Re: [PATCH 07/10] rust: qemu_api: add vmstate_struct

[Zhao Liu <zhao1.liu@intel.com>]

On Fri, Jan 17, 2025 at 10:00:43AM +0100, Paolo Bonzini wrote:
> Date: Fri, 17 Jan 2025 10:00:43 +0100
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: [PATCH 07/10] rust: qemu_api: add vmstate_struct
> X-Mailer: git-send-email 2.47.1
> 
> It is not type safe, but it's the best that can be done without
> const_refs_static.  It can also be used with BqlCell and BqlRefCell.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  rust/qemu-api/src/vmstate.rs | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)

...

> +#[doc(alias = "VMSTATE_STRUCT")]
> +#[macro_export]
> +macro_rules! vmstate_struct {
> +    ($struct_name:ty, $field_name:ident $([0 .. $num:ident $(* $factor:expr)?])?, $vmsd:expr, $type:ty $(,)?) => {
> +        $crate::bindings::VMStateField {
> +            name: ::core::concat!(::core::stringify!($field_name), "\0")
> +                .as_bytes()
> +                .as_ptr() as *const ::std::os::raw::c_char,
> +            $(.num_offset: $crate::offset_of!($struct_name, $num),)?
> +            offset: {
> +                $crate::assert_field_type!($struct_name, $field_name, $type);
> +                $crate::offset_of!($struct_name, $field_name)
> +            },
> +            size: ::core::mem::size_of::<$type>(),
> +            flags: $crate::bindings::VMStateFlags::VMS_STRUCT,
> +            vmsd: unsafe { $vmsd },

Yes, this `unsafe` is fitting.

> +            ..$crate::zeroable::Zeroable::ZERO $(
> +                .with_varray_flag($crate::call_func_with_field!(
> +                    $crate::vmstate::vmstate_varray_flag,
> +                    $struct_name,
> +                    $num))
> +               $(.with_varray_multiply($factor))?)?
> +        }
> +    };
> +}
> +

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>