gh-118507 : Refactor nt._path_is* to improve applicability for other cases (GH-118755)

Author: nineteendo

Lib/ntpath.py

@@ -288,21 +288,6 @@ def dirname(p):
     return split(p)[0]
 
 
-# Is a path a junction?
-
-if hasattr(os.stat_result, 'st_reparse_tag'):
-    def isjunction(path):
-        """Test whether a path is a junction"""
-        try:
-            st = os.lstat(path)
-        except (OSError, ValueError, AttributeError):
-            return False
-        return st.st_reparse_tag == stat.IO_REPARSE_TAG_MOUNT_POINT
-else:
-    # Use genericpath.isjunction as imported above
-    pass
-
-
 # Is a path a mount point?
 # Any drive letter root (eg c:\)
 # Any share UNC (eg \\server\share)
@@ -911,13 +896,15 @@ def commonpath(paths):
 
 
 try:
-    # The isdir(), isfile(), islink() and exists() implementations in
-    # genericpath use os.stat(). This is overkill on Windows. Use simpler
+    # The isdir(), isfile(), islink(), exists() and lexists() implementations
+    # in genericpath use os.stat(). This is overkill on Windows. Use simpler
     # builtin functions if they are available.
     from nt import _path_isdir as isdir
     from nt import _path_isfile as isfile
     from nt import _path_islink as islink
+    from nt import _path_isjunction as isjunction
     from nt import _path_exists as exists
+    from nt import _path_lexists as lexists
 except ImportError:
     # Use genericpath.* as imported above
     pass

Lib/test/test_genericpath.py

@@ -135,6 +135,9 @@ def test_exists(self):
         self.assertIs(self.pathmodule.exists(filename), False)
         self.assertIs(self.pathmodule.exists(bfilename), False)
 
+        self.assertIs(self.pathmodule.lexists(filename), False)
+        self.assertIs(self.pathmodule.lexists(bfilename), False)
+
         create_file(filename)
 
         self.assertIs(self.pathmodule.exists(filename), True)
@@ -145,14 +148,13 @@ def test_exists(self):
         self.assertIs(self.pathmodule.exists(filename + '\x00'), False)
         self.assertIs(self.pathmodule.exists(bfilename + b'\x00'), False)
 
-        if self.pathmodule is not genericpath:
-            self.assertIs(self.pathmodule.lexists(filename), True)
-            self.assertIs(self.pathmodule.lexists(bfilename), True)
+        self.assertIs(self.pathmodule.lexists(filename), True)
+        self.assertIs(self.pathmodule.lexists(bfilename), True)
 
-            self.assertIs(self.pathmodule.lexists(filename + '\udfff'), False)
-            self.assertIs(self.pathmodule.lexists(bfilename + b'\xff'), False)
-            self.assertIs(self.pathmodule.lexists(filename + '\x00'), False)
-            self.assertIs(self.pathmodule.lexists(bfilename + b'\x00'), False)
+        self.assertIs(self.pathmodule.lexists(filename + '\udfff'), False)
+        self.assertIs(self.pathmodule.lexists(bfilename + b'\xff'), False)
+        self.assertIs(self.pathmodule.lexists(filename + '\x00'), False)
+        self.assertIs(self.pathmodule.lexists(bfilename + b'\x00'), False)
 
     @unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
     @unittest.skipIf(is_emscripten, "Emscripten pipe fds have no stat")

Lib/test/test_ntpath.py

@@ -1095,6 +1095,27 @@ def test_isfile_driveletter(self):
             raise unittest.SkipTest('SystemDrive is not defined or malformed')
         self.assertFalse(os.path.isfile('\\\\.\\' + drive))
 
+    @unittest.skipUnless(hasattr(os, 'pipe'), "need os.pipe()")
+    def test_isfile_anonymous_pipe(self):
+        pr, pw = os.pipe()
+        try:
+            self.assertFalse(ntpath.isfile(pr))
+        finally:
+            os.close(pr)
+            os.close(pw)
+
+    @unittest.skipIf(sys.platform != 'win32', "windows only")
+    def test_isfile_named_pipe(self):
+        import _winapi
+        named_pipe = f'//./PIPE/python_isfile_test_{os.getpid()}'
+        h = _winapi.CreateNamedPipe(named_pipe,
+                                    _winapi.PIPE_ACCESS_INBOUND,
+                                    0, 1, 0, 0, 0, 0)
+        try:
+            self.assertFalse(ntpath.isfile(named_pipe))
+        finally:
+            _winapi.CloseHandle(h)
+
     @unittest.skipIf(sys.platform != 'win32', "windows only")
     def test_con_device(self):
         self.assertFalse(os.path.isfile(r"\\.\CON"))
@@ -1114,8 +1135,12 @@ def test_fast_paths_in_use(self):
         self.assertFalse(inspect.isfunction(os.path.isfile))
         self.assertTrue(os.path.islink is nt._path_islink)
         self.assertFalse(inspect.isfunction(os.path.islink))
+        self.assertTrue(os.path.isjunction is nt._path_isjunction)
+        self.assertFalse(inspect.isfunction(os.path.isjunction))
         self.assertTrue(os.path.exists is nt._path_exists)
         self.assertFalse(inspect.isfunction(os.path.exists))
+        self.assertTrue(os.path.lexists is nt._path_lexists)
+        self.assertFalse(inspect.isfunction(os.path.lexists))
 
     @unittest.skipIf(os.name != 'nt', "Dev Drives only exist on Win32")
     def test_isdevdrive(self):

Misc/NEWS.d/next/Core and Builtins/2024-05-08-18-33-07.gh-issue-118507.OCQsAY.rst

@@ -0,0 +1 @@
+Speedup :func:`os.path.isjunction` and :func:`os.path.lexists` on Windows with a native implementation.