Define a separate trait for fields that also applies to classes that are
defined by C code. This makes it possible to add metadata to core classes,
which has multiple uses:
- it makes it possible to access the parent struct's TYPE_* for types
that are defined in Rust code, and to avoid repeating it in every subclass
- implementors of ObjectType will be allowed to implement the IsA<> trait and
therefore to perform typesafe casts from one class to another.
- in the future, an ObjectType could be created with Foo::new() in a type-safe
manner, without having to pass a TYPE_* constant.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
rust/hw/char/pl011/src/device.rs | 17 ++++++++++++-----
rust/qemu-api/src/definitions.rs | 9 ++++++---
rust/qemu-api/src/device_class.rs | 11 ++++++-----
rust/qemu-api/src/prelude.rs | 2 ++
rust/qemu-api/src/sysbus.rs | 10 ++++++++--
rust/qemu-api/tests/tests.rs | 12 +++++++++---
6 files changed, 43 insertions(+), 18 deletions(-)
diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs
index b9f8fb134b5..0ab825b1ca4 100644
--- a/rust/hw/char/pl011/src/device.rs
+++ b/rust/hw/char/pl011/src/device.rs
@@ -12,9 +12,10 @@
bindings::{self, *},
c_str,
definitions::ObjectImpl,
- device_class::{DeviceImpl, TYPE_SYS_BUS_DEVICE},
+ device_class::DeviceImpl,
impl_device_class,
irq::InterruptSource,
+ prelude::*,
};
use crate::{
@@ -106,10 +107,13 @@ pub struct PL011State {
device_id: DeviceId,
}
-impl ObjectImpl for PL011State {
+unsafe impl ObjectType for PL011State {
type Class = PL011Class;
const TYPE_NAME: &'static CStr = crate::TYPE_PL011;
- const PARENT_TYPE_NAME: Option<&'static CStr> = Some(TYPE_SYS_BUS_DEVICE);
+}
+
+impl ObjectImpl for PL011State {
+ const PARENT_TYPE_NAME: Option<&'static CStr> = Some(<SysBusDevice as
ObjectType>::TYPE_NAME);
const INSTANCE_INIT: Option<unsafe fn(&mut Self)> = Some(Self::init);
}
@@ -640,10 +644,13 @@ unsafe fn init(&mut self) {
}
}
-impl ObjectImpl for PL011Luminary {
+unsafe impl ObjectType for PL011Luminary {
type Class = PL011LuminaryClass;
const TYPE_NAME: &'static CStr = crate::TYPE_PL011_LUMINARY;
- const PARENT_TYPE_NAME: Option<&'static CStr> = Some(crate::TYPE_PL011);
+}
+
+impl ObjectImpl for PL011Luminary {
+ const PARENT_TYPE_NAME: Option<&'static CStr> = Some(<PL011State as
ObjectType>::TYPE_NAME);
const INSTANCE_INIT: Option<unsafe fn(&mut Self)> = Some(Self::init);
}
diff --git a/rust/qemu-api/src/definitions.rs b/rust/qemu-api/src/definitions.rs
index 078ba30d61a..1c412dbc876 100644
--- a/rust/qemu-api/src/definitions.rs
+++ b/rust/qemu-api/src/definitions.rs
@@ -33,7 +33,7 @@
unsafe { std::ptr::drop_in_place(obj.cast::<T>()) }
}
-/// Trait a type must implement to be registered with QEMU.
+/// Trait exposed by all structs corresponding to QOM objects.
///
/// # Safety
///
@@ -43,15 +43,18 @@
/// automatic if the class is defined via `ObjectImpl`).
///
/// - the first field of the struct must be of the instance struct
corresponding
-/// to the superclass declared as `PARENT_TYPE_NAME`
-pub trait ObjectImpl: ClassInitImpl + Sized {
+/// to the superclass declared in the `TypeInfo`
+pub unsafe trait ObjectType: Sized {
/// The QOM class object corresponding to this struct. Not used yet.
type Class;
/// The name of the type, which can be passed to `object_new()` to
/// generate an instance of this type.
const TYPE_NAME: &'static CStr;
+}
+/// Trait a type must implement to be registered with QEMU.
+pub trait ObjectImpl: ObjectType + ClassInitImpl {
/// The parent of the type. This should match the first field of
/// the struct that implements `ObjectImpl`:
const PARENT_TYPE_NAME: Option<&'static CStr>;
diff --git a/rust/qemu-api/src/device_class.rs
b/rust/qemu-api/src/device_class.rs
index f25904be4f6..03d03feee83 100644
--- a/rust/qemu-api/src/device_class.rs
+++ b/rust/qemu-api/src/device_class.rs
@@ -6,6 +6,7 @@
use crate::{
bindings::{self, DeviceClass, DeviceState, Error, ObjectClass, Property,
VMStateDescription},
+ prelude::*,
zeroable::Zeroable,
};
@@ -146,8 +147,8 @@ macro_rules! declare_properties {
};
}
-// workaround until we can use --generate-cstr in bindgen.
-pub const TYPE_DEVICE: &CStr =
- unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_DEVICE) };
-pub const TYPE_SYS_BUS_DEVICE: &CStr =
- unsafe {
CStr::from_bytes_with_nul_unchecked(bindings::TYPE_SYS_BUS_DEVICE) };
+unsafe impl ObjectType for bindings::DeviceState {
+ type Class = bindings::DeviceClass;
+ const TYPE_NAME: &'static CStr =
+ unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_DEVICE) };
+}
diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs
index a39e228babf..1b8677b2d9a 100644
--- a/rust/qemu-api/src/prelude.rs
+++ b/rust/qemu-api/src/prelude.rs
@@ -6,3 +6,5 @@
pub use crate::cell::BqlCell;
pub use crate::cell::BqlRefCell;
+
+pub use crate::definitions::ObjectType;
diff --git a/rust/qemu-api/src/sysbus.rs b/rust/qemu-api/src/sysbus.rs
index 4e192c75898..5ee068541cf 100644
--- a/rust/qemu-api/src/sysbus.rs
+++ b/rust/qemu-api/src/sysbus.rs
@@ -2,11 +2,17 @@
// Author(s): Paolo Bonzini <pbonz...@redhat.com>
// SPDX-License-Identifier: GPL-2.0-or-later
-use std::ptr::addr_of;
+use std::{ffi::CStr, ptr::addr_of};
pub use bindings::{SysBusDevice, SysBusDeviceClass};
-use crate::{bindings, cell::bql_locked, irq::InterruptSource};
+use crate::{bindings, cell::bql_locked, irq::InterruptSource, prelude::*};
+
+unsafe impl ObjectType for SysBusDevice {
+ type Class = SysBusDeviceClass;
+ const TYPE_NAME: &'static CStr =
+ unsafe {
CStr::from_bytes_with_nul_unchecked(bindings::TYPE_SYS_BUS_DEVICE) };
+}
impl SysBusDevice {
/// Return `self` cast to a mutable pointer, for use in calls to C code.
diff --git a/rust/qemu-api/tests/tests.rs b/rust/qemu-api/tests/tests.rs
index b8b12a40422..1be03eb685c 100644
--- a/rust/qemu-api/tests/tests.rs
+++ b/rust/qemu-api/tests/tests.rs
@@ -8,8 +8,9 @@
bindings::*,
c_str, declare_properties, define_property,
definitions::ObjectImpl,
- device_class::{self, DeviceImpl},
+ device_class::DeviceImpl,
impl_device_class,
+ prelude::*,
zeroable::Zeroable,
};
@@ -46,10 +47,15 @@ pub struct DummyClass {
),
}
- impl ObjectImpl for DummyState {
+ unsafe impl ObjectType for DummyState {
type Class = DummyClass;
const TYPE_NAME: &'static CStr = c_str!("dummy");
- const PARENT_TYPE_NAME: Option<&'static CStr> =
Some(device_class::TYPE_DEVICE);
+ }
+
+ impl ObjectImpl for DummyState {
+ const PARENT_TYPE_NAME: Option<&'static CStr> =
+ Some(<DeviceState as ObjectType>::TYPE_NAME);
+ const ABSTRACT: bool = false;
}
impl DeviceImpl for DummyState {
--
2.47.1
