1 files changed, 76 insertions, 25 deletions

diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib.rs
index 59aba592d9..cf99ac04b8 100644
--- a/rust/qemu-api-macros/src/lib.rs
+++ b/rust/qemu-api-macros/src/lib.rs
@@ -3,41 +3,92 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 use proc_macro::TokenStream;
-use quote::{format_ident, quote};
-use syn::{parse_macro_input, DeriveInput};
+use proc_macro2::Span;
+use quote::{quote, quote_spanned};
+use syn::{
+    parse_macro_input, parse_quote, punctuated::Punctuated, token::Comma, Data, DeriveInput, Field,
+    Fields, Ident, Type, Visibility,
+};
+
+struct CompileError(String, Span);
+
+impl From<CompileError> for proc_macro2::TokenStream {
+    fn from(err: CompileError) -> Self {
+        let CompileError(msg, span) = err;
+        quote_spanned! { span => compile_error!(#msg); }
+    }
+}
+
+fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), CompileError> {
+    let expected = parse_quote! { #[repr(C)] };
+
+    if input.attrs.iter().any(|attr| attr == &expected) {
+        Ok(())
+    } else {
+        Err(CompileError(
+            format!("#[repr(C)] required for {}", msg),
+            input.ident.span(),
+        ))
+    }
+}
 
 #[proc_macro_derive(Object)]
 pub fn derive_object(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-
     let name = input.ident;
-    let module_static = format_ident!("__{}_LOAD_MODULE", name);
 
     let expanded = quote! {
-        #[allow(non_upper_case_globals)]
-        #[used]
-        #[cfg_attr(target_os = "linux", link_section = ".ctors")]
-        #[cfg_attr(target_os = "macos", link_section = "__DATA,__mod_init_func")]
-        #[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
-        pub static #module_static: extern "C" fn() = {
-            extern "C" fn __register() {
-                unsafe {
-                    ::qemu_api::bindings::type_register_static(&<#name as ::qemu_api::definitions::ObjectImpl>::TYPE_INFO);
-                }
+        ::qemu_api::module_init! {
+            MODULE_INIT_QOM => unsafe {
+                ::qemu_api::bindings::type_register_static(&<#name as ::qemu_api::definitions::ObjectImpl>::TYPE_INFO);
             }
+        }
+    };
 
-            extern "C" fn __load() {
-                unsafe {
-                    ::qemu_api::bindings::register_module_init(
-                        Some(__register),
-                        ::qemu_api::bindings::module_init_type::MODULE_INIT_QOM
-                    );
-                }
-            }
+    TokenStream::from(expanded)
+}
 
-            __load
-        };
-    };
+fn get_fields(input: &DeriveInput) -> Result<&Punctuated<Field, Comma>, CompileError> {
+    if let Data::Struct(s) = &input.data {
+        if let Fields::Named(fs) = &s.fields {
+            Ok(&fs.named)
+        } else {
+            Err(CompileError(
+                "Cannot generate offsets for unnamed fields.".to_string(),
+                input.ident.span(),
+            ))
+        }
+    } else {
+        Err(CompileError(
+            "Cannot generate offsets for union or enum.".to_string(),
+            input.ident.span(),
+        ))
+    }
+}
+
+#[rustfmt::skip::macros(quote)]
+fn derive_offsets_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, CompileError> {
+    is_c_repr(&input, "#[derive(offsets)]")?;
+
+    let name = &input.ident;
+    let fields = get_fields(&input)?;
+    let field_names: Vec<&Ident> = fields.iter().map(|f| f.ident.as_ref().unwrap()).collect();
+    let field_types: Vec<&Type> = fields.iter().map(|f| &f.ty).collect();
+    let field_vis: Vec<&Visibility> = fields.iter().map(|f| &f.vis).collect();
+
+    Ok(quote! {
+	::qemu_api::with_offsets! {
+	    struct #name {
+		#(#field_vis #field_names: #field_types,)*
+	    }
+	}
+    })
+}
+
+#[proc_macro_derive(offsets)]
+pub fn derive_offsets(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+    let expanded = derive_offsets_or_error(input).unwrap_or_else(Into::into);
 
     TokenStream::from(expanded)
 }