crates/zerocopy/src/pointer/mod.rs

// Copyright 2023 The Fuchsia Authors
//
// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
// This file may not be copied, modified, or distributed except according to
// those terms.

//! Abstractions over raw pointers.

mod inner;
#[doc(hidden)]
pub mod invariant;
mod ptr;
mod transmute;

#[doc(hidden)]
pub(crate) use transmute::*;
#[doc(hidden)]
pub use {
    invariant::{BecauseExclusive, BecauseImmutable, Read},
    ptr::Ptr,
};

/// A shorthand for a maybe-valid, maybe-aligned reference. Used as the argument
/// to [`TryFromBytes::is_bit_valid`].
///
/// [`TryFromBytes::is_bit_valid`]: crate::TryFromBytes::is_bit_valid
pub type Maybe<'a, T, Aliasing = invariant::Shared, Alignment = invariant::Unaligned> =
    Ptr<'a, T, (Aliasing, Alignment, invariant::Initialized)>;

/// Checks if the referent is zeroed.
pub(crate) fn is_zeroed<T, I>(ptr: Ptr<'_, T, I>) -> bool
where
    T: crate::Immutable + crate::KnownLayout,
    I: invariant::Invariants<Validity = invariant::Initialized>,
    I::Aliasing: invariant::Reference,
{
    ptr.as_bytes::<BecauseImmutable>().as_ref().iter().all(|&byte| byte == 0)
}