diff options
Diffstat (limited to 'rust/qemu-macros/src')
| -rw-r--r-- | rust/qemu-macros/src/lib.rs | 97 | ||||
| -rw-r--r-- | rust/qemu-macros/src/migration_state.rs | 298 | ||||
| -rw-r--r-- | rust/qemu-macros/src/tests.rs | 113 |
3 files changed, 505 insertions, 3 deletions
diff --git a/rust/qemu-macros/src/lib.rs b/rust/qemu-macros/src/lib.rs index 3e21b67..50239f2 100644 --- a/rust/qemu-macros/src/lib.rs +++ b/rust/qemu-macros/src/lib.rs @@ -13,9 +13,13 @@ use syn::{ Attribute, Data, DeriveInput, Error, Field, Fields, FieldsUnnamed, Ident, Meta, Path, Token, Variant, }; + mod bits; use bits::BitsConstInternal; +mod migration_state; +use migration_state::MigrationStateDerive; + #[cfg(test)] mod tests; @@ -401,7 +405,98 @@ pub fn bits_const_internal(ts: TokenStream) -> TokenStream { let ts = proc_macro2::TokenStream::from(ts); let mut it = ts.into_iter(); - BitsConstInternal::parse(&mut it) + let out = BitsConstInternal::parse(&mut it).unwrap_or_else(syn::Error::into_compile_error); + + // https://github.com/rust-lang/rust-clippy/issues/15852 + quote! { + { + #[allow(clippy::double_parens)] + #out + } + } + .into() +} + +/// Derive macro for generating migration state structures and trait +/// implementations. +/// +/// This macro generates a migration state struct and implements the +/// `ToMigrationState` trait for the annotated struct, enabling state +/// serialization and restoration. Note that defining a `VMStateDescription` +/// for the migration state struct is left to the user. +/// +/// # Container attributes +/// +/// The following attributes can be applied to the struct: +/// +/// - `#[migration_state(rename = CustomName)]` - Customizes the name of the +/// generated migration struct. By default, the generated struct is named +/// `{OriginalName}Migration`. +/// +/// # Field attributes +/// +/// The following attributes can be applied to individual fields: +/// +/// - `#[migration_state(omit)]` - Excludes the field from the migration state +/// entirely. +/// +/// - `#[migration_state(into(Type))]` - Converts the field using `.into()` +/// during both serialization and restoration. +/// +/// - `#[migration_state(try_into(Type))]` - Converts the field using +/// `.try_into()` during both serialization and restoration. Returns +/// `InvalidError` on conversion failure. +/// +/// - `#[migration_state(clone)]` - Clones the field value. +/// +/// Fields without any attributes use `ToMigrationState` recursively; note that +/// this is a simple copy for types that implement `Copy`. +/// +/// # Attribute compatibility +/// +/// - `omit` cannot be used with any other attributes +/// - only one of `into(Type)`, `try_into(Type)` can be used, but they can be +/// coupled with `clone`. +/// +/// # Examples +/// +/// Basic usage: +/// ```ignore +/// #[derive(ToMigrationState)] +/// struct MyStruct { +/// field1: u32, +/// field2: Timer, +/// } +/// ``` +/// +/// With attributes: +/// ```ignore +/// #[derive(ToMigrationState)] +/// #[migration_state(rename = CustomMigration)] +/// struct MyStruct { +/// #[migration_state(omit)] +/// runtime_field: u32, +/// +/// #[migration_state(clone)] +/// shared_data: String, +/// +/// #[migration_state(into(Cow<'static, str>), clone)] +/// converted_field: String, +/// +/// #[migration_state(try_into(i8))] +/// fallible_field: u32, +/// +/// // Default: use ToMigrationState trait recursively +/// nested_field: NestedStruct, +/// +/// // Primitive types have a default implementation of ToMigrationState +/// simple_field: u32, +/// } +/// ``` +#[proc_macro_derive(ToMigrationState, attributes(migration_state))] +pub fn derive_to_migration_state(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input as DeriveInput); + MigrationStateDerive::expand(input) .unwrap_or_else(syn::Error::into_compile_error) .into() } diff --git a/rust/qemu-macros/src/migration_state.rs b/rust/qemu-macros/src/migration_state.rs new file mode 100644 index 0000000..5edf0ef --- /dev/null +++ b/rust/qemu-macros/src/migration_state.rs @@ -0,0 +1,298 @@ +use std::borrow::Cow; + +use proc_macro2::TokenStream; +use quote::{format_ident, quote, ToTokens}; +use syn::{spanned::Spanned, DeriveInput, Error, Field, Ident, Result, Type}; + +use crate::get_fields; + +#[derive(Debug, Default)] +enum ConversionMode { + #[default] + None, + Omit, + Into(Type), + TryInto(Type), + ToMigrationState, +} + +impl ConversionMode { + fn target_type(&self, original_type: &Type) -> TokenStream { + match self { + ConversionMode::Into(ty) | ConversionMode::TryInto(ty) => ty.to_token_stream(), + ConversionMode::ToMigrationState => { + quote! { <#original_type as ToMigrationState>::Migrated } + } + _ => original_type.to_token_stream(), + } + } +} + +#[derive(Debug, Default)] +struct ContainerAttrs { + rename: Option<Ident>, +} + +impl ContainerAttrs { + fn parse_from(&mut self, attrs: &[syn::Attribute]) -> Result<()> { + use attrs::{set, with, Attrs}; + Attrs::new() + .once("rename", with::eq(set::parse(&mut self.rename))) + .parse_attrs("migration_state", attrs)?; + Ok(()) + } + + fn parse(attrs: &[syn::Attribute]) -> Result<Self> { + let mut container_attrs = Self::default(); + container_attrs.parse_from(attrs)?; + Ok(container_attrs) + } +} + +#[derive(Debug, Default)] +struct FieldAttrs { + conversion: ConversionMode, + clone: bool, +} + +impl FieldAttrs { + fn parse_from(&mut self, attrs: &[syn::Attribute]) -> Result<()> { + let mut omit_flag = false; + let mut into_type: Option<Type> = None; + let mut try_into_type: Option<Type> = None; + + use attrs::{set, with, Attrs}; + Attrs::new() + .once("omit", set::flag(&mut omit_flag)) + .once("into", with::paren(set::parse(&mut into_type))) + .once("try_into", with::paren(set::parse(&mut try_into_type))) + .once("clone", set::flag(&mut self.clone)) + .parse_attrs("migration_state", attrs)?; + + self.conversion = match (omit_flag, into_type, try_into_type, self.clone) { + // Valid combinations of attributes first... + (true, None, None, false) => ConversionMode::Omit, + (false, Some(ty), None, _) => ConversionMode::Into(ty), + (false, None, Some(ty), _) => ConversionMode::TryInto(ty), + (false, None, None, true) => ConversionMode::None, // clone without conversion + (false, None, None, false) => ConversionMode::ToMigrationState, // default behavior + + // ... then the error cases + (true, _, _, _) => { + return Err(Error::new( + attrs[0].span(), + "ToMigrationState: omit cannot be used with other attributes", + )); + } + (_, Some(_), Some(_), _) => { + return Err(Error::new( + attrs[0].span(), + "ToMigrationState: into and try_into attributes cannot be used together", + )); + } + }; + + Ok(()) + } + + fn parse(attrs: &[syn::Attribute]) -> Result<Self> { + let mut field_attrs = Self::default(); + field_attrs.parse_from(attrs)?; + Ok(field_attrs) + } +} + +#[derive(Debug)] +struct MigrationStateField { + name: Ident, + original_type: Type, + attrs: FieldAttrs, +} + +impl MigrationStateField { + fn maybe_clone(&self, mut value: TokenStream) -> TokenStream { + if self.attrs.clone { + value = quote! { #value.clone() }; + } + value + } + + fn generate_migration_state_field(&self) -> TokenStream { + let name = &self.name; + let field_type = self.attrs.conversion.target_type(&self.original_type); + + quote! { + pub #name: #field_type, + } + } + + fn generate_snapshot_field(&self) -> TokenStream { + let name = &self.name; + let value = self.maybe_clone(quote! { self.#name }); + + match &self.attrs.conversion { + ConversionMode::Omit => { + unreachable!("Omitted fields are filtered out during processing") + } + ConversionMode::None => quote! { + target.#name = #value; + }, + ConversionMode::Into(_) => quote! { + target.#name = #value.into(); + }, + ConversionMode::TryInto(_) => quote! { + target.#name = #value.try_into().map_err(|_| migration::InvalidError)?; + }, + ConversionMode::ToMigrationState => quote! { + self.#name.snapshot_migration_state(&mut target.#name)?; + }, + } + } + + fn generate_restore_field(&self) -> TokenStream { + let name = &self.name; + + match &self.attrs.conversion { + ConversionMode::Omit => { + unreachable!("Omitted fields are filtered out during processing") + } + ConversionMode::None => quote! { + self.#name = #name; + }, + ConversionMode::Into(_) => quote! { + self.#name = #name.into(); + }, + ConversionMode::TryInto(_) => quote! { + self.#name = #name.try_into().map_err(|_| migration::InvalidError)?; + }, + ConversionMode::ToMigrationState => quote! { + self.#name.restore_migrated_state_mut(#name, _version_id)?; + }, + } + } +} + +#[derive(Debug)] +pub struct MigrationStateDerive { + input: DeriveInput, + fields: Vec<MigrationStateField>, + container_attrs: ContainerAttrs, +} + +impl MigrationStateDerive { + fn parse(input: DeriveInput) -> Result<Self> { + let container_attrs = ContainerAttrs::parse(&input.attrs)?; + let fields = get_fields(&input, "ToMigrationState")?; + let fields = Self::process_fields(fields)?; + + Ok(Self { + input, + fields, + container_attrs, + }) + } + + fn process_fields( + fields: &syn::punctuated::Punctuated<Field, syn::token::Comma>, + ) -> Result<Vec<MigrationStateField>> { + let processed = fields + .iter() + .map(|field| { + let attrs = FieldAttrs::parse(&field.attrs)?; + Ok((field, attrs)) + }) + .collect::<Result<Vec<_>>>()? + .into_iter() + .filter(|(_, attrs)| !matches!(attrs.conversion, ConversionMode::Omit)) + .map(|(field, attrs)| MigrationStateField { + name: field.ident.as_ref().unwrap().clone(), + original_type: field.ty.clone(), + attrs, + }) + .collect(); + + Ok(processed) + } + + fn migration_state_name(&self) -> Cow<'_, Ident> { + match &self.container_attrs.rename { + Some(rename) => Cow::Borrowed(rename), + None => Cow::Owned(format_ident!("{}Migration", &self.input.ident)), + } + } + + fn generate_migration_state_struct(&self) -> TokenStream { + let name = self.migration_state_name(); + let fields = self + .fields + .iter() + .map(MigrationStateField::generate_migration_state_field); + + quote! { + #[derive(Default)] + pub struct #name { + #(#fields)* + } + } + } + + fn generate_snapshot_migration_state(&self) -> TokenStream { + let fields = self + .fields + .iter() + .map(MigrationStateField::generate_snapshot_field); + + quote! { + fn snapshot_migration_state(&self, target: &mut Self::Migrated) -> Result<(), migration::InvalidError> { + #(#fields)* + Ok(()) + } + } + } + + fn generate_restore_migrated_state(&self) -> TokenStream { + let names: Vec<_> = self.fields.iter().map(|f| &f.name).collect(); + let fields = self + .fields + .iter() + .map(MigrationStateField::generate_restore_field); + + // version_id could be used or not depending on conversion attributes + quote! { + #[allow(clippy::used_underscore_binding)] + fn restore_migrated_state_mut(&mut self, source: Self::Migrated, _version_id: u8) -> Result<(), migration::InvalidError> { + let Self::Migrated { #(#names),* } = source; + #(#fields)* + Ok(()) + } + } + } + + fn generate(&self) -> TokenStream { + let struct_name = &self.input.ident; + let generics = &self.input.generics; + + let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); + let name = self.migration_state_name(); + let migration_state_struct = self.generate_migration_state_struct(); + let snapshot_impl = self.generate_snapshot_migration_state(); + let restore_impl = self.generate_restore_migrated_state(); + + quote! { + #migration_state_struct + + impl #impl_generics ToMigrationState for #struct_name #ty_generics #where_clause { + type Migrated = #name; + + #snapshot_impl + + #restore_impl + } + } + } + + pub fn expand(input: DeriveInput) -> Result<TokenStream> { + let tokens = Self::parse(input)?.generate(); + Ok(tokens) + } +} diff --git a/rust/qemu-macros/src/tests.rs b/rust/qemu-macros/src/tests.rs index ac998d2..6569141 100644 --- a/rust/qemu-macros/src/tests.rs +++ b/rust/qemu-macros/src/tests.rs @@ -7,7 +7,7 @@ use quote::quote; use super::*; macro_rules! derive_compile_fail { - ($derive_fn:ident, $input:expr, $($error_msg:expr),+ $(,)?) => {{ + ($derive_fn:path, $input:expr, $($error_msg:expr),+ $(,)?) => {{ let input: proc_macro2::TokenStream = $input; let error_msg = &[$( quote! { ::core::compile_error! { $error_msg } } ),*]; let derive_fn: fn(input: syn::DeriveInput) -> Result<proc_macro2::TokenStream, syn::Error> = @@ -24,7 +24,7 @@ macro_rules! derive_compile_fail { } macro_rules! derive_compile { - ($derive_fn:ident, $input:expr, $($expected:tt)*) => {{ + ($derive_fn:path, $input:expr, $($expected:tt)*) => {{ let input: proc_macro2::TokenStream = $input; let expected: proc_macro2::TokenStream = $($expected)*; let derive_fn: fn(input: syn::DeriveInput) -> Result<proc_macro2::TokenStream, syn::Error> = @@ -345,3 +345,112 @@ fn test_derive_tryinto() { } ); } + +#[test] +fn test_derive_to_migration_state() { + derive_compile_fail!( + MigrationStateDerive::expand, + quote! { + struct MyStruct { + #[migration_state(omit, clone)] + bad: u32, + } + }, + "ToMigrationState: omit cannot be used with other attributes" + ); + derive_compile_fail!( + MigrationStateDerive::expand, + quote! { + struct MyStruct { + #[migration_state(into)] + bad: u32, + } + }, + "unexpected end of input, expected parentheses" + ); + derive_compile_fail!( + MigrationStateDerive::expand, + quote! { + struct MyStruct { + #[migration_state(into(String), try_into(String))] + bad: &'static str, + } + }, + "ToMigrationState: into and try_into attributes cannot be used together" + ); + derive_compile!( + MigrationStateDerive::expand, + quote! { + #[migration_state(rename = CustomMigration)] + struct MyStruct { + #[migration_state(omit)] + runtime_field: u32, + + #[migration_state(clone)] + shared_data: String, + + #[migration_state(into(Cow<'static, str>), clone)] + converted_field: String, + + #[migration_state(try_into(i8))] + fallible_field: u32, + + nested_field: NestedStruct, + simple_field: u32, + } + }, + quote! { + #[derive(Default)] + pub struct CustomMigration { + pub shared_data: String, + pub converted_field: Cow<'static, str>, + pub fallible_field: i8, + pub nested_field: <NestedStruct as ToMigrationState>::Migrated, + pub simple_field: <u32 as ToMigrationState>::Migrated, + } + impl ToMigrationState for MyStruct { + type Migrated = CustomMigration; + fn snapshot_migration_state( + &self, + target: &mut Self::Migrated + ) -> Result<(), migration::InvalidError> { + target.shared_data = self.shared_data.clone(); + target.converted_field = self.converted_field.clone().into(); + target.fallible_field = self + .fallible_field + .try_into() + .map_err(|_| migration::InvalidError)?; + self.nested_field + .snapshot_migration_state(&mut target.nested_field)?; + self.simple_field + .snapshot_migration_state(&mut target.simple_field)?; + Ok(()) + } + #[allow(clippy::used_underscore_binding)] + fn restore_migrated_state_mut( + &mut self, + source: Self::Migrated, + _version_id: u8 + ) -> Result<(), migration::InvalidError> { + let Self::Migrated { + shared_data, + converted_field, + fallible_field, + nested_field, + simple_field + } = source; + self.shared_data = shared_data; + self.converted_field = converted_field.into(); + self.fallible_field = fallible_field + .try_into() + .map_err(|_| migration::InvalidError)?; + self.nested_field + .restore_migrated_state_mut(nested_field, _version_id)?; + self.simple_field + .restore_migrated_state_mut(simple_field, _version_id)?; + Ok(()) + } + } + } + ); +} |