| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/rand_core-0.6.4/src/os.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>os.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" href="https://www.rust-lang.org/favicon.ico"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../rand_core/index.html"><div class="logo-container"> |
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| <img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="comment">// Copyright 2019 Developers of the Rand project. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| </span><span class="doccomment">//! Interface to the random number generator of the operating system. |
| |
| </span><span class="kw">use crate</span>::{impls, CryptoRng, Error, RngCore}; |
| <span class="kw">use </span>getrandom::getrandom; |
| |
| <span class="doccomment">/// A random number generator that retrieves randomness from the |
| /// operating system. |
| /// |
| /// This is a zero-sized struct. It can be freely constructed with `OsRng`. |
| /// |
| /// The implementation is provided by the [getrandom] crate. Refer to |
| /// [getrandom] documentation for details. |
| /// |
| /// This struct is only available when specifying the crate feature `getrandom` |
| /// or `std`. When using the `rand` lib, it is also available as `rand::rngs::OsRng`. |
| /// |
| /// # Blocking and error handling |
| /// |
| /// It is possible that when used during early boot the first call to `OsRng` |
| /// will block until the system's RNG is initialised. It is also possible |
| /// (though highly unlikely) for `OsRng` to fail on some platforms, most |
| /// likely due to system mis-configuration. |
| /// |
| /// After the first successful call, it is highly unlikely that failures or |
| /// significant delays will occur (although performance should be expected to |
| /// be much slower than a user-space PRNG). |
| /// |
| /// # Usage example |
| /// ``` |
| /// use rand_core::{RngCore, OsRng}; |
| /// |
| /// let mut key = [0u8; 16]; |
| /// OsRng.fill_bytes(&mut key); |
| /// let random_u64 = OsRng.next_u64(); |
| /// ``` |
| /// |
| /// [getrandom]: https://crates.io/crates/getrandom |
| </span><span class="attribute">#[cfg_attr(doc_cfg, doc(cfg(feature = <span class="string">"getrandom"</span>)))] |
| #[derive(Clone, Copy, Debug, Default)] |
| </span><span class="kw">pub struct </span>OsRng; |
| |
| <span class="kw">impl </span>CryptoRng <span class="kw">for </span>OsRng {} |
| |
| <span class="kw">impl </span>RngCore <span class="kw">for </span>OsRng { |
| <span class="kw">fn </span>next_u32(<span class="kw-2">&mut </span><span class="self">self</span>) -> u32 { |
| impls::next_u32_via_fill(<span class="self">self</span>) |
| } |
| |
| <span class="kw">fn </span>next_u64(<span class="kw-2">&mut </span><span class="self">self</span>) -> u64 { |
| impls::next_u64_via_fill(<span class="self">self</span>) |
| } |
| |
| <span class="kw">fn </span>fill_bytes(<span class="kw-2">&mut </span><span class="self">self</span>, dest: <span class="kw-2">&mut </span>[u8]) { |
| <span class="kw">if let </span><span class="prelude-val">Err</span>(e) = <span class="self">self</span>.try_fill_bytes(dest) { |
| <span class="macro">panic!</span>(<span class="string">"Error: {}"</span>, e); |
| } |
| } |
| |
| <span class="kw">fn </span>try_fill_bytes(<span class="kw-2">&mut </span><span class="self">self</span>, dest: <span class="kw-2">&mut </span>[u8]) -> <span class="prelude-ty">Result</span><(), Error> { |
| getrandom(dest)<span class="question-mark">?</span>; |
| <span class="prelude-val">Ok</span>(()) |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_os_rng() { |
| <span class="kw">let </span>x = OsRng.next_u64(); |
| <span class="kw">let </span>y = OsRng.next_u64(); |
| <span class="macro">assert!</span>(x != <span class="number">0</span>); |
| <span class="macro">assert!</span>(x != y); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_construction() { |
| <span class="kw">let </span><span class="kw-2">mut </span>rng = OsRng::default(); |
| <span class="macro">assert!</span>(rng.next_u64() != <span class="number">0</span>); |
| } |
| </code></pre></div> |
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