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Merged
youknowone merged 4 commits into from
Jul 15, 2026
Merged

Add descriptor support to c-api #8283

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6a68731
Add descriptor support to c-api
bschoenmaeckers Jul 14, 2026
54ff206
Review
bschoenmaeckers Jul 14, 2026
4b29795
Extract getset builder
bschoenmaeckers Jul 14, 2026
f99a214
Extract memberdef builder
bschoenmaeckers Jul 14, 2026
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249 changes: 247 additions & 2 deletions crates/capi/src/descrobject.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,201 @@
use crate::PyObject;
use crate::methodobject::{PyMethodDef, build_method_def};
use crate::object::PyTypeObject;
use crate::pystate::with_vm;
use rustpython_vm::PyPayload;
use rustpython_vm::builtins::PyMappingProxy;
use core::ffi::{CStr, c_char, c_int, c_void};
use core::ptr::NonNull;
use rustpython_vm::builtins::{
DescriptorMemberDef, MemberGetter, MemberKind, MemberSetter, PyDescriptorOwned, PyGetSet,
PyMappingProxy, PyMemberDescriptor, PyType,
};
use rustpython_vm::common::lock::PyRwLock;
use rustpython_vm::function::PySetterValue;
use rustpython_vm::{Py, PyObjectRef, PyPayload, PyRef, PyResult, VirtualMachine};

#[repr(C)]
pub struct PyGetSetDef {

@youknowone youknowone Jul 15, 2026

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this is part of api... painful

@bschoenmaeckers bschoenmaeckers Jul 15, 2026

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Yes it is...

pub name: *const c_char,
pub get:
Option<unsafe extern "C" fn(slf: *mut PyObject, closure: *mut c_void) -> *mut PyObject>,
pub set: Option<
unsafe extern "C" fn(
slf: *mut PyObject,
value: *mut PyObject,
closure: *mut c_void,
) -> c_int,
>,
pub doc: *const c_char,
pub closure: *mut c_void,
}

impl PyGetSetDef {
pub(crate) fn build(
&self,
ty: &'static Py<PyType>,
vm: &VirtualMachine,
) -> PyResult<PyRef<PyGetSet>> {
let name = unsafe { CStr::from_ptr(self.name) }
.to_str()
.map_err(|_| vm.new_system_error("PyGetSetDef name was not valid UTF-8"))?;
let closure = self.closure as usize;

let descriptor = match (self.get, self.set) {
(Some(get), Some(set)) => vm.ctx.new_static_getset(
name,
ty,
move |obj: PyObjectRef, vm: &VirtualMachine| -> PyResult<PyObjectRef> {
unsafe {
let closure = closure as *mut c_void;
let ret_ptr = get(obj.as_raw().cast_mut(), closure);
let ret_ptr = NonNull::new(ret_ptr).ok_or_else(|| {
vm.take_raised_exception().unwrap_or_else(|| {
vm.new_system_error(
"Native function returned NULL, but there was no exception set",
)
})
})?;
Ok(PyObjectRef::from_raw(ret_ptr))
}
},
move |obj: PyObjectRef, value: PySetterValue, vm: &VirtualMachine| unsafe {
let closure = closure as *mut c_void;
let value = value.unwrap_or_none(vm);
let result = set(obj.as_raw().cast_mut(), value.as_raw().cast_mut(), closure);
if result == 0 {
Ok(())
} else {
Err(vm.take_raised_exception().unwrap_or_else(|| {
vm.new_system_error(
"C setter returned error but did not set an exception",
)
}))
}
},
),
(Some(get), None) => vm.ctx.new_readonly_getset(
name,
ty,
move |obj: PyObjectRef, vm: &VirtualMachine| -> PyResult<PyObjectRef> {
unsafe {
let closure = closure as *mut c_void;
let ret_ptr = get(obj.as_raw().cast_mut(), closure);
let ret_ptr = NonNull::new(ret_ptr).ok_or_else(|| {
vm.take_raised_exception().unwrap_or_else(|| {
vm.new_system_error(
"Native function returned NULL, but there was no exception set",
)
})
})?;
Ok(PyObjectRef::from_raw(ret_ptr))
}
},
),
(None, Some(set)) => vm.ctx.new_static_getset(
name,
ty,
move |_obj: PyObjectRef, vm: &VirtualMachine| -> PyResult<PyObjectRef> {
Err(vm.new_attribute_error("unreadable attribute"))
},
move |obj: PyObjectRef, value: PySetterValue, vm: &VirtualMachine| unsafe {
let closure = closure as *mut c_void;
let value = value.unwrap_or_none(vm);
let result = set(obj.as_raw().cast_mut(), value.as_raw().cast_mut(), closure);
if result == 0 {
Ok(())
} else {
Err(vm.take_raised_exception().unwrap_or_else(|| {
vm.new_system_error(
"C setter returned error but did not set an exception",
)
}))
}
},
),
(None, None) => vm.ctx.new_readonly_getset(
name,
ty,
move |_obj: PyObjectRef, vm: &VirtualMachine| -> PyResult<PyObjectRef> {
Err(vm.new_attribute_error("unreadable attribute"))
},
),
};

Ok(descriptor)
}
}

#[repr(C)]
pub struct PyMemberDef {
pub name: *const c_char,
pub type_code: c_int,
pub offset: isize,
pub flags: c_int,
pub doc: *const c_char,
}

impl PyMemberDef {
const PY_READONLY: c_int = 1;
const PY_RELATIVE_OFFSET: c_int = 8;

pub(crate) fn build(
&self,
ty: &Py<PyType>,
vm: &VirtualMachine,
) -> PyResult<PyRef<PyMemberDescriptor>> {
let name = unsafe { CStr::from_ptr(self.name) }
.to_str()
.map_err(|_| vm.new_system_error("PyMemberDef name was not valid UTF-8"))?;
let kind = match self.type_code {
6 => MemberKind::Object,
16 => MemberKind::ObjectEx,
14 => MemberKind::Bool,
_ => {
return Err(vm.new_system_error(format!(
"PyDescr_NewMember does not support member type code {}",
self.type_code
)));
}
};
if self.offset < 0 {
return Err(vm.new_system_error("PyDescr_NewMember does not support negative offsets"));
}
if self.flags & Self::PY_RELATIVE_OFFSET != 0 {
return Err(
vm.new_system_error("PyDescr_NewMember does not support Py_RELATIVE_OFFSET")
);
}

let doc = NonNull::new(self.doc.cast_mut())
.map(|doc| {
unsafe { CStr::from_ptr(doc.as_ptr()) }
.to_str()
.map(|s| s.to_owned())
.map_err(|_| vm.new_system_error("PyMemberDef doc was not valid UTF-8"))
})
.transpose()?;

let descriptor = PyMemberDescriptor {
common: PyDescriptorOwned {
typ: ty.to_owned(),
name: vm.ctx.intern_str(name),
qualname: PyRwLock::new(None),
},
member: DescriptorMemberDef {
name: name.to_owned(),
kind,
getter: MemberGetter::Offset(self.offset as usize),
setter: if self.flags & Self::PY_READONLY != 0 {
MemberSetter::Setter(None)
} else {
MemberSetter::Offset(self.offset as usize)
},
doc,
},
};

Ok(descriptor.into_ref(&vm.ctx))
}
}

#[unsafe(no_mangle)]
pub unsafe extern "C" fn PyDictProxy_New(mapping: *mut PyObject) -> *mut PyObject {
Expand All @@ -11,6 +205,57 @@ pub unsafe extern "C" fn PyDictProxy_New(mapping: *mut PyObject) -> *mut PyObjec
})
}

#[unsafe(no_mangle)]
pub unsafe extern "C" fn PyDescr_NewMethod(
typ: *mut PyTypeObject,
method: *mut PyMethodDef,
) -> *mut PyObject {
with_vm(|vm| {
let method = build_method_def(vm, unsafe { &*method }, true)?;
Ok(method.build_method(unsafe { &*typ }, vm))
})
}

#[unsafe(no_mangle)]
pub unsafe extern "C" fn PyDescr_NewClassMethod(
typ: *mut PyTypeObject,
method: *mut PyMethodDef,
) -> *mut PyObject {
with_vm(|vm| {
let method = build_method_def(vm, unsafe { &*method }, true)?;
Ok(method.build_method(unsafe { &*typ }, vm))
})
}

#[unsafe(no_mangle)]
pub unsafe extern "C" fn PyDescr_NewGetSet(
typ: *mut PyTypeObject,
getset: *mut PyGetSetDef,
) -> *mut PyObject {
with_vm(|vm| unsafe { &*getset }.build(unsafe { &*typ }, vm))
}

#[unsafe(no_mangle)]
pub unsafe extern "C" fn PyDescr_NewMember(
typ: *mut PyTypeObject,
member: *mut PyMemberDef,
) -> *mut PyObject {
with_vm(|vm| Ok(unsafe { &*member }.build(unsafe { &*typ }, vm)))
}

#[unsafe(no_mangle)]
pub unsafe extern "C" fn PyWrapper_New(descr: *mut PyObject, obj: *mut PyObject) -> *mut PyObject {
with_vm(|vm| {
let descr = unsafe { &*descr };
let obj = unsafe { &*obj };
vm.call_special_method(
descr,
vm.ctx.names.__get__,
(obj.to_owned(), obj.class().to_owned()),
)
})
}

#[cfg(test)]
mod tests {
use pyo3::prelude::*;
Expand Down
4 changes: 4 additions & 0 deletions crates/vm/src/builtins/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,10 @@ pub use zip::PyZip;
pub(crate) mod union_;
pub use union_::{PyUnion, make_union};
pub(crate) mod descriptor;
pub use descriptor::{
MemberGetter, MemberKind, MemberSetter, PyDescriptorOwned, PyMemberDef as DescriptorMemberDef,
PyMemberDescriptor,
};

pub use float::float_from_string as parse_float_from_string;
pub use float::try_to_bigint as try_f64_to_bigint;
Expand Down
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