1 // Copyright 2024, Linaro Limited
2 // Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
3 // SPDX-License-Identifier: GPL-2.0-or-later
4
5 use proc_macro::TokenStream;
6 use quote::quote;
7 use syn::{
8 parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spanned, token::Comma, Data,
9 DeriveInput, Field, Fields, FieldsUnnamed, Ident, Meta, Path, Token, Variant,
10 };
11
12 mod utils;
13 use utils::MacroError;
14
15 mod bits;
16 use bits::BitsConstInternal;
17
get_fields<'a>( input: &'a DeriveInput, msg: &str, ) -> Result<&'a Punctuated<Field, Comma>, MacroError>18 fn get_fields<'a>(
19 input: &'a DeriveInput,
20 msg: &str,
21 ) -> Result<&'a Punctuated<Field, Comma>, MacroError> {
22 let Data::Struct(ref s) = &input.data else {
23 return Err(MacroError::Message(
24 format!("Struct required for {msg}"),
25 input.ident.span(),
26 ));
27 };
28 let Fields::Named(ref fs) = &s.fields else {
29 return Err(MacroError::Message(
30 format!("Named fields required for {msg}"),
31 input.ident.span(),
32 ));
33 };
34 Ok(&fs.named)
35 }
36
get_unnamed_field<'a>(input: &'a DeriveInput, msg: &str) -> Result<&'a Field, MacroError>37 fn get_unnamed_field<'a>(input: &'a DeriveInput, msg: &str) -> Result<&'a Field, MacroError> {
38 let Data::Struct(ref s) = &input.data else {
39 return Err(MacroError::Message(
40 format!("Struct required for {msg}"),
41 input.ident.span(),
42 ));
43 };
44 let Fields::Unnamed(FieldsUnnamed { ref unnamed, .. }) = &s.fields else {
45 return Err(MacroError::Message(
46 format!("Tuple struct required for {msg}"),
47 s.fields.span(),
48 ));
49 };
50 if unnamed.len() != 1 {
51 return Err(MacroError::Message(
52 format!("A single field is required for {msg}"),
53 s.fields.span(),
54 ));
55 }
56 Ok(&unnamed[0])
57 }
58
is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError>59 fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError> {
60 let expected = parse_quote! { #[repr(C)] };
61
62 if input.attrs.iter().any(|attr| attr == &expected) {
63 Ok(())
64 } else {
65 Err(MacroError::Message(
66 format!("#[repr(C)] required for {msg}"),
67 input.ident.span(),
68 ))
69 }
70 }
71
is_transparent_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError>72 fn is_transparent_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError> {
73 let expected = parse_quote! { #[repr(transparent)] };
74
75 if input.attrs.iter().any(|attr| attr == &expected) {
76 Ok(())
77 } else {
78 Err(MacroError::Message(
79 format!("#[repr(transparent)] required for {msg}"),
80 input.ident.span(),
81 ))
82 }
83 }
84
derive_object_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError>85 fn derive_object_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> {
86 is_c_repr(&input, "#[derive(Object)]")?;
87
88 let name = &input.ident;
89 let parent = &get_fields(&input, "#[derive(Object)]")?[0].ident;
90
91 Ok(quote! {
92 ::qemu_api::assert_field_type!(#name, #parent,
93 ::qemu_api::qom::ParentField<<#name as ::qemu_api::qom::ObjectImpl>::ParentType>);
94
95 ::qemu_api::module_init! {
96 MODULE_INIT_QOM => unsafe {
97 ::qemu_api::bindings::type_register_static(&<#name as ::qemu_api::qom::ObjectImpl>::TYPE_INFO);
98 }
99 }
100 })
101 }
102
103 #[proc_macro_derive(Object)]
derive_object(input: TokenStream) -> TokenStream104 pub fn derive_object(input: TokenStream) -> TokenStream {
105 let input = parse_macro_input!(input as DeriveInput);
106 let expanded = derive_object_or_error(input).unwrap_or_else(Into::into);
107
108 TokenStream::from(expanded)
109 }
110
derive_opaque_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError>111 fn derive_opaque_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> {
112 is_transparent_repr(&input, "#[derive(Wrapper)]")?;
113
114 let name = &input.ident;
115 let field = &get_unnamed_field(&input, "#[derive(Wrapper)]")?;
116 let typ = &field.ty;
117
118 // TODO: how to add "::qemu_api"? For now, this is only used in the
119 // qemu_api crate so it's not a problem.
120 Ok(quote! {
121 unsafe impl crate::cell::Wrapper for #name {
122 type Wrapped = <#typ as crate::cell::Wrapper>::Wrapped;
123 }
124 impl #name {
125 pub unsafe fn from_raw<'a>(ptr: *mut <Self as crate::cell::Wrapper>::Wrapped) -> &'a Self {
126 let ptr = ::std::ptr::NonNull::new(ptr).unwrap().cast::<Self>();
127 unsafe { ptr.as_ref() }
128 }
129
130 pub const fn as_mut_ptr(&self) -> *mut <Self as crate::cell::Wrapper>::Wrapped {
131 self.0.as_mut_ptr()
132 }
133
134 pub const fn as_ptr(&self) -> *const <Self as crate::cell::Wrapper>::Wrapped {
135 self.0.as_ptr()
136 }
137
138 pub const fn as_void_ptr(&self) -> *mut ::core::ffi::c_void {
139 self.0.as_void_ptr()
140 }
141
142 pub const fn raw_get(slot: *mut Self) -> *mut <Self as crate::cell::Wrapper>::Wrapped {
143 slot.cast()
144 }
145 }
146 })
147 }
148
149 #[proc_macro_derive(Wrapper)]
derive_opaque(input: TokenStream) -> TokenStream150 pub fn derive_opaque(input: TokenStream) -> TokenStream {
151 let input = parse_macro_input!(input as DeriveInput);
152 let expanded = derive_opaque_or_error(input).unwrap_or_else(Into::into);
153
154 TokenStream::from(expanded)
155 }
156
157 #[allow(non_snake_case)]
get_repr_uN(input: &DeriveInput, msg: &str) -> Result<Path, MacroError>158 fn get_repr_uN(input: &DeriveInput, msg: &str) -> Result<Path, MacroError> {
159 let repr = input.attrs.iter().find(|attr| attr.path().is_ident("repr"));
160 if let Some(repr) = repr {
161 let nested = repr.parse_args_with(Punctuated::<Meta, Token![,]>::parse_terminated)?;
162 for meta in nested {
163 match meta {
164 Meta::Path(path) if path.is_ident("u8") => return Ok(path),
165 Meta::Path(path) if path.is_ident("u16") => return Ok(path),
166 Meta::Path(path) if path.is_ident("u32") => return Ok(path),
167 Meta::Path(path) if path.is_ident("u64") => return Ok(path),
168 _ => {}
169 }
170 }
171 }
172
173 Err(MacroError::Message(
174 format!("#[repr(u8/u16/u32/u64) required for {msg}"),
175 input.ident.span(),
176 ))
177 }
178
get_variants(input: &DeriveInput) -> Result<&Punctuated<Variant, Comma>, MacroError>179 fn get_variants(input: &DeriveInput) -> Result<&Punctuated<Variant, Comma>, MacroError> {
180 let Data::Enum(ref e) = &input.data else {
181 return Err(MacroError::Message(
182 "Cannot derive TryInto for union or struct.".to_string(),
183 input.ident.span(),
184 ));
185 };
186 if let Some(v) = e.variants.iter().find(|v| v.fields != Fields::Unit) {
187 return Err(MacroError::Message(
188 "Cannot derive TryInto for enum with non-unit variants.".to_string(),
189 v.fields.span(),
190 ));
191 }
192 Ok(&e.variants)
193 }
194
195 #[rustfmt::skip::macros(quote)]
derive_tryinto_body( name: &Ident, variants: &Punctuated<Variant, Comma>, repr: &Path, ) -> Result<proc_macro2::TokenStream, MacroError>196 fn derive_tryinto_body(
197 name: &Ident,
198 variants: &Punctuated<Variant, Comma>,
199 repr: &Path,
200 ) -> Result<proc_macro2::TokenStream, MacroError> {
201 let discriminants: Vec<&Ident> = variants.iter().map(|f| &f.ident).collect();
202
203 Ok(quote! {
204 #(const #discriminants: #repr = #name::#discriminants as #repr;)*;
205 match value {
206 #(#discriminants => core::result::Result::Ok(#name::#discriminants),)*
207 _ => core::result::Result::Err(value),
208 }
209 })
210 }
211
212 #[rustfmt::skip::macros(quote)]
derive_tryinto_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError>213 fn derive_tryinto_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, MacroError> {
214 let repr = get_repr_uN(&input, "#[derive(TryInto)]")?;
215 let name = &input.ident;
216 let body = derive_tryinto_body(name, get_variants(&input)?, &repr)?;
217 let errmsg = format!("invalid value for {name}");
218
219 Ok(quote! {
220 impl #name {
221 #[allow(dead_code)]
222 pub const fn into_bits(self) -> #repr {
223 self as #repr
224 }
225
226 #[allow(dead_code)]
227 pub const fn from_bits(value: #repr) -> Self {
228 match ({
229 #body
230 }) {
231 Ok(x) => x,
232 Err(_) => panic!(#errmsg)
233 }
234 }
235 }
236 impl core::convert::TryFrom<#repr> for #name {
237 type Error = #repr;
238
239 #[allow(ambiguous_associated_items)]
240 fn try_from(value: #repr) -> Result<Self, #repr> {
241 #body
242 }
243 }
244 })
245 }
246
247 #[proc_macro_derive(TryInto)]
derive_tryinto(input: TokenStream) -> TokenStream248 pub fn derive_tryinto(input: TokenStream) -> TokenStream {
249 let input = parse_macro_input!(input as DeriveInput);
250 let expanded = derive_tryinto_or_error(input).unwrap_or_else(Into::into);
251
252 TokenStream::from(expanded)
253 }
254
255 #[proc_macro]
bits_const_internal(ts: TokenStream) -> TokenStream256 pub fn bits_const_internal(ts: TokenStream) -> TokenStream {
257 let ts = proc_macro2::TokenStream::from(ts);
258 let mut it = ts.into_iter();
259
260 let expanded = BitsConstInternal::parse(&mut it).unwrap_or_else(Into::into);
261 TokenStream::from(expanded)
262 }
263