From 713c2646caf54d7bf35801c8277780dc657fe71b Mon Sep 17 00:00:00 2001
From: Bas Schoenmaeckers <7943856+bschoenmaeckers@users.noreply.github.com>
Date: Mon, 11 May 2026 20:20:01 +0200
Subject: [PATCH] Fix `ctypes.py_object` handling (#7836)

* Fix `ctypes.py_object` handling

* Assume owned pointer
---
 crates/vm/src/stdlib/_ctypes/base.rs   | 12 ++++++++++++
 crates/vm/src/stdlib/_ctypes/simple.rs | 11 +++++++++++
 2 files changed, 23 insertions(+)

diff --git a/crates/vm/src/stdlib/_ctypes/base.rs b/crates/vm/src/stdlib/_ctypes/base.rs
index 9eda289b5..8bd8d106e 100644
--- a/crates/vm/src/stdlib/_ctypes/base.rs
+++ b/crates/vm/src/stdlib/_ctypes/base.rs
@@ -2342,6 +2342,18 @@ pub(super) fn bytes_to_pyobject(
                 }
                 Ok(vm.ctx.new_int(val).into())
             }
+            "O" => {
+                // py_object: return Python object from pointer
+                let ptr = read_ptr_from_buffer(bytes);
+                if ptr == 0 {
+                    return Err(vm.new_value_error("PyObject is NULL"));
+                }
+                unsafe {
+                    let obj =
+                        PyObjectRef::from_raw(core::ptr::NonNull::new_unchecked(ptr as *mut _));
+                    Ok(obj)
+                }
+            }
             "u" => {
                 let val = if bytes.len() >= mem::size_of::<WideChar>() {
                     let wc = if mem::size_of::<WideChar>() == 2 {
diff --git a/crates/vm/src/stdlib/_ctypes/simple.rs b/crates/vm/src/stdlib/_ctypes/simple.rs
index bb00d4830..f3ef925be 100644
--- a/crates/vm/src/stdlib/_ctypes/simple.rs
+++ b/crates/vm/src/stdlib/_ctypes/simple.rs
@@ -466,6 +466,17 @@ impl PyCSimpleType {
                     }
                 }
             }
+            // py_object: pass any Python object as PyObject*
+            Some("O") => {
+                return Ok(CArgObject {
+                    tag: b'O',
+                    value: FfiArgValue::Pointer(value.get_id()),
+                    obj: value,
+                    size: 0,
+                    offset: 0,
+                }
+                .to_pyobject(vm));
+            }
             // c_bool
             Some("?") => {
                 let bool_val = value.is_true(vm)?;