typed-bytes

A ![no_std], const first Rust library for strongly-typed data size units (KiB, MiB, KB, MB, etc.).

Features

• no_std
• Fully typed data size units (IEC and SI)
• Operator overloading

Why

During our work at haxiom.io we found many cases of file size comparisons where we accidentally mixed IEC and SI units. Likewise, using plain u64 for file sizes led to many bugs even if they are named correctly, for example MAX_FILE_SIZE could be interpreted as either bytes or kilobytes! This library provides a safe and type-safe way to handle file sizes with proper units, ensuring that the correct unit is used in each comparison. Note that most of the work has been lifted from the internal implementation at haxiom internal repository.

Installation

Add this to your Cargo.toml:

[dependencies]
typed-bytes = "1.0.0"

Usage

This library provides both IEC and SI units.

IEC Units (Base 2)

use typed_bytes::iec::{KiB, MiB, GiB};
use typed_bytes::Bytes;

let size = KiB(5);
let bytes: Bytes = size.into(); // 5 * 1024 = 5120 bytes

assert_eq!(bytes, Bytes(5120));
assert_eq!(MiB(1).as_kib(), KiB(1024));

SI Units (Base 10)

use typed_bytes::si::{KB, MB, GB};
use typed_bytes::Bytes;

let size = KB(5);
let bytes: Bytes = size.into(); // 5 * 1000 = 5000 bytes

assert_eq!(bytes, Bytes(5000));
assert_eq!(MB(1).as_kb(), KB(1000));

Comparisons & Safety

To prevent "footguns" (accidental mixing of binary and decimal units), there are no implicit comparisons between SI and IEC units. You must strictly convert them to a common type (like Bytes) or explicitly convert one to the other before comparing.

This compilation failure is a feature, not a bug:

use typed_bytes::iec::KiB;
use typed_bytes::si::KB;

let kib = KiB(1);
let kb = KB(1);

// This fails to compile!
if kib > kb {
    println!("Mixed comparison");
}

This will compile:

use typed_bytes::iec::KiB;
use typed_bytes::si::KB;
use typed_bytes::Bytes;

let kib = KiB(1);
let kb = KB(1);

if Bytes::from(kib) > Bytes::from(kb) {
    println!("1 KiB is greater than 1 KB");
}

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.