[3.11] gh-113086: Add tests for os.chmod() and os.lchmod() (GH-113087) (GH-113089)

Also make test_copymode_symlink_to_symlink in test_shutil more strict.
(cherry picked from commit b4f2c89)

Co-authored-by: Serhiy Storchaka <[email protected]>

Author: miss-islington

Lib/test/test_posix.py

@@ -935,6 +935,122 @@ def test_utime(self):
         posix.utime(os_helper.TESTFN, (int(now), int(now)))
         posix.utime(os_helper.TESTFN, (now, now))
 
+    def check_chmod(self, chmod_func, target, **kwargs):
+        mode = os.stat(target).st_mode
+        try:
+            new_mode = mode & ~(stat.S_IWOTH | stat.S_IWGRP | stat.S_IWUSR)
+            chmod_func(target, new_mode, **kwargs)
+            self.assertEqual(os.stat(target).st_mode, new_mode)
+            if stat.S_ISREG(mode):
+                try:
+                    with open(target, 'wb+'):
+                        pass
+                except PermissionError:
+                    pass
+            new_mode = mode | (stat.S_IWOTH | stat.S_IWGRP | stat.S_IWUSR)
+            chmod_func(target, new_mode, **kwargs)
+            self.assertEqual(os.stat(target).st_mode, new_mode)
+            if stat.S_ISREG(mode):
+                with open(target, 'wb+'):
+                    pass
+        finally:
+            posix.chmod(target, mode)
+
+    def test_chmod_file(self):
+        self.check_chmod(posix.chmod, os_helper.TESTFN)
+
+    def tempdir(self):
+        target = os_helper.TESTFN + 'd'
+        posix.mkdir(target)
+        self.addCleanup(posix.rmdir, target)
+        return target
+
+    def test_chmod_dir(self):
+        target = self.tempdir()
+        self.check_chmod(posix.chmod, target)
+
+    @unittest.skipUnless(hasattr(posix, 'lchmod'), 'test needs os.lchmod()')
+    def test_lchmod_file(self):
+        self.check_chmod(posix.lchmod, os_helper.TESTFN)
+        self.check_chmod(posix.chmod, os_helper.TESTFN, follow_symlinks=False)
+
+    @unittest.skipUnless(hasattr(posix, 'lchmod'), 'test needs os.lchmod()')
+    def test_lchmod_dir(self):
+        target = self.tempdir()
+        self.check_chmod(posix.lchmod, target)
+        self.check_chmod(posix.chmod, target, follow_symlinks=False)
+
+    def check_chmod_link(self, chmod_func, target, link, **kwargs):
+        target_mode = os.stat(target).st_mode
+        link_mode = os.lstat(link).st_mode
+        try:
+            new_mode = target_mode & ~(stat.S_IWOTH | stat.S_IWGRP | stat.S_IWUSR)
+            chmod_func(link, new_mode, **kwargs)
+            self.assertEqual(os.stat(target).st_mode, new_mode)
+            self.assertEqual(os.lstat(link).st_mode, link_mode)
+            new_mode = target_mode | (stat.S_IWOTH | stat.S_IWGRP | stat.S_IWUSR)
+            chmod_func(link, new_mode, **kwargs)
+            self.assertEqual(os.stat(target).st_mode, new_mode)
+            self.assertEqual(os.lstat(link).st_mode, link_mode)
+        finally:
+            posix.chmod(target, target_mode)
+
+    def check_lchmod_link(self, chmod_func, target, link, **kwargs):
+        target_mode = os.stat(target).st_mode
+        link_mode = os.lstat(link).st_mode
+        new_mode = link_mode & ~(stat.S_IWOTH | stat.S_IWGRP | stat.S_IWUSR)
+        chmod_func(link, new_mode, **kwargs)
+        self.assertEqual(os.stat(target).st_mode, target_mode)
+        self.assertEqual(os.lstat(link).st_mode, new_mode)
+        new_mode = link_mode | (stat.S_IWOTH | stat.S_IWGRP | stat.S_IWUSR)
+        chmod_func(link, new_mode, **kwargs)
+        self.assertEqual(os.stat(target).st_mode, target_mode)
+        self.assertEqual(os.lstat(link).st_mode, new_mode)
+
+    @os_helper.skip_unless_symlink
+    def test_chmod_file_symlink(self):
+        target = os_helper.TESTFN
+        link = os_helper.TESTFN + '-link'
+        os.symlink(target, link)
+        self.addCleanup(posix.unlink, link)
+        if os.name == 'nt':
+            self.check_lchmod_link(posix.chmod, target, link)
+        else:
+            self.check_chmod_link(posix.chmod, target, link)
+            self.check_chmod_link(posix.chmod, target, link, follow_symlinks=True)
+
+    @os_helper.skip_unless_symlink
+    def test_chmod_dir_symlink(self):
+        target = self.tempdir()
+        link = os_helper.TESTFN + '-link'
+        os.symlink(target, link, target_is_directory=True)
+        self.addCleanup(posix.unlink, link)
+        if os.name == 'nt':
+            self.check_lchmod_link(posix.chmod, target, link)
+        else:
+            self.check_chmod_link(posix.chmod, target, link)
+            self.check_chmod_link(posix.chmod, target, link, follow_symlinks=True)
+
+    @unittest.skipUnless(hasattr(posix, 'lchmod'), 'test needs os.lchmod()')
+    @os_helper.skip_unless_symlink
+    def test_lchmod_file_symlink(self):
+        target = os_helper.TESTFN
+        link = os_helper.TESTFN + '-link'
+        os.symlink(target, link)
+        self.addCleanup(posix.unlink, link)
+        self.check_lchmod_link(posix.chmod, target, link, follow_symlinks=False)
+        self.check_lchmod_link(posix.lchmod, target, link)
+
+    @unittest.skipUnless(hasattr(posix, 'lchmod'), 'test needs os.lchmod()')
+    @os_helper.skip_unless_symlink
+    def test_lchmod_dir_symlink(self):
+        target = self.tempdir()
+        link = os_helper.TESTFN + '-link'
+        os.symlink(target, link)
+        self.addCleanup(posix.unlink, link)
+        self.check_lchmod_link(posix.chmod, target, link, follow_symlinks=False)
+        self.check_lchmod_link(posix.lchmod, target, link)
+
     def _test_chflags_regular_file(self, chflags_func, target_file, **kwargs):
         st = os.stat(target_file)
         self.assertTrue(hasattr(st, 'st_flags'))

Lib/test/test_shutil.py

@@ -908,10 +908,11 @@ def test_copymode_symlink_to_symlink(self):
         os.lchmod(src_link, stat.S_IRWXO|stat.S_IRWXG)
         # link to link
         os.lchmod(dst_link, stat.S_IRWXO)
+        old_mode = os.stat(dst).st_mode
         shutil.copymode(src_link, dst_link, follow_symlinks=False)
         self.assertEqual(os.lstat(src_link).st_mode,
                          os.lstat(dst_link).st_mode)
-        self.assertNotEqual(os.stat(src).st_mode, os.stat(dst).st_mode)
+        self.assertEqual(os.stat(dst).st_mode, old_mode)
         # src link - use chmod
         os.lchmod(dst_link, stat.S_IRWXO)
         shutil.copymode(src_link, dst, follow_symlinks=False)