Skip to content

Latest commit

 

History

History
27 lines (20 loc) · 1.13 KB

README.md

File metadata and controls

27 lines (20 loc) · 1.13 KB
Raw

Mem Markers

A crate for traits that describe certain memory layout invariants of a given type along with derive macros for deriving these traits for custom types.

Traits

This crate currently contains the following traits:

  • FixedLayout: types that have a well-defined layout that can be relied on
  • NoUninit: types that do not have any unintialized bytes
  • ByteComplete: types where any appropriately sized and aligned array of bytes is a valid representation of that type
  • Zeroable: types where all zeros are a valid representation of the type in memory
  • FromBytes: types where any appropriately sized and aligned array of bytes can be viewed as the type.
  • AsBytes: The type can reliably be turned into a slice of bytes

Examples

Safe Transmute

fn safe_transmute<From: AsBytes, To: FromBytes>(from: From) -> To {
    let from = &std::mem::ManuallyDrop::new(from);
    assert!(std::mem::size_of::<From>() == std::mem::size_of::<To>(), "Cannot transmute to smaller type");
    assert!(std::mem::align_of::<From>() % std::mem::align_of::<To>() == 0, "Not aligned");
    
    unsafe { std::mem::transmute_copy(from) }
}