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| </pre><pre class="rust"><code><span class="comment">// Copyright 2019 Developers of the Rand project.</span> |
| <span class="comment">//</span> |
| <span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span> |
| <span class="comment">// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span> |
| <span class="comment">// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your</span> |
| <span class="comment">// option. This file may not be copied, modified, or distributed</span> |
| <span class="comment">// except according to those terms.</span> |
| |
| <span class="doccomment">//! Interface to the operating system's random number generator.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! # Supported targets</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! | Target | Target Triple | Implementation</span> |
| <span class="doccomment">//! | ----------------- | ------------------ | --------------</span> |
| <span class="doccomment">//! | Linux, Android | `*‑linux‑*` | [`getrandom`][1] system call if available, otherwise [`/dev/urandom`][2] after successfully polling `/dev/random` |</span> |
| <span class="doccomment">//! | Windows | `*‑windows‑*` | [`BCryptGenRandom`][3] |</span> |
| <span class="doccomment">//! | macOS | `*‑apple‑darwin` | [`getentropy()`][19] if available, otherwise [`/dev/random`][20] (identical to `/dev/urandom`)</span> |
| <span class="doccomment">//! | iOS | `*‑apple‑ios` | [`SecRandomCopyBytes`][4]</span> |
| <span class="doccomment">//! | FreeBSD | `*‑freebsd` | [`getrandom()`][21] if available, otherwise [`kern.arandom`][5]</span> |
| <span class="doccomment">//! | OpenBSD | `*‑openbsd` | [`getentropy`][6]</span> |
| <span class="doccomment">//! | NetBSD | `*‑netbsd` | [`kern.arandom`][7]</span> |
| <span class="doccomment">//! | Dragonfly BSD | `*‑dragonfly` | [`getrandom()`][22] if available, otherwise [`/dev/random`][8]</span> |
| <span class="doccomment">//! | Solaris, illumos | `*‑solaris`, `*‑illumos` | [`getrandom()`][9] if available, otherwise [`/dev/random`][10]</span> |
| <span class="doccomment">//! | Fuchsia OS | `*‑fuchsia` | [`cprng_draw`][11]</span> |
| <span class="doccomment">//! | Redox | `*‑redox` | [`rand:`][12]</span> |
| <span class="doccomment">//! | Haiku | `*‑haiku` | `/dev/random` (identical to `/dev/urandom`)</span> |
| <span class="doccomment">//! | SGX | `x86_64‑*‑sgx` | [RDRAND][18]</span> |
| <span class="doccomment">//! | VxWorks | `*‑wrs‑vxworks‑*` | `randABytes` after checking entropy pool initialization with `randSecure`</span> |
| <span class="doccomment">//! | Emscripten | `*‑emscripten` | `/dev/random` (identical to `/dev/urandom`)</span> |
| <span class="doccomment">//! | WASI | `wasm32‑wasi` | [`random_get`][17]</span> |
| <span class="doccomment">//! | Web Browser | `wasm32‑*‑unknown` | [`Crypto.getRandomValues()`][14], see [WebAssembly support][16]</span> |
| <span class="doccomment">//! | Node.js | `wasm32‑*‑unknown` | [`crypto.randomBytes`][15], see [WebAssembly support][16]</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! There is no blanket implementation on `unix` targets that reads from</span> |
| <span class="doccomment">//! `/dev/urandom`. This ensures all supported targets are using the recommended</span> |
| <span class="doccomment">//! interface and respect maximum buffer sizes.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! Pull Requests that add support for new targets to `getrandom` are always welcome.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! ## Unsupported targets</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! By default, `getrandom` will not compile on unsupported targets, but certain</span> |
| <span class="doccomment">//! features allow a user to select a "fallback" implementation if no supported</span> |
| <span class="doccomment">//! implementation exists.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! All of the below mechanisms only affect unsupported</span> |
| <span class="doccomment">//! targets. Supported targets will _always_ use their supported implementations.</span> |
| <span class="doccomment">//! This prevents a crate from overriding a secure source of randomness</span> |
| <span class="doccomment">//! (either accidentally or intentionally).</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! ### RDRAND on x86</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! *If the `"rdrand"` Cargo feature is enabled*, `getrandom` will fallback to using</span> |
| <span class="doccomment">//! the [`RDRAND`][18] instruction to get randomness on `no_std` `x86`/`x86_64`</span> |
| <span class="doccomment">//! targets. This feature has no effect on other CPU architectures.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! ### WebAssembly support</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! This crate fully supports the</span> |
| <span class="doccomment">//! [`wasm32-wasi`](https://github.com/CraneStation/wasi) and</span> |
| <span class="doccomment">//! [`wasm32-unknown-emscripten`](https://www.hellorust.com/setup/emscripten/)</span> |
| <span class="doccomment">//! targets. However, the `wasm32-unknown-unknown` target (i.e. the target used</span> |
| <span class="doccomment">//! by `wasm-pack`) is not automatically</span> |
| <span class="doccomment">//! supported since, from the target name alone, we cannot deduce which</span> |
| <span class="doccomment">//! JavaScript interface is in use (or if JavaScript is available at all).</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! Instead, *if the `"js"` Cargo feature is enabled*, this crate will assume</span> |
| <span class="doccomment">//! that you are building for an environment containing JavaScript, and will</span> |
| <span class="doccomment">//! call the appropriate methods. Both web browser (main window and Web Workers)</span> |
| <span class="doccomment">//! and Node.js environments are supported, invoking the methods</span> |
| <span class="doccomment">//! [described above](#supported-targets) using the</span> |
| <span class="doccomment">//! [wasm-bindgen](https://github.com/rust-lang/rust-bindgen) toolchain.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! This feature has no effect on targets other than `wasm32-unknown-unknown`.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! ### Custom implementations</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! The [`register_custom_getrandom!`] macro allows a user to mark their own</span> |
| <span class="doccomment">//! function as the backing implementation for [`getrandom`]. See the macro's</span> |
| <span class="doccomment">//! documentation for more information about writing and registering your own</span> |
| <span class="doccomment">//! custom implementations.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! Note that registering a custom implementation only has an effect on targets</span> |
| <span class="doccomment">//! that would otherwise not compile. Any supported targets (including those</span> |
| <span class="doccomment">//! using `"rdrand"` and `"js"` Cargo features) continue using their normal</span> |
| <span class="doccomment">//! implementations even if a function is registered.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! ### Indirect Dependencies</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! If `getrandom` is not a direct dependency of your crate, you can still</span> |
| <span class="doccomment">//! enable any of the above fallback behaviors by enabling the relevant</span> |
| <span class="doccomment">//! feature in your root crate's `Cargo.toml`:</span> |
| <span class="doccomment">//! ```toml</span> |
| <span class="doccomment">//! [dependencies]</span> |
| <span class="doccomment">//! getrandom = { version = "0.2", features = ["js"] }</span> |
| <span class="doccomment">//! ```</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! ## Early boot</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! Sometimes, early in the boot process, the OS has not collected enough</span> |
| <span class="doccomment">//! entropy to securely seed its RNG. This is especially common on virtual</span> |
| <span class="doccomment">//! machines, where standard "random" events are hard to come by.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! Some operating system interfaces always block until the RNG is securely</span> |
| <span class="doccomment">//! seeded. This can take anywhere from a few seconds to more than a minute.</span> |
| <span class="doccomment">//! A few (Linux, NetBSD and Solaris) offer a choice between blocking and</span> |
| <span class="doccomment">//! getting an error; in these cases, we always choose to block.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! On Linux (when the `getrandom` system call is not available), reading from</span> |
| <span class="doccomment">//! `/dev/urandom` never blocks, even when the OS hasn't collected enough</span> |
| <span class="doccomment">//! entropy yet. To avoid returning low-entropy bytes, we first poll</span> |
| <span class="doccomment">//! `/dev/random` and only switch to `/dev/urandom` once this has succeeded.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! ## Error handling</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! We always choose failure over returning insecure "random" bytes. In general,</span> |
| <span class="doccomment">//! on supported platforms, failure is highly unlikely, though not impossible.</span> |
| <span class="doccomment">//! If an error does occur, then it is likely that it will occur on every call to</span> |
| <span class="doccomment">//! `getrandom`, hence after the first successful call one can be reasonably</span> |
| <span class="doccomment">//! confident that no errors will occur.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! [1]: http://man7.org/linux/man-pages/man2/getrandom.2.html</span> |
| <span class="doccomment">//! [2]: http://man7.org/linux/man-pages/man4/urandom.4.html</span> |
| <span class="doccomment">//! [3]: https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom</span> |
| <span class="doccomment">//! [4]: https://developer.apple.com/documentation/security/1399291-secrandomcopybytes?language=objc</span> |
| <span class="doccomment">//! [5]: https://www.freebsd.org/cgi/man.cgi?query=random&sektion=4</span> |
| <span class="doccomment">//! [6]: https://man.openbsd.org/getentropy.2</span> |
| <span class="doccomment">//! [7]: https://man.netbsd.org/sysctl.7</span> |
| <span class="doccomment">//! [8]: https://leaf.dragonflybsd.org/cgi/web-man?command=random&section=4</span> |
| <span class="doccomment">//! [9]: https://docs.oracle.com/cd/E88353_01/html/E37841/getrandom-2.html</span> |
| <span class="doccomment">//! [10]: https://docs.oracle.com/cd/E86824_01/html/E54777/random-7d.html</span> |
| <span class="doccomment">//! [11]: https://fuchsia.dev/fuchsia-src/zircon/syscalls/cprng_draw</span> |
| <span class="doccomment">//! [12]: https://github.com/redox-os/randd/blob/master/src/main.rs</span> |
| <span class="doccomment">//! [14]: https://www.w3.org/TR/WebCryptoAPI/#Crypto-method-getRandomValues</span> |
| <span class="doccomment">//! [15]: https://nodejs.org/api/crypto.html#crypto_crypto_randombytes_size_callback</span> |
| <span class="doccomment">//! [16]: #webassembly-support</span> |
| <span class="doccomment">//! [17]: https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md#-random_getbuf-pointeru8-buf_len-size---errno</span> |
| <span class="doccomment">//! [18]: https://software.intel.com/en-us/articles/intel-digital-random-number-generator-drng-software-implementation-guide</span> |
| <span class="doccomment">//! [19]: https://www.unix.com/man-page/mojave/2/getentropy/</span> |
| <span class="doccomment">//! [20]: https://www.unix.com/man-page/mojave/4/random/</span> |
| <span class="doccomment">//! [21]: https://www.freebsd.org/cgi/man.cgi?query=getrandom&manpath=FreeBSD+12.0-stable</span> |
| <span class="doccomment">//! [22]: https://leaf.dragonflybsd.org/cgi/web-man?command=getrandom</span> |
| |
| <span class="attribute">#![<span class="ident">doc</span>( |
| <span class="ident">html_logo_url</span> <span class="op">=</span> <span class="string">"https://www.rust-lang.org/logos/rust-logo-128x128-blk.png"</span>, |
| <span class="ident">html_favicon_url</span> <span class="op">=</span> <span class="string">"https://www.rust-lang.org/favicon.ico"</span>, |
| <span class="ident">html_root_url</span> <span class="op">=</span> <span class="string">"https://docs.rs/getrandom/0.2.3"</span> |
| )]</span> |
| <span class="attribute">#![<span class="ident">no_std</span>]</span> |
| <span class="attribute">#![<span class="ident">warn</span>(<span class="ident">rust_2018_idioms</span>, <span class="ident">unused_lifetimes</span>, <span class="ident">missing_docs</span>)]</span> |
| <span class="attribute">#![<span class="ident">cfg_attr</span>(<span class="ident">docsrs</span>, <span class="ident">feature</span>(<span class="ident">doc_cfg</span>))]</span> |
| |
| <span class="attribute">#[<span class="ident">macro_use</span>]</span> |
| <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">cfg_if</span>; |
| |
| <span class="kw">mod</span> <span class="ident">error</span>; |
| <span class="kw">mod</span> <span class="ident">util</span>; |
| <span class="comment">// To prevent a breaking change when targets are added, we always export the</span> |
| <span class="comment">// register_custom_getrandom macro, so old Custom RNG crates continue to build.</span> |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"custom"</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">custom</span>; |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"std"</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">error_impls</span>; |
| |
| <span class="kw">pub</span> <span class="kw">use</span> <span class="ident"><span class="kw">crate</span>::error::Error</span>; |
| |
| <span class="comment">// System-specific implementations.</span> |
| <span class="comment">//</span> |
| <span class="comment">// These should all provide getrandom_inner with the same signature as getrandom.</span> |
| <span class="macro">cfg_if!</span> { |
| <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"emscripten"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"haiku"</span>, |
| <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"redox"</span>))]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"use_file.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"android"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"linux"</span>))]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="kw">mod</span> <span class="ident">use_file</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"linux_android.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"illumos"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"solaris"</span>))]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="kw">mod</span> <span class="ident">use_file</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"solaris_illumos.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"freebsd"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"netbsd"</span>))]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"bsd_arandom.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"dragonfly"</span>)]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="kw">mod</span> <span class="ident">use_file</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"dragonfly.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"fuchsia"</span>)]</span> { |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"fuchsia.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"ios"</span>)]</span> { |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"ios.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"macos"</span>)]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="kw">mod</span> <span class="ident">use_file</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"macos.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"openbsd"</span>)]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"openbsd.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"wasi"</span>)]</span> { |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"wasi.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"vxworks"</span>)]</span> { |
| <span class="kw">mod</span> <span class="ident">util_libc</span>; |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"vxworks.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">windows</span>)]</span> { |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"windows.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86_64"</span>, <span class="ident">target_env</span> <span class="op">=</span> <span class="string">"sgx"</span>))]</span> { |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"rdrand.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rdrand"</span>, |
| <span class="ident">any</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86_64"</span>, <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86"</span>)))]</span> { |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"rdrand.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"js"</span>, |
| <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"wasm32"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"unknown"</span>))]</span> { |
| <span class="attribute">#[<span class="ident">path</span> <span class="op">=</span> <span class="string">"js.rs"</span>]</span> <span class="kw">mod</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"custom"</span>)]</span> { |
| <span class="kw">use</span> <span class="ident">custom</span> <span class="kw">as</span> <span class="ident">imp</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"wasm32"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"unknown"</span>))]</span> { |
| <span class="macro">compile_error!</span>(<span class="string">"the wasm32-unknown-unknown target is not supported by \ |
| default, you may need to enable the \"js\" feature. \ |
| For more information see: \ |
| https://docs.rs/getrandom/#webassembly-support"</span>); |
| } <span class="kw">else</span> { |
| <span class="macro">compile_error!</span>(<span class="string">"target is not supported, for more information see: \ |
| https://docs.rs/getrandom/#unsupported-targets"</span>); |
| } |
| } |
| |
| <span class="doccomment">/// Fill `dest` with random bytes from the system's preferred random number</span> |
| <span class="doccomment">/// source.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This function returns an error on any failure, including partial reads. We</span> |
| <span class="doccomment">/// make no guarantees regarding the contents of `dest` on error. If `dest` is</span> |
| <span class="doccomment">/// empty, `getrandom` immediately returns success, making no calls to the</span> |
| <span class="doccomment">/// underlying operating system.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Blocking is possible, at least during early boot; see module documentation.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// In general, `getrandom` will be fast enough for interactive usage, though</span> |
| <span class="doccomment">/// significantly slower than a user-space CSPRNG; for the latter consider</span> |
| <span class="doccomment">/// [`rand::thread_rng`](https://docs.rs/rand/*/rand/fn.thread_rng.html).</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">getrandom</span>(<span class="ident">dest</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]) -> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> { |
| <span class="kw">if</span> <span class="ident">dest</span>.<span class="ident">is_empty</span>() { |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(()); |
| } |
| <span class="ident">imp::getrandom_inner</span>(<span class="ident">dest</span>) |
| } |
| </code></pre></div> |
| </section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="getrandom" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.60.0-nightly (1bd4fdc94 2022-01-12)" ></div> |
| </body></html> |
