Fix gh-140774: os.chmod fails to clear Read-Only if Archive bit is cleared

Author: pareshjoshij

Lib/test/test_pathlib/test_pathlib.py

@@ -12,6 +12,7 @@
 import stat
 import tempfile
 import unittest
+import subprocess
 from unittest import mock
 from urllib.request import pathname2url
 
@@ -3622,33 +3623,52 @@ def test_walk_symlink_location(self):
 class PosixPathTest(PathTest, PurePosixPathTest):
     cls = pathlib.PosixPath
 
+@unittest.skipIf(os.name != 'nt', 'test requires a Windows-compatible system')
+class WindowsPathTest(PathTest, PureWindowsPathTest):
+    cls = pathlib.WindowsPath
+
     def test_chmod_archive_bit_behavior(self):
+        import subprocess
+
+        # gh-140774: Fix chmod failing to clear Read-Only if Archive bit is cleared.
         base = self.cls(self.base)
         filename = base / 'test_chmod_archive.txt'
         filename.touch()
-        self.addCleanup(filename.unlink, missing_ok=True)
 
-        # Helper to check read-only status
+        # Robust cleanup: Force write permission before deleting
+        def force_remove():
+            try:
+                os.chmod(filename, stat.S_IWRITE)
+            except OSError:
+                pass
+            try:
+                filename.unlink(missing_ok=True)
+            except OSError:
+                pass
+
+        self.addCleanup(force_remove)
+
         def is_read_only(p):
-            return (p.stat().st_file_attributes & stat.FILE_ATTRIBUTE_READONLY) > 0
+            try:
+                return (p.stat().st_file_attributes & stat.FILE_ATTRIBUTE_READONLY) > 0
+            except AttributeError:
+                return False
+
         try:
             # Case 1: Archive bit CLEARED, Read-Only SET
-            # We use attrib command to manipulate the Archive bit directly
+            # We use the Windows 'attrib' command to manipulate the Archive bit directly
             subprocess.run(['attrib', '-a', '+r', str(filename)], check=True, shell=True)
 
-            # This line used to fail silently (bug #140774)
+            # Try to make it Writable (clearing the Read-Only flag)
             filename.chmod(stat.S_IWRITE | stat.S_IREAD)
 
             self.assertFalse(is_read_only(filename),
-                "chmod failed to clear Read-Only when Archive bit was cleared")
+                             "chmod failed to clear Read-Only when Archive bit was cleared")
 
         except subprocess.CalledProcessError:
-            self.skipTest("attrib command failed or not available")
-
-@unittest.skipIf(os.name != 'nt', 'test requires a Windows-compatible system')
-class WindowsPathTest(PathTest, PureWindowsPathTest):
-    cls = pathlib.WindowsPath
-
+            self.skipTest("attrib command failed")
+        except FileNotFoundError:
+            self.skipTest("attrib command not found")
 
 class PathSubclassTest(PathTest):
     class cls(pathlib.Path):

Modules/posixmodule.c

@@ -3987,6 +3987,11 @@ win32_lchmod(LPCWSTR path, int mode)
     if (mode & _S_IWRITE) {
         attr &= ~FILE_ATTRIBUTE_READONLY;
     }
+    if (attr == 0) {
+        /* gh-140774: If all attributes are cleared, set to NORMAL
+           to avoid failing to clear the Read-Only bit. */
+        attr = FILE_ATTRIBUTE_NORMAL;
+    }
     else {
         attr |= FILE_ATTRIBUTE_READONLY;
     }