mnemosyne-memory-core 0.2.0

//! Compile-time allocator behaviors and memory safety policies.

#[doc(hidden)]
pub mod private {
    pub trait Sealed {}
}

/// A sealed trait representing an allocator behavior and safety policy.
pub trait AllocPolicy: private::Sealed + Send + Sync + 'static {
    /// If true, write poison bytes to memory on allocation and deallocation to detect heap corruption.
    const ENABLE_POISONING: bool;

    /// If true, zero-initialize all memory allocations.
    const ZERO_INITIALIZE: bool;

    /// Byte pattern to write into memory when it is freed.
    const POISON_FREE_BYTE: u8 = 0xDE;

    /// Byte pattern to write into memory when it is allocated.
    const POISON_ALLOC_BYTE: u8 = 0xAD;

    /// If true, encrypt free list next pointers.
    const ENABLE_FREE_LIST_ENCRYPTION: bool = false;

    /// If true, randomize the allocation order of blocks in a page.
    const RANDOMIZE_ALLOCATION: bool = false;
}

/// Zero-Sized Type (ZST) representing the standard allocation policy with maximum performance.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub struct StandardPolicy;

impl private::Sealed for StandardPolicy {}
impl AllocPolicy for StandardPolicy {
    const ENABLE_POISONING: bool = false;
    const ZERO_INITIALIZE: bool = false;
}

/// Zero-Sized Type (ZST) representing a secure allocation policy with memory
/// poisoning and zero-initialization.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub struct SecurePolicy;

impl private::Sealed for SecurePolicy {}
impl AllocPolicy for SecurePolicy {
    const ENABLE_POISONING: bool = true;
    const ZERO_INITIALIZE: bool = true;
    const RANDOMIZE_ALLOCATION: bool = true;
}

/// Zero-Sized Type (ZST) representing a hardened allocation policy with memory
/// poisoning, zero-initialization, and free-list encryption.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub struct HardenedPolicy;

impl private::Sealed for HardenedPolicy {}
impl AllocPolicy for HardenedPolicy {
    const ENABLE_POISONING: bool = true;
    const ZERO_INITIALIZE: bool = true;
    const ENABLE_FREE_LIST_ENCRYPTION: bool = true;
    const RANDOMIZE_ALLOCATION: bool = true;
}