memsafe 1.0.1

A Secure cross-platform Rust library for securely wrapping data in memory
Documentation 
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use std::sync::atomic::{Ordering, compiler_fence};

/// Volatile, compiler-fenced zeroization of `*ptr`.
///
/// Writes `size_of::<T>()` zero bytes through `ptr` using `write_volatile`,
/// followed by a `SeqCst` compiler fence. The optimizer is forbidden from
/// eliding volatile stores even when no observable read follows — the
/// language-level guarantee we need for any byte that just held a secret.
///
/// **Important:** `size_of::<T>()` is the *inline* size of `T`. For owned-pointer
/// types (`String`, `Vec<U>`, `Box<U>`) this is the header size only — the
/// heap payload they point to is **not** wiped by this function. The
/// inline-data invariant is enforced upstream by restricting the public
/// secret-handling API to `[u8; N]`.
pub fn ptr_fill_zero<T>(ptr: *mut T) {
    let len = std::mem::size_of::<T>();
    let bytes = ptr as *mut u8;
    for i in 0..len {
        unsafe { std::ptr::write_volatile(bytes.add(i), 0) };
    }
    compiler_fence(Ordering::SeqCst);
}

/// Volatile, compiler-fenced zeroization of a byte slice.
///
/// Use for sources that must be wiped before they are dropped — e.g. a
/// caller-supplied `Vec<u8>` whose contents have just been copied into a
/// protected page.
pub fn secure_zero(slice: &mut [u8]) {
    let ptr = slice.as_mut_ptr();
    for i in 0..slice.len() {
        unsafe { std::ptr::write_volatile(ptr.add(i), 0) };
    }
    compiler_fence(Ordering::SeqCst);
}

pub fn ptr_deref<'a, T>(ptr: *const T) -> &'a T {
    unsafe { &*ptr }
}

pub fn ptr_deref_mut<'a, T>(ptr: *mut T) -> &'a mut T {
    unsafe { &mut *ptr }
}

pub fn ptr_drop_in_place<T>(ptr: *mut T) {
    unsafe { ptr.drop_in_place() };
}