possiblyrandom/lib.rs
1// This file is Copyright its original authors, visible in version control
2// history.
3//
4// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7// You may not use this file except in accordance with one or both of these
8// licenses.
9
10//! [`getrandom`] provides access to OS randomness, but will fail to compile on platforms that do
11//! not support fetching OS randomness. This is exactly what you want when you're doing
12//! cryptographic operations, but when you're just opportunistically randomizing, we're fine with
13//! compiling and simply disabling randomization.
14//!
15//! This crate does that, returning only possibly-random data.
16//!
17//! Note that this crate only enables getrandom on a subset of platforms it supports. As getrandom
18//! evolves this crate is unlikely to carefully track all getrandom-supported platforms, however
19//! will use random data on popular platforms.
20
21#![no_std]
22
23#[cfg(feature = "getrandom")]
24extern crate getrandom;
25
26/// Possibly fills `dest` with random data. May fill it with zeros.
27#[inline]
28pub fn getpossiblyrandom(dest: &mut [u8]) {
29 #[cfg(feature = "getrandom")]
30 if getrandom::getrandom(dest).is_err() {
31 dest.fill(0);
32 }
33 #[cfg(not(feature = "getrandom"))]
34 dest.fill(0);
35}