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gh-153711: Guard dup3/pipe2 with __builtin_available on Apple platforms #154718

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gh-153711: Guard dup3/pipe2 with __builtin_available on Apple platforms #154718

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e5fbe3b
gh-153711: Guard dup3/pipe2 with __builtin_available on Apple platforms
Vamsi-klu Jul 26, 2026
548b366
gh-153711: Fix os.pipe2 availability directive syntax
Vamsi-klu Jul 26, 2026
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2 changes: 1 addition & 1 deletion Doc/library/os.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -1448,7 +1448,7 @@ or `the MSDN <https://msdn.microsoft.com/en-us/library/z0kc8e3z.aspx>`_ on Windo
Return a pair of file descriptors ``(r, w)`` usable for reading and writing,
respectively.

.. availability:: Unix, not WASI, not macOS, not iOS.
.. availability:: Unix, not WASI, macOS >= 27.0, iOS >= 27.0.

@chatgpt-codex-connector chatgpt-codex-connector Bot Jul 26, 2026

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P2 Badge Correct the iOS availability claim

The documentation promises os.pipe2 on iOS 27+, but configure.ac deliberately skips the AC_CHECK_FUNCS invocation containing pipe2 whenever ac_sys_system is iOS (lines 5526–5532). Consequently HAVE_PIPE2 is never defined and the method is not compiled or exported on any iOS version; either enable the configure check for supported iOS versions or continue documenting this as unavailable on iOS.

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.. versionadded:: 3.3

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16 changes: 16 additions & 0 deletions Lib/test/test_os/test_posix.py
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Expand Up @@ -2388,6 +2388,22 @@ def test_pwritev(self):
self.assertNotHasAttr(os, "pwritev")
self.assertNotHasAttr(os, "preadv")

def test_pipe2(self):
self._verify_available("HAVE_PIPE2")
if self.mac_ver >= (27, 0):
self.assertHasAttr(os, "pipe2")
else:
self.assertNotHasAttr(os, "pipe2")

def test_dup3(self):
self._verify_available("HAVE_DUP3")
r, w = os.pipe()
self.addCleanup(os.close, r)
self.addCleanup(os.close, w)
# Must not crash even when dup3 unavailable at runtime.
# os.dup2 returns fd2 (here w); do not double-close.
os.dup2(r, w, inheritable=False)

def test_stat(self):
self._verify_available("HAVE_FSTATAT")
if self.mac_ver >= (10, 10):
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/macOS/2026-07-26-07-01-41.gh-issue-153711.ad8g_Q.rst
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@@ -0,0 +1,3 @@
Guard ``os.dup2`` and ``os.pipe``/``os.pipe2`` against calling ``dup3``/``pipe2``
when the symbols are weak-imported but unavailable at runtime (Xcode 27 SDKs on
older macOS).
57 changes: 45 additions & 12 deletions Modules/posixmodule.c
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Expand Up @@ -504,6 +504,8 @@ static const unsigned int _Py_STATX_KNOWN = (STATX_BASIC_STATS | STATX_BTIME
# define HAVE_MKFIFOAT_RUNTIME __builtin_available(macOS 13.0, iOS 16.0, tvOS 16.0, watchOS 9.0, *)
# define HAVE_MKNODAT_RUNTIME __builtin_available(macOS 13.0, iOS 16.0, tvOS 16.0, watchOS 9.0, *)
# define HAVE_PTSNAME_R_RUNTIME __builtin_available(macOS 10.13.4, iOS 11.3, tvOS 11.3, watchOS 4.3, *)
# define HAVE_DUP3_RUNTIME __builtin_available(macOS 27.0, iOS 27.0, tvOS 27.0, watchOS 27.0, *)
# define HAVE_PIPE2_RUNTIME __builtin_available(macOS 27.0, iOS 27.0, tvOS 27.0, watchOS 27.0, *)

# define HAVE_POSIX_SPAWN_SETSID_RUNTIME __builtin_available(macOS 10.15, *)

Expand Down Expand Up @@ -589,6 +591,14 @@ static const unsigned int _Py_STATX_KNOWN = (STATX_BASIC_STATS | STATX_BTIME
# define HAVE_PTSNAME_R_RUNTIME (ptsname_r != NULL)
# endif

# ifdef HAVE_DUP3
# define HAVE_DUP3_RUNTIME (dup3 != NULL)
# endif

# ifdef HAVE_PIPE2
# define HAVE_PIPE2_RUNTIME (pipe2 != NULL)
# endif

#endif

#ifdef HAVE_FUTIMESAT
Expand Down Expand Up @@ -619,6 +629,8 @@ static const unsigned int _Py_STATX_KNOWN = (STATX_BASIC_STATS | STATX_BTIME
# define HAVE_MKFIFOAT_RUNTIME 1
# define HAVE_MKNODAT_RUNTIME 1
# define HAVE_PTSNAME_R_RUNTIME 1
# define HAVE_DUP3_RUNTIME 1
# define HAVE_PIPE2_RUNTIME 1
#endif


Expand Down Expand Up @@ -11910,17 +11922,22 @@ os_dup2_impl(PyObject *module, int fd, int fd2, int inheritable)

#ifdef HAVE_DUP3
if (!inheritable && dup3_works != 0) {
Py_BEGIN_ALLOW_THREADS
res = dup3(fd, fd2, O_CLOEXEC);
Py_END_ALLOW_THREADS
if (res < 0) {
if (dup3_works == -1)
dup3_works = (errno != ENOSYS);
if (dup3_works) {
posix_error();
return -1;
if (HAVE_DUP3_RUNTIME) {
Py_BEGIN_ALLOW_THREADS
res = dup3(fd, fd2, O_CLOEXEC);
Py_END_ALLOW_THREADS
if (res < 0) {
if (dup3_works == -1)
dup3_works = (errno != ENOSYS);
if (dup3_works) {
posix_error();
return -1;
}
}
}
else {
dup3_works = 0;
}
}

if (inheritable || dup3_works == 0)
Expand Down Expand Up @@ -12779,9 +12796,13 @@ os_pipe_impl(PyObject *module)
#else

#ifdef HAVE_PIPE2
Py_BEGIN_ALLOW_THREADS
res = pipe2(fds, O_CLOEXEC);
Py_END_ALLOW_THREADS
res = -1;
errno = ENOSYS;
if (HAVE_PIPE2_RUNTIME) {
Py_BEGIN_ALLOW_THREADS
res = pipe2(fds, O_CLOEXEC);
Py_END_ALLOW_THREADS
}

if (res != 0 && errno == ENOSYS)
{
Expand Down Expand Up @@ -18811,6 +18832,18 @@ posixmodule_exec(PyObject *m)
}
#endif

#if defined(HAVE_PIPE2)
if (HAVE_PIPE2_RUNTIME) {} else {

@chatgpt-codex-connector chatgpt-codex-connector Bot Jul 26, 2026

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P1 Badge Guard the remaining direct pipe2 call at compile time

When building with an Xcode 27 SDK for a macOS deployment target below 27, removing pipe2 from the module dictionary happens too late to make the build succeed: os_pipe2_impl still calls the availability-annotated pipe2 unguarded at Modules/posixmodule.c:12861, while configure.ac:2797-2802 promotes Clang's unguarded-availability diagnostic to an error. The call needs a lexical availability guard or the same targeted diagnostic suppression used for the runtime-removed preadv/pwritev methods.

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PyObject *dct = PyModule_GetDict(m);
if (dct == NULL) {
return -1;
}
if (PyDict_PopString(dct, "pipe2", NULL) < 0) {
return -1;
}
}
#endif

#ifdef HAVE_STATX
if (statx == NULL) {
PyObject* dct = PyModule_GetDict(m);
Expand Down
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