[3.13] gh-153711: Avoid use of dup3 and pipe2 calls introduced in macOS 27 (#155211)

https://github.com/python/cpython/commit/e86913423b4e1aa7b7ff8de3b0df9055d5117159
commit: e86913423b4e1aa7b7ff8de3b0df9055d5117159
branch: 3.13
author: Ned Deily <[email protected]>
committer: ned-deily <[email protected]>
date: 2026-08-05T03:30:17-04:00
summary:

[3.13] gh-153711: Avoid use of dup3 and pipe2 calls introduced in macOS 27 (#155211)

This prevents potential segfaults when builds are used on older
systems and avoids adding new code for supporting weaklinking.

files:
A Misc/NEWS.d/next/macOS/2026-08-05-02-02-33.gh-issue-153711.pO9fFb.rst
M configure
M configure.ac

diff --git a/Misc/NEWS.d/next/macOS/2026-08-05-02-02-33.gh-issue-153711.pO9fFb.rst b/Misc/NEWS.d/next/macOS/2026-08-05-02-02-33.gh-issue-153711.pO9fFb.rst
new file mode 100644
index 000000000000000..90804c179a4b4a4
--- /dev/null
+++ b/Misc/NEWS.d/next/macOS/2026-08-05-02-02-33.gh-issue-153711.pO9fFb.rst
@@ -0,0 +1,3 @@
+On macOS, do not attempt to use the :manpage:`dup3(2)` and
+:manpage:`pipe2(2)` system calls introduced in
+macOS 27 to prevent problems when running on older systems.
diff --git a/configure b/configure
index c42bffecdcfcdd8..51e657ff0d61e31 100755
--- a/configure
+++ b/configure
@@ -19381,13 +19381,7 @@ fi
 # header definition prevents usage - autoconf doesn't use the headers), or
 # raise an error if used at runtime. Force these symbols off.
 if test "$ac_sys_system" != "iOS" ; then
-  ac_fn_c_check_func "$LINENO" "dup3" "ac_cv_func_dup3"
-if test "x$ac_cv_func_dup3" = xyes
-then :
-  printf "%s\n" "#define HAVE_DUP3 1" >>confdefs.h
-
-fi
-ac_fn_c_check_func "$LINENO" "getentropy" "ac_cv_func_getentropy"
+  ac_fn_c_check_func "$LINENO" "getentropy" "ac_cv_func_getentropy"
 if test "x$ac_cv_func_getentropy" = xyes
 then :
   printf "%s\n" "#define HAVE_GETENTROPY 1" >>confdefs.h
@@ -19398,12 +19392,6 @@ if test "x$ac_cv_func_getgroups" = xyes
 then :
   printf "%s\n" "#define HAVE_GETGROUPS 1" >>confdefs.h
 
-fi
-ac_fn_c_check_func "$LINENO" "pipe2" "ac_cv_func_pipe2"
-if test "x$ac_cv_func_pipe2" = xyes
-then :
-  printf "%s\n" "#define HAVE_PIPE2 1" >>confdefs.h
-
 fi
 ac_fn_c_check_func "$LINENO" "system" "ac_cv_func_system"
 if test "x$ac_cv_func_system" = xyes
@@ -19412,6 +19400,24 @@ then :
 
 fi
 
+fi
+# In addition, macOS introduced dup3 and pipe2 in macOS 27, late in the
+# lifetime of this version of Python. Rather than adding weaklinking
+# support for them, just continue to ignore them.
+if test "$ac_sys_system" != "iOS" -a "$ac_sys_system" != "Darwin"; then
+  ac_fn_c_check_func "$LINENO" "dup3" "ac_cv_func_dup3"
+if test "x$ac_cv_func_dup3" = xyes
+then :
+  printf "%s\n" "#define HAVE_DUP3 1" >>confdefs.h
+
+fi
+ac_fn_c_check_func "$LINENO" "pipe2" "ac_cv_func_pipe2"
+if test "x$ac_cv_func_pipe2" = xyes
+then :
+  printf "%s\n" "#define HAVE_PIPE2 1" >>confdefs.h
+
+fi
+
 fi
 
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $CC options needed to detect all undeclared functions" >&5
diff --git a/configure.ac b/configure.ac
index 047005fd7177b6f..f93a9f29b39aff8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5282,7 +5282,13 @@ fi
 # header definition prevents usage - autoconf doesn't use the headers), or
 # raise an error if used at runtime. Force these symbols off.
 if test "$ac_sys_system" != "iOS" ; then
-  AC_CHECK_FUNCS([dup3 getentropy getgroups pipe2 system])
+  AC_CHECK_FUNCS([getentropy getgroups system])
+fi
+# In addition, macOS introduced dup3 and pipe2 in macOS 27, late in the
+# lifetime of this version of Python. Rather than adding weaklinking
+# support for them, just continue to ignore them.
+if test "$ac_sys_system" != "iOS" -a "$ac_sys_system" != "Darwin"; then
+  AC_CHECK_FUNCS([dup3 pipe2])
 fi
 
 AC_CHECK_DECL([dirfd],

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