diff options
Diffstat (limited to 'rust/qemu-api')
| -rw-r--r-- | rust/qemu-api/src/prelude.rs | 1 | ||||
| -rw-r--r-- | rust/qemu-api/src/qom.rs | 45 |
2 files changed, 44 insertions, 2 deletions
diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs index 87e3ce90f2..254edb476d 100644 --- a/rust/qemu-api/src/prelude.rs +++ b/rust/qemu-api/src/prelude.rs @@ -9,6 +9,7 @@ pub use crate::cell::BqlRefCell; pub use crate::qdev::DeviceMethods; +pub use crate::qom::InterfaceType; pub use crate::qom::IsA; pub use crate::qom::Object; pub use crate::qom::ObjectCast; diff --git a/rust/qemu-api/src/qom.rs b/rust/qemu-api/src/qom.rs index 3e63cb30ca..3d5ab2d901 100644 --- a/rust/qemu-api/src/qom.rs +++ b/rust/qemu-api/src/qom.rs @@ -66,8 +66,8 @@ pub use bindings::{Object, ObjectClass}; use crate::{ bindings::{ - self, object_dynamic_cast, object_get_class, object_get_typename, object_new, object_ref, - object_unref, TypeInfo, + self, object_class_dynamic_cast, object_dynamic_cast, object_get_class, + object_get_typename, object_new, object_ref, object_unref, TypeInfo, }, cell::bql_locked, }; @@ -263,6 +263,47 @@ pub unsafe trait ObjectType: Sized { } } +/// Trait exposed by all structs corresponding to QOM interfaces. +/// Unlike `ObjectType`, it is implemented on the class type (which provides +/// the vtable for the interfaces). +/// +/// # Safety +/// +/// `TYPE` must match the contents of the `TypeInfo` as found in the C code; +/// right now, interfaces can only be declared in C. +pub unsafe trait InterfaceType: Sized { + /// The name of the type, which can be passed to + /// `object_class_dynamic_cast()` to obtain the pointer to the vtable + /// for this interface. + const TYPE_NAME: &'static CStr; + + /// Initialize the vtable for the interface; the generic argument `T` is the + /// type being initialized, while the generic argument `U` is the type that + /// lists the interface in its `TypeInfo`. + /// + /// # Panics + /// + /// Panic if the incoming argument if `T` does not implement the interface. + fn interface_init< + T: ObjectType + ClassInitImpl<Self> + ClassInitImpl<U::Class>, + U: ObjectType, + >( + klass: &mut U::Class, + ) { + unsafe { + // SAFETY: upcasting to ObjectClass is always valid, and the + // return type is either NULL or the argument itself + let result: *mut Self = object_class_dynamic_cast( + (klass as *mut U::Class).cast(), + Self::TYPE_NAME.as_ptr(), + ) + .cast(); + + <T as ClassInitImpl<Self>>::class_init(result.as_mut().unwrap()) + } + } +} + /// This trait provides safe casting operations for QOM objects to raw pointers, /// to be used for example for FFI. The trait can be applied to any kind of /// reference or smart pointers, and enforces correctness through the [`IsA`] |