rust: rename qemu_api_macros -> qemu_macros

Since "qemu_api" is no longer the unique crate to provide APIs.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Link: https://lore.kernel.org/r/20250827104147.717203-17-marcandre.lureau@redhat.com
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 415 insertions, 0 deletions

diff --git a/rust/qemu-macros/src/lib.rs b/rust/qemu-macros/src/lib.rs
new file mode 100644
index 0000000000..830b432698
--- /dev/null
+++ b/rust/qemu-macros/src/lib.rs
@@ -0,0 +1,415 @@
+// 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, quote_spanned, ToTokens};
+use syn::{
+    parse::Parse, parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spanned,
+    token::Comma, Data, DeriveInput, Error, Field, Fields, FieldsUnnamed, Ident, Meta, Path, Token,
+    Variant,
+};
+mod bits;
+use bits::BitsConstInternal;
+
+#[cfg(test)]
+mod tests;
+
+fn get_fields<'a>(
+    input: &'a DeriveInput,
+    msg: &str,
+) -> Result<&'a Punctuated<Field, Comma>, Error> {
+    let Data::Struct(ref s) = &input.data else {
+        return Err(Error::new(
+            input.ident.span(),
+            format!("Struct required for {msg}"),
+        ));
+    };
+    let Fields::Named(ref fs) = &s.fields else {
+        return Err(Error::new(
+            input.ident.span(),
+            format!("Named fields required for {msg}"),
+        ));
+    };
+    Ok(&fs.named)
+}
+
+fn get_unnamed_field<'a>(input: &'a DeriveInput, msg: &str) -> Result<&'a Field, Error> {
+    let Data::Struct(ref s) = &input.data else {
+        return Err(Error::new(
+            input.ident.span(),
+            format!("Struct required for {msg}"),
+        ));
+    };
+    let Fields::Unnamed(FieldsUnnamed { ref unnamed, .. }) = &s.fields else {
+        return Err(Error::new(
+            s.fields.span(),
+            format!("Tuple struct required for {msg}"),
+        ));
+    };
+    if unnamed.len() != 1 {
+        return Err(Error::new(
+            s.fields.span(),
+            format!("A single field is required for {msg}"),
+        ));
+    }
+    Ok(&unnamed[0])
+}
+
+fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), Error> {
+    let expected = parse_quote! { #[repr(C)] };
+
+    if input.attrs.iter().any(|attr| attr == &expected) {
+        Ok(())
+    } else {
+        Err(Error::new(
+            input.ident.span(),
+            format!("#[repr(C)] required for {msg}"),
+        ))
+    }
+}
+
+fn is_transparent_repr(input: &DeriveInput, msg: &str) -> Result<(), Error> {
+    let expected = parse_quote! { #[repr(transparent)] };
+
+    if input.attrs.iter().any(|attr| attr == &expected) {
+        Ok(())
+    } else {
+        Err(Error::new(
+            input.ident.span(),
+            format!("#[repr(transparent)] required for {msg}"),
+        ))
+    }
+}
+
+fn derive_object_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, Error> {
+    is_c_repr(&input, "#[derive(Object)]")?;
+
+    let name = &input.ident;
+    let parent = &get_fields(&input, "#[derive(Object)]")?
+        .get(0)
+        .ok_or_else(|| {
+            Error::new(
+                input.ident.span(),
+                "#[derive(Object)] requires a parent field",
+            )
+        })?
+        .ident;
+
+    Ok(quote! {
+        ::common::assert_field_type!(#name, #parent,
+            ::qom::ParentField<<#name as ::qom::ObjectImpl>::ParentType>);
+
+        ::util::module_init! {
+            MODULE_INIT_QOM => unsafe {
+                ::qom::type_register_static(&<#name as ::qom::ObjectImpl>::TYPE_INFO);
+            }
+        }
+    })
+}
+
+#[proc_macro_derive(Object)]
+pub fn derive_object(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+
+    derive_object_or_error(input)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}
+
+fn derive_opaque_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, Error> {
+    is_transparent_repr(&input, "#[derive(Wrapper)]")?;
+
+    let name = &input.ident;
+    let field = &get_unnamed_field(&input, "#[derive(Wrapper)]")?;
+    let typ = &field.ty;
+
+    Ok(quote! {
+        unsafe impl ::common::opaque::Wrapper for #name {
+            type Wrapped = <#typ as ::common::opaque::Wrapper>::Wrapped;
+        }
+        impl #name {
+            pub unsafe fn from_raw<'a>(ptr: *mut <Self as ::common::opaque::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 ::common::opaque::Wrapper>::Wrapped {
+                self.0.as_mut_ptr()
+            }
+
+            pub const fn as_ptr(&self) -> *const <Self as ::common::opaque::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 ::common::opaque::Wrapper>::Wrapped {
+                slot.cast()
+            }
+        }
+    })
+}
+
+#[derive(Debug)]
+enum DevicePropertyName {
+    CStr(syn::LitCStr),
+    Str(syn::LitStr),
+}
+
+#[derive(Debug)]
+struct DeviceProperty {
+    rename: Option<DevicePropertyName>,
+    defval: Option<syn::Expr>,
+}
+
+impl Parse for DeviceProperty {
+    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
+        let _: syn::Token![#] = input.parse()?;
+        let bracketed;
+        _ = syn::bracketed!(bracketed in input);
+        let attribute = bracketed.parse::<syn::Ident>()?;
+        debug_assert_eq!(&attribute.to_string(), "property");
+        let mut retval = Self {
+            rename: None,
+            defval: None,
+        };
+        let content;
+        _ = syn::parenthesized!(content in bracketed);
+        while !content.is_empty() {
+            let value: syn::Ident = content.parse()?;
+            if value == "rename" {
+                let _: syn::Token![=] = content.parse()?;
+                if retval.rename.is_some() {
+                    return Err(syn::Error::new(
+                        value.span(),
+                        "`rename` can only be used at most once",
+                    ));
+                }
+                if content.peek(syn::LitStr) {
+                    retval.rename = Some(DevicePropertyName::Str(content.parse::<syn::LitStr>()?));
+                } else {
+                    retval.rename =
+                        Some(DevicePropertyName::CStr(content.parse::<syn::LitCStr>()?));
+                }
+            } else if value == "default" {
+                let _: syn::Token![=] = content.parse()?;
+                if retval.defval.is_some() {
+                    return Err(syn::Error::new(
+                        value.span(),
+                        "`default` can only be used at most once",
+                    ));
+                }
+                retval.defval = Some(content.parse()?);
+            } else {
+                return Err(syn::Error::new(
+                    value.span(),
+                    format!("unrecognized field `{value}`"),
+                ));
+            }
+
+            if !content.is_empty() {
+                let _: syn::Token![,] = content.parse()?;
+            }
+        }
+        Ok(retval)
+    }
+}
+
+#[proc_macro_derive(Device, attributes(property))]
+pub fn derive_device(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+
+    derive_device_or_error(input)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}
+
+fn derive_device_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream, Error> {
+    is_c_repr(&input, "#[derive(Device)]")?;
+    let properties: Vec<(syn::Field, DeviceProperty)> = get_fields(&input, "#[derive(Device)]")?
+        .iter()
+        .flat_map(|f| {
+            f.attrs
+                .iter()
+                .filter(|a| a.path().is_ident("property"))
+                .map(|a| Ok((f.clone(), syn::parse2(a.to_token_stream())?)))
+        })
+        .collect::<Result<Vec<_>, Error>>()?;
+    let name = &input.ident;
+    let mut properties_expanded = vec![];
+
+    for (field, prop) in properties {
+        let DeviceProperty { rename, defval } = prop;
+        let field_name = field.ident.unwrap();
+        macro_rules! str_to_c_str {
+            ($value:expr, $span:expr) => {{
+                let (value, span) = ($value, $span);
+                let cstr = std::ffi::CString::new(value.as_str()).map_err(|err| {
+                    Error::new(
+                        span,
+                        format!(
+                            "Property name `{value}` cannot be represented as a C string: {err}"
+                        ),
+                    )
+                })?;
+                let cstr_lit = syn::LitCStr::new(&cstr, span);
+                Ok(quote! { #cstr_lit })
+            }};
+        }
+
+        let prop_name = rename.map_or_else(
+            || str_to_c_str!(field_name.to_string(), field_name.span()),
+            |rename| -> Result<proc_macro2::TokenStream, Error> {
+                match rename {
+                    DevicePropertyName::CStr(cstr_lit) => Ok(quote! { #cstr_lit }),
+                    DevicePropertyName::Str(str_lit) => {
+                        str_to_c_str!(str_lit.value(), str_lit.span())
+                    }
+                }
+            },
+        )?;
+        let field_ty = field.ty.clone();
+        let qdev_prop = quote! { <#field_ty as ::hwcore::QDevProp>::VALUE };
+        let set_default = defval.is_some();
+        let defval = defval.unwrap_or(syn::Expr::Verbatim(quote! { 0 }));
+        properties_expanded.push(quote! {
+            ::hwcore::bindings::Property {
+                name: ::std::ffi::CStr::as_ptr(#prop_name),
+                info: #qdev_prop ,
+                offset: ::core::mem::offset_of!(#name, #field_name) as isize,
+                set_default: #set_default,
+                defval: ::hwcore::bindings::Property__bindgen_ty_1 { u: #defval as u64 },
+                ..::common::Zeroable::ZERO
+            }
+        });
+    }
+
+    Ok(quote_spanned! {input.span() =>
+        unsafe impl ::hwcore::DevicePropertiesImpl for #name {
+            const PROPERTIES: &'static [::hwcore::bindings::Property] = &[
+                #(#properties_expanded),*
+            ];
+        }
+    })
+}
+
+#[proc_macro_derive(Wrapper)]
+pub fn derive_opaque(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+
+    derive_opaque_or_error(input)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}
+
+#[allow(non_snake_case)]
+fn get_repr_uN(input: &DeriveInput, msg: &str) -> Result<Path, Error> {
+    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(Error::new(
+        input.ident.span(),
+        format!("#[repr(u8/u16/u32/u64) required for {msg}"),
+    ))
+}
+
+fn get_variants(input: &DeriveInput) -> Result<&Punctuated<Variant, Comma>, Error> {
+    let Data::Enum(ref e) = &input.data else {
+        return Err(Error::new(
+            input.ident.span(),
+            "Cannot derive TryInto for union or struct.",
+        ));
+    };
+    if let Some(v) = e.variants.iter().find(|v| v.fields != Fields::Unit) {
+        return Err(Error::new(
+            v.fields.span(),
+            "Cannot derive TryInto for enum with non-unit variants.",
+        ));
+    }
+    Ok(&e.variants)
+}
+
+#[rustfmt::skip::macros(quote)]
+fn derive_tryinto_body(
+    name: &Ident,
+    variants: &Punctuated<Variant, Comma>,
+    repr: &Path,
+) -> Result<proc_macro2::TokenStream, Error> {
+    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, Error> {
+    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);
+
+    derive_tryinto_or_error(input)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}
+
+#[proc_macro]
+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)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}