From: Rok Mandeljc <rok.mandeljc@gmail.com>
Date: Wed, 24 Sep 2025 10:57:00 +0000 (+0200)
Subject: gh-139231: Fix estimation of available stack size for recursion limit on macOS (GH... 
X-Git-Tag: v3.15.0a1~213
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7016044de919fa2f14f7c0e0d15ac076b00f16a0;p=thirdparty%2FPython%2Fcpython.git

gh-139231: Fix estimation of available stack size for recursion limit on macOS (GH-139232)

Use `pthread_get_stackaddr_np()` and `pthread_get_stacksize_np()` to determine the stack address and size.
---

diff --git a/Python/ceval.c b/Python/ceval.c
index 7abbc9e9fd12..0ccaacaf3ed5 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -451,6 +451,13 @@ _Py_InitializeRecursionLimits(PyThreadState *tstate)
     SetThreadStackGuarantee(&guarantee);
     _tstate->c_stack_hard_limit = ((uintptr_t)low) + guarantee + _PyOS_STACK_MARGIN_BYTES;
     _tstate->c_stack_soft_limit = _tstate->c_stack_hard_limit + _PyOS_STACK_MARGIN_BYTES;
+#elif defined(__APPLE__)
+    pthread_t this_thread = pthread_self();
+    void *stack_addr = pthread_get_stackaddr_np(this_thread); // top of the stack
+    size_t stack_size = pthread_get_stacksize_np(this_thread);
+    _tstate->c_stack_top = (uintptr_t)stack_addr;
+    _tstate->c_stack_hard_limit = _tstate->c_stack_top - stack_size;
+    _tstate->c_stack_soft_limit = _tstate->c_stack_hard_limit + _PyOS_STACK_MARGIN_BYTES;
 #else
     uintptr_t here_addr = _Py_get_machine_stack_pointer();
 /// XXX musl supports HAVE_PTHRED_GETATTR_NP, but the resulting stack size