| <!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 `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/getrandom-0.2.3/src/use_file.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>use_file.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" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../../dark.css" disabled><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script src="../../crates.js"></script><script defer src="../../main.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script> |
| <noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="shortcut 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"><div class="sidebar-menu" role="button">☰</div><a class="sidebar-logo" href="../../getrandom/index.html"><div class="logo-container"><img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></div> |
| </a></nav><main><div class="width-limiter"><div class="sub-container"><a class="sub-logo-container" href="../../getrandom/index.html"><img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></a><nav class="sub"><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu" title="themes"><img width="18" height="18" alt="Pick another theme!" src="../../brush.svg"></button><div id="theme-choices" role="menu"></div></div><form class="search-form"><div class="search-container"><div> |
| <input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><button type="button" id="help-button" title="help">?</button><a id="settings-menu" href="../../settings.html" title="settings"><img width="18" height="18" alt="Change settings" src="../../wheel.svg"></a></div></form></nav></div><section id="main-content" class="content"><div class="example-wrap"><pre class="line-numbers"><span id="1"> 1</span> |
| <span id="2"> 2</span> |
| <span id="3"> 3</span> |
| <span id="4"> 4</span> |
| <span id="5"> 5</span> |
| <span id="6"> 6</span> |
| <span id="7"> 7</span> |
| <span id="8"> 8</span> |
| <span id="9"> 9</span> |
| <span id="10"> 10</span> |
| <span id="11"> 11</span> |
| <span id="12"> 12</span> |
| <span id="13"> 13</span> |
| <span id="14"> 14</span> |
| <span id="15"> 15</span> |
| <span id="16"> 16</span> |
| <span id="17"> 17</span> |
| <span id="18"> 18</span> |
| <span id="19"> 19</span> |
| <span id="20"> 20</span> |
| <span id="21"> 21</span> |
| <span id="22"> 22</span> |
| <span id="23"> 23</span> |
| <span id="24"> 24</span> |
| <span id="25"> 25</span> |
| <span id="26"> 26</span> |
| <span id="27"> 27</span> |
| <span id="28"> 28</span> |
| <span id="29"> 29</span> |
| <span id="30"> 30</span> |
| <span id="31"> 31</span> |
| <span id="32"> 32</span> |
| <span id="33"> 33</span> |
| <span id="34"> 34</span> |
| <span id="35"> 35</span> |
| <span id="36"> 36</span> |
| <span id="37"> 37</span> |
| <span id="38"> 38</span> |
| <span id="39"> 39</span> |
| <span id="40"> 40</span> |
| <span id="41"> 41</span> |
| <span id="42"> 42</span> |
| <span id="43"> 43</span> |
| <span id="44"> 44</span> |
| <span id="45"> 45</span> |
| <span id="46"> 46</span> |
| <span id="47"> 47</span> |
| <span id="48"> 48</span> |
| <span id="49"> 49</span> |
| <span id="50"> 50</span> |
| <span id="51"> 51</span> |
| <span id="52"> 52</span> |
| <span id="53"> 53</span> |
| <span id="54"> 54</span> |
| <span id="55"> 55</span> |
| <span id="56"> 56</span> |
| <span id="57"> 57</span> |
| <span id="58"> 58</span> |
| <span id="59"> 59</span> |
| <span id="60"> 60</span> |
| <span id="61"> 61</span> |
| <span id="62"> 62</span> |
| <span id="63"> 63</span> |
| <span id="64"> 64</span> |
| <span id="65"> 65</span> |
| <span id="66"> 66</span> |
| <span id="67"> 67</span> |
| <span id="68"> 68</span> |
| <span id="69"> 69</span> |
| <span id="70"> 70</span> |
| <span id="71"> 71</span> |
| <span id="72"> 72</span> |
| <span id="73"> 73</span> |
| <span id="74"> 74</span> |
| <span id="75"> 75</span> |
| <span id="76"> 76</span> |
| <span id="77"> 77</span> |
| <span id="78"> 78</span> |
| <span id="79"> 79</span> |
| <span id="80"> 80</span> |
| <span id="81"> 81</span> |
| <span id="82"> 82</span> |
| <span id="83"> 83</span> |
| <span id="84"> 84</span> |
| <span id="85"> 85</span> |
| <span id="86"> 86</span> |
| <span id="87"> 87</span> |
| <span id="88"> 88</span> |
| <span id="89"> 89</span> |
| <span id="90"> 90</span> |
| <span id="91"> 91</span> |
| <span id="92"> 92</span> |
| <span id="93"> 93</span> |
| <span id="94"> 94</span> |
| <span id="95"> 95</span> |
| <span id="96"> 96</span> |
| <span id="97"> 97</span> |
| <span id="98"> 98</span> |
| <span id="99"> 99</span> |
| <span id="100">100</span> |
| <span id="101">101</span> |
| <span id="102">102</span> |
| <span id="103">103</span> |
| <span id="104">104</span> |
| <span id="105">105</span> |
| <span id="106">106</span> |
| <span id="107">107</span> |
| <span id="108">108</span> |
| <span id="109">109</span> |
| <span id="110">110</span> |
| <span id="111">111</span> |
| <span id="112">112</span> |
| <span id="113">113</span> |
| <span id="114">114</span> |
| <span id="115">115</span> |
| <span id="116">116</span> |
| <span id="117">117</span> |
| <span id="118">118</span> |
| <span id="119">119</span> |
| <span id="120">120</span> |
| <span id="121">121</span> |
| <span id="122">122</span> |
| <span id="123">123</span> |
| <span id="124">124</span> |
| <span id="125">125</span> |
| <span id="126">126</span> |
| <span id="127">127</span> |
| <span id="128">128</span> |
| <span id="129">129</span> |
| <span id="130">130</span> |
| <span id="131">131</span> |
| <span id="132">132</span> |
| <span id="133">133</span> |
| <span id="134">134</span> |
| <span id="135">135</span> |
| <span id="136">136</span> |
| <span id="137">137</span> |
| <span id="138">138</span> |
| <span id="139">139</span> |
| <span id="140">140</span> |
| <span id="141">141</span> |
| </pre><pre class="rust"><code><span class="comment">// Copyright 2018 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">//! Implementations that just need to read from a file</span> |
| <span class="kw">use</span> <span class="kw">crate</span>::{ |
| <span class="ident">util::LazyUsize</span>, |
| <span class="ident">util_libc</span>::{<span class="ident">open_readonly</span>, <span class="ident">sys_fill_exact</span>}, |
| <span class="ident">Error</span>, |
| }; |
| <span class="kw">use</span> <span class="ident">core</span>::{ |
| <span class="ident">cell::UnsafeCell</span>, |
| <span class="ident">sync::atomic</span>::{<span class="ident">AtomicUsize</span>, <span class="ident">Ordering::Relaxed</span>}, |
| }; |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"redox"</span>)]</span> |
| <span class="kw">const</span> <span class="ident">FILE_PATH</span>: <span class="kw-2">&</span><span class="ident">str</span> <span class="op">=</span> <span class="string">"rand:\0"</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">"dragonfly"</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">"macos"</span>, |
| <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"solaris"</span>, |
| <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"illumos"</span> |
| ))]</span> |
| <span class="kw">const</span> <span class="ident">FILE_PATH</span>: <span class="kw-2">&</span><span class="ident">str</span> <span class="op">=</span> <span class="string">"/dev/random\0"</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">const</span> <span class="ident">FILE_PATH</span>: <span class="kw-2">&</span><span class="ident">str</span> <span class="op">=</span> <span class="string">"/dev/urandom\0"</span>; |
| |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">getrandom_inner</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">let</span> <span class="ident">fd</span> <span class="op">=</span> <span class="ident">get_rng_fd</span>()<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="ident">read</span> <span class="op">=</span> <span class="op">|</span><span class="ident">buf</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]<span class="op">|</span> <span class="kw">unsafe</span> { <span class="ident">libc::read</span>(<span class="ident">fd</span>, <span class="ident">buf</span>.<span class="ident">as_mut_ptr</span>() <span class="kw">as</span> <span class="kw-2">*mut</span> <span class="kw">_</span>, <span class="ident">buf</span>.<span class="ident">len</span>()) }; |
| |
| <span class="kw">if</span> <span class="macro">cfg!</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"emscripten"</span>) { |
| <span class="comment">// `Crypto.getRandomValues` documents `dest` should be at most 65536 bytes.</span> |
| <span class="kw">for</span> <span class="ident">chunk</span> <span class="kw">in</span> <span class="ident">dest</span>.<span class="ident">chunks_mut</span>(<span class="number">65536</span>) { |
| <span class="ident">sys_fill_exact</span>(<span class="ident">chunk</span>, <span class="ident">read</span>)<span class="question-mark">?</span>; |
| } |
| } <span class="kw">else</span> { |
| <span class="ident">sys_fill_exact</span>(<span class="ident">dest</span>, <span class="ident">read</span>)<span class="question-mark">?</span>; |
| } |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="comment">// Returns the file descriptor for the device file used to retrieve random</span> |
| <span class="comment">// bytes. The file will be opened exactly once. All successful calls will</span> |
| <span class="comment">// return the same file descriptor. This file descriptor is never closed.</span> |
| <span class="kw">fn</span> <span class="ident">get_rng_fd</span>() -> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">libc::c_int</span>, <span class="ident">Error</span><span class="op">></span> { |
| <span class="kw">static</span> <span class="ident">FD</span>: <span class="ident">AtomicUsize</span> <span class="op">=</span> <span class="ident">AtomicUsize::new</span>(<span class="ident">LazyUsize::UNINIT</span>); |
| <span class="kw">fn</span> <span class="ident">get_fd</span>() -> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">libc::c_int</span><span class="op">></span> { |
| <span class="kw">match</span> <span class="ident">FD</span>.<span class="ident">load</span>(<span class="ident">Relaxed</span>) { |
| <span class="ident">LazyUsize::UNINIT</span> => <span class="prelude-val">None</span>, |
| <span class="ident">val</span> => <span class="prelude-val">Some</span>(<span class="ident">val</span> <span class="kw">as</span> <span class="ident">libc::c_int</span>), |
| } |
| } |
| |
| <span class="comment">// Use double-checked locking to avoid acquiring the lock if possible.</span> |
| <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">fd</span>) <span class="op">=</span> <span class="ident">get_fd</span>() { |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">fd</span>); |
| } |
| |
| <span class="comment">// SAFETY: We use the mutex only in this method, and we always unlock it</span> |
| <span class="comment">// before returning, making sure we don't violate the pthread_mutex_t API.</span> |
| <span class="kw">static</span> <span class="ident">MUTEX</span>: <span class="ident">Mutex</span> <span class="op">=</span> <span class="ident">Mutex::new</span>(); |
| <span class="kw">unsafe</span> { <span class="ident">MUTEX</span>.<span class="ident">lock</span>() }; |
| <span class="kw">let</span> <span class="ident">_guard</span> <span class="op">=</span> <span class="ident">DropGuard</span>(<span class="op">|</span><span class="op">|</span> <span class="kw">unsafe</span> { <span class="ident">MUTEX</span>.<span class="ident">unlock</span>() }); |
| |
| <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">fd</span>) <span class="op">=</span> <span class="ident">get_fd</span>() { |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">fd</span>); |
| } |
| |
| <span class="comment">// On Linux, /dev/urandom might return insecure values.</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="ident">wait_until_rng_ready</span>()<span class="question-mark">?</span>; |
| |
| <span class="kw">let</span> <span class="ident">fd</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">open_readonly</span>(<span class="ident">FILE_PATH</span>)<span class="question-mark">?</span> }; |
| <span class="comment">// The fd always fits in a usize without conflicting with UNINIT.</span> |
| <span class="macro">debug_assert!</span>(<span class="ident">fd</span> <span class="op">></span><span class="op">=</span> <span class="number">0</span> <span class="op">&&</span> (<span class="ident">fd</span> <span class="kw">as</span> <span class="ident">usize</span>) <span class="op"><</span> <span class="ident">LazyUsize::UNINIT</span>); |
| <span class="ident">FD</span>.<span class="ident">store</span>(<span class="ident">fd</span> <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">Relaxed</span>); |
| |
| <span class="prelude-val">Ok</span>(<span class="ident">fd</span>) |
| } |
| |
| <span class="comment">// Succeeds once /dev/urandom is safe to read from</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">fn</span> <span class="ident">wait_until_rng_ready</span>() -> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> { |
| <span class="comment">// Poll /dev/random to make sure it is ok to read from /dev/urandom.</span> |
| <span class="kw">let</span> <span class="ident">fd</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">open_readonly</span>(<span class="string">"/dev/random\0"</span>)<span class="question-mark">?</span> }; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pfd</span> <span class="op">=</span> <span class="ident">libc::pollfd</span> { |
| <span class="ident">fd</span>, |
| <span class="ident">events</span>: <span class="ident">libc::POLLIN</span>, |
| <span class="ident">revents</span>: <span class="number">0</span>, |
| }; |
| <span class="kw">let</span> <span class="ident">_guard</span> <span class="op">=</span> <span class="ident">DropGuard</span>(<span class="op">|</span><span class="op">|</span> <span class="kw">unsafe</span> { |
| <span class="ident">libc::close</span>(<span class="ident">fd</span>); |
| }); |
| |
| <span class="kw">loop</span> { |
| <span class="comment">// A negative timeout means an infinite timeout.</span> |
| <span class="kw">let</span> <span class="ident">res</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">libc::poll</span>(<span class="kw-2">&mut</span> <span class="ident">pfd</span>, <span class="number">1</span>, <span class="op">-</span><span class="number">1</span>) }; |
| <span class="kw">if</span> <span class="ident">res</span> <span class="op">></span><span class="op">=</span> <span class="number">0</span> { |
| <span class="macro">debug_assert_eq!</span>(<span class="ident">res</span>, <span class="number">1</span>); <span class="comment">// We only used one fd, and cannot timeout.</span> |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(()); |
| } |
| <span class="kw">let</span> <span class="ident">err</span> <span class="op">=</span> <span class="ident"><span class="kw">crate</span>::util_libc::last_os_error</span>(); |
| <span class="kw">match</span> <span class="ident">err</span>.<span class="ident">raw_os_error</span>() { |
| <span class="prelude-val">Some</span>(<span class="ident">libc::EINTR</span>) <span class="op">|</span> <span class="prelude-val">Some</span>(<span class="ident">libc::EAGAIN</span>) => <span class="kw">continue</span>, |
| <span class="kw">_</span> => <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">err</span>), |
| } |
| } |
| } |
| |
| <span class="kw">struct</span> <span class="ident">Mutex</span>(<span class="ident">UnsafeCell</span><span class="op"><</span><span class="ident">libc::pthread_mutex_t</span><span class="op">></span>); |
| |
| <span class="kw">impl</span> <span class="ident">Mutex</span> { |
| <span class="kw">const</span> <span class="kw">fn</span> <span class="ident">new</span>() -> <span class="self">Self</span> { |
| <span class="self">Self</span>(<span class="ident">UnsafeCell::new</span>(<span class="ident">libc::PTHREAD_MUTEX_INITIALIZER</span>)) |
| } |
| <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">lock</span>(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="kw">let</span> <span class="ident">r</span> <span class="op">=</span> <span class="ident">libc::pthread_mutex_lock</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">get</span>()); |
| <span class="macro">debug_assert_eq!</span>(<span class="ident">r</span>, <span class="number">0</span>); |
| } |
| <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">unlock</span>(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="kw">let</span> <span class="ident">r</span> <span class="op">=</span> <span class="ident">libc::pthread_mutex_unlock</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">get</span>()); |
| <span class="macro">debug_assert_eq!</span>(<span class="ident">r</span>, <span class="number">0</span>); |
| } |
| } |
| |
| <span class="kw">unsafe</span> <span class="kw">impl</span> <span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">Mutex</span> {} |
| |
| <span class="kw">struct</span> <span class="ident">DropGuard</span><span class="op"><</span><span class="ident">F</span>: <span class="ident">FnMut</span>()<span class="op">></span>(<span class="ident">F</span>); |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">F</span>: <span class="ident">FnMut</span>()<span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">DropGuard</span><span class="op"><</span><span class="ident">F</span><span class="op">></span> { |
| <span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) { |
| <span class="self">self</span>.<span class="number">0</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> |
