Oct 5, 2023 · Oct 3, 2023
diff --git a/Doc/library/os.path.rst b/Doc/library/os.path.rst

   Return the canonical path of the specified filename, eliminating any symbolic
   links encountered in the path (if they are supported by the operating
   system).
   system). On Windows, this function will also resolve MS-DOS (also called 8.3)
   style names such as ``C:\\PROGRA~1`` to ``C:\\Program Files``.

   If a path doesn't exist or a symlink loop is encountered, and *strict* is
   ``True``, :exc:`OSError` is raised. If *strict* is ``False``, the path is
diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
  if supported.
  (Contributed by Victor Stinner in :gh:`109649`.)

 * :func:`os.path.realpath` now resolves MS-DOS style file names even if
  the file is not accessible.
  (Contributed by Moonsik Park in :gh:`82367`.)

 New Modules
 ===========
diff --git a/Lib/ntpath.py b/Lib/ntpath.py
 import genericpath
 from genericpath import *


 __all__ = ["normcase","isabs","join","splitdrive","splitroot","split","splitext",
           "basename","dirname","commonprefix","getsize","getmtime",
           "getatime","getctime", "islink","exists","lexists","isdir","isfile",
            return _abspath_fallback(path)

 try:
    from nt import _getfinalpathname, readlink as _nt_readlink
    from nt import_findfirstfile,_getfinalpathname, readlink as _nt_readlink
 except ImportError:
    # realpath is a no-op on systems without _getfinalpathname support.
    realpath = abspath
                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 we get these errors, try to get the real name of the file without accessing it.
                if ex.winerror in (1, 5, 32, 50, 87, 1920, 1921):
                    try:
                        name = _findfirstfile(path)
                        path, _ = split(path)
                    except OSError:
                        path, name = split(path)
                else:
                    path, name = split(path)
                if path and not name:
                    return path + tail
                tail = join(name, tail) if tail else name
diff --git a/Lib/test/test_ntpath.py b/Lib/test/test_ntpath.py
 import ntpath
 import os
 import string
 import subprocess
 import sys
 import unittest
 import warnings
        with os_helper.change_cwd(test_dir_short):
            self.assertPathEqual(test_file_long, ntpath.realpath("file.txt"))

    @unittest.skipUnless(HAVE_GETFINALPATHNAME, 'need _getfinalpathname')
    def test_realpath_permission(self):
        # Test whether python can resolve the real filename of a
        # shortened file name even if it does not have permission to access it.
        ABSTFN = ntpath.realpath(os_helper.TESTFN)

        os_helper.unlink(ABSTFN)
        os_helper.rmtree(ABSTFN)
        os.mkdir(ABSTFN)
        self.addCleanup(os_helper.rmtree, ABSTFN)

        test_file = ntpath.join(ABSTFN, "LongFileName123.txt")
        test_file_short = ntpath.join(ABSTFN, "LONGFI~1.TXT")

        with open(test_file, "wb") as f:
            f.write(b"content")
        # Automatic generation of short names may be disabled on
        # NTFS volumes for the sake of performance.
        # They're not supported at all on ReFS and exFAT.
        subprocess.run(
            # Try to set the short name manually.
            ['fsutil.exe', 'file', 'setShortName', test_file, 'LONGFI~1.TXT'],
            creationflags=subprocess.DETACHED_PROCESS
        )

        try:
            self.assertPathEqual(test_file, ntpath.realpath(test_file_short))
        except AssertionError:
            raise unittest.SkipTest('the filesystem seems to lack support for short filenames')

        # Deny the right to [S]YNCHRONIZE on the file to
        # force nt._getfinalpathname to fail with ERROR_ACCESS_DENIED.
        p = subprocess.run(
            ['icacls.exe', test_file, '/deny', '*S-1-5-32-545:(S)'],
            creationflags=subprocess.DETACHED_PROCESS
        )

        if p.returncode:
            raise unittest.SkipTest('failed to deny access to the test file')

        self.assertPathEqual(test_file, ntpath.realpath(test_file_short))

    def test_expandvars(self):
        with os_helper.EnvironmentVarGuard() as env:
            env.clear()
diff --git a/Misc/ACKS b/Misc/ACKS
 Alexandre Parenteau
 Dan Parisien
 HyeSoo Park
 Moonsik Park
 William Park
 Claude Paroz
 Heikki Partanen
diff --git a/Misc/NEWS.d/next/Windows/2023-10-03-12-30-59.gh-issue-82367.nxwfMx.rst b/Misc/NEWS.d/next/Windows/2023-10-03-12-30-59.gh-issue-82367.nxwfMx.rst
 :func:`os.path.realpath` now resolves MS-DOS style file names even if
 the file is not accessible. Patch by Moonsik Park.
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
    return result;
 }

 /*[clinic input]
 os._findfirstfile
    path: path_t
    /
 A function to get the real file name without accessing the file in Windows.
 [clinic start generated code]*/

 static PyObject *
 os__findfirstfile_impl(PyObject *module, path_t *path)
 /*[clinic end generated code: output=106dd3f0779c83dd input=0734dff70f60e1a8]*/
 {
    PyObject *result;
    HANDLE hFindFile;
    WIN32_FIND_DATAW wFileData;
    WCHAR *wRealFileName;

    Py_BEGIN_ALLOW_THREADS
    hFindFile = FindFirstFileW(path->wide, &wFileData);
    Py_END_ALLOW_THREADS

    if (hFindFile == INVALID_HANDLE_VALUE) {
        path_error(path);
        return NULL;
    }

    wRealFileName = wFileData.cFileName;
    result = PyUnicode_FromWideChar(wRealFileName, wcslen(wRealFileName));
    FindClose(hFindFile);
    return result;
 }


 /*[clinic input]
 os._getvolumepathname
    OS__GETFULLPATHNAME_METHODDEF
    OS__GETDISKUSAGE_METHODDEF
    OS__GETFINALPATHNAME_METHODDEF
    OS__FINDFIRSTFILE_METHODDEF
    OS__GETVOLUMEPATHNAME_METHODDEF
    OS__PATH_SPLITROOT_METHODDEF
    OS__PATH_NORMPATH_METHODDEF
Original file line number	Diff line number	Diff line change
Expand Up		@@ -377,7 +377,8 @@ the :mod:`glob` module.)

		Return the canonical path of the specified filename, eliminating any symbolic
		links encountered in the path (if they are supported by the operating
		system).
		system). On Windows, this function will also resolve MS-DOS (also called 8.3)
		style names such as ``C:\\PROGRA~1`` to ``C:\\Program Files``.

		If a path doesn't exist or a symlink loop is encountered, and strict is
		``True``, :exc:`OSError` is raised. If strict is ``False``, the path is
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -97,6 +97,9 @@ Other Language Changes
		if supported.
		(Contributed by Victor Stinner in :gh:`109649`.)

		* :func:`os.path.realpath` now resolves MS-DOS style file names even if
		the file is not accessible.
		(Contributed by Moonsik Park in :gh:`82367`.)

		New Modules
		===========
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -23,7 +23,6 @@
		import genericpath
		from genericpath import *


		__all__ = ["normcase","isabs","join","splitdrive","splitroot","split","splitext",
		"basename","dirname","commonprefix","getsize","getmtime",
		"getatime","getctime", "islink","exists","lexists","isdir","isfile",
Expand DownExpand Up		@@ -601,7 +600,7 @@ def abspath(path):
		return _abspath_fallback(path)

		try:
		from nt import _getfinalpathname, readlink as _nt_readlink
		from nt import_findfirstfile,_getfinalpathname, readlink as _nt_readlink
		except ImportError:
		# realpath is a no-op on systems without _getfinalpathname support.
		realpath = abspath
Expand DownExpand Up		@@ -688,10 +687,15 @@ def _getfinalpathname_nonstrict(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 we get these errors, try to get the real name of the file without accessing it.
		if ex.winerror in (1, 5, 32, 50, 87, 1920, 1921):
		try:
		name = _findfirstfile(path)
		path, _ = split(path)
		except OSError:
		path, name = split(path)
		else:
		path, name = split(path)
		if path and not name:
		return path + tail
		tail = join(name, tail) if tail else name
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2,6 +2,7 @@
		import ntpath
		import os
		import string
		import subprocess
		import sys
		import unittest
		import warnings
Expand DownExpand Up		@@ -637,6 +638,48 @@ def test_realpath_cwd(self):
		with os_helper.change_cwd(test_dir_short):
		self.assertPathEqual(test_file_long, ntpath.realpath("file.txt"))

		@unittest.skipUnless(HAVE_GETFINALPATHNAME, 'need _getfinalpathname')
		def test_realpath_permission(self):
		# Test whether python can resolve the real filename of a
		# shortened file name even if it does not have permission to access it.
		ABSTFN = ntpath.realpath(os_helper.TESTFN)

		os_helper.unlink(ABSTFN)
		os_helper.rmtree(ABSTFN)
		os.mkdir(ABSTFN)
		self.addCleanup(os_helper.rmtree, ABSTFN)

		test_file = ntpath.join(ABSTFN, "LongFileName123.txt")
		test_file_short = ntpath.join(ABSTFN, "LONGFI~1.TXT")

		with open(test_file, "wb") as f:
		f.write(b"content")
moonsikpark marked this conversation as resolved. Show resolvedHide resolved
		# Automatic generation of short names may be disabled on
		# NTFS volumes for the sake of performance.
		# They're not supported at all on ReFS and exFAT.
		subprocess.run(
		# Try to set the short name manually.
		['fsutil.exe', 'file', 'setShortName', test_file, 'LONGFI~1.TXT'],
		creationflags=subprocess.DETACHED_PROCESS
		)

		try:
		self.assertPathEqual(test_file, ntpath.realpath(test_file_short))
		except AssertionError:
		raise unittest.SkipTest('the filesystem seems to lack support for short filenames')

		# Deny the right to [S]YNCHRONIZE on the file to
		# force nt._getfinalpathname to fail with ERROR_ACCESS_DENIED.
		p = subprocess.run(
		['icacls.exe', test_file, '/deny', '*S-1-5-32-545:(S)'],
		creationflags=subprocess.DETACHED_PROCESS
		)

		if p.returncode:
		raise unittest.SkipTest('failed to deny access to the test file')

		self.assertPathEqual(test_file, ntpath.realpath(test_file_short))

		def test_expandvars(self):
		with os_helper.EnvironmentVarGuard() as env:
		env.clear()
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1373,6 +1373,7 @@ Peter Parente
		Alexandre Parenteau
		Dan Parisien
		HyeSoo Park
		Moonsik Park
		William Park
		Claude Paroz
		Heikki Partanen
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		:func:`os.path.realpath` now resolves MS-DOS style file names even if
		the file is not accessible. Patch by Moonsik Park.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -4809,6 +4809,37 @@ os__getfinalpathname_impl(PyObject module, path_t path)
		return result;
		}

		/*[clinic input]
		os._findfirstfile
		path: path_t
		/
		A function to get the real file name without accessing the file in Windows.
		[clinic start generated code]*/

		static PyObject *
		os__findfirstfile_impl(PyObject module, path_t path)
		/[clinic end generated code: output=106dd3f0779c83dd input=0734dff70f60e1a8]/
		{
		PyObject *result;
		HANDLE hFindFile;
		WIN32_FIND_DATAW wFileData;
		WCHAR *wRealFileName;

		Py_BEGIN_ALLOW_THREADS
		hFindFile = FindFirstFileW(path->wide, &wFileData);
		Py_END_ALLOW_THREADS

		if (hFindFile == INVALID_HANDLE_VALUE) {
		path_error(path);
		return NULL;
		}

		wRealFileName = wFileData.cFileName;
		result = PyUnicode_FromWideChar(wRealFileName, wcslen(wRealFileName));
		FindClose(hFindFile);
		return result;
		}


		/*[clinic input]
		os._getvolumepathname
Expand DownExpand Up		@@ -15961,6 +15992,7 @@ static PyMethodDef posix_methods[] = {
		OS__GETFULLPATHNAME_METHODDEF
		OS__GETDISKUSAGE_METHODDEF
		OS__GETFINALPATHNAME_METHODDEF
		OS__FINDFIRSTFILE_METHODDEF
		OS__GETVOLUMEPATHNAME_METHODDEF
		OS__PATH_SPLITROOT_METHODDEF
		OS__PATH_NORMPATH_METHODDEF
Expand Down