youknowone · Aug 25, 2026 · Aug 25, 2026 · Aug 25, 2026 · Aug 25, 2026 · Aug 25, 2026
diff --git a/Lib/compression/zstd/_zstdfile.py b/Lib/compression/zstd/_zstdfile.py
@@ -34,7 +34,7 @@ def __init__(self, file, /, mode='r', *,
                  level=None, options=None, zstd_dict=None):
         """Open a Zstandard compressed file in binary mode.
 
-        *file* can be either an file-like object, or a file name to open.
+        *file* can be either a file-like object, or a file name to open.
 
         *mode* can be 'r' for reading (default), 'w' for (over)writing, 'x'
         for creating exclusively, or 'a' for appending.  These can
@@ -246,6 +246,7 @@ def peek(self, size=-1):
         return self._buffer.peek(size)
 
     def __next__(self):
+        self._check_can_read()
         if ret := self._buffer.readline():
             return ret
         raise StopIteration

diff --git a/Lib/socket.py b/Lib/socket.py
@@ -891,7 +891,9 @@ def has_dualstack_ipv6():
     try:
         with socket(AF_INET6, SOCK_STREAM) as sock:
             sock.setsockopt(IPPROTO_IPV6, IPV6_V6ONLY, 0)
-            return True
+            # On some platforms (e.g. DragonFly BSD) setting IPV6_V6ONLY to 0
+            # silently has no effect, so check that it was actually cleared.
+            return sock.getsockopt(IPPROTO_IPV6, IPV6_V6ONLY) == 0
     except error:
         return False
 

diff --git a/Lib/string/__init__.py b/Lib/string/__init__.py
@@ -83,7 +83,14 @@ def __init_subclass__(cls):
     def _compile_pattern(cls):
         import re  # deferred import, for performance
 
+        # `pattern` may be the `_TemplatePattern` sentinel (not yet compiled), an
+        # already-compiled regular expression object (as documented), or a string
+        # regular expression.  An already-compiled object is returned as-is; the
+        # other two are compiled and cached back on the class.
         pattern = cls.__dict__.get('pattern', _TemplatePattern)
+        if isinstance(pattern, re.Pattern):
+            # re.compile() rejects flags on an already-compiled pattern.
+            return pattern
         if pattern is _TemplatePattern:
             delim = re.escape(cls.delimiter)
             id = cls.idpattern

diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
@@ -1075,6 +1075,48 @@ def test_frame_readline(self):
         #   15: .    STOP
         self.assertEqual(self.loads(pickled), 42)
 
+    def test_frame_ends_at_opcode_boundary(self):
+        # A frame may end exactly between two opcodes; the following opcodes
+        # are then read from outside the frame.
+        for pickled in [
+            b'\x80\x04\x95\x01\x00\x00\x00\x00\x00\x00\x00N.',  # FRAME 1, NONE, STOP
+            b'\x80\x04\x95\x00\x00\x00\x00\x00\x00\x00\x00N.',  # empty FRAME, NONE, STOP
+        ]:
+            with self.subTest(pickled=pickled):
+                self.assertIsNone(self.loads(pickled))
+
+    def test_frame_does_not_straddle_boundary(self):
+        # An opcode or its argument must not cross a frame boundary
+        # (PEP 3154).  Such a pickle must be rejected rather than silently
+        # reading past the declared frame length, which would make the
+        # meaning of the pickle diverge from its pickletools disassembly.
+        # See gh-154848.
+        for pickled in [
+            # FRAME 6; UNICODE argument read by readline() straddles the frame.
+            b'\x80\x04\x95\x06\x00\x00\x00\x00\x00\x00\x00Vhelloworld\n.',
+            # FRAME 6; BINUNICODE argument straddles the frame.
+            b'\x80\x04\x95\x06\x00\x00\x00\x00\x00\x00\x00'
+            b'X\x0a\x00\x00\x00helloworld.',
+            # FRAME 3; SHORT_BINBYTES argument straddles the frame.
+            b'\x80\x04\x95\x03\x00\x00\x00\x00\x00\x00\x00C\x0ahelloworld.',
+            # FRAME 9; GLOBAL argument (second line) straddles the frame.
+            b'\x80\x04\x95\x09\x00\x00\x00\x00\x00\x00\x00cbuiltins\nprint\n.',
+        ]:
+            self.check_unpickling_error(self.truncated_errors, pickled)
+
+    def test_nested_frame(self):
+        # A new frame must not begin before the current one has ended: here
+        # the outer frame still has data left after the inner frame header.
+        pickled = (b'\x80\x04\x95\x0c\x00\x00\x00\x00\x00\x00\x00'
+                   b'N\x95\x00\x00\x00\x00\x00\x00\x00\x00NN.')
+        self.check_unpickling_error(self.truncated_errors, pickled)
+
+        # But the inner frame header may lie inside the outer frame as long as
+        # it exactly consumes it.
+        pickled = (b'\x80\x04\x95\x0a\x00\x00\x00\x00\x00\x00\x00'
+                   b'N\x95\x00\x00\x00\x00\x00\x00\x00\x00N.')
+        self.assertIsNone(self.loads(pickled))
+
     def test_compat_unpickle(self):
         # xrange(1, 7)
         pickled = b'\x80\x02c__builtin__\nxrange\nK\x01K\x07K\x01\x87R.'

diff --git a/Lib/test/test_ast/test_ast.py b/Lib/test/test_ast/test_ast.py
@@ -24,7 +24,9 @@
 
 from test import support
 from test.support import os_helper
-from test.support import skip_emscripten_stack_overflow, skip_wasi_stack_overflow, skip_if_unlimited_stack_size
+from test.support import (skip_emscripten_stack_overflow,
+                          skip_wasi_stack_overflow,
+                          skip_if_unlimited_stack_size, skip_if_huge_c_stack)
 from test.support.ast_helper import ASTTestMixin
 from test.support.import_helper import ensure_lazy_imports
 from test.test_ast.utils import to_tuple
@@ -990,7 +992,8 @@ def next(self):
         enum._test_simple_enum(_Precedence, _ast_unparse._Precedence)
 
     @support.cpython_only
-    @skip_if_unlimited_stack_size
+    @support.run_with_limited_c_stack(
+        100_000 if sys.platform == "android" else 500_000)
     @skip_wasi_stack_overflow()
     @skip_emscripten_stack_overflow()
     def test_ast_recursion_limit(self):
@@ -1973,7 +1976,7 @@ def test_level_as_none(self):
         exec(code, ns)
         self.assertIn('sleep', ns)
 
-    @skip_if_unlimited_stack_size
+    @skip_if_huge_c_stack()
     @skip_emscripten_stack_overflow()
     def test_recursion_direct(self):
         e = ast.UnaryOp(op=ast.Not(), lineno=0, col_offset=0, operand=ast.Constant(1))
@@ -1982,7 +1985,7 @@ def test_recursion_direct(self):
             with support.infinite_recursion():
                 compile(ast.Expression(e), "<test>", "eval")
 
-    @skip_if_unlimited_stack_size
+    @skip_if_huge_c_stack()
     @skip_emscripten_stack_overflow()
     def test_recursion_indirect(self):
         e = ast.UnaryOp(op=ast.Not(), lineno=0, col_offset=0, operand=ast.Constant(1))

diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
@@ -371,6 +371,7 @@ def test_deepcopy_list(self):
         self.assertIsNot(x, y)
         self.assertIsNot(x[0], y[0])
 
+    @support.skip_if_huge_c_stack()
     @support.skip_emscripten_stack_overflow()
     @support.skip_wasi_stack_overflow()
     def test_deepcopy_reflexive_list(self):
@@ -400,6 +401,7 @@ def test_deepcopy_tuple_of_immutables(self):
         y = copy.deepcopy(x)
         self.assertIs(x, y)
 
+    @support.skip_if_huge_c_stack()
     @support.skip_emscripten_stack_overflow()
     @support.skip_wasi_stack_overflow()
     def test_deepcopy_reflexive_tuple(self):
@@ -419,6 +421,7 @@ def test_deepcopy_dict(self):
         self.assertIsNot(x, y)
         self.assertIsNot(x["foo"], y["foo"])
 
+    @support.skip_if_huge_c_stack()
     @support.skip_emscripten_stack_overflow()
     @support.skip_wasi_stack_overflow()
     def test_deepcopy_reflexive_dict(self):
@@ -579,6 +582,7 @@ def __eq__(self, other):
         self.assertIsNot(y, x)
         self.assertIsNot(y.foo, x.foo)
 
+    @support.skip_if_huge_c_stack()
     def test_deepcopy_reflexive_inst(self):
         class C:
             pass
@@ -641,6 +645,7 @@ def __eq__(self, other):
         self.assertEqual(y, x)
         self.assertIsNot(y.foo, x.foo)
 
+    @support.skip_if_huge_c_stack()
     def test_reconstruct_reflexive(self):
         class C(object):
             pass

diff --git a/Lib/test/test_inspect/test_inspect.py b/Lib/test/test_inspect/test_inspect.py
@@ -7,6 +7,7 @@
 import functools
 import gc
 import importlib
+import importlib.util
 import inspect
 import io
 import linecache
@@ -6443,6 +6444,19 @@ def test_wrapped_descriptor(self):
 
 
 class TestMain(unittest.TestCase):
+    @staticmethod
+    def _expected_cached(module):
+        # assert_python_ok() runs the subprocess in isolated mode (-I), which
+        # ignores PYTHONPYCACHEPREFIX, so compute the expected cached path the
+        # same way (i.e. without any pycache prefix) to stay independent of the
+        # environment the test suite is run in.  Modules without a cached path
+        # (e.g. frozen modules such as ntpath/importlib.machinery on Windows)
+        # report None, so preserve that.
+        if module.__spec__.cached is None:
+            return None
+        with support.swap_attr(sys, 'pycache_prefix', None):
+            return importlib.util.cache_from_source(module.__spec__.origin)
+
     def test_only_source(self):
         module = importlib.import_module('unittest')
         rc, out, err = assert_python_ok('-m', 'inspect',
@@ -6482,13 +6496,13 @@ def test_details(self):
         rc, out, err = assert_python_ok(*args, '-m', 'inspect',
                                         'unittest', '--details')
         output = out.decode()
+        cached = self._expected_cached(module)
         # Just a quick sanity check on the output
         self.assertIn(module.__spec__.name, output)
         self.assertIn(module.__name__, output)
         self.assertIn(module.__spec__.origin, output)
         self.assertIn(module.__file__, output)
-        self.assertIn(module.__spec__.cached, output)
-        self.assertIn(module.__cached__, output)
+        self.assertIn(cached, output)
         self.assertEqual(err, b'')
 
 

diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
@@ -98,6 +98,15 @@ def create_file(filename, content=b'content'):
         fp.write(content)
 
 
+# On platforms without a native spawnv(), os.py provides a Python fallback
+# built on fork()+exec*() that reports argument conversion failures from the
+# child as exit status 127 instead of raising, so tests of the C
+# implementation's error paths cannot run against it.
+requires_native_spawnv = unittest.skipUnless(
+    isinstance(getattr(os, 'spawnv', None), types.BuiltinFunctionType),
+    'requires the native C os.spawnv')
+
+
 # bpo-41625: On AIX, splice() only works with a socket, not with a pipe.
 requires_splice_pipe = unittest.skipIf(sys.platform.startswith("aix"),
                                        'on AIX, splice() only accepts sockets')
@@ -159,7 +168,8 @@ def test_getcwd_long_path(self):
                         # ("The filename or extension is too long")
                         break
                     except OSError as exc:
-                        if exc.errno == errno.ENAMETOOLONG:
+                        # DragonFly BSD raises EFAULT for a too long path.
+                        if exc.errno in (errno.ENAMETOOLONG, errno.EFAULT):
                             break
                         else:
                             raise
@@ -890,11 +900,18 @@ def support_subsecond(self, filename):
                 or (st.st_mtime != st[8])
                 or (st.st_ctime != st[9]))
 
+    def support_atime(self, filename):
+        # Heuristic to check if the filesystem stores the access time.
+        # Use whole seconds, to not depend on the timestamp resolution.
+        os.utime(filename, (1, 2))
+        return os.stat(filename).st_atime == 1
+
     def _test_utime(self, set_time, filename=None):
         if not filename:
             filename = self.fname
 
         support_subsecond = self.support_subsecond(filename)
+        support_atime = self.support_atime(filename)
         if support_subsecond:
             # Timestamp with a resolution of 1 microsecond (10^-6).
             #
@@ -921,18 +938,22 @@ def _test_utime(self, set_time, filename=None):
             # digits worth of sub-second precision.
             # Some day it would be good to fix this upstream.
             delta=1e-5
-            self.assertAlmostEqual(st.st_atime, atime_ns * 1e-9, delta=1e-5)
+            if support_atime:
+                self.assertAlmostEqual(st.st_atime, atime_ns * 1e-9, delta=1e-5)
+                self.assertAlmostEqual(st.st_atime_ns, atime_ns, delta=1e9 * 1e-5)
             self.assertAlmostEqual(st.st_mtime, mtime_ns * 1e-9, delta=1e-5)
-            self.assertAlmostEqual(st.st_atime_ns, atime_ns, delta=1e9 * 1e-5)
             self.assertAlmostEqual(st.st_mtime_ns, mtime_ns, delta=1e9 * 1e-5)
         else:
             if support_subsecond:
-                self.assertAlmostEqual(st.st_atime, atime_ns * 1e-9, delta=1e-6)
+                if support_atime:
+                    self.assertAlmostEqual(st.st_atime, atime_ns * 1e-9, delta=1e-6)
                 self.assertAlmostEqual(st.st_mtime, mtime_ns * 1e-9, delta=1e-6)
             else:
-                self.assertEqual(st.st_atime, atime_ns * 1e-9)
+                if support_atime:
+                    self.assertEqual(st.st_atime, atime_ns * 1e-9)
                 self.assertEqual(st.st_mtime, mtime_ns * 1e-9)
-            self.assertEqual(st.st_atime_ns, atime_ns)
+            if support_atime:
+                self.assertEqual(st.st_atime_ns, atime_ns)
             self.assertEqual(st.st_mtime_ns, mtime_ns)
 
     def test_utime(self):
@@ -3763,6 +3784,26 @@ def test_spawnve_noargs(self):
         self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, program, ('',), {})
         self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, program, [''], {})
 
+    @unittest.expectedFailureIfWindows('TODO: RUSTPYTHON; AssertionError: "must contain only strings" does not match "expected str, bytes or os.PathLike object, not int"')
+    @requires_native_spawnv
+    def test_spawnv_arg_conversion_errors(self):
+        # A non-path argv item gets a TypeError naming the argument...
+        with self.assertRaisesRegex(TypeError, 'must contain only strings'):
+            os.spawnv(os.P_NOWAIT, sys.executable, [sys.executable, 123])
+        # ...but other conversion errors must not be masked as TypeError
+        # (gh-151416).
+        with self.assertRaises(ValueError):
+            os.spawnv(os.P_NOWAIT, sys.executable,
+                      [sys.executable, 'embedded\0null'])
+
+        class RaisingPath:
+            def __fspath__(self):
+                raise RuntimeError('gotcha')
+
+        with self.assertRaisesRegex(RuntimeError, 'gotcha'):
+            os.spawnv(os.P_NOWAIT, sys.executable,
+                      [sys.executable, RaisingPath()])
+
     def _test_invalid_env(self, spawn):
         program = sys.executable
         args = self.quote_args([program, '-c', 'pass'])
@@ -4927,6 +4968,28 @@ def test_posix_pty_functions(self):
         son_path = os.ptsname(mother_fd)
         son_fd = os.open(son_path, os.O_RDWR|os.O_NOCTTY)
         self.addCleanup(os.close, son_fd)
+        if sys.platform.startswith('sunos'):
+            import fcntl
+            I_PUSH = 0x5302
+            TIOCNOTTY = 0x7471
+            # Pushing "ptem" makes the slave a terminal, which a session
+            # leader without a controlling terminal then acquires as one
+            # despite O_NOCTTY.  Note whether we already had one.
+            try:
+                os.close(os.open('/dev/tty', os.O_RDONLY|os.O_NOCTTY))
+                had_ctty = True
+            except OSError:
+                had_ctty = False
+            fcntl.ioctl(son_fd, I_PUSH, b'ptem\0')
+            fcntl.ioctl(son_fd, I_PUSH, b'ldterm\0')
+            if not had_ctty and os.getsid(0) == os.getpid():
+                # Disown it, otherwise closing the file descriptors sends
+                # SIGHUP to the session.  TIOCNOTTY sends it too.
+                old_handler = signal.signal(signal.SIGHUP, signal.SIG_IGN)
+                try:
+                    fcntl.ioctl(son_fd, TIOCNOTTY)
+                finally:
+                    signal.signal(signal.SIGHUP, old_handler)
         self.assertEqual(os.ptsname(mother_fd), os.ttyname(son_fd))
 
     @unittest.skipUnless(hasattr(os, 'spawnl'), "need os.spawnl()")
@@ -5258,6 +5321,31 @@ def test_current_directory(self):
         finally:
             os.chdir(old_dir)
 
+    @unittest.expectedFailureIfWindows("TODO: RUSTPYTHON; FileNotFoundError")
+    @unittest.skipIf(sys.platform != 'win32', "Win32 specific test")
+    def test_windows_trailing_space_path(self):
+        import pathlib
+
+        filename = self.create_file("file.txt")
+        path = self.path + " "
+
+        self.assertTrue(os.path.exists(path))
+        os.stat(path)
+        with open(filename + " ", "rb") as file:
+            self.assertEqual(file.read(), b"python")
+
+        self.assertEqual(os.listdir(path), ["file.txt"])
+        with os.scandir(path) as entries:
+            self.assertEqual([entry.name for entry in entries], ["file.txt"])
+        pathlib_entries = list(pathlib.Path(path).iterdir())
+        self.assertEqual([entry.name for entry in pathlib_entries], ["file.txt"])
+        del pathlib_entries
+
+        extended_path = "\\\\?\\" + path
+        self.assertFalse(os.path.exists(extended_path))
+        self.assertRaises(FileNotFoundError, os.listdir, extended_path)
+        self.assertRaises(FileNotFoundError, os.scandir, extended_path)
+
     def test_repr(self):
         entry = self.create_file_entry()
         self.assertEqual(repr(entry), "<DirEntry 'file.txt'>")

diff --git a/Lib/test/test_pickle.py b/Lib/test/test_pickle.py
@@ -594,7 +594,7 @@ def test_pickler(self):
                 0)  # Write buffer is cleared after every dump().
 
         def test_unpickler(self):
-            basesize = support.calcobjsize('2P2n2P 2P2n2i5P 2P3n8P2n3i')
+            basesize = support.calcobjsize('2P2n2P 2P2n2i5P 2P5n8P2n3i')
             unpickler = _pickle.Unpickler
             P = struct.calcsize('P')  # Size of memo table entry.
             n = struct.calcsize('n')  # Size of mark table entry.