[PATCH 08/14] rust: define wrappers for methods of the QOM Device class

[Paolo Bonzini]

Provide a trait that can be used to invoke methods of the QOM Device
class.  The trait extends Deref and has a blanket implementation for any
type that dereferences to IsA<DeviceState>.  This way, it can be used on any
struct that dereferences to Object or a subclass.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 qemu/src/hw/core/device.rs | 56 ++++++++++++++++++++++++++++++++++++++
 qemu/src/hw/core/mod.rs    |  1 +
 qemu/src/hw/mod.rs         |  1 +
 qemu/src/lib.rs            |  4 +++
 4 files changed, 62 insertions(+)
 create mode 100644 qemu/src/hw/core/device.rs
 create mode 100644 qemu/src/hw/core/mod.rs
 create mode 100644 qemu/src/hw/mod.rs

diff --git a/qemu/src/hw/core/device.rs b/qemu/src/hw/core/device.rs
new file mode 100644
index 0000000..294251e
--- /dev/null
+++ b/qemu/src/hw/core/device.rs
@@ -0,0 +1,56 @@
+//! Bindings for the QOM Device class
+//!
+//! @author Paolo Bonzini
+
+use crate::qom::object::ObjectType;
+
+use crate::qom::refs::IsA;
+use crate::qom::refs::ObjectCast;
+
+use crate::bindings;
+use crate::bindings::device_cold_reset;
+use crate::bindings::device_realize;
+use crate::bindings::DeviceState;
+use crate::bindings::Object;
+
+use crate::qom_isa;
+
+use crate::Result;
+
+use std::ffi::CStr;
+use std::ops::Deref;
+use std::ptr::null_mut;
+
+unsafe impl ObjectType for DeviceState {
+    const TYPE: &'static CStr = c"device";
+}
+
+qom_isa!(DeviceState, Object);
+
+/// Trait for methods exposed by the Object class.  The methods can be
+/// called on all objects that have the trait `IsA<Object>`.
+///
+/// The trait should only be used through the blanket implementation,
+/// which guarantees safety via `IsA`
+pub trait DeviceMethods: Deref
+where
+    Self::Target: IsA<DeviceState>,
+{
+    fn realize(&self) -> Result<()> {
+        let device = self.upcast::<DeviceState>();
+        let mut err: *mut bindings::Error = null_mut();
+        // SAFETY: safety of this is the requirement for implementing IsA
+        unsafe {
+            device_realize(device.as_mut_ptr(), &mut err);
+            crate::Error::err_or_default(err)
+        }
+    }
+
+    fn cold_reset(&self) {
+        let device = self.upcast::<DeviceState>();
+        // SAFETY: safety of this is the requirement for implementing IsA
+        unsafe { device_cold_reset(device.as_mut_ptr()) }
+    }
+}
+
+impl<R: Deref> DeviceMethods for R where R::Target: IsA<DeviceState> {}
diff --git a/qemu/src/hw/core/mod.rs b/qemu/src/hw/core/mod.rs
new file mode 100644
index 0000000..5458924
--- /dev/null
+++ b/qemu/src/hw/core/mod.rs
@@ -0,0 +1 @@
+pub mod device;
diff --git a/qemu/src/hw/mod.rs b/qemu/src/hw/mod.rs
new file mode 100644
index 0000000..5a7ca06
--- /dev/null
+++ b/qemu/src/hw/mod.rs
@@ -0,0 +1 @@
+pub mod core;
diff --git a/qemu/src/lib.rs b/qemu/src/lib.rs
index a6e7b17..b0dcce1 100644
--- a/qemu/src/lib.rs
+++ b/qemu/src/lib.rs
@@ -2,8 +2,12 @@
 #![allow(dead_code)]
 
 pub mod bindings;
+pub use bindings::DeviceState;
 pub use bindings::Object;
 
+pub mod hw;
+pub use hw::core::device::DeviceMethods;
+
 pub mod qom;
 pub use qom::object::ObjectClassMethods;
 pub use qom::object::ObjectMethods;
-- 
2.45.2