Improve accuracy of ntpath.normpath() & ntpath.abspath()

python · nineteendo · May 31, 2024 · May 31, 2024 · May 31, 2024 · May 31, 2024
commit a7687c468ea88ec5fd2d71a48ed2e1d57183a8c6
diff --git a/Include/internal/pycore_fileutils.h b/Include/internal/pycore_fileutils.h
@@ -279,7 +279,8 @@ extern size_t _Py_find_basename(const wchar_t *filename);
 // Export for '_testinternalcapi' shared extension
 PyAPI_FUNC(wchar_t*) _Py_normpath(wchar_t *path, Py_ssize_t size);
 
-extern wchar_t *_Py_normpath_and_size(wchar_t *path, Py_ssize_t size, Py_ssize_t *length);
+extern wchar_t *_Py_normpath_and_size(wchar_t *path, Py_ssize_t size, Py_ssize_t *length,
+                                      int explicit_curdir);
 
 // The Windows Games API family does not provide these functions
 // so provide our own implementations. Remove them in case they get added

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
@@ -554,36 +554,48 @@ def normpath(path):
         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
+    def abspath(path):
+        """Return the absolute version of a path."""
+        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)
 
 else:  # use native Windows method on Windows
     def abspath(path):
         """Return the absolute version of a path."""
         try:
             return _getfullpathname(normpath(path))
         except (OSError, ValueError):
-            return _abspath_fallback(path)
+            # See gh-75230, handle outside for cleaner traceback
+            pass
+        path = os.fspath(path)
+        if not isabs(path):
+            if isinstance(path, bytes):
                sep = b'/'
+                cwd = os.getcwdb()
+            else:
+                sep = '/'
+                cwd = os.getcwd()
+            drive, root, path = splitroot(path)
+            if drive and drive != splitroot(cwd)[0]:
+                try:
+                    path = join(_getfullpathname(drive), path)
+                except (OSError, ValueError):
+                    # Invalid drive \x00: on Windows; assume root directory
+                    path = drive + sep + path
+            else:
+                path = join(cwd, root + path)
+        return normpath(path)
 
 try:
     from nt import _findfirstfile, _getfinalpathname, readlink as _nt_readlink

diff --git a/Lib/test/test_ntpath.py b/Lib/test/test_ntpath.py
@@ -347,13 +347,15 @@ def test_normpath(self):
 
         tester("ntpath.normpath('..')", r'..')
         tester("ntpath.normpath('.')", r'.')
+        tester("ntpath.normpath('c:.')", 'c:')
         tester("ntpath.normpath('')", r'.')
         tester("ntpath.normpath('/')", '\\')
         tester("ntpath.normpath('c:/')", 'c:\\')
         tester("ntpath.normpath('/../.././..')", '\\')
         tester("ntpath.normpath('c:/../../..')", 'c:\\')
         tester("ntpath.normpath('../.././..')", r'..\..\..')
         tester("ntpath.normpath('K:../.././..')", r'K:..\..\..')
+        tester("ntpath.normpath('./a/b')", r'a\b')
         tester("ntpath.normpath('C:////a/b')", r'C:\a\b')
         tester("ntpath.normpath('//machine/share//a/b')", r'\\machine\share\a\b')
 
@@ -806,6 +808,9 @@ def test_abspath(self):
         tester('ntpath.abspath("C:\\spam. . .")', "C:\\spam")
         tester('ntpath.abspath("C:/nul")',  "\\\\.\\nul")
         tester('ntpath.abspath("C:\\nul")', "\\\\.\\nul")
+        self.assertTrue(ntpath.isabs(ntpath.abspath("C:spam")))
+        self.assertTrue(ntpath.isabs(ntpath.abspath("C:\x00")))
+        self.assertTrue(ntpath.isabs(ntpath.abspath("\x00:spam")))
         tester('ntpath.abspath("//..")',           "\\\\")
         tester('ntpath.abspath("//../")',          "\\\\..\\")
         tester('ntpath.abspath("//../..")',        "\\\\..\\")
@@ -836,6 +841,20 @@ def test_abspath(self):
             tester('ntpath.abspath("")', cwd_dir)
             tester('ntpath.abspath(" ")', cwd_dir + "\\ ")
             tester('ntpath.abspath("?")', cwd_dir + "\\?")
+            tester('ntpath.abspath("con")', r"\\.\con")
+            # bpo-45354: Windows 11 changed MS-DOS device name handling
+            if sys.getwindowsversion()[:3] < (10, 0, 22000):
+                tester('ntpath.abspath("./con")', r"\\.\con")
+                tester('ntpath.abspath("foo/../con")', r"\\.\con")
+                tester('ntpath.abspath("con/foo/..")', r"\\.\con")
+                tester('ntpath.abspath("con/.")', r"\\.\con")
+            else:
+                tester('ntpath.abspath("./con")', cwd_dir + r"\con")
+                tester('ntpath.abspath("foo/../con")', cwd_dir + r"\con")
+                tester('ntpath.abspath("con/foo/..")', cwd_dir + r"\con")
+                tester('ntpath.abspath("con/.")', cwd_dir + r"\con")
+            tester('ntpath.abspath("./Z:spam")', cwd_dir + r"\Z:spam")
+            tester('ntpath.abspath("spam/../Z:eggs")', cwd_dir + r"\Z:eggs")
             drive, _ = ntpath.splitdrive(cwd_dir)
             tester('ntpath.abspath("/abc/")', drive + "\\abc")
 

diff --git a/Lib/test/test_posixpath.py b/Lib/test/test_posixpath.py
@@ -382,6 +382,7 @@ def test_expanduser_pwd2(self):
         ("///..//./foo/.//bar", "/foo/bar"),
         (".", "."),
         (".//.", "."),
+        ("./foo/bar", "foo/bar"),
         ("..", ".."),
         ("../", ".."),
         ("../foo", "../foo"),

diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
@@ -5526,21 +5526,25 @@ os__path_splitroot_ex_impl(PyObject *module, path_t *path)
 
 
 /*[clinic input]
-os._path_normpath
+os._path_normpath_ex
 
     path: path_t(make_wide=True, nonstrict=True)
+    *
+    explicit_curdir: bool = False
 
 Normalize path, eliminating double slashes, etc.
 [clinic start generated code]*/
 
 static PyObject *
-os__path_normpath_impl(PyObject *module, path_t *path)
-/*[clinic end generated code: output=d353e7ed9410c044 input=3d4ac23b06332dcb]*/
+os__path_normpath_ex_impl(PyObject *module, path_t *path,
+                          int explicit_curdir)
+/*[clinic end generated code: output=4c4c3bf33a70fe57 input=90fe0dfc4b3a751b]*/
 {
     PyObject *result;
     Py_ssize_t norm_len;
     wchar_t *norm_path = _Py_normpath_and_size((wchar_t *)path->wide,
-                                               path->length, &norm_len);
+                                               path->length, &norm_len,
+                                               explicit_curdir);
     if (!norm_len) {
         result = PyUnicode_FromOrdinal('.');
     }
@@ -5553,6 +5557,23 @@ os__path_normpath_impl(P
9E82
yObject *module, path_t *path)
     return result;
 }
 
+
+/*[clinic input]
+os._path_normpath
+
+    path: path_t(make_wide=True, nonstrict=True)
+
+Normalize path, eliminating double slashes, etc.
+[clinic start generated code]*/
+
+static PyObject *
+os__path_normpath_impl(PyObject *module, path_t *path)
+/*[clinic end generated code: output=d353e7ed9410c044 input=3d4ac23b06332dcb]*/
+{
+
+    return os__path_normpath_ex_impl(module, path, 0);
+}
+
 /*[clinic input]
 os.mkdir
 
@@ -16891,6 +16912,7 @@ static PyMethodDef posix_methods[] = {
     OS__GETVOLUMEPATHNAME_METHODDEF
     OS__PATH_SPLITROOT_METHODDEF
     OS__PATH_SPLITROOT_EX_METHODDEF
+    OS__PATH_NORMPATH_EX_METHODDEF
     OS__PATH_NORMPATH_METHODDEF
     OS_GETLOADAVG_METHODDEF
     OS_URANDOM_METHODDEF