From nobody Sat Apr 5 13:01:29 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1740666354; cv=none; d=zohomail.com; s=zohoarc; b=ivY3QLnvuECBquKjh/5k+tUR+vUXdQKLA1PUpM5hvSCQOAD6pAh0wGpNvjw29IfqYS5l9dXlR8osXG/E31HuJF3OAMcx26Whywj4KrokjKSRYe85AM5DT36Svw+6GGJm1UDFdZ8wTbT/1xOZZbc2Lg9Hn7QIP+mSk957wGZ1YLM= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1740666354; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=DU8RnwXUCUOFmlQq7LelOhzzqajTuinw3yOxvFn4Jv4=; b=SqZ6F73yvajEgGcCs8FhYLmBeJYOTf+KOWigAeep57F4pBxBrtjMrADC+obO/fu9egXiU5xAwZTBw3TOnZs81UTxk6lbOGYcnoik6iTUqI7m+q/if3qmozHxRGifku/4zsojhpoSThf41yPJVbfT9Te/qj6wUYXi80RcxLBWUYs= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1740666354847338.1473428188216; Thu, 27 Feb 2025 06:25:54 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tnen5-0005ID-Vy; Thu, 27 Feb 2025 09:23:08 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tnemc-0003qC-KE for qemu-devel@nongnu.org; Thu, 27 Feb 2025 09:22:41 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tnemY-00044k-0Q for qemu-devel@nongnu.org; Thu, 27 Feb 2025 09:22:37 -0500 Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-316-qEoIOJalO4CJ1DBp2bJ3LQ-1; Thu, 27 Feb 2025 09:22:28 -0500 Received: by mail-ed1-f72.google.com with SMTP id 4fb4d7f45d1cf-5e04de6583bso1482253a12.1 for ; Thu, 27 Feb 2025 06:22:27 -0800 (PST) Received: from [192.168.10.48] ([176.206.102.52]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5e4c3fb58f7sm1145654a12.57.2025.02.27.06.22.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Feb 2025 06:22:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1740666149; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DU8RnwXUCUOFmlQq7LelOhzzqajTuinw3yOxvFn4Jv4=; b=EhibYWNi/d12bTzwyHSBJfF9ksaLodeM6ENU+gZFhtmTMjy4txbFFJ4Ch2UA6UhltmgT0k 75At1fMyVF96Ofe6Gq3e4uqZAEg1wXcdN20M4AkcH758bwiUAnlHAiKK1OR0S8O3dPeX7t 6BnW7TBm2V1Owg3VPkj3C5xJCDMWBMI= X-MC-Unique: qEoIOJalO4CJ1DBp2bJ3LQ-1 X-Mimecast-MFC-AGG-ID: qEoIOJalO4CJ1DBp2bJ3LQ_1740666147 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740666145; x=1741270945; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=DU8RnwXUCUOFmlQq7LelOhzzqajTuinw3yOxvFn4Jv4=; b=d+Lfmk7w7chkMroCjY3sq1o9+1shjwoj+qRxW/QPIoHyOqQoDsnCFadYd4ocXHwB9U gnHmUEWLovch3tSLnkjWUu0f25i0MJJcDIIzORQc2w7pyfXI2Y4xBvFi+5mIraYUXKzI /y+2U3QRFRztQoSgMVPrtQDzqRpKyWvr1ASczmhASyB2ypVM92d4P8balN1BOzmktH6n IJ3g+VxNZBZFJVE83qyF9jY4Kz/CsLyWSwMWwlUxZ+fADDSEh3zaAXuo2hpKnemMFtNA zNE0dM/5JsEMeZgbpTXPc+FD1ZPqhI20lCxMrvbzuMHU7EyAVZz4tEbOh39gJi35m0pi bwVg== X-Gm-Message-State: AOJu0Yz32/JK8eyghBbbQm4f7VzgUKEH9Ztphz51cau2spatxmcJ+FwM Afw2aLd/7XOSMLHNOhtpvQX19IPxR+WVf8un8GCz1NLh1sUUNrueOfDy7Cn/iSaToiGRSdcYSF3 puu8CCddMylbiRfomCT3QedzFjHh1HbDNa552WTDNoltfWj0W9w7ql6WAt0W9LKS0nuAE+Zr/JC Rv4AqfzuzfAFUecJavkiN/5PKJM9gNQQX7joMI1Xo= X-Gm-Gg: ASbGnct3zwxhjYMcCnq6IejMO7w7NHnBIwYUI+KbHBuThdyItO+uKXNKncGbGA0Y2rW /WLT0FFvPpVFYvK18BnZ7HXCMNhZU6tIHv8GTqzNaM8YfGyzuolWqDw8SNxlj55feuvwre6nK5T /jTvzN99RqvTae0FgkUZ4Yp7sjT9AUQvzcC9ue4+dafG35wZCpqbd1EKeIK/6Vu4DI3B+Ee1IO2 jEMey2I72IkrU6q6VfkDOsZPUbFo+mCD2ijQDVKZhDWg4+giuHqlkBdt3OwbhF1LJ9tjeYDVTrq JOz5O7cnxNjGQKk0m1Uf X-Received: by 2002:a05:6402:3595:b0:5e0:8c55:536 with SMTP id 4fb4d7f45d1cf-5e444481531mr13914557a12.4.1740666145476; Thu, 27 Feb 2025 06:22:25 -0800 (PST) X-Google-Smtp-Source: AGHT+IHQEvRXKFNO8uqehyPrMvfwzyUwe/T2t9ikClNPL5YVhQNUna8NZ1lwhLuT9lhaB++h80+AvQ== X-Received: by 2002:a05:6402:3595:b0:5e0:8c55:536 with SMTP id 4fb4d7f45d1cf-5e444481531mr13914532a12.4.1740666145018; Thu, 27 Feb 2025 06:22:25 -0800 (PST) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: qemu-rust@nongnu.org, zhao1.liu@intel.com Subject: [PATCH 02/12] rust: qemu_api_macros: add Wrapper derive macro Date: Thu, 27 Feb 2025 15:22:09 +0100 Message-ID: <20250227142219.812270-3-pbonzini@redhat.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250227142219.812270-1-pbonzini@redhat.com> References: <20250227142219.812270-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.438, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1740666356989019100 Content-Type: text/plain; charset="utf-8" Add a derive macro that makes it easy to peel off all the layers of specialness (UnsafeCell, MaybeUninit, etc.) and just get a pointer to the wrapped type; and likewise add them back starting from a *mut. Reviewed-by: Zhao Liu Signed-off-by: Paolo Bonzini --- docs/devel/rust.rst | 8 +-- rust/qemu-api-macros/src/lib.rs | 86 ++++++++++++++++++++++++++++++++- rust/qemu-api/meson.build | 7 +-- rust/qemu-api/src/cell.rs | 31 ++++++++++++ 4 files changed, 123 insertions(+), 9 deletions(-) diff --git a/docs/devel/rust.rst b/docs/devel/rust.rst index 784c3e40bdc..64e04bc5c41 100644 --- a/docs/devel/rust.rst +++ b/docs/devel/rust.rst @@ -315,11 +315,13 @@ a raw pointer, for use in calls to C functions. It c= an be used for example as follows:: =20 #[repr(transparent)] - #[derive(Debug)] + #[derive(Debug, qemu_api_macros::Wrapper)] pub struct Object(Opaque); =20 -The bindings will then manually check for the big QEMU lock with -assertions, which allows the wrapper to be declared thread-safe:: +where the special ``derive`` macro provides useful methods such as +``from_raw``, ``as_ptr`` and ``as_mut_ptr``. The bindings will then +manually check for the big QEMU lock with assertions, which allows +the wrapper to be declared thread-safe:: =20 unsafe impl Send for Object {} unsafe impl Sync for Object {} diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib= .rs index 7ec218202f4..3df9c48035d 100644 --- a/rust/qemu-api-macros/src/lib.rs +++ b/rust/qemu-api-macros/src/lib.rs @@ -6,7 +6,7 @@ use quote::quote; use syn::{ parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spann= ed, token::Comma, Data, - DeriveInput, Field, Fields, Ident, Meta, Path, Token, Type, Variant, V= isibility, + DeriveInput, Field, Fields, FieldsUnnamed, Ident, Meta, Path, Token, T= ype, Variant, Visibility, }; =20 mod utils; @@ -33,6 +33,35 @@ fn get_fields<'a>( } } =20 +fn get_unnamed_field<'a>(input: &'a DeriveInput, msg: &str) -> Result<&'a = Field, MacroError> { + if let Data::Struct(s) =3D &input.data { + let unnamed =3D match &s.fields { + Fields::Unnamed(FieldsUnnamed { + unnamed: ref fields, + .. + }) =3D> fields, + _ =3D> { + return Err(MacroError::Message( + format!("Tuple struct required for {}", msg), + s.fields.span(), + )) + } + }; + if unnamed.len() !=3D 1 { + return Err(MacroError::Message( + format!("A single field is required for {}", msg), + s.fields.span(), + )); + } + Ok(&unnamed[0]) + } else { + Err(MacroError::Message( + format!("Struct required for {}", msg), + input.ident.span(), + )) + } +} + fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError> { let expected =3D parse_quote! { #[repr(C)] }; =20 @@ -46,6 +75,19 @@ fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(= ), MacroError> { } } =20 +fn is_transparent_repr(input: &DeriveInput, msg: &str) -> Result<(), Macro= Error> { + let expected =3D parse_quote! { #[repr(transparent)] }; + + if input.attrs.iter().any(|attr| attr =3D=3D &expected) { + Ok(()) + } else { + Err(MacroError::Message( + format!("#[repr(transparent)] required for {}", msg), + input.ident.span(), + )) + } +} + fn derive_object_or_error(input: DeriveInput) -> Result { is_c_repr(&input, "#[derive(Object)]")?; =20 @@ -72,6 +114,48 @@ pub fn derive_object(input: TokenStream) -> TokenStream= { TokenStream::from(expanded) } =20 +fn derive_opaque_or_error(input: DeriveInput) -> Result { + is_transparent_repr(&input, "#[derive(Wrapper)]")?; + + let name =3D &input.ident; + let field =3D &get_unnamed_field(&input, "#[derive(Wrapper)]")?; + let typ =3D &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 =3D <#typ as crate::cell::Wrapper>::Wrapped; + } + impl #name { + pub unsafe fn from_raw<'a>(ptr: *mut ::Wrapped) -> &'a Self { + let ptr =3D ::std::ptr::NonNull::new(ptr).unwrap().cast::<= Self>(); + unsafe { ptr.as_ref() } + } + + pub const fn as_mut_ptr(&self) -> *mut ::Wrapped { + self.0.as_mut_ptr() + } + + pub const fn as_ptr(&self) -> *const ::Wrapped { + self.0.as_ptr() + } + + pub const fn as_void_ptr(&self) -> *mut ::core::ffi::c_void { + self.0.as_void_ptr() + } + } + }) +} + +#[proc_macro_derive(Wrapper)] +pub fn derive_opaque(input: TokenStream) -> TokenStream { + let input =3D parse_macro_input!(input as DeriveInput); + let expanded =3D derive_opaque_or_error(input).unwrap_or_else(Into::in= to); + + TokenStream::from(expanded) +} + #[rustfmt::skip::macros(quote)] fn derive_offsets_or_error(input: DeriveInput) -> Result { is_c_repr(&input, "#[derive(offsets)]")?; diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index bcf1cf780f3..6e52c4bad74 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -42,16 +42,13 @@ _qemu_api_rs =3D static_library( override_options: ['rust_std=3D2021', 'build.rust_std=3D2021'], rust_abi: 'rust', rust_args: _qemu_api_cfg, - dependencies: libc_dep, + dependencies: [libc_dep, qemu_api_macros], ) =20 rust.test('rust-qemu-api-tests', _qemu_api_rs, suite: ['unit', 'rust']) =20 -qemu_api =3D declare_dependency( - link_with: _qemu_api_rs, - dependencies: qemu_api_macros, -) +qemu_api =3D declare_dependency(link_with: _qemu_api_rs) =20 # Rust executables do not support objects, so add an intermediate step. rust_qemu_api_objs =3D static_library( diff --git a/rust/qemu-api/src/cell.rs b/rust/qemu-api/src/cell.rs index 7c00109d0e9..24efb3a2f2a 100644 --- a/rust/qemu-api/src/cell.rs +++ b/rust/qemu-api/src/cell.rs @@ -1023,3 +1023,34 @@ pub unsafe fn new() -> Self { } } } + +/// Annotates [`Self`] as a transparent wrapper for another type. +/// +/// Usually defined via the [`qemu_api_macros::Wrapper`] derive macro. +/// +/// # Examples +/// +/// ``` +/// # use std::mem::ManuallyDrop; +/// # use qemu_api::cell::Wrapper; +/// #[repr(transparent)] +/// pub struct Example { +/// inner: ManuallyDrop, +/// } +/// +/// unsafe impl Wrapper for Example { +/// type Wrapped =3D String; +/// } +/// ``` +/// +/// # Safety +/// +/// `Self` must be a `#[repr(transparent)]` wrapper for the `Wrapped` type, +/// whether directly or indirectly. +pub unsafe trait Wrapper { + type Wrapped; +} + +unsafe impl Wrapper for Opaque { + type Wrapped =3D T; +} --=20 2.48.1