gh-116401: Fix blocking os.fwalk() and shutil.rmtree() on opening a named pipe (GH-116421)

Author: serhiy-storchaka

Lib/os.py

@@ -475,7 +475,7 @@ def fwalk(top=".", topdown=True, onerror=None, *, follow_symlinks=False, dir_fd=
         # lstat()/open()/fstat() trick.
         if not follow_symlinks:
             orig_st = stat(top, follow_symlinks=False, dir_fd=dir_fd)
-        topfd = open(top, O_RDONLY, dir_fd=dir_fd)
+        topfd = open(top, O_RDONLY | O_NONBLOCK, dir_fd=dir_fd)
         try:
             if (follow_symlinks or (st.S_ISDIR(orig_st.st_mode) and
                                     path.samestat(orig_st, stat(topfd)))):
@@ -524,7 +524,7 @@ def _fwalk(topfd, toppath, isbytes, topdown, onerror, follow_symlinks):
                         assert entries is not None
                         name, entry = name
                         orig_st = entry.stat(follow_symlinks=False)
-                dirfd = open(name, O_RDONLY, dir_fd=topfd)
+                dirfd = open(name, O_RDONLY | O_NONBLOCK, dir_fd=topfd)
             except OSError as err:
                 if onerror is not None:
                     onerror(err)

Lib/shutil.py

@@ -681,7 +681,7 @@ def _rmtree_safe_fd(topfd, path, onexc):
                     continue
         if is_dir:
             try:
-                dirfd = os.open(entry.name, os.O_RDONLY, dir_fd=topfd)
+                dirfd = os.open(entry.name, os.O_RDONLY | os.O_NONBLOCK, dir_fd=topfd)
                 dirfd_closed = False
             except FileNotFoundError:
                 continue
@@ -786,7 +786,7 @@ def onexc(*args):
             onexc(os.lstat, path, err)
             return
         try:
-            fd = os.open(path, os.O_RDONLY, dir_fd=dir_fd)
+            fd = os.open(path, os.O_RDONLY | os.O_NONBLOCK, dir_fd=dir_fd)
             fd_closed = False
         except OSError as err:
             onexc(os.open, path, err)

Lib/test/test_glob.py

@@ -344,6 +344,18 @@ def test_glob_non_directory(self):
         eq(self.rglob('nonexistent', '*'), [])
         eq(self.rglob('nonexistent', '**'), [])
 
+    @unittest.skipUnless(hasattr(os, "mkfifo"), 'requires os.mkfifo()')
+    @unittest.skipIf(sys.platform == "vxworks",
+                    "fifo requires special path on VxWorks")
+    def test_glob_named_pipe(self):
+        path = os.path.join(self.tempdir, 'mypipe')
+        os.mkfifo(path)
+        self.assertEqual(self.rglob('mypipe'), [path])
+        self.assertEqual(self.rglob('mypipe*'), [path])
+        self.assertEqual(self.rglob('mypipe', ''), [])
+        self.assertEqual(self.rglob('mypipe', 'sub'), [])
+        self.assertEqual(self.rglob('mypipe', '*'), [])
+
     def test_glob_many_open_files(self):
         depth = 30
         base = os.path.join(self.tempdir, 'deep')

Lib/test/test_os.py

@@ -1298,6 +1298,7 @@ def test_ror_operator(self):
 
 class WalkTests(unittest.TestCase):
     """Tests for os.walk()."""
+    is_fwalk = False
 
     # Wrapper to hide minor differences between os.walk and os.fwalk
     # to tests both functions with the same code base
@@ -1332,14 +1333,14 @@ def setUp(self):
         self.sub11_path = join(self.sub1_path, "SUB11")
         sub2_path = join(self.walk_path, "SUB2")
         sub21_path = join(sub2_path, "SUB21")
-        tmp1_path = join(self.walk_path, "tmp1")
+        self.tmp1_path = join(self.walk_path, "tmp1")
         tmp2_path = join(self.sub1_path, "tmp2")
         tmp3_path = join(sub2_path, "tmp3")
         tmp5_path = join(sub21_path, "tmp3")
         self.link_path = join(sub2_path, "link")
         t2_path = join(os_helper.TESTFN, "TEST2")
         tmp4_path = join(os_helper.TESTFN, "TEST2", "tmp4")
-        broken_link_path = join(sub2_path, "broken_link")
+        self.broken_link_path = join(sub2_path, "broken_link")
         broken_link2_path = join(sub2_path, "broken_link2")
         broken_link3_path = join(sub2_path, "broken_link3")
 
@@ -1349,13 +1350,13 @@ def setUp(self):
         os.makedirs(sub21_path)
         os.makedirs(t2_path)
 
-        for path in tmp1_path, tmp2_path, tmp3_path, tmp4_path, tmp5_path:
+        for path in self.tmp1_path, tmp2_path, tmp3_path, tmp4_path, tmp5_path:
             with open(path, "x", encoding='utf-8') as f:
                 f.write("I'm " + path + " and proud of it.  Blame test_os.\n")
 
         if os_helper.can_symlink():
             os.symlink(os.path.abspath(t2_path), self.link_path)
-            os.symlink('broken', broken_link_path, True)
+            os.symlink('broken', self.broken_link_path, True)
             os.symlink(join('tmp3', 'broken'), broken_link2_path, True)
             os.symlink(join('SUB21', 'tmp5'), broken_link3_path, True)
             self.sub2_tree = (sub2_path, ["SUB21", "link"],
@@ -1451,6 +1452,11 @@ def test_walk_symlink(self):
         else:
             self.fail("Didn't follow symlink with followlinks=True")
 
+        walk_it = self.walk(self.broken_link_path, follow_symlinks=True)
+        if self.is_fwalk:
+            self.assertRaises(FileNotFoundError, next, walk_it)
+        self.assertRaises(StopIteration, next, walk_it)
+
     def test_walk_bad_dir(self):
         # Walk top-down.
         errors = []
@@ -1472,6 +1478,73 @@ def test_walk_bad_dir(self):
         finally:
             os.rename(path1new, path1)
 
+    def test_walk_bad_dir2(self):
+        walk_it = self.walk('nonexisting')
+        if self.is_fwalk:
+            self.assertRaises(FileNotFoundError, next, walk_it)
+        self.assertRaises(StopIteration, next, walk_it)
+
+        walk_it = self.walk('nonexisting', follow_symlinks=True)
+        if self.is_fwalk:
+            self.assertRaises(FileNotFoundError, next, walk_it)
+        self.assertRaises(StopIteration, next, walk_it)
+
+        walk_it = self.walk(self.tmp1_path)
+        self.assertRaises(StopIteration, next, walk_it)
+
+        walk_it = self.walk(self.tmp1_path, follow_symlinks=True)
+        if self.is_fwalk:
+            self.assertRaises(NotADirectoryError, next, walk_it)
+        self.assertRaises(StopIteration, next, walk_it)
+
+    @unittest.skipUnless(hasattr(os, "mkfifo"), 'requires os.mkfifo()')
+    @unittest.skipIf(sys.platform == "vxworks",
+                    "fifo requires special path on VxWorks")
+    def test_walk_named_pipe(self):
+        path = os_helper.TESTFN + '-pipe'
+        os.mkfifo(path)
+        self.addCleanup(os.unlink, path)
+
+        walk_it = self.walk(path)
+        self.assertRaises(StopIteration, next, walk_it)
+
+        walk_it = self.walk(path, follow_symlinks=True)
+        if self.is_fwalk:
+            self.assertRaises(NotADirectoryError, next, walk_it)
+        self.assertRaises(StopIteration, next, walk_it)
+
+    @unittest.skipUnless(hasattr(os, "mkfifo"), 'requires os.mkfifo()')
+    @unittest.skipIf(sys.platform == "vxworks",
+                    "fifo requires special path on VxWorks")
+    def test_walk_named_pipe2(self):
+        path = os_helper.TESTFN + '-dir'
+        os.mkdir(path)
+        self.addCleanup(shutil.rmtree, path)
+        os.mkfifo(os.path.join(path, 'mypipe'))
+
+        errors = []
+        walk_it = self.walk(path, onerror=errors.append)
+        next(walk_it)
+        self.assertRaises(StopIteration, next, walk_it)
+        self.assertEqual(errors, [])
+
+        errors = []
+        walk_it = self.walk(path, onerror=errors.append)
+        root, dirs, files = next(walk_it)
+        self.assertEqual(root, path)
+        self.assertEqual(dirs, [])
+        self.assertEqual(files, ['mypipe'])
+        dirs.extend(files)
+        files.clear()
+        if self.is_fwalk:
+            self.assertRaises(NotADirectoryError, next, walk_it)
+        self.assertRaises(StopIteration, next, walk_it)
+        if self.is_fwalk:
+            self.assertEqual(errors, [])
+        else:
+            self.assertEqual(len(errors), 1, errors)
+            self.assertIsInstance(errors[0], NotADirectoryError)
+
     def test_walk_many_open_files(self):
         depth = 30
         base = os.path.join(os_helper.TESTFN, 'deep')
@@ -1537,6 +1610,7 @@ def test_walk_above_recursion_limit(self):
 @unittest.skipUnless(hasattr(os, 'fwalk'), "Test needs os.fwalk()")
 class FwalkTests(WalkTests):
     """Tests for os.fwalk()."""
+    is_fwalk = True
 
     def walk(self, top, **kwargs):
         for root, dirs, files, root_fd in self.fwalk(top, **kwargs):

Lib/test/test_shutil.py

@@ -667,6 +667,23 @@ def test_rmtree_on_junction(self):
         finally:
             shutil.rmtree(TESTFN, ignore_errors=True)
 
+    @unittest.skipUnless(hasattr(os, "mkfifo"), 'requires os.mkfifo()')
+    @unittest.skipIf(sys.platform == "vxworks",
+                    "fifo requires special path on VxWorks")
+    def test_rmtree_on_named_pipe(self):
+        os.mkfifo(TESTFN)
+        try:
+            with self.assertRaises(NotADirectoryError):
+                shutil.rmtree(TESTFN)
+            self.assertTrue(os.path.exists(TESTFN))
+        finally:
+            os.unlink(TESTFN)
+
+        os.mkdir(TESTFN)
+        os.mkfifo(os.path.join(TESTFN, 'mypipe'))
+        shutil.rmtree(TESTFN)
+        self.assertFalse(os.path.exists(TESTFN))
+
     @unittest.skipIf(sys.platform[:6] == 'cygwin',
                      "This test can't be run on Cygwin (issue #1071513).")
     @os_helper.skip_if_dac_override

Misc/NEWS.d/next/Library/2024-03-06-18-30-37.gh-issue-116401.3Wcda2.rst

@@ -0,0 +1,2 @@
+Fix blocking :func:`os.fwalk` and :func:`shutil.rmtree` on opening named
+pipe.