binary_macros

Rust macros for decoding binary-to-text encodings in string literals to [u8] literals.

This library decodes string literals that may contain various binary-to-text encodings, such as Base64, to binary literals at compile-time.

Version 0.2.*. Tested and working on rustc 1.15.0-nightly (7b3eeea22 2016-11-21). I'll release a stable 1.0.0 once the Procedural macros 1.1 land on stable Rust. Bug reports, pull requests etc. welcome!

Why is this useful? Let's say you want to include a binary blob inside your crate, a public key, for example. You can do that with include_bytes!() from the Rust std. However, if you want your data to be easily editable and copy-pasteable, a raw binary blob is not going to make it. (Besides, public keys are often distributed as Base64.) On the other hand, if you include text with include_str!(), you'll have to decode it runtime.

The macros from this crate support expanding other macros inside them first, and then decoding the result so can easily do the job compile-time. To get started, include this in your Cargo.toml dependencies:

[dependencies]
binary_macros = "0.2"

Stick this to the start of your source code to enable the unstable plugins feature and enable binary_macros:

#![feature(plugin)]
#![plugin(binary_macros)]

...and then you are ready to decode!

let public_key = base64!(include_str!("id_rsa.pub"));

You might also want to pull data from environmental variables:

#![feature(plugin)]
#![plugin(binary_macros, dotenv_macros)]
...
let public_key = base64!(dotenv!("MYCRATE_PUBLIC_KEY"));

Included macros:

Number 97 (ASCII 'a') included with different encodings for example:

base2!("01100001") // Binary. Uses numbers 0-1. Group of 8 digits = 1 byte.
base4!("1201") // Base4. Uses numbers 0-3. Group of 4 digits = 1 byte.
base8!("302=====") // Octal. Uses numbers 0-7. Group of 8 digits = 3 bytes, uses = as end padding.
base16!("61") // Hexadecimal. Uses numbers 0-7. Group of 2 digits = 1 byte.
base32!("C4======") // Base32. Uses numbers A-Z and 2-7. Group of 8 digits = 5 bytes, uses = as end padding.
base32hex!("ME======") // Base32 that uses extended hexadecimal: 0-9 and A-V. Group of 8 digits = 5 bytes, uses = as end padding.
base64!("YQ==") // Base64. Uses numbers A-Z, a-z, 0-9, + and /. Group of 4 digits = 3 bytes, uses = as end padding.
base64url!("_A==") // URL-compatible Base64. Uses numbers A-Z, a-z, 0-9, - and _. Group of 4 digits = 3 bytes, uses = as end padding.

Huge kudos to the data-encoding crate for providing a wide variety of encodings!