How to Implement Zero-Copy Deserialization in Rust

Crates/Serde
2026-04-17T12:05:42+00:00
Zero-copy deserialization in Rust is achieved by using `unsafe` blocks to transmute raw byte slices directly into struct references without allocating new memory. This requires the struct to be `#[repr(C)]` and the data to be properly aligned and initialized. Use `std::mem::transmute` or `std::slice

How to Implement Zero-Copy Deserialization in Rust

Zero-copy deserialization in Rust is achieved by using unsafe blocks to transmute raw byte slices directly into struct references without allocating new memory. This requires the struct to be #[repr(C)] and the data to be properly aligned and initialized. Use std::mem::transmute or std::slice::from_raw_parts to interpret the bytes as a reference to your struct.

#[repr(C)]
struct Data {
    id: u32,
    value: f64,
}

unsafe fn deserialize_zero_copy(bytes: &[u8]) -> Option<&Data> {
    if bytes.len() < std::mem::size_of::<Data>() {
        return None;
    }
    
    if bytes.as_ptr().align_offset(std::mem::align_of::<Data>()) != 0 {
        return None;
    }

    let ptr = bytes.as_ptr() as *const Data;
    Some(&*ptr)
}

fn main() {
    let data = Data { id: 42, value: 3.14 };
    let size = std::mem::size_of::<Data>();
    let aligned_ptr = &data as *const Data as *const u8;
    
    // Create a slice that is guaranteed to be aligned and sized correctly
    let bytes = unsafe { std::slice::from_raw_parts(aligned_ptr, size) };

    if let Some(deserialized) = unsafe { deserialize_zero_copy(bytes) } {
        println!("ID: {}, Value: {}", deserialized.id, deserialized.value);
    } else {
        println!("Deserialization failed due to alignment or size constraints.");
    }
}

Ensure the input slice length matches std::mem::size_of::<Data>() and is aligned before calling this function to avoid undefined behavior.