diff options
Diffstat (limited to 'rust/qemu-api-macros/src')
| -rw-r--r-- | rust/qemu-api-macros/src/bits.rs | 229 | ||||
| -rw-r--r-- | rust/qemu-api-macros/src/lib.rs | 262 | ||||
| -rw-r--r-- | rust/qemu-api-macros/src/utils.rs | 26 |
3 files changed, 517 insertions, 0 deletions
diff --git a/rust/qemu-api-macros/src/bits.rs b/rust/qemu-api-macros/src/bits.rs new file mode 100644 index 0000000..5ba8475 --- /dev/null +++ b/rust/qemu-api-macros/src/bits.rs @@ -0,0 +1,229 @@ +// SPDX-License-Identifier: MIT or Apache-2.0 or GPL-2.0-or-later + +// shadowing is useful together with "if let" +#![allow(clippy::shadow_unrelated)] + +use proc_macro2::{ + Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree, TokenTree as TT, +}; + +use crate::utils::MacroError; + +pub struct BitsConstInternal { + typ: TokenTree, +} + +fn paren(ts: TokenStream) -> TokenTree { + TT::Group(Group::new(Delimiter::Parenthesis, ts)) +} + +fn ident(s: &'static str) -> TokenTree { + TT::Ident(Ident::new(s, Span::call_site())) +} + +fn punct(ch: char) -> TokenTree { + TT::Punct(Punct::new(ch, Spacing::Alone)) +} + +/// Implements a recursive-descent parser that translates Boolean expressions on +/// bitmasks to invocations of `const` functions defined by the `bits!` macro. +impl BitsConstInternal { + // primary ::= '(' or ')' + // | ident + // | '!' ident + fn parse_primary( + &self, + tok: TokenTree, + it: &mut dyn Iterator<Item = TokenTree>, + out: &mut TokenStream, + ) -> Result<Option<TokenTree>, MacroError> { + let next = match tok { + TT::Group(ref g) => { + if g.delimiter() != Delimiter::Parenthesis && g.delimiter() != Delimiter::None { + return Err(MacroError::Message("expected parenthesis".into(), g.span())); + } + let mut stream = g.stream().into_iter(); + let Some(first_tok) = stream.next() else { + return Err(MacroError::Message( + "expected operand, found ')'".into(), + g.span(), + )); + }; + let mut output = TokenStream::new(); + // start from the lowest precedence + let next = self.parse_or(first_tok, &mut stream, &mut output)?; + if let Some(tok) = next { + return Err(MacroError::Message( + format!("unexpected token {tok}"), + tok.span(), + )); + } + out.extend(Some(paren(output))); + it.next() + } + TT::Ident(_) => { + let mut output = TokenStream::new(); + output.extend([ + self.typ.clone(), + TT::Punct(Punct::new(':', Spacing::Joint)), + TT::Punct(Punct::new(':', Spacing::Joint)), + tok, + ]); + out.extend(Some(paren(output))); + it.next() + } + TT::Punct(ref p) => { + if p.as_char() != '!' { + return Err(MacroError::Message("expected operand".into(), p.span())); + } + let Some(rhs_tok) = it.next() else { + return Err(MacroError::Message( + "expected operand at end of input".into(), + p.span(), + )); + }; + let next = self.parse_primary(rhs_tok, it, out)?; + out.extend([punct('.'), ident("invert"), paren(TokenStream::new())]); + next + } + _ => { + return Err(MacroError::Message("unexpected literal".into(), tok.span())); + } + }; + Ok(next) + } + + fn parse_binop< + F: Fn( + &Self, + TokenTree, + &mut dyn Iterator<Item = TokenTree>, + &mut TokenStream, + ) -> Result<Option<TokenTree>, MacroError>, + >( + &self, + tok: TokenTree, + it: &mut dyn Iterator<Item = TokenTree>, + out: &mut TokenStream, + ch: char, + f: F, + method: &'static str, + ) -> Result<Option<TokenTree>, MacroError> { + let mut next = f(self, tok, it, out)?; + while next.is_some() { + let op = next.as_ref().unwrap(); + let TT::Punct(ref p) = op else { break }; + if p.as_char() != ch { + break; + } + + let Some(rhs_tok) = it.next() else { + return Err(MacroError::Message( + "expected operand at end of input".into(), + p.span(), + )); + }; + let mut rhs = TokenStream::new(); + next = f(self, rhs_tok, it, &mut rhs)?; + out.extend([punct('.'), ident(method), paren(rhs)]); + } + Ok(next) + } + + // sub ::= primary ('-' primary)* + pub fn parse_sub( + &self, + tok: TokenTree, + it: &mut dyn Iterator<Item = TokenTree>, + out: &mut TokenStream, + ) -> Result<Option<TokenTree>, MacroError> { + self.parse_binop(tok, it, out, '-', Self::parse_primary, "difference") + } + + // and ::= sub ('&' sub)* + fn parse_and( + &self, + tok: TokenTree, + it: &mut dyn Iterator<Item = TokenTree>, + out: &mut TokenStream, + ) -> Result<Option<TokenTree>, MacroError> { + self.parse_binop(tok, it, out, '&', Self::parse_sub, "intersection") + } + + // xor ::= and ('&' and)* + fn parse_xor( + &self, + tok: TokenTree, + it: &mut dyn Iterator<Item = TokenTree>, + out: &mut TokenStream, + ) -> Result<Option<TokenTree>, MacroError> { + self.parse_binop(tok, it, out, '^', Self::parse_and, "symmetric_difference") + } + + // or ::= xor ('|' xor)* + pub fn parse_or( + &self, + tok: TokenTree, + it: &mut dyn Iterator<Item = TokenTree>, + out: &mut TokenStream, + ) -> Result<Option<TokenTree>, MacroError> { + self.parse_binop(tok, it, out, '|', Self::parse_xor, "union") + } + + pub fn parse( + it: &mut dyn Iterator<Item = TokenTree>, + ) -> Result<proc_macro2::TokenStream, MacroError> { + let mut pos = Span::call_site(); + let mut typ = proc_macro2::TokenStream::new(); + + // Gobble everything up to an `@` sign, which is followed by a + // parenthesized expression; that is, all token trees except the + // last two form the type. + let next = loop { + let tok = it.next(); + if let Some(ref t) = tok { + pos = t.span(); + } + match tok { + None => break None, + Some(TT::Punct(ref p)) if p.as_char() == '@' => { + let tok = it.next(); + if let Some(ref t) = tok { + pos = t.span(); + } + break tok; + } + Some(x) => typ.extend(Some(x)), + } + }; + + let Some(tok) = next else { + return Err(MacroError::Message( + "expected expression, do not call this macro directly".into(), + pos, + )); + }; + let TT::Group(ref _group) = tok else { + return Err(MacroError::Message( + "expected parenthesis, do not call this macro directly".into(), + tok.span(), + )); + }; + let mut out = TokenStream::new(); + let state = Self { + typ: TT::Group(Group::new(Delimiter::None, typ)), + }; + + let next = state.parse_primary(tok, it, &mut out)?; + + // A parenthesized expression is a single production of the grammar, + // so the input must have reached the last token. + if let Some(tok) = next { + return Err(MacroError::Message( + format!("unexpected token {tok}"), + tok.span(), + )); + } + Ok(out) + } +} diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib.rs new file mode 100644 index 0000000..c18bb4e --- /dev/null +++ b/rust/qemu-api-macros/src/lib.rs @@ -0,0 +1,262 @@ +// Copyright 2024, Linaro Limited +// Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org> +// SPDX-License-Identifier: GPL-2.0-or-later + +use proc_macro::TokenStream; +use quote::quote; +use syn::{ + parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spanned, token::Comma, Data, + DeriveInput, Field, Fields, FieldsUnnamed, Ident, Meta, Path, Token, Variant, +}; + +mod utils; +use utils::MacroError; + +mod bits; +use bits::BitsConstInternal; + +fn get_fields<'a>( + input: &'a DeriveInput, + msg: &str, +) -> Result<&'a Punctuated<Field, Comma>, MacroError> { + let Data::Struct(ref s) = &input.data else { + return Err(MacroError::Message( + format!("Struct required for {msg}"), + input.ident.span(), + )); + }; + let Fields::Named(ref fs) = &s.fields else { + return Err(MacroError::Message( + format!("Named fields required for {msg}"), + input.ident.span(), + )); + }; + Ok(&fs.named) +} + +fn get_unnamed_field<'a>(input: &'a DeriveInput, msg: &str) -> Result<&'a Field, MacroError> { + let Data::Struct(ref s) = &input.data else { + return Err(MacroError::Message( + format!("Struct required for {msg}"), + input.ident.span(), + )); + }; + let Fields::Unnamed(FieldsUnnamed { ref unnamed, .. }) = &s.fields else { + return Err(MacroError::Message( + format!("Tuple struct required for {msg}"), + s.fields.span(), + )); + }; + if unnamed.len() != 1 { + return Err(MacroError::Message( + format!("A single field is required for {msg}"), + s.fields.span(), + )); + } + Ok(&unnamed[0]) +} + +fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError> { + let expected = parse_quote! { #[repr(C)] }; + + if input.attrs.iter().any(|attr| attr == &expected) { + Ok(()) + } else { + Err(MacroError::Message( + format!("#[repr(C)] required for {msg}"), + input.ident.span(), + )) + } +} + +fn is_transparent_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError> { + let expected = parse_quote! { #[repr(transparent)] }; + + if input.attrs.iter().any(|attr| attr == &expected) { + Ok(()) + } else { + Err(MacroError::Message( + format!("#[repr(transparent)] required for {msg}"), + input.ident.span(), + )) + } +} + +fn derive_object_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> { + is_c_repr(&input, "#[derive(Object)]")?; + + let name = &input.ident; + let parent = &get_fields(&input, "#[derive(Object)]")?[0].ident; + + Ok(quote! { + ::qemu_api::assert_field_type!(#name, #parent, + ::qemu_api::qom::ParentField<<#name as ::qemu_api::qom::ObjectImpl>::ParentType>); + + ::qemu_api::module_init! { + MODULE_INIT_QOM => unsafe { + ::qemu_api::bindings::type_register_static(&<#name as ::qemu_api::qom::ObjectImpl>::TYPE_INFO); + } + } + }) +} + +#[proc_macro_derive(Object)] +pub fn derive_object(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input as DeriveInput); + let expanded = derive_object_or_error(input).unwrap_or_else(Into::into); + + TokenStream::from(expanded) +} + +fn derive_opaque_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> { + is_transparent_repr(&input, "#[derive(Wrapper)]")?; + + let name = &input.ident; + let field = &get_unnamed_field(&input, "#[derive(Wrapper)]")?; + let typ = &field.ty; + + // TODO: how to add "::qemu_api"? For now, this is only used in the + // qemu_api crate so it's not a problem. + Ok(quote! { + unsafe impl crate::cell::Wrapper for #name { + type Wrapped = <#typ as crate::cell::Wrapper>::Wrapped; + } + impl #name { + pub unsafe fn from_raw<'a>(ptr: *mut <Self as crate::cell::Wrapper>::Wrapped) -> &'a Self { + let ptr = ::std::ptr::NonNull::new(ptr).unwrap().cast::<Self>(); + unsafe { ptr.as_ref() } + } + + pub const fn as_mut_ptr(&self) -> *mut <Self as crate::cell::Wrapper>::Wrapped { + self.0.as_mut_ptr() + } + + pub const fn as_ptr(&self) -> *const <Self as crate::cell::Wrapper>::Wrapped { + self.0.as_ptr() + } + + pub const fn as_void_ptr(&self) -> *mut ::core::ffi::c_void { + self.0.as_void_ptr() + } + + pub const fn raw_get(slot: *mut Self) -> *mut <Self as crate::cell::Wrapper>::Wrapped { + slot.cast() + } + } + }) +} + +#[proc_macro_derive(Wrapper)] +pub fn derive_opaque(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input as DeriveInput); + let expanded = derive_opaque_or_error(input).unwrap_or_else(Into::into); + + TokenStream::from(expanded) +} + +#[allow(non_snake_case)] +fn get_repr_uN(input: &DeriveInput, msg: &str) -> Result<Path, MacroError> { + let repr = input.attrs.iter().find(|attr| attr.path().is_ident("repr")); + if let Some(repr) = repr { + let nested = repr.parse_args_with(Punctuated::<Meta, Token![,]>::parse_terminated)?; + for meta in nested { + match meta { + Meta::Path(path) if path.is_ident("u8") => return Ok(path), + Meta::Path(path) if path.is_ident("u16") => return Ok(path), + Meta::Path(path) if path.is_ident("u32") => return Ok(path), + Meta::Path(path) if path.is_ident("u64") => return Ok(path), + _ => {} + } + } + } + + Err(MacroError::Message( + format!("#[repr(u8/u16/u32/u64) required for {msg}"), + input.ident.span(), + )) +} + +fn get_variants(input: &DeriveInput) -> Result<&Punctuated<Variant, Comma>, MacroError> { + let Data::Enum(ref e) = &input.data else { + return Err(MacroError::Message( + "Cannot derive TryInto for union or struct.".to_string(), + input.ident.span(), + )); + }; + if let Some(v) = e.variants.iter().find(|v| v.fields != Fields::Unit) { + return Err(MacroError::Message( + "Cannot derive TryInto for enum with non-unit variants.".to_string(), + v.fields.span(), + )); + } + Ok(&e.variants) +} + +#[rustfmt::skip::macros(quote)] +fn derive_tryinto_body( + name: &Ident, + variants: &Punctuated<Variant, Comma>, + repr: &Path, +) -> Result<proc_macro2::TokenStream, MacroError> { + let discriminants: Vec<&Ident> = variants.iter().map(|f| &f.ident).collect(); + + Ok(quote! { + #(const #discriminants: #repr = #name::#discriminants as #repr;)*; + match value { + #(#discriminants => core::result::Result::Ok(#name::#discriminants),)* + _ => core::result::Result::Err(value), + } + }) +} + +#[rustfmt::skip::macros(quote)] +fn derive_tryinto_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> { + let repr = get_repr_uN(&input, "#[derive(TryInto)]")?; + let name = &input.ident; + let body = derive_tryinto_body(name, get_variants(&input)?, &repr)?; + let errmsg = format!("invalid value for {name}"); + + Ok(quote! { + impl #name { + #[allow(dead_code)] + pub const fn into_bits(self) -> #repr { + self as #repr + } + + #[allow(dead_code)] + pub const fn from_bits(value: #repr) -> Self { + match ({ + #body + }) { + Ok(x) => x, + Err(_) => panic!(#errmsg) + } + } + } + impl core::convert::TryFrom<#repr> for #name { + type Error = #repr; + + #[allow(ambiguous_associated_items)] + fn try_from(value: #repr) -> Result<Self, #repr> { + #body + } + } + }) +} + +#[proc_macro_derive(TryInto)] +pub fn derive_tryinto(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input as DeriveInput); + let expanded = derive_tryinto_or_error(input).unwrap_or_else(Into::into); + + TokenStream::from(expanded) +} + +#[proc_macro] +pub fn bits_const_internal(ts: TokenStream) -> TokenStream { + let ts = proc_macro2::TokenStream::from(ts); + let mut it = ts.into_iter(); + + let expanded = BitsConstInternal::parse(&mut it).unwrap_or_else(Into::into); + TokenStream::from(expanded) +} diff --git a/rust/qemu-api-macros/src/utils.rs b/rust/qemu-api-macros/src/utils.rs new file mode 100644 index 0000000..02c91ae --- /dev/null +++ b/rust/qemu-api-macros/src/utils.rs @@ -0,0 +1,26 @@ +// Procedural macro utilities. +// Author(s): Paolo Bonzini <pbonzini@redhat.com> +// SPDX-License-Identifier: GPL-2.0-or-later + +use proc_macro2::Span; +use quote::quote_spanned; + +pub enum MacroError { + Message(String, Span), + ParseError(syn::Error), +} + +impl From<syn::Error> for MacroError { + fn from(err: syn::Error) -> Self { + MacroError::ParseError(err) + } +} + +impl From<MacroError> for proc_macro2::TokenStream { + fn from(err: MacroError) -> Self { + match err { + MacroError::Message(msg, span) => quote_spanned! { span => compile_error!(#msg); }, + MacroError::ParseError(err) => err.into_compile_error(), + } + } +} |