[3.15] gh-159320: Enable stack size detection on Android (GH-159321) (#159409)

gh-159320: Enable stack size detection on Android (GH-159321)

Extend the use of pthread_getattr_np in stack size detection from any glibc linux to any glibc *or* android linux. Update tests for android's new recursion limit.
(cherry picked from commit 8ff41c2)

Co-authored-by: T. Wouters <thomas@python.org>
Co-authored-by: Malcolm Smith <smith@chaquo.com>

Author: 3 people

Lib/test/test_ast/test_ast.py

@@ -1056,13 +1056,11 @@ def next(self):
         enum._test_simple_enum(_Precedence, _ast_unparse._Precedence)
 
     @support.cpython_only
-    @support.run_with_limited_c_stack(
-        100_000 if sys.platform == "android" else 500_000)
+    @support.run_with_limited_c_stack(500_000)
     @skip_wasi_stack_overflow()
     @skip_emscripten_stack_overflow()
     def test_ast_recursion_limit(self):
-        # Android test devices have less memory.
-        crash_depth = 100_000 if sys.platform == "android" else 500_000
+        crash_depth = 500_000
         success_depth = 200
         if _testinternalcapi is not None:
             remaining = _testinternalcapi.get_c_recursion_remaining()

Lib/test/test_compile.py

@@ -724,14 +724,12 @@ def test_yet_more_evil_still_undecodable(self):
 
     @support.cpython_only
     @unittest.skipIf(support.is_wasi, "exhausts limited stack on WASI")
-    @support.run_with_limited_c_stack(
-        100_000 if sys.platform == "android" else 500_000)
+    @support.run_with_limited_c_stack(500_000)
     @support.skip_emscripten_stack_overflow()
     def test_compiler_recursion_limit(self):
         # Compiler frames are small
         limit = 100
-        # Android test devices have less memory.
-        crash_depth = limit * (1000 if sys.platform == "android" else 5000)
+        crash_depth = limit * 5000
         success_depth = limit
 
         def check_limit(prefix, repeated, mode="single"):
@@ -1043,8 +1041,7 @@ def test_path_like_objects(self):
     # complex statements.
     @support.requires_resource('cpu')
     def test_stack_overflow(self):
-        # Android test devices have less memory.
-        size = 100_000 if sys.platform == "android" else 200_000
+        size = 200_000
         compile("if a: b\n" * size, "<dummy>", "exec")
 
     # Multiple users rely on the fact that CPython does not generate

Misc/NEWS.d/next/Core_and_Builtins/2026-10-13-16-38-00.gh-issue-159320._Yhg1s.rst

@@ -0,0 +1,2 @@
+Add dynamic detection of stack sizes on Android, allowing safer deep
+recursion.

Python/ceval.c

@@ -154,11 +154,14 @@ hardware_stack_limits(uintptr_t *base, uintptr_t *top, uintptr_t sp)
     *top = (uintptr_t)stack_addr;
     *base = ((uintptr_t)stack_addr) - stack_size;
 #else
-    /// XXX musl supports HAVE_PTHRED_GETATTR_NP, but the resulting stack size
-    /// (on alpine at least) is much smaller than expected and imposes undue limits
-    /// compared to the old stack size estimation.  (We assume musl is not glibc.)
+    // musl supports HAVE_PTHREAD_GETATTR_NP, but the resulting stack size
+    // (on alpine at least) is much smaller than expected and imposes undue
+    // limits compared to the old stack size estimation. musl doesn't give
+    // us a way to detect it, so we have to assume any non-glibc,
+    // non-Android Linux is musl and mustn't rely on pthread_getattr_np.
 #  if defined(HAVE_PTHREAD_GETATTR_NP) && !defined(_AIX) && \
-        !defined(__NetBSD__) && (defined(__GLIBC__) || !defined(__linux__))
+        !defined(__NetBSD__) && \
+        (defined(__GLIBC__) || defined(__ANDROID__) || !defined(__linux__))
     size_t stack_size, guard_size;
     void *stack_addr;
     pthread_attr_t attr;