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authorSang-Heon Jeon <ekffu200098@gmail.com>2026-08-24 01:18:14 +0900
committerJulia Lawall <Julia.Lawall@inria.fr>2026-08-23 22:12:11 +0200
commit2bd30b8dc75b823dd7bbef9d7bc68e1fd7ecee5c (patch)
treedcc4da1d99f17541c5590ac63c77da4bf372a4ab /rust/pin-init/src/alloc.rs
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coccinelle: alloc_cast: drop removed allocatorsgrafted
- pci_alloc_consistent() and pci_zalloc_consistent() were removed by commit 7968778914e5 ("PCI: Remove the deprecated "pci-dma-compat.h" API") - kmem_alloc() was removed by commit f078d4ea8276 ("xfs: convert kmem_alloc() to kmalloc()") - kmem_zalloc() was removed by commit 10634530f7ba ("xfs: convert kmem_zalloc() to kzalloc()") - kmem_zone_alloc() and kmem_zone_zalloc() were removed by commit bae633a4a283 ("xfs: remove xfs_zone_{alloc,zalloc} helpers") So drop them from the rules. No functional change. Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com> Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Diffstat (limited to 'rust/pin-init/src/alloc.rs')
-rw-r--r--rust/pin-init/src/alloc.rs160
1 files changed, 160 insertions, 0 deletions
diff --git a/rust/pin-init/src/alloc.rs b/rust/pin-init/src/alloc.rs
new file mode 100644
index 000000000..471652e86
--- /dev/null
+++ b/rust/pin-init/src/alloc.rs
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::{boxed::Box, sync::Arc};
+#[cfg(feature = "alloc")]
+use core::alloc::AllocError;
+use core::{mem::MaybeUninit, pin::Pin};
+#[cfg(feature = "std")]
+use std::sync::Arc;
+
+#[cfg(not(feature = "alloc"))]
+type AllocError = core::convert::Infallible;
+
+use crate::{
+ init_from_closure, pin_init_from_closure, InPlaceWrite, Init, PinInit, ZeroableOption,
+};
+
+pub extern crate alloc;
+
+// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
+// <https://doc.rust-lang.org/stable/std/option/index.html#representation>).
+unsafe impl<T> ZeroableOption for Box<T> {}
+
+/// Smart pointer that can initialize memory in-place.
+pub trait InPlaceInit<T>: Sized {
+ /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this
+ /// type.
+ ///
+ /// If `T: !Unpin` it will not be able to move afterwards.
+ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+ where
+ E: From<AllocError>;
+
+ /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this
+ /// type.
+ ///
+ /// If `T: !Unpin` it will not be able to move afterwards.
+ #[inline]
+ fn pin_init(init: impl PinInit<T>) -> Result<Pin<Self>, AllocError> {
+ // SAFETY: We delegate to `init` and only change the error type.
+ let init = unsafe {
+ pin_init_from_closure(|slot| match init.__init(slot) {
+ Ok(()) => Ok(()),
+ Err(i) => match i {},
+ })
+ };
+ Self::try_pin_init(init)
+ }
+
+ /// Use the given initializer to in-place initialize a `T`.
+ fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+ where
+ E: From<AllocError>;
+
+ /// Use the given initializer to in-place initialize a `T`.
+ #[inline]
+ fn init(init: impl Init<T>) -> Result<Self, AllocError> {
+ // SAFETY: We delegate to `init` and only change the error type.
+ let init = unsafe {
+ init_from_closure(|slot| match init.__init(slot) {
+ Ok(()) => Ok(()),
+ Err(i) => match i {},
+ })
+ };
+ Self::try_init(init)
+ }
+}
+
+#[cfg(feature = "alloc")]
+macro_rules! try_new_uninit {
+ ($type:ident) => {
+ $type::try_new_uninit()?
+ };
+}
+#[cfg(all(feature = "std", not(feature = "alloc")))]
+macro_rules! try_new_uninit {
+ ($type:ident) => {
+ $type::new_uninit()
+ };
+}
+
+impl<T> InPlaceInit<T> for Box<T> {
+ #[inline]
+ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+ where
+ E: From<AllocError>,
+ {
+ try_new_uninit!(Box).write_pin_init(init)
+ }
+
+ #[inline]
+ fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+ where
+ E: From<AllocError>,
+ {
+ try_new_uninit!(Box).write_init(init)
+ }
+}
+
+impl<T> InPlaceInit<T> for Arc<T> {
+ #[inline]
+ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+ where
+ E: From<AllocError>,
+ {
+ let mut this = try_new_uninit!(Arc);
+ let Some(slot) = Arc::get_mut(&mut this) else {
+ // SAFETY: the Arc has just been created and has no external references
+ unsafe { core::hint::unreachable_unchecked() }
+ };
+ let slot = slot.as_mut_ptr();
+ // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
+ // slot is valid and will not be moved, because we pin it later.
+ unsafe { init.__init(slot)? };
+ // SAFETY: All fields have been initialized and this is the only `Arc` to that data.
+ Ok(unsafe { Pin::new_unchecked(this.assume_init()) })
+ }
+
+ #[inline]
+ fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+ where
+ E: From<AllocError>,
+ {
+ let mut this = try_new_uninit!(Arc);
+ let Some(slot) = Arc::get_mut(&mut this) else {
+ // SAFETY: the Arc has just been created and has no external references
+ unsafe { core::hint::unreachable_unchecked() }
+ };
+ let slot = slot.as_mut_ptr();
+ // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
+ // slot is valid.
+ unsafe { init.__init(slot)? };
+ // SAFETY: All fields have been initialized.
+ Ok(unsafe { this.assume_init() })
+ }
+}
+
+impl<T> InPlaceWrite<T> for Box<MaybeUninit<T>> {
+ type Initialized = Box<T>;
+
+ #[inline]
+ fn write_init<E>(mut self, init: impl Init<T, E>) -> Result<Self::Initialized, E> {
+ let slot = self.as_mut_ptr();
+ // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
+ // slot is valid.
+ unsafe { init.__init(slot)? };
+ // SAFETY: All fields have been initialized.
+ Ok(unsafe { self.assume_init() })
+ }
+
+ #[inline]
+ fn write_pin_init<E>(mut self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E> {
+ let slot = self.as_mut_ptr();
+ // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
+ // slot is valid and will not be moved, because we pin it later.
+ unsafe { init.__init(slot)? };
+ // SAFETY: All fields have been initialized.
+ Ok(unsafe { self.assume_init() }.into())
+ }
+}