diff options
Diffstat (limited to 'rust/pin-init/src/macros.rs')
| -rw-r--r-- | rust/pin-init/src/macros.rs | 348 |
1 files changed, 305 insertions, 43 deletions
diff --git a/rust/pin-init/src/macros.rs b/rust/pin-init/src/macros.rs index 361623324d5c..682c61a587a0 100644 --- a/rust/pin-init/src/macros.rs +++ b/rust/pin-init/src/macros.rs @@ -506,6 +506,8 @@ pub use ::paste::paste; /// Creates a `unsafe impl<...> PinnedDrop for $type` block. /// /// See [`PinnedDrop`] for more information. +/// +/// [`PinnedDrop`]: crate::PinnedDrop #[doc(hidden)] #[macro_export] macro_rules! __pinned_drop { @@ -831,6 +833,17 @@ macro_rules! __pin_data { $($fields)* } + $crate::__pin_data!(make_pin_projections: + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @decl_generics($($decl_generics)*), + @where($($whr)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + ); + // We put the rest into this const item, because it then will not be accessible to anything // outside. const _: () = { @@ -980,6 +993,56 @@ macro_rules! __pin_data { stringify!($($rest)*), ); }; + (make_pin_projections: + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @decl_generics($($decl_generics:tt)*), + @where($($whr:tt)*), + @pinned($($(#[$($p_attr:tt)*])* $pvis:vis $p_field:ident : $p_type:ty),* $(,)?), + @not_pinned($($(#[$($attr:tt)*])* $fvis:vis $field:ident : $type:ty),* $(,)?), + ) => { + $crate::macros::paste! { + #[doc(hidden)] + $vis struct [< $name Projection >] <'__pin, $($decl_generics)*> { + $($(#[$($p_attr)*])* $pvis $p_field : ::core::pin::Pin<&'__pin mut $p_type>,)* + $($(#[$($attr)*])* $fvis $field : &'__pin mut $type,)* + ___pin_phantom_data: ::core::marker::PhantomData<&'__pin mut ()>, + } + + impl<$($impl_generics)*> $name<$($ty_generics)*> + where $($whr)* + { + /// Pin-projects all fields of `Self`. + /// + /// These fields are structurally pinned: + $(#[doc = ::core::concat!(" - `", ::core::stringify!($p_field), "`")])* + /// + /// These fields are **not** structurally pinned: + $(#[doc = ::core::concat!(" - `", ::core::stringify!($field), "`")])* + #[inline] + $vis fn project<'__pin>( + self: ::core::pin::Pin<&'__pin mut Self>, + ) -> [< $name Projection >] <'__pin, $($ty_generics)*> { + // SAFETY: we only give access to `&mut` for fields not structurally pinned. + let this = unsafe { ::core::pin::Pin::get_unchecked_mut(self) }; + [< $name Projection >] { + $( + // SAFETY: `$p_field` is structurally pinned. + $(#[$($p_attr)*])* + $p_field : unsafe { ::core::pin::Pin::new_unchecked(&mut this.$p_field) }, + )* + $( + $(#[$($attr)*])* + $field : &mut this.$field, + )* + ___pin_phantom_data: ::core::marker::PhantomData, + } + } + } + } + }; (make_pin_data: @pin_data($pin_data:ident), @impl_generics($($impl_generics:tt)*), @@ -988,38 +1051,56 @@ macro_rules! __pin_data { @pinned($($(#[$($p_attr:tt)*])* $pvis:vis $p_field:ident : $p_type:ty),* $(,)?), @not_pinned($($(#[$($attr:tt)*])* $fvis:vis $field:ident : $type:ty),* $(,)?), ) => { - // For every field, we create a projection function according to its projection type. If a - // field is structurally pinned, then it must be initialized via `PinInit`, if it is not - // structurally pinned, then it can be initialized via `Init`. - // - // The functions are `unsafe` to prevent accidentally calling them. - #[allow(dead_code)] - #[expect(clippy::missing_safety_doc)] - impl<$($impl_generics)*> $pin_data<$($ty_generics)*> - where $($whr)* - { - $( - $(#[$($p_attr)*])* - $pvis unsafe fn $p_field<E>( - self, - slot: *mut $p_type, - init: impl $crate::PinInit<$p_type, E>, - ) -> ::core::result::Result<(), E> { - // SAFETY: TODO. - unsafe { $crate::PinInit::__pinned_init(init, slot) } - } - )* - $( - $(#[$($attr)*])* - $fvis unsafe fn $field<E>( - self, - slot: *mut $type, - init: impl $crate::Init<$type, E>, - ) -> ::core::result::Result<(), E> { - // SAFETY: TODO. - unsafe { $crate::Init::__init(init, slot) } - } - )* + $crate::macros::paste! { + // For every field, we create a projection function according to its projection type. If a + // field is structurally pinned, then it must be initialized via `PinInit`, if it is not + // structurally pinned, then it can be initialized via `Init`. + // + // The functions are `unsafe` to prevent accidentally calling them. + #[allow(dead_code)] + #[expect(clippy::missing_safety_doc)] + impl<$($impl_generics)*> $pin_data<$($ty_generics)*> + where $($whr)* + { + $( + $(#[$($p_attr)*])* + $pvis unsafe fn $p_field<E>( + self, + slot: *mut $p_type, + init: impl $crate::PinInit<$p_type, E>, + ) -> ::core::result::Result<(), E> { + // SAFETY: TODO. + unsafe { $crate::PinInit::__pinned_init(init, slot) } + } + + $(#[$($p_attr)*])* + $pvis unsafe fn [<__project_ $p_field>]<'__slot>( + self, + slot: &'__slot mut $p_type, + ) -> ::core::pin::Pin<&'__slot mut $p_type> { + ::core::pin::Pin::new_unchecked(slot) + } + )* + $( + $(#[$($attr)*])* + $fvis unsafe fn $field<E>( + self, + slot: *mut $type, + init: impl $crate::Init<$type, E>, + ) -> ::core::result::Result<(), E> { + // SAFETY: TODO. + unsafe { $crate::Init::__init(init, slot) } + } + + $(#[$($attr)*])* + $fvis unsafe fn [<__project_ $field>]<'__slot>( + self, + slot: &'__slot mut $type, + ) -> &'__slot mut $type { + slot + } + )* + } } }; } @@ -1030,7 +1111,7 @@ macro_rules! __pin_data { /// /// This macro has multiple internal call configurations, these are always the very first ident: /// - nothing: this is the base case and called by the `{try_}{pin_}init!` macros. -/// - `with_update_parsed`: when the `..Zeroable::zeroed()` syntax has been handled. +/// - `with_update_parsed`: when the `..Zeroable::init_zeroed()` syntax has been handled. /// - `init_slot`: recursively creates the code that initializes all fields in `slot`. /// - `make_initializer`: recursively create the struct initializer that guarantees that every /// field has been initialized exactly once. @@ -1059,7 +1140,7 @@ macro_rules! __init_internal { @data($data, $($use_data)?), @has_data($has_data, $get_data), @construct_closure($construct_closure), - @zeroed(), // Nothing means default behavior. + @init_zeroed(), // Nothing means default behavior. ) }; ( @@ -1074,7 +1155,7 @@ macro_rules! __init_internal { @has_data($has_data:ident, $get_data:ident), // `pin_init_from_closure` or `init_from_closure`. @construct_closure($construct_closure:ident), - @munch_fields(..Zeroable::zeroed()), + @munch_fields(..Zeroable::init_zeroed()), ) => { $crate::__init_internal!(with_update_parsed: @this($($this)?), @@ -1084,7 +1165,7 @@ macro_rules! __init_internal { @data($data, $($use_data)?), @has_data($has_data, $get_data), @construct_closure($construct_closure), - @zeroed(()), // `()` means zero all fields not mentioned. + @init_zeroed(()), // `()` means zero all fields not mentioned. ) }; ( @@ -1124,7 +1205,7 @@ macro_rules! __init_internal { @has_data($has_data:ident, $get_data:ident), // `pin_init_from_closure` or `init_from_closure`. @construct_closure($construct_closure:ident), - @zeroed($($init_zeroed:expr)?), + @init_zeroed($($init_zeroed:expr)?), ) => {{ // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return // type and shadow it later when we insert the arbitrary user code. That way there will be @@ -1196,12 +1277,27 @@ macro_rules! __init_internal { @data($data:ident), @slot($slot:ident), @guards($($guards:ident,)*), - @munch_fields($(..Zeroable::zeroed())? $(,)?), + @munch_fields($(..Zeroable::init_zeroed())? $(,)?), ) => { // Endpoint of munching, no fields are left. If execution reaches this point, all fields // have been initialized. Therefore we can now dismiss the guards by forgetting them. $(::core::mem::forget($guards);)* }; + (init_slot($($use_data:ident)?): + @data($data:ident), + @slot($slot:ident), + @guards($($guards:ident,)*), + // arbitrary code block + @munch_fields(_: { $($code:tt)* }, $($rest:tt)*), + ) => { + { $($code)* } + $crate::__init_internal!(init_slot($($use_data)?): + @data($data), + @slot($slot), + @guards($($guards,)*), + @munch_fields($($rest)*), + ); + }; (init_slot($use_data:ident): // `use_data` is present, so we use the `data` to init fields. @data($data:ident), @slot($slot:ident), @@ -1216,6 +1312,13 @@ macro_rules! __init_internal { // return when an error/panic occurs. // We also use the `data` to require the correct trait (`Init` or `PinInit`) for `$field`. unsafe { $data.$field(::core::ptr::addr_of_mut!((*$slot).$field), init)? }; + // SAFETY: + // - the project function does the correct field projection, + // - the field has been initialized, + // - the reference is only valid until the end of the initializer. + #[allow(unused_variables)] + let $field = $crate::macros::paste!(unsafe { $data.[< __project_ $field >](&mut (*$slot).$field) }); + // Create the drop guard: // // We rely on macro hygiene to make it impossible for users to access this local variable. @@ -1247,6 +1350,14 @@ macro_rules! __init_internal { // SAFETY: `slot` is valid, because we are inside of an initializer closure, we // return when an error/panic occurs. unsafe { $crate::Init::__init(init, ::core::ptr::addr_of_mut!((*$slot).$field))? }; + + // SAFETY: + // - the field is not structurally pinned, since the line above must compile, + // - the field has been initialized, + // - the reference is only valid until the end of the initializer. + #[allow(unused_variables)] + let $field = unsafe { &mut (*$slot).$field }; + // Create the drop guard: // // We rely on macro hygiene to make it impossible for users to access this local variable. @@ -1265,7 +1376,7 @@ macro_rules! __init_internal { ); } }; - (init_slot($($use_data:ident)?): + (init_slot(): // No `use_data`, so all fields are not structurally pinned @data($data:ident), @slot($slot:ident), @guards($($guards:ident,)*), @@ -1279,6 +1390,15 @@ macro_rules! __init_internal { // SAFETY: The memory at `slot` is uninitialized. unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; } + + #[allow(unused_variables)] + // SAFETY: + // - the field is not structurally pinned, since no `use_data` was required to create this + // initializer, + // - the field has been initialized, + // - the reference is only valid until the end of the initializer. + let $field = unsafe { &mut (*$slot).$field }; + // Create the drop guard: // // We rely on macro hygiene to make it impossible for users to access this local variable. @@ -1289,7 +1409,46 @@ macro_rules! __init_internal { $crate::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) }; - $crate::__init_internal!(init_slot($($use_data)?): + $crate::__init_internal!(init_slot(): + @data($data), + @slot($slot), + @guards([< __ $field _guard >], $($guards,)*), + @munch_fields($($rest)*), + ); + } + }; + (init_slot($use_data:ident): + @data($data:ident), + @slot($slot:ident), + @guards($($guards:ident,)*), + // Init by-value. + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) => { + { + $(let $field = $val;)? + // Initialize the field. + // + // SAFETY: The memory at `slot` is uninitialized. + unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; + } + // SAFETY: + // - the project function does the correct field projection, + // - the field has been initialized, + // - the reference is only valid until the end of the initializer. + #[allow(unused_variables)] + let $field = $crate::macros::paste!(unsafe { $data.[< __project_ $field >](&mut (*$slot).$field) }); + + // Create the drop guard: + // + // We rely on macro hygiene to make it impossible for users to access this local variable. + // We use `paste!` to create new hygiene for `$field`. + $crate::macros::paste! { + // SAFETY: We forget the guard later when initialization has succeeded. + let [< __ $field _guard >] = unsafe { + $crate::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::__init_internal!(init_slot($use_data): @data($data), @slot($slot), @guards([< __ $field _guard >], $($guards,)*), @@ -1300,11 +1459,25 @@ macro_rules! __init_internal { (make_initializer: @slot($slot:ident), @type_name($t:path), - @munch_fields(..Zeroable::zeroed() $(,)?), + @munch_fields(_: { $($code:tt)* }, $($rest:tt)*), + @acc($($acc:tt)*), + ) => { + // code blocks are ignored for the initializer check + $crate::__init_internal!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)*), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:path), + @munch_fields(..Zeroable::init_zeroed() $(,)?), @acc($($acc:tt)*), ) => { // Endpoint, nothing more to munch, create the initializer. Since the users specified - // `..Zeroable::zeroed()`, the slot will already have been zeroed and all field that have + // `..Zeroable::init_zeroed()`, the slot will already have been zeroed and all field that have // not been overwritten are thus zero and initialized. We still check that all fields are // actually accessible by using the struct update syntax ourselves. // We are inside of a closure that is never executed and thus we can abuse `slot` to @@ -1393,7 +1566,37 @@ macro_rules! __derive_zeroable { @body({ $( $(#[$($field_attr:tt)*])* - $field:ident : $field_ty:ty + $field_vis:vis $field:ident : $field_ty:ty + ),* $(,)? + }), + ) => { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl<$($impl_generics)*> $crate::Zeroable for $name<$($ty_generics)*> + where + $($($whr)*)? + {} + const _: () = { + fn assert_zeroable<T: ?::core::marker::Sized + $crate::Zeroable>() {} + fn ensure_zeroable<$($impl_generics)*>() + where $($($whr)*)? + { + $(assert_zeroable::<$field_ty>();)* + } + }; + }; + (parse_input: + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis union $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ + $( + $(#[$($field_attr:tt)*])* + $field_vis:vis $field:ident : $field_ty:ty ),* $(,)? }), ) => { @@ -1413,3 +1616,62 @@ macro_rules! __derive_zeroable { }; }; } + +#[doc(hidden)] +#[macro_export] +macro_rules! __maybe_derive_zeroable { + (parse_input: + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis struct $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ + $( + $(#[$($field_attr:tt)*])* + $field_vis:vis $field:ident : $field_ty:ty + ),* $(,)? + }), + ) => { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl<$($impl_generics)*> $crate::Zeroable for $name<$($ty_generics)*> + where + $( + // the `for<'__dummy>` HRTB makes this not error without the `trivial_bounds` + // feature <https://github.com/rust-lang/rust/issues/48214#issuecomment-2557829956>. + $field_ty: for<'__dummy> $crate::Zeroable, + )* + $($($whr)*)? + {} + }; + (parse_input: + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis union $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ + $( + $(#[$($field_attr:tt)*])* + $field_vis:vis $field:ident : $field_ty:ty + ),* $(,)? + }), + ) => { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl<$($impl_generics)*> $crate::Zeroable for $name<$($ty_generics)*> + where + $( + // the `for<'__dummy>` HRTB makes this not error without the `trivial_bounds` + // feature <https://github.com/rust-lang/rust/issues/48214#issuecomment-2557829956>. + $field_ty: for<'__dummy> $crate::Zeroable, + )* + $($($whr)*)? + {} + }; +} |