From 33aa660575f7174752a7308229e5fc108921c2a6 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 11 Dec 2024 10:33:31 +0100
Subject: rust: qom: automatically use Drop trait to implement
instance_finalize
Replace the customizable INSTANCE_FINALIZE with a generic function
that drops the Rust object.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
rust/qemu-api/src/qom.rs | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
(limited to 'rust/qemu-api/src')
diff --git a/rust/qemu-api/src/qom.rs b/rust/qemu-api/src/qom.rs
index 40d17a9..b0332ba 100644
--- a/rust/qemu-api/src/qom.rs
+++ b/rust/qemu-api/src/qom.rs
@@ -180,6 +180,16 @@ unsafe extern "C" fn rust_class_init<T: ObjectType + ClassInitImpl<T::Class>>(
T::class_init(unsafe { &mut *klass.cast::<T::Class>() })
}
+unsafe extern "C" fn drop_object<T: ObjectImpl>(obj: *mut Object) {
+ // SAFETY: obj is an instance of T, since drop_object<T> is called
+ // from the QOM core function object_deinit() as the instance_finalize
+ // function for class T. Note that while object_deinit() will drop the
+ // superclass field separately after this function returns, `T` must
+ // implement the unsafe trait ObjectType; the safety rules for the
+ // trait mandate that the parent field is manually dropped.
+ unsafe { std::ptr::drop_in_place(obj.cast::<T>()) }
+}
+
/// Trait exposed by all structs corresponding to QOM objects.
///
/// # Safety
@@ -442,7 +452,6 @@ pub trait ObjectImpl: ObjectType + ClassInitImpl<Self::Class> {
/// Whether the object can be instantiated
const ABSTRACT: bool = false;
- const INSTANCE_FINALIZE: Option<unsafe extern "C" fn(obj: *mut Object)> = None;
/// Function that is called to initialize an object. The parent class will
/// have already been initialized so the type is only responsible for
@@ -478,7 +487,7 @@ pub trait ObjectImpl: ObjectType + ClassInitImpl<Self::Class> {
None => None,
Some(_) => Some(rust_instance_post_init::<Self>),
},
- instance_finalize: Self::INSTANCE_FINALIZE,
+ instance_finalize: Some(drop_object::<Self>),
abstract_: Self::ABSTRACT,
class_size: core::mem::size_of::<Self::Class>(),
class_init: Some(rust_class_init::<Self>),
--
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