B', keep_pardir=True)", r'e:A\foo\..\B')

tester("ntpath.normpath('C:///A//B', keep_pardir=True)", r'C:\A\B')
tester("ntpath.normpath('D:///A/./B', keep_pardir=True)", r'D:\A\B')
tester("ntpath.normpath('e:///A/foo/../B', keep_pardir=True)", r'e:\A\foo\..\B')

tester("ntpath.normpath('..', keep_pardir=True)", r'..')
tester("ntpath.normpath('.', keep_pardir=True)", r'.')
tester("ntpath.normpath('', keep_pardir=True)", r'.')
tester("ntpath.normpath('/', keep_pardir=True)", '\\')
tester("ntpath.normpath('c:/', keep_pardir=True)", 'c:\\')
tester("ntpath.normpath('/../.././..', keep_pardir=True)", '\\..\\..\\..')
tester("ntpath.normpath('c:/../../..', keep_pardir=True)", 'c:\\..\\..\\..')
tester("ntpath.normpath('../.././..', keep_pardir=True)", r'..\..\..')
tester("ntpath.normpath('K:../.././..', keep_pardir=True)", r'K:..\..\..')
tester("ntpath.normpath('C:////a/b', keep_pardir=True)", r'C:\a\b')
tester("ntpath.normpath('//machine/share//a/b', keep_pardir=True)", r'\\machine\share\a\b')

tester("ntpath.normpath('\\\\.\\NUL', keep_pardir=True)", r'\\.\NUL')
tester("ntpath.normpath('\\\\?\\D:/XY\\Z', keep_pardir=True)", r'\\?\D:/XY\Z')

def test_normpath_keep_curdir_and_pardir(self):
tester("ntpath.normpath("
"'A//////././//.//B', keep_curdir=True, keep_pardir=True)",
r'A\.\.\.\B')
tester("ntpath.normpath("
"'A/./B', keep_curdir=True, keep_pardir=True)",
r'A\.\B')
tester("ntpath.normpath("
"'A/foo/../B', keep_curdir=True, keep_pardir=True)",
r'A\foo\..\B')
tester("ntpath.normpath("
"'C:A//B', keep_curdir=True, keep_pardir=True)",
r'C:A\B')
tester("ntpath.normpath("
"'D:A/./B', keep_curdir=True, keep_pardir=True)",
r'D:A\.\B')
tester("ntpath.normpath("
"'e:A/foo/../B', keep_curdir=True, keep_pardir=True)",
r'e:A\foo\..\B')

tester("ntpath.normpath("
"'C:///A//B', keep_curdir=True, keep_pardir=True)",
r'C:\A\B')
tester("ntpath.normpath("
"'D:///A/./B', keep_curdir=True, keep_pardir=True)",
r'D:\A\.\B')
tester("ntpath.normpath("
"'e:///A/foo/../B', keep_curdir=True, keep_pardir=True)",
r'e:\A\foo\..\B')

tester("ntpath.normpath("
"'..', keep_curdir=True, keep_pardir=True)",
r'..')
tester("ntpath.normpath("
"'.', keep_curdir=True, keep_pardir=True)",
r'.')
tester("ntpath.normpath("
"'', keep_curdir=True, keep_pardir=True)",
r'.')
tester("ntpath.normpath("
"'/', keep_curdir=True, keep_pardir=True)",
'\\')
tester("ntpath.normpath("
"'c:/', keep_curdir=True, keep_pardir=True)",
'c:\\')
tester("ntpath.normpath("
"'/../.././..', keep_curdir=True, keep_pardir=True)",
'\\..\\..\\.\\..')
tester("ntpath.normpath("
"'c:/../../..', keep_curdir=True, keep_pardir=True)",
'c:\\..\\..\\..')
tester("ntpath.normpath("
"'../.././..', keep_curdir=True, keep_pardir=True)",
r'..\..\.\..')
tester("ntpath.normpath("
"'K:../.././..', keep_curdir=True, keep_pardir=True)",
r'K:..\..\.\..')
tester("ntpath.normpath("
"'C:////a/b', keep_curdir=True, keep_pardir=True)",
r'C:\a\b')
tester("ntpath.normpath("
"'//machine/share//a/b', keep_curdir=True, keep_pardir=True)",
r'\\machine\share\a\b')

tester("ntpath.normpath("
"'\\\\.\\NUL', keep_curdir=True, keep_pardir=True)",
r'\\.\NUL')
tester("ntpath.normpath("
"'\\\\?\\D:/XY\\Z', keep_curdir=True, keep_pardir=True)",
r'\\?\D:/XY\Z')

def test_realpath_curdir(self):
expected = ntpath.normpath(os.getcwd())
tester("ntpath.realpath('.')", expected)
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103 changes: 103 additions & 0 deletions Lib/test/test_posixpath.py
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Expand Up @@ -324,6 +324,109 @@ def test_normpath(self):
self.assertEqual(posixpath.normpath(b"///..//./foo/.//bar"),
b"/foo/bar")

def test_normpath_keep_curdir(self):
self.assertEqual(posixpath.normpath("", keep_curdir=True), ".")
self.assertEqual(posixpath.normpath("/", keep_curdir=True), "/")
self.assertEqual(posixpath.normpath("//", keep_curdir=True), "//")
self.assertEqual(posixpath.normpath("///", keep_curdir=True), "/")
self.assertEqual(posixpath.normpath(
"///foo/.//bar//", keep_curdir=True),
"/foo/./bar")
self.assertEqual(posixpath.normpath(
"///foo/.//bar//.//..//.//baz", keep_curdir=True),
"/foo/./bar/./baz")
self.assertEqual(posixpath.normpath(
"///..//./foo/.//bar", keep_curdir=True),
"/./foo/./bar")

self.assertEqual(posixpath.normpath(b"", keep_curdir=True), b".")
self.assertEqual(posixpath.normpath(b"/", keep_curdir=True), b"/")
self.assertEqual(posixpath.normpath(b"//", keep_curdir=True), b"//")
self.assertEqual(posixpath.normpath(b"///", keep_curdir=True), b"/")
self.assertEqual(posixpath.normpath(
b"///foo/.//bar//", keep_curdir=True),
b"/foo/./bar")
self.assertEqual(posixpath.normpath(
b"///foo/.//bar//.//..//.//baz", keep_curdir=True),
b"/foo/./bar/./baz")
self.assertEqual(posixpath.normpath(
b"///..//./foo/.//bar", keep_curdir=True),
b"/./foo/./bar")

def test_normpath_keep_pardir(self):
self.assertEqual(posixpath.normpath("", keep_pardir=True), ".")
self.assertEqual(posixpath.normpath("/", keep_pardir=True), "/")
self.assertEqual(posixpath.normpath("//", keep_pardir=True), "//")
self.assertEqual(posixpath.normpath("///", keep_pardir=True), "/")
self.assertEqual(posixpath.normpath(
"///foo/.//bar//", keep_pardir=True),
"/foo/bar")
self.assertEqual(posixpath.normpath(
"///foo/.//bar//.//..//.//baz", keep_pardir=True),
"/foo/bar/../baz")
self.assertEqual(posixpath.normpath(
"///..//./foo/.//bar", keep_pardir=True),
"/../foo/bar")

self.assertEqual(posixpath.normpath(b"", keep_pardir=True), b".")
self.assertEqual(posixpath.normpath(b"/", keep_pardir=True), b"/")
self.assertEqual(posixpath.normpath(b"//", keep_pardir=True), b"//")
self.assertEqual(posixpath.normpath(b"///", keep_pardir=True), b"/")
self.assertEqual(posixpath.normpath(
b"///foo/.//bar//", keep_pardir=True),
b"/foo/bar")
self.assertEqual(posixpath.normpath(
b"///foo/.//bar//.//..//.//baz", keep_pardir=True),
b"/foo/bar/../baz")
self.assertEqual(posixpath.normpath(
b"///..//./foo/.//bar", keep_pardir=True),
b"/../foo/bar")

def test_normpath_keep_curdir_and_pardir(self):
self.assertEqual(posixpath.normpath(
"", keep_curdir=True, keep_pardir=True),
".")
self.assertEqual(posixpath.normpath(
"/", keep_curdir=True, keep_pardir=True),
"/")
self.assertEqual(posixpath.normpath(
"//", keep_curdir=True, keep_pardir=True),
"//")
self.assertEqual(posixpath.normpath(
"///", keep_curdir=True, keep_pardir=True),
"/")
self.assertEqual(posixpath.normpath(
"///foo/.//bar//", keep_curdir=True, keep_pardir=True),
"/foo/./bar")
self.assertEqual(posixpath.normpath(
"///foo/.//bar//.//..//.//baz", keep_curdir=True, keep_pardir=True),
"/foo/./bar/./.././baz")
self.assertEqual(posixpath.normpath(
"///..//./foo/.//bar", keep_curdir=True, keep_pardir=True),
"/.././foo/./bar")

self.assertEqual(posixpath.normpath(
b"", keep_curdir=True, keep_pardir=True),
b".")
self.assertEqual(posixpath.normpath(
b"/", keep_curdir=True, keep_pardir=True),
b"/")
self.assertEqual(posixpath.normpath(
b"//", keep_curdir=True, keep_pardir=True),
b"//")
self.assertEqual(posixpath.normpath(
b"///", keep_curdir=True, keep_pardir=True),
b"/")
self.assertEqual(posixpath.normpath(
b"///foo/.//bar//", keep_curdir=True, keep_pardir=True),
b"/foo/./bar")
self.assertEqual(posixpath.normpath(
b"///foo/.//bar//.//..//.//baz", keep_curdir=True, keep_pardir=True),
b"/foo/./bar/./.././baz")
self.assertEqual(posixpath.normpath(
b"///..//./foo/.//bar", keep_curdir=True, keep_pardir=True),
b"/.././foo/./bar")

@skip_if_ABSTFN_contains_backslash
def test_realpath_curdir(self):
self.assertEqual(realpath('.'), os.getcwd())
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2021-06-12-18-36-31.bpo-44316.XaUjsk.rst
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@@ -0,0 +1,3 @@
:func:`os.path.normpath` now accepts *keep_curdir* and *keep_pardir*
keyword-only arguments. When set to ``True``, references to the current or
parent directory (``.`` or ``..``) are retained respectively.