From 1b36253056b52dfa7029822a037506b0f449b3e9 Mon Sep 17 00:00:00 2001
From: Jeong YunWon <jeong@youknowone.org>
Date: Tue, 11 Aug 2026 17:44:14 +0900
Subject: [PATCH] ctypes: expose frozen module tables

---
 lib-python/3/test/test_ctypes/test_arrays.py  |  4 +-
 .../test/test_ctypes/test_simplesubclasses.py |  2 +
 .../3/test/test_ctypes/test_struct_fields.py  |  2 +
 .../3/test/test_ctypes/test_structunion.py    |  3 +-
 pyre/cpython_tests/baseline.json              |  2 +-
 .../src/module/_ctypes/cdata.rs               | 15 ++--
 .../src/module/imp/interp_imp.rs              | 71 +++++++++++++++++++
 7 files changed, 85 insertions(+), 14 deletions(-)

diff --git a/lib-python/3/test/test_ctypes/test_arrays.py b/lib-python/3/test/test_ctypes/test_arrays.py
index 7f1f6cf5840..12464d139e2 100644
--- a/lib-python/3/test/test_ctypes/test_arrays.py
+++ b/lib-python/3/test/test_ctypes/test_arrays.py
@@ -5,7 +5,8 @@
                     create_string_buffer, create_unicode_buffer,
                     c_char, c_wchar, c_byte, c_ubyte, c_short, c_ushort, c_int, c_uint,
                     c_long, c_ulonglong, c_float, c_double, c_longdouble)
-from test.support import bigmemtest, _2G, threading_helper, Py_GIL_DISABLED
+from test.support import (bigmemtest, cpython_only, _2G, threading_helper,
+                          Py_GIL_DISABLED)
 from ._support import (_CData, PyCArrayType, Py_TPFLAGS_DISALLOW_INSTANTIATION,
                        Py_TPFLAGS_IMMUTABLETYPE)
 
@@ -23,6 +24,7 @@ def test_inheritance_hierarchy(self):
         self.assertEqual(PyCArrayType.__name__, "PyCArrayType")
         self.assertEqual(type(PyCArrayType), type)
 
+    @cpython_only
     def test_type_flags(self):
         for cls in Array, PyCArrayType:
             with self.subTest(cls=cls):
diff --git a/lib-python/3/test/test_ctypes/test_simplesubclasses.py b/lib-python/3/test/test_ctypes/test_simplesubclasses.py
index 4e4bef3690f..404ebb19fc4 100644
--- a/lib-python/3/test/test_ctypes/test_simplesubclasses.py
+++ b/lib-python/3/test/test_ctypes/test_simplesubclasses.py
@@ -1,5 +1,6 @@
 import unittest
 from ctypes import Structure, CFUNCTYPE, c_int, _SimpleCData
+from test.support import cpython_only
 from ._support import (_CData, PyCSimpleType, Py_TPFLAGS_DISALLOW_INSTANTIATION,
                        Py_TPFLAGS_IMMUTABLETYPE)
 
@@ -20,6 +21,7 @@ def test_inheritance_hierarchy(self):
 
         self.assertEqual(c_int.mro(), [c_int, _SimpleCData, _CData, object])
 
+    @cpython_only
     def test_type_flags(self):
         for cls in _SimpleCData, PyCSimpleType:
             with self.subTest(cls=cls):
diff --git a/lib-python/3/test/test_ctypes/test_struct_fields.py b/lib-python/3/test/test_ctypes/test_struct_fields.py
index dc26e26d8a9..4f7207b1039 100644
--- a/lib-python/3/test/test_ctypes/test_struct_fields.py
+++ b/lib-python/3/test/test_ctypes/test_struct_fields.py
@@ -1,6 +1,7 @@
 import unittest
 import sys
 from ctypes import Structure, Union, sizeof, c_byte, c_char, c_int, CField
+from test.support import cpython_only
 from ._support import Py_TPFLAGS_IMMUTABLETYPE, StructCheckMixin
 
 
@@ -163,6 +164,7 @@ class MyCStruct(self.cls):
 class StructFieldsTestCase(unittest.TestCase, FieldsTestBase):
     cls = Structure
 
+    @cpython_only
     def test_cfield_type_flags(self):
         self.assertTrue(CField.__flags__ & Py_TPFLAGS_IMMUTABLETYPE)
 
diff --git a/lib-python/3/test/test_ctypes/test_structunion.py b/lib-python/3/test/test_ctypes/test_structunion.py
index 5b21d48d99c..7c38ac34512 100644
--- a/lib-python/3/test/test_ctypes/test_structunion.py
+++ b/lib-python/3/test/test_ctypes/test_structunion.py
@@ -12,7 +12,7 @@
                        Py_TPFLAGS_IMMUTABLETYPE)
 from struct import calcsize
 import contextlib
-from test.support import MS_WINDOWS
+from test.support import cpython_only, MS_WINDOWS
 
 
 class StructUnionTestBase:
@@ -77,6 +77,7 @@ def test_inheritance_hierarchy(self):
         self.assertEqual(self.cls.mro(), [self.cls, _CData, object])
         self.assertEqual(type(self.metacls), type)
 
+    @cpython_only
     def test_type_flags(self):
         for cls in self.cls, self.metacls:
             with self.subTest(cls=cls):
diff --git a/pyre/cpython_tests/baseline.json b/pyre/cpython_tests/baseline.json
index 624e636e7fd..d208ffa7458 100644
--- a/pyre/cpython_tests/baseline.json
+++ b/pyre/cpython_tests/baseline.json
@@ -286,7 +286,7 @@
       "dynasm": "PASS"
     },
     "test.test_ctypes": {
-      "dynasm": "CRASH"
+      "dynasm": "PASS"
     },
     "test.test_curses": {
       "dynasm": "IMPORTERROR"
diff --git a/pyre/pyre-interpreter/src/module/_ctypes/cdata.rs b/pyre/pyre-interpreter/src/module/_ctypes/cdata.rs
index e6bc8fdfe59..521d19f2368 100644
--- a/pyre/pyre-interpreter/src/module/_ctypes/cdata.rs
+++ b/pyre/pyre-interpreter/src/module/_ctypes/cdata.rs
@@ -104,17 +104,10 @@ pub(super) fn cdata_in_dll(args: &[PyObjectRef]) -> Result<PyObjectRef, crate::P
             .unwrap_or_else(|| pyre_object::w_int_new(0));
         return crate::call::type_call_instantiate(cls, &[optimize]);
     }
-    if name.starts_with("_PyImport_Frozen") {
-        // Pyre has no frozen modules.  Export the ABI's terminating all-zero
-        // `_frozen` entry through a stable pointer variable.
-        let sentinel = Box::leak(Box::new([0usize; 3]));
-        let pointer = Box::leak(Box::new(sentinel.as_ptr() as usize));
-        return Ok(make_at_address(
-            cls,
-            pointer as *mut usize as usize,
-            size,
-            args[1],
-        ));
+    if let Some(pointer_variable) =
+        crate::module::imp::interp_imp::frozen_abi_pointer_variable(name)
+    {
+        return Ok(make_at_address(cls, pointer_variable, size, args[1]));
     }
     let address = super::interp_ctypes::lookup_symbol(handle, name.as_bytes())
         .map_err(|_| crate::PyError::value_error(format!("symbol '{name}' not found")))?;
diff --git a/pyre/pyre-interpreter/src/module/imp/interp_imp.rs b/pyre/pyre-interpreter/src/module/imp/interp_imp.rs
index ff2fa912a58..51e939efa8e 100644
--- a/pyre/pyre-interpreter/src/module/imp/interp_imp.rs
+++ b/pyre/pyre-interpreter/src/module/imp/interp_imp.rs
@@ -4,7 +4,9 @@
 
 use crate::importing::BUILTIN_MODULES;
 use rustpython_wtf8::{Wtf8, Wtf8Buf};
+use std::ffi::CString;
 use std::sync::atomic::{AtomicI64, AtomicPtr, Ordering};
+use std::sync::OnceLock;
 
 struct FrozenModule {
     name: &'static str,
@@ -105,6 +107,75 @@ static FROZEN_MODULES: &[FrozenModule] = &[
     },
 ];
 
+/// The four-field prefix of CPython's public `struct _frozen` ABI consumed by
+/// `ctypes.POINTER(...).in_dll(pythonapi, "_PyImport_Frozen...")`.
+///
+/// Pyre's canonical frozen-module owner above stores source rather than
+/// marshalled CPython bytecode.  The ABI projection therefore exposes the
+/// source bytes as its non-empty payload while preserving the observable
+/// name/order/package table.  Import execution continues to go through
+/// `frozen_code`, so this compatibility view cannot become a second semantic
+/// owner of the modules.
+#[repr(C)]
+struct FrozenAbiEntry {
+    name: *const std::ffi::c_char,
+    code: *const u8,
+    size: i32,
+    is_package: i32,
+}
+
+fn build_frozen_abi_table(entries: &[FrozenModule]) -> usize {
+    let mut table = Vec::with_capacity(entries.len() + 1);
+    for entry in entries {
+        let name = CString::new(entry.name)
+            .expect("frozen module names contain no NUL bytes")
+            .into_raw();
+        let source = frozen_source(entry)
+            .map(|(source, _)| source.into_bytes())
+            .unwrap_or_else(|_| b"# frozen source unavailable\n".to_vec());
+        let source = Box::leak(source.into_boxed_slice());
+        let size = i32::try_from(source.len()).unwrap_or(i32::MAX);
+        table.push(FrozenAbiEntry {
+            name,
+            code: source.as_ptr(),
+            size,
+            is_package: i32::from(entry.is_package),
+        });
+    }
+    table.push(FrozenAbiEntry {
+        name: std::ptr::null(),
+        code: std::ptr::null(),
+        size: 0,
+        is_package: 0,
+    });
+
+    let table = Box::leak(table.into_boxed_slice());
+    Box::leak(Box::new(table.as_ptr() as usize)) as *mut usize as usize
+}
+
+/// Address of the stable pointer variable exported by CPython for each frozen
+/// table.  The split matches CPython's Bootstrap/Stdlib/Test ABI while the
+/// concatenated order remains exactly `FROZEN_MODULES`, the list returned by
+/// `_imp._frozen_module_names()`.
+pub(crate) fn frozen_abi_pointer_variable(name: &str) -> Option<usize> {
+    static BOOTSTRAP: OnceLock<usize> = OnceLock::new();
+    static STDLIB: OnceLock<usize> = OnceLock::new();
+    static TEST: OnceLock<usize> = OnceLock::new();
+
+    match name {
+        "_PyImport_FrozenBootstrap" => {
+            Some(*BOOTSTRAP.get_or_init(|| build_frozen_abi_table(&FROZEN_MODULES[..3])))
+        }
+        "_PyImport_FrozenStdlib" => {
+            Some(*STDLIB.get_or_init(|| build_frozen_abi_table(&FROZEN_MODULES[3..3])))
+        }
+        "_PyImport_FrozenTest" => {
+            Some(*TEST.get_or_init(|| build_frozen_abi_table(&FROZEN_MODULES[3..])))
+        }
+        _ => None,
+    }
+}
+
 static FROZEN_OVERRIDE: AtomicI64 = AtomicI64::new(0);
 
 /// `importing.py:159 ImportRLock` — the interpreter's reentrant import lock.