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<!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/newkirk/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/signal-hook-registry-1.4.8/src/half_lock.rs`."><title>half_lock.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="signal_hook_registry" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../../static.files/src-script-813739b1.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc src"><!--[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="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">signal_hook_registry/</div>half_lock.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap digits-3"><pre class="rust"><code><a href=#1 id=1 data-nosnippet>1</a><span class="doccomment">//! The half-lock structure
<a href=#2 id=2 data-nosnippet>2</a>//!
<a href=#3 id=3 data-nosnippet>3</a>//! We need a way to protect the structure with configured hooks a signal may happen in arbitrary
<a href=#4 id=4 data-nosnippet>4</a>//! thread and needs to read them while another thread might be manipulating the structure.
<a href=#5 id=5 data-nosnippet>5</a>//!
<a href=#6 id=6 data-nosnippet>6</a>//! Under ordinary circumstances we would be happy to just use `Mutex&lt;HashMap&lt;c_int, _&gt;&gt;`. However,
<a href=#7 id=7 data-nosnippet>7</a>//! as we use it in the signal handler, we are severely limited in what we can or can't use. So we
<a href=#8 id=8 data-nosnippet>8</a>//! choose to implement kind of spin-look thing with atomics.
<a href=#9 id=9 data-nosnippet>9</a>//!
<a href=#10 id=10 data-nosnippet>10</a>//! In the reader it is always simply locked and then unlocked, making sure it doesn't disappear
<a href=#11 id=11 data-nosnippet>11</a>//! while in use.
<a href=#12 id=12 data-nosnippet>12</a>//!
<a href=#13 id=13 data-nosnippet>13</a>//! The writer has a separate mutex (that prevents other writers; this is used outside of the
<a href=#14 id=14 data-nosnippet>14</a>//! signal handler), makes a copy of the data and swaps an atomic pointer to the data structure.
<a href=#15 id=15 data-nosnippet>15</a>//! But it waits until everything is unlocked (no signal handler has the old data) for dropping the
<a href=#16 id=16 data-nosnippet>16</a>//! old instance. There's a generation trick to make sure that new signal locks another instance.
<a href=#17 id=17 data-nosnippet>17</a>//!
<a href=#18 id=18 data-nosnippet>18</a>//! The downside is, this is an active spin lock at the writer end. However, we assume than:
<a href=#19 id=19 data-nosnippet>19</a>//!
<a href=#20 id=20 data-nosnippet>20</a>//! * Signals are one time setup before we actually have threads. We just need to make *sure* we
<a href=#21 id=21 data-nosnippet>21</a>//! are safe even if this is not true.
<a href=#22 id=22 data-nosnippet>22</a>//! * Signals are rare, happening at the same time as the write even rarer.
<a href=#23 id=23 data-nosnippet>23</a>//! * Signals are short, as there is mostly nothing allowed inside them anyway.
<a href=#24 id=24 data-nosnippet>24</a>//! * Our tool box is severely limited.
<a href=#25 id=25 data-nosnippet>25</a>//!
<a href=#26 id=26 data-nosnippet>26</a>//! Therefore this is hopefully reasonable trade-off.
<a href=#27 id=27 data-nosnippet>27</a>//!
<a href=#28 id=28 data-nosnippet>28</a>//! # Atomic orderings
<a href=#29 id=29 data-nosnippet>29</a>//!
<a href=#30 id=30 data-nosnippet>30</a>//! The whole code uses SeqCst conservatively. Atomics are not used because of performance here and
<a href=#31 id=31 data-nosnippet>31</a>//! are the minor price around signals anyway. But the comments state which orderings should be
<a href=#32 id=32 data-nosnippet>32</a>//! enough in practice in case someone wants to get inspired (but do make your own check through
<a href=#33 id=33 data-nosnippet>33</a>//! them anyway).
<a href=#34 id=34 data-nosnippet>34</a>
<a href=#35 id=35 data-nosnippet>35</a></span><span class="kw">use </span>std::isize;
<a href=#36 id=36 data-nosnippet>36</a><span class="kw">use </span>std::marker::PhantomData;
<a href=#37 id=37 data-nosnippet>37</a><span class="kw">use </span>std::ops::Deref;
<a href=#38 id=38 data-nosnippet>38</a><span class="kw">use </span>std::sync::atomic::{<span class="self">self</span>, AtomicPtr, AtomicUsize, Ordering};
<a href=#39 id=39 data-nosnippet>39</a><span class="kw">use </span>std::sync::{Mutex, MutexGuard, PoisonError};
<a href=#40 id=40 data-nosnippet>40</a><span class="kw">use </span>std::thread;
<a href=#41 id=41 data-nosnippet>41</a>
<a href=#42 id=42 data-nosnippet>42</a><span class="kw">use </span>libc;
<a href=#43 id=43 data-nosnippet>43</a>
<a href=#44 id=44 data-nosnippet>44</a><span class="kw">const </span>YIELD_EVERY: usize = <span class="number">16</span>;
<a href=#45 id=45 data-nosnippet>45</a><span class="kw">const </span>MAX_GUARDS: usize = (isize::MAX) <span class="kw">as </span>usize;
<a href=#46 id=46 data-nosnippet>46</a>
<a href=#47 id=47 data-nosnippet>47</a><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>ReadGuard&lt;<span class="lifetime">'a</span>, T: <span class="lifetime">'a</span>&gt; {
<a href=#48 id=48 data-nosnippet>48</a> data: <span class="kw-2">&amp;</span><span class="lifetime">'a </span>T,
<a href=#49 id=49 data-nosnippet>49</a> lock: <span class="kw-2">&amp;</span><span class="lifetime">'a </span>AtomicUsize,
<a href=#50 id=50 data-nosnippet>50</a>}
<a href=#51 id=51 data-nosnippet>51</a>
<a href=#52 id=52 data-nosnippet>52</a><span class="kw">impl</span>&lt;<span class="lifetime">'a</span>, T&gt; Deref <span class="kw">for </span>ReadGuard&lt;<span class="lifetime">'a</span>, T&gt; {
<a href=#53 id=53 data-nosnippet>53</a> <span class="kw">type </span>Target = T;
<a href=#54 id=54 data-nosnippet>54</a> <span class="kw">fn </span>deref(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>T {
<a href=#55 id=55 data-nosnippet>55</a> <span class="self">self</span>.data
<a href=#56 id=56 data-nosnippet>56</a> }
<a href=#57 id=57 data-nosnippet>57</a>}
<a href=#58 id=58 data-nosnippet>58</a>
<a href=#59 id=59 data-nosnippet>59</a><span class="kw">impl</span>&lt;<span class="lifetime">'a</span>, T&gt; Drop <span class="kw">for </span>ReadGuard&lt;<span class="lifetime">'a</span>, T&gt; {
<a href=#60 id=60 data-nosnippet>60</a> <span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<a href=#61 id=61 data-nosnippet>61</a> <span class="comment">// We effectively unlock; Release would be enough.
<a href=#62 id=62 data-nosnippet>62</a> </span><span class="self">self</span>.lock.fetch_sub(<span class="number">1</span>, Ordering::SeqCst);
<a href=#63 id=63 data-nosnippet>63</a> }
<a href=#64 id=64 data-nosnippet>64</a>}
<a href=#65 id=65 data-nosnippet>65</a>
<a href=#66 id=66 data-nosnippet>66</a><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>WriteGuard&lt;<span class="lifetime">'a</span>, T: <span class="lifetime">'a</span>&gt; {
<a href=#67 id=67 data-nosnippet>67</a> _guard: MutexGuard&lt;<span class="lifetime">'a</span>, ()&gt;,
<a href=#68 id=68 data-nosnippet>68</a> lock: <span class="kw-2">&amp;</span><span class="lifetime">'a </span>HalfLock&lt;T&gt;,
<a href=#69 id=69 data-nosnippet>69</a> data: <span class="kw-2">&amp;</span><span class="lifetime">'a </span>T,
<a href=#70 id=70 data-nosnippet>70</a>}
<a href=#71 id=71 data-nosnippet>71</a>
<a href=#72 id=72 data-nosnippet>72</a><span class="kw">impl</span>&lt;<span class="lifetime">'a</span>, T&gt; WriteGuard&lt;<span class="lifetime">'a</span>, T&gt; {
<a href=#73 id=73 data-nosnippet>73</a> <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>store(<span class="kw-2">&amp;mut </span><span class="self">self</span>, val: T) {
<a href=#74 id=74 data-nosnippet>74</a> <span class="comment">// Move to the heap and convert to raw pointer for AtomicPtr.
<a href=#75 id=75 data-nosnippet>75</a> </span><span class="kw">let </span>new = Box::into_raw(Box::new(val));
<a href=#76 id=76 data-nosnippet>76</a>
<a href=#77 id=77 data-nosnippet>77</a> <span class="self">self</span>.data = <span class="kw">unsafe </span>{ <span class="kw-2">&amp;*</span>new };
<a href=#78 id=78 data-nosnippet>78</a>
<a href=#79 id=79 data-nosnippet>79</a> <span class="comment">// We can just put the new value in here safely, we worry only about dropping the old one.
<a href=#80 id=80 data-nosnippet>80</a> // Release might (?) be enough, to "upload" the data.
<a href=#81 id=81 data-nosnippet>81</a> </span><span class="kw">let </span>old = <span class="self">self</span>.lock.data.swap(new, Ordering::SeqCst);
<a href=#82 id=82 data-nosnippet>82</a>
<a href=#83 id=83 data-nosnippet>83</a> <span class="comment">// Now we make sure there's no reader having the old data.
<a href=#84 id=84 data-nosnippet>84</a> </span><span class="self">self</span>.lock.write_barrier();
<a href=#85 id=85 data-nosnippet>85</a>
<a href=#86 id=86 data-nosnippet>86</a> drop(<span class="kw">unsafe </span>{ Box::from_raw(old) });
<a href=#87 id=87 data-nosnippet>87</a> }
<a href=#88 id=88 data-nosnippet>88</a>}
<a href=#89 id=89 data-nosnippet>89</a>
<a href=#90 id=90 data-nosnippet>90</a><span class="kw">impl</span>&lt;<span class="lifetime">'a</span>, T&gt; Deref <span class="kw">for </span>WriteGuard&lt;<span class="lifetime">'a</span>, T&gt; {
<a href=#91 id=91 data-nosnippet>91</a> <span class="kw">type </span>Target = T;
<a href=#92 id=92 data-nosnippet>92</a> <span class="kw">fn </span>deref(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>T {
<a href=#93 id=93 data-nosnippet>93</a> <span class="comment">// Protected by that mutex
<a href=#94 id=94 data-nosnippet>94</a> </span><span class="self">self</span>.data
<a href=#95 id=95 data-nosnippet>95</a> }
<a href=#96 id=96 data-nosnippet>96</a>}
<a href=#97 id=97 data-nosnippet>97</a>
<a href=#98 id=98 data-nosnippet>98</a><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>HalfLock&lt;T&gt; {
<a href=#99 id=99 data-nosnippet>99</a> <span class="comment">// We conceptually contain an instance of T
<a href=#100 id=100 data-nosnippet>100</a> </span>_t: PhantomData&lt;T&gt;,
<a href=#101 id=101 data-nosnippet>101</a> <span class="comment">// The actual data as a pointer.
<a href=#102 id=102 data-nosnippet>102</a> </span>data: AtomicPtr&lt;T&gt;,
<a href=#103 id=103 data-nosnippet>103</a> <span class="comment">// The generation of the data. Influences which slot of the lock counter we use.
<a href=#104 id=104 data-nosnippet>104</a> </span>generation: AtomicUsize,
<a href=#105 id=105 data-nosnippet>105</a> <span class="comment">// How many active locks are there?
<a href=#106 id=106 data-nosnippet>106</a> </span>lock: [AtomicUsize; <span class="number">2</span>],
<a href=#107 id=107 data-nosnippet>107</a> <span class="comment">// Mutex for the writers; only one writer.
<a href=#108 id=108 data-nosnippet>108</a> </span>write_mutex: Mutex&lt;()&gt;,
<a href=#109 id=109 data-nosnippet>109</a>}
<a href=#110 id=110 data-nosnippet>110</a>
<a href=#111 id=111 data-nosnippet>111</a><span class="kw">impl</span>&lt;T&gt; HalfLock&lt;T&gt; {
<a href=#112 id=112 data-nosnippet>112</a> <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(data: T) -&gt; <span class="self">Self </span>{
<a href=#113 id=113 data-nosnippet>113</a> <span class="comment">// Move to the heap so we can safely point there. Then convert to raw pointer as AtomicPtr
<a href=#114 id=114 data-nosnippet>114</a> // operates on raw pointers. The AtomicPtr effectively acts like Box for us semantically.
<a href=#115 id=115 data-nosnippet>115</a> </span><span class="kw">let </span>ptr = Box::into_raw(Box::new(data));
<a href=#116 id=116 data-nosnippet>116</a> <span class="self">Self </span>{
<a href=#117 id=117 data-nosnippet>117</a> _t: PhantomData,
<a href=#118 id=118 data-nosnippet>118</a> data: AtomicPtr::new(ptr),
<a href=#119 id=119 data-nosnippet>119</a> generation: AtomicUsize::new(<span class="number">0</span>),
<a href=#120 id=120 data-nosnippet>120</a> lock: [AtomicUsize::new(<span class="number">0</span>), AtomicUsize::new(<span class="number">0</span>)],
<a href=#121 id=121 data-nosnippet>121</a> write_mutex: Mutex::new(()),
<a href=#122 id=122 data-nosnippet>122</a> }
<a href=#123 id=123 data-nosnippet>123</a> }
<a href=#124 id=124 data-nosnippet>124</a>
<a href=#125 id=125 data-nosnippet>125</a> <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>read(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; ReadGuard&lt;<span class="lifetime">'_</span>, T&gt; {
<a href=#126 id=126 data-nosnippet>126</a> <span class="comment">// Relaxed should be enough; we only pick one or the other slot and the writer observes
<a href=#127 id=127 data-nosnippet>127</a> // that both were 0 at some time. So the actual value doesn't really matter for safety,
<a href=#128 id=128 data-nosnippet>128</a> // only the changing improves the performance.
<a href=#129 id=129 data-nosnippet>129</a> </span><span class="kw">let gen </span>= <span class="self">self</span>.generation.load(Ordering::SeqCst);
<a href=#130 id=130 data-nosnippet>130</a> <span class="kw">let </span>lock = <span class="kw-2">&amp;</span><span class="self">self</span>.lock[<span class="kw">gen </span>% <span class="number">2</span>];
<a href=#131 id=131 data-nosnippet>131</a> <span class="comment">// Effectively locking something, acquire should be enough.
<a href=#132 id=132 data-nosnippet>132</a> </span><span class="kw">let </span>guard_cnt = lock.fetch_add(<span class="number">1</span>, Ordering::SeqCst);
<a href=#133 id=133 data-nosnippet>133</a>
<a href=#134 id=134 data-nosnippet>134</a> <span class="comment">// This is to prevent overflowing the counter in some degenerate cases, which could lead to
<a href=#135 id=135 data-nosnippet>135</a> // UB (freeing data while still in use). However, as this data structure is used only
<a href=#136 id=136 data-nosnippet>136</a> // internally and it's not possible to leak the guard and the guard itself takes some
<a href=#137 id=137 data-nosnippet>137</a> // memory, it should be really impossible to trigger this case. Still, we include it from
<a href=#138 id=138 data-nosnippet>138</a> // abundance of caution.
<a href=#139 id=139 data-nosnippet>139</a> //
<a href=#140 id=140 data-nosnippet>140</a> // This technically is not fully correct as enough threads being in between here and the
<a href=#141 id=141 data-nosnippet>141</a> // abort below could still overflow it and it could get freed for some *other* thread, but
<a href=#142 id=142 data-nosnippet>142</a> // that would mean having too many active threads to fit into RAM too and is even more
<a href=#143 id=143 data-nosnippet>143</a> // absurd corner case than the above.
<a href=#144 id=144 data-nosnippet>144</a> </span><span class="kw">if </span>guard_cnt &gt; MAX_GUARDS {
<a href=#145 id=145 data-nosnippet>145</a> <span class="kw">unsafe </span>{ libc::abort() };
<a href=#146 id=146 data-nosnippet>146</a> }
<a href=#147 id=147 data-nosnippet>147</a>
<a href=#148 id=148 data-nosnippet>148</a> <span class="comment">// Acquire should be enough; we need to "download" the data, paired with the swap on the
<a href=#149 id=149 data-nosnippet>149</a> // same pointer.
<a href=#150 id=150 data-nosnippet>150</a> </span><span class="kw">let </span>data = <span class="self">self</span>.data.load(Ordering::SeqCst);
<a href=#151 id=151 data-nosnippet>151</a> <span class="comment">// Safe:
<a href=#152 id=152 data-nosnippet>152</a> // * It did point to valid data when put in.
<a href=#153 id=153 data-nosnippet>153</a> // * Protected by lock, so still valid.
<a href=#154 id=154 data-nosnippet>154</a> </span><span class="kw">let </span>data = <span class="kw">unsafe </span>{ <span class="kw-2">&amp;*</span>data };
<a href=#155 id=155 data-nosnippet>155</a>
<a href=#156 id=156 data-nosnippet>156</a> ReadGuard { data, lock }
<a href=#157 id=157 data-nosnippet>157</a> }
<a href=#158 id=158 data-nosnippet>158</a>
<a href=#159 id=159 data-nosnippet>159</a> <span class="kw">fn </span>update_seen(<span class="kw-2">&amp;</span><span class="self">self</span>, seen_zero: <span class="kw-2">&amp;mut </span>[bool; <span class="number">2</span>]) {
<a href=#160 id=160 data-nosnippet>160</a> <span class="kw">for </span>(seen, slot) <span class="kw">in </span>seen_zero.iter_mut().zip(<span class="kw-2">&amp;</span><span class="self">self</span>.lock) {
<a href=#161 id=161 data-nosnippet>161</a> <span class="kw-2">*</span>seen = <span class="kw-2">*</span>seen || slot.load(Ordering::SeqCst) == <span class="number">0</span>;
<a href=#162 id=162 data-nosnippet>162</a> }
<a href=#163 id=163 data-nosnippet>163</a> }
<a href=#164 id=164 data-nosnippet>164</a>
<a href=#165 id=165 data-nosnippet>165</a> <span class="kw">fn </span>write_barrier(<span class="kw-2">&amp;</span><span class="self">self</span>) {
<a href=#166 id=166 data-nosnippet>166</a> <span class="comment">// Do a first check of seeing zeroes before we switch the generation. At least one of them
<a href=#167 id=167 data-nosnippet>167</a> // should be zero by now, due to having drained the generation before leaving the previous
<a href=#168 id=168 data-nosnippet>168</a> // writer.
<a href=#169 id=169 data-nosnippet>169</a> </span><span class="kw">let </span><span class="kw-2">mut </span>seen_zero = [<span class="bool-val">false</span>; <span class="number">2</span>];
<a href=#170 id=170 data-nosnippet>170</a> <span class="self">self</span>.update_seen(<span class="kw-2">&amp;mut </span>seen_zero);
<a href=#171 id=171 data-nosnippet>171</a> <span class="comment">// By switching the generation to the other slot, we make sure the currently active starts
<a href=#172 id=172 data-nosnippet>172</a> // draining while the other will start filling up.
<a href=#173 id=173 data-nosnippet>173</a> </span><span class="self">self</span>.generation.fetch_add(<span class="number">1</span>, Ordering::SeqCst); <span class="comment">// Overflow is fine.
<a href=#174 id=174 data-nosnippet>174</a>
<a href=#175 id=175 data-nosnippet>175</a> </span><span class="kw">let </span><span class="kw-2">mut </span>iter = <span class="number">0usize</span>;
<a href=#176 id=176 data-nosnippet>176</a> <span class="kw">while </span>!seen_zero.iter().all(|s| <span class="kw-2">*</span>s) {
<a href=#177 id=177 data-nosnippet>177</a> iter = iter.wrapping_add(<span class="number">1</span>);
<a href=#178 id=178 data-nosnippet>178</a>
<a href=#179 id=179 data-nosnippet>179</a> <span class="comment">// Be somewhat less aggressive while looping, switch to the other threads if possible.
<a href=#180 id=180 data-nosnippet>180</a> </span><span class="kw">if </span><span class="macro">cfg!</span>(not(miri)) {
<a href=#181 id=181 data-nosnippet>181</a> <span class="kw">if </span>iter % YIELD_EVERY == <span class="number">0 </span>{
<a href=#182 id=182 data-nosnippet>182</a> thread::yield_now();
<a href=#183 id=183 data-nosnippet>183</a> } <span class="kw">else </span>{
<a href=#184 id=184 data-nosnippet>184</a> <span class="comment">// Replaced by hint::spin_loop, but we want to support older compiler
<a href=#185 id=185 data-nosnippet>185</a> </span><span class="attr">#[allow(deprecated)]
<a href=#186 id=186 data-nosnippet>186</a> </span>atomic::spin_loop_hint();
<a href=#187 id=187 data-nosnippet>187</a> }
<a href=#188 id=188 data-nosnippet>188</a> }
<a href=#189 id=189 data-nosnippet>189</a>
<a href=#190 id=190 data-nosnippet>190</a> <span class="self">self</span>.update_seen(<span class="kw-2">&amp;mut </span>seen_zero);
<a href=#191 id=191 data-nosnippet>191</a> }
<a href=#192 id=192 data-nosnippet>192</a> }
<a href=#193 id=193 data-nosnippet>193</a>
<a href=#194 id=194 data-nosnippet>194</a> <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>write(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; WriteGuard&lt;<span class="lifetime">'_</span>, T&gt; {
<a href=#195 id=195 data-nosnippet>195</a> <span class="comment">// While it's possible the user code panics, our code in store doesn't and the data gets
<a href=#196 id=196 data-nosnippet>196</a> // swapped atomically. So if it panics, nothing gets changed, therefore poisons are of no
<a href=#197 id=197 data-nosnippet>197</a> // interest here.
<a href=#198 id=198 data-nosnippet>198</a> </span><span class="kw">let </span>guard = <span class="self">self
<a href=#199 id=199 data-nosnippet>199</a> </span>.write_mutex
<a href=#200 id=200 data-nosnippet>200</a> .lock()
<a href=#201 id=201 data-nosnippet>201</a> .unwrap_or_else(PoisonError::into_inner);
<a href=#202 id=202 data-nosnippet>202</a>
<a href=#203 id=203 data-nosnippet>203</a> <span class="comment">// Relaxed should be enough, as we are under the same mutex that was used to get the data
<a href=#204 id=204 data-nosnippet>204</a> // in.
<a href=#205 id=205 data-nosnippet>205</a> </span><span class="kw">let </span>data = <span class="self">self</span>.data.load(Ordering::SeqCst);
<a href=#206 id=206 data-nosnippet>206</a> <span class="comment">// Safe:
<a href=#207 id=207 data-nosnippet>207</a> // * Stored as valid data
<a href=#208 id=208 data-nosnippet>208</a> // * Only this method, protected by mutex, can change the pointer, so it didn't go away.
<a href=#209 id=209 data-nosnippet>209</a> </span><span class="kw">let </span>data = <span class="kw">unsafe </span>{ <span class="kw-2">&amp;*</span>data };
<a href=#210 id=210 data-nosnippet>210</a>
<a href=#211 id=211 data-nosnippet>211</a> WriteGuard {
<a href=#212 id=212 data-nosnippet>212</a> data,
<a href=#213 id=213 data-nosnippet>213</a> _guard: guard,
<a href=#214 id=214 data-nosnippet>214</a> lock: <span class="self">self</span>,
<a href=#215 id=215 data-nosnippet>215</a> }
<a href=#216 id=216 data-nosnippet>216</a> }
<a href=#217 id=217 data-nosnippet>217</a>}
<a href=#218 id=218 data-nosnippet>218</a>
<a href=#219 id=219 data-nosnippet>219</a><span class="kw">impl</span>&lt;T&gt; Drop <span class="kw">for </span>HalfLock&lt;T&gt; {
<a href=#220 id=220 data-nosnippet>220</a> <span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<a href=#221 id=221 data-nosnippet>221</a> <span class="comment">// During drop we are sure there are no other borrows of the data so we are free to just
<a href=#222 id=222 data-nosnippet>222</a> // drop it. Also, the drop impl won't be called in practice in our case, as it is used
<a href=#223 id=223 data-nosnippet>223</a> // solely as a global variable, but we provide it for completeness and tests anyway.
<a href=#224 id=224 data-nosnippet>224</a> //
<a href=#225 id=225 data-nosnippet>225</a> // unsafe: the pointer in there is always valid, we just take the last instance out.
<a href=#226 id=226 data-nosnippet>226</a> </span><span class="kw">unsafe </span>{
<a href=#227 id=227 data-nosnippet>227</a> <span class="comment">// Acquire should be enough.
<a href=#228 id=228 data-nosnippet>228</a> </span><span class="kw">let </span>data = Box::from_raw(<span class="self">self</span>.data.load(Ordering::SeqCst));
<a href=#229 id=229 data-nosnippet>229</a> drop(data);
<a href=#230 id=230 data-nosnippet>230</a> }
<a href=#231 id=231 data-nosnippet>231</a> }
<a href=#232 id=232 data-nosnippet>232</a>}
</code></pre></div></section></main></body></html>

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<!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/newkirk/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/signal-hook-registry-1.4.8/src/lib.rs`."><title>lib.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="signal_hook_registry" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../../static.files/src-script-813739b1.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc src"><!--[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="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">signal_hook_registry/</div>lib.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap digits-3"><pre class="rust"><code><a href=#1 id=1 data-nosnippet>1</a><span class="attr">#![doc(test(attr(deny(warnings))))]
<a href=#2 id=2 data-nosnippet>2</a>#![warn(missing_docs)]
<a href=#3 id=3 data-nosnippet>3</a>#![allow(unknown_lints, renamed_and_remove_lints, bare_trait_objects)]
<a href=#4 id=4 data-nosnippet>4</a>
<a href=#5 id=5 data-nosnippet>5</a></span><span class="doccomment">//! Backend of the [signal-hook] crate.
<a href=#6 id=6 data-nosnippet>6</a>//!
<a href=#7 id=7 data-nosnippet>7</a>//! The [signal-hook] crate tries to provide an API to the unix signals, which are a global
<a href=#8 id=8 data-nosnippet>8</a>//! resource. Therefore, it is desirable an application contains just one version of the crate
<a href=#9 id=9 data-nosnippet>9</a>//! which manages this global resource. But that makes it impossible to make breaking changes in
<a href=#10 id=10 data-nosnippet>10</a>//! the API.
<a href=#11 id=11 data-nosnippet>11</a>//!
<a href=#12 id=12 data-nosnippet>12</a>//! Therefore, this crate provides very minimal and low level API to the signals that is unlikely
<a href=#13 id=13 data-nosnippet>13</a>//! to have to change, while there may be multiple versions of the [signal-hook] that all use this
<a href=#14 id=14 data-nosnippet>14</a>//! low-level API to provide different versions of the high level APIs.
<a href=#15 id=15 data-nosnippet>15</a>//!
<a href=#16 id=16 data-nosnippet>16</a>//! It is also possible some other crates might want to build a completely different API. This
<a href=#17 id=17 data-nosnippet>17</a>//! split allows these crates to still reuse the same low-level routines in this crate instead of
<a href=#18 id=18 data-nosnippet>18</a>//! going to the (much more dangerous) unix calls.
<a href=#19 id=19 data-nosnippet>19</a>//!
<a href=#20 id=20 data-nosnippet>20</a>//! # What this crate provides
<a href=#21 id=21 data-nosnippet>21</a>//!
<a href=#22 id=22 data-nosnippet>22</a>//! The only thing this crate does is multiplexing the signals. An application or library can add
<a href=#23 id=23 data-nosnippet>23</a>//! or remove callbacks and have multiple callbacks for the same signal.
<a href=#24 id=24 data-nosnippet>24</a>//!
<a href=#25 id=25 data-nosnippet>25</a>//! It handles dispatching the callbacks and managing them in a way that uses only the
<a href=#26 id=26 data-nosnippet>26</a>//! [async-signal-safe] functions inside the signal handler. Note that the callbacks are still run
<a href=#27 id=27 data-nosnippet>27</a>//! inside the signal handler, so it is up to the caller to ensure they are also
<a href=#28 id=28 data-nosnippet>28</a>//! [async-signal-safe].
<a href=#29 id=29 data-nosnippet>29</a>//!
<a href=#30 id=30 data-nosnippet>30</a>//! # What this is for
<a href=#31 id=31 data-nosnippet>31</a>//!
<a href=#32 id=32 data-nosnippet>32</a>//! This is a building block for other libraries creating reasonable abstractions on top of
<a href=#33 id=33 data-nosnippet>33</a>//! signals. The [signal-hook] is the generally preferred way if you need to handle signals in your
<a href=#34 id=34 data-nosnippet>34</a>//! application and provides several safe patterns of doing so.
<a href=#35 id=35 data-nosnippet>35</a>//!
<a href=#36 id=36 data-nosnippet>36</a>//! # Rust version compatibility
<a href=#37 id=37 data-nosnippet>37</a>//!
<a href=#38 id=38 data-nosnippet>38</a>//! Currently builds on 1.26.0 an newer and this is very unlikely to change. However, tests
<a href=#39 id=39 data-nosnippet>39</a>//! require dependencies that don't build there, so tests need newer Rust version (they are run on
<a href=#40 id=40 data-nosnippet>40</a>//! stable).
<a href=#41 id=41 data-nosnippet>41</a>//!
<a href=#42 id=42 data-nosnippet>42</a>//! Note that this ancient version of rustc no longer compiles current versions of `libc`. If you
<a href=#43 id=43 data-nosnippet>43</a>//! want to use rustc this old, you need to force your dependency resolution to pick old enough
<a href=#44 id=44 data-nosnippet>44</a>//! version of `libc` (`0.2.156` was found to work, but newer ones may too).
<a href=#45 id=45 data-nosnippet>45</a>//!
<a href=#46 id=46 data-nosnippet>46</a>//! # Portability
<a href=#47 id=47 data-nosnippet>47</a>//!
<a href=#48 id=48 data-nosnippet>48</a>//! This crate includes a limited support for Windows, based on `signal`/`raise` in the CRT.
<a href=#49 id=49 data-nosnippet>49</a>//! There are differences in both API and behavior:
<a href=#50 id=50 data-nosnippet>50</a>//!
<a href=#51 id=51 data-nosnippet>51</a>//! - Due to lack of `siginfo_t`, we don't provide `register_sigaction` or `register_unchecked`.
<a href=#52 id=52 data-nosnippet>52</a>//! - Due to lack of signal blocking, there's a race condition.
<a href=#53 id=53 data-nosnippet>53</a>//! After the call to `signal`, there's a moment where we miss a signal.
<a href=#54 id=54 data-nosnippet>54</a>//! That means when you register a handler, there may be a signal which invokes
<a href=#55 id=55 data-nosnippet>55</a>//! neither the default handler or the handler you register.
<a href=#56 id=56 data-nosnippet>56</a>//! - Handlers registered by `signal` in Windows are cleared on first signal.
<a href=#57 id=57 data-nosnippet>57</a>//! To match behavior in other platforms, we re-register the handler each time the handler is
<a href=#58 id=58 data-nosnippet>58</a>//! called, but there's a moment where we miss a handler.
<a href=#59 id=59 data-nosnippet>59</a>//! That means when you receive two signals in a row, there may be a signal which invokes
<a href=#60 id=60 data-nosnippet>60</a>//! the default handler, nevertheless you certainly have registered the handler.
<a href=#61 id=61 data-nosnippet>61</a>//!
<a href=#62 id=62 data-nosnippet>62</a>//! [signal-hook]: https://docs.rs/signal-hook
<a href=#63 id=63 data-nosnippet>63</a>//! [async-signal-safe]: http://www.man7.org/linux/man-pages/man7/signal-safety.7.html
<a href=#64 id=64 data-nosnippet>64</a>
<a href=#65 id=65 data-nosnippet>65</a></span><span class="kw">extern crate </span>errno;
<a href=#66 id=66 data-nosnippet>66</a><span class="kw">extern crate </span>libc;
<a href=#67 id=67 data-nosnippet>67</a>
<a href=#68 id=68 data-nosnippet>68</a><span class="kw">mod </span>half_lock;
<a href=#69 id=69 data-nosnippet>69</a><span class="kw">mod </span>vec_map;
<a href=#70 id=70 data-nosnippet>70</a>
<a href=#71 id=71 data-nosnippet>71</a><span class="kw">use </span>std::io::Error;
<a href=#72 id=72 data-nosnippet>72</a><span class="kw">use </span>std::mem;
<a href=#73 id=73 data-nosnippet>73</a><span class="kw">use </span>std::ptr;
<a href=#74 id=74 data-nosnippet>74</a><span class="kw">use </span>std::sync::atomic::{AtomicPtr, Ordering};
<a href=#75 id=75 data-nosnippet>75</a><span class="comment">// Once::new is now a const-fn. But it is not stable in all the rustc versions we want to support
<a href=#76 id=76 data-nosnippet>76</a>// yet.
<a href=#77 id=77 data-nosnippet>77</a></span><span class="attr">#[allow(deprecated)]
<a href=#78 id=78 data-nosnippet>78</a></span><span class="kw">use </span>std::sync::ONCE_INIT;
<a href=#79 id=79 data-nosnippet>79</a><span class="kw">use </span>std::sync::{Arc, Once};
<a href=#80 id=80 data-nosnippet>80</a>
<a href=#81 id=81 data-nosnippet>81</a><span class="kw">use </span>errno::Errno;
<a href=#82 id=82 data-nosnippet>82</a><span class="attr">#[cfg(not(windows))]
<a href=#83 id=83 data-nosnippet>83</a></span><span class="kw">use </span>libc::{c_int, c_void, sigaction, siginfo_t};
<a href=#84 id=84 data-nosnippet>84</a><span class="attr">#[cfg(windows)]
<a href=#85 id=85 data-nosnippet>85</a></span><span class="kw">use </span>libc::{c_int, sighandler_t};
<a href=#86 id=86 data-nosnippet>86</a>
<a href=#87 id=87 data-nosnippet>87</a><span class="attr">#[cfg(not(windows))]
<a href=#88 id=88 data-nosnippet>88</a></span><span class="kw">use </span>libc::{SIGFPE, SIGILL, SIGKILL, SIGSEGV, SIGSTOP};
<a href=#89 id=89 data-nosnippet>89</a><span class="attr">#[cfg(windows)]
<a href=#90 id=90 data-nosnippet>90</a></span><span class="kw">use </span>libc::{SIGFPE, SIGILL, SIGSEGV};
<a href=#91 id=91 data-nosnippet>91</a>
<a href=#92 id=92 data-nosnippet>92</a><span class="kw">use </span>half_lock::HalfLock;
<a href=#93 id=93 data-nosnippet>93</a><span class="kw">use </span>vec_map::VecMap;
<a href=#94 id=94 data-nosnippet>94</a>
<a href=#95 id=95 data-nosnippet>95</a><span class="comment">// These constants are not defined in the current version of libc, but it actually
<a href=#96 id=96 data-nosnippet>96</a>// exists in Windows CRT.
<a href=#97 id=97 data-nosnippet>97</a></span><span class="attr">#[cfg(windows)]
<a href=#98 id=98 data-nosnippet>98</a></span><span class="kw">const </span>SIG_DFL: sighandler_t = <span class="number">0</span>;
<a href=#99 id=99 data-nosnippet>99</a><span class="attr">#[cfg(windows)]
<a href=#100 id=100 data-nosnippet>100</a></span><span class="kw">const </span>SIG_IGN: sighandler_t = <span class="number">1</span>;
<a href=#101 id=101 data-nosnippet>101</a><span class="attr">#[cfg(windows)]
<a href=#102 id=102 data-nosnippet>102</a></span><span class="kw">const </span>SIG_GET: sighandler_t = <span class="number">2</span>;
<a href=#103 id=103 data-nosnippet>103</a><span class="attr">#[cfg(windows)]
<a href=#104 id=104 data-nosnippet>104</a></span><span class="kw">const </span>SIG_ERR: sighandler_t = !<span class="number">0</span>;
<a href=#105 id=105 data-nosnippet>105</a>
<a href=#106 id=106 data-nosnippet>106</a><span class="comment">// To simplify implementation. Not to be exposed.
<a href=#107 id=107 data-nosnippet>107</a></span><span class="attr">#[cfg(windows)]
<a href=#108 id=108 data-nosnippet>108</a>#[allow(non_camel_case_types)]
<a href=#109 id=109 data-nosnippet>109</a></span><span class="kw">struct </span>siginfo_t;
<a href=#110 id=110 data-nosnippet>110</a>
<a href=#111 id=111 data-nosnippet>111</a><span class="comment">// # Internal workings
<a href=#112 id=112 data-nosnippet>112</a>//
<a href=#113 id=113 data-nosnippet>113</a>// This uses a form of RCU. There's an atomic pointer to the current action descriptors (in the
<a href=#114 id=114 data-nosnippet>114</a>// form of IndependentArcSwap, to be able to track what, if any, signal handlers still use the
<a href=#115 id=115 data-nosnippet>115</a>// version). A signal handler takes a copy of the pointer and calls all the relevant actions.
<a href=#116 id=116 data-nosnippet>116</a>//
<a href=#117 id=117 data-nosnippet>117</a>// Modifications to that are protected by a mutex, to avoid juggling multiple signal handlers at
<a href=#118 id=118 data-nosnippet>118</a>// once (eg. not calling sigaction concurrently). This should not be a problem, because modifying
<a href=#119 id=119 data-nosnippet>119</a>// the signal actions should be initialization only anyway. To avoid all allocations and also
<a href=#120 id=120 data-nosnippet>120</a>// deallocations inside the signal handler, after replacing the pointer, the modification routine
<a href=#121 id=121 data-nosnippet>121</a>// needs to busy-wait for the reference count on the old pointer to drop to 1 and take ownership
<a href=#122 id=122 data-nosnippet>122</a>// that way the one deallocating is the modification routine, outside of the signal handler.
<a href=#123 id=123 data-nosnippet>123</a>
<a href=#124 id=124 data-nosnippet>124</a></span><span class="attr">#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
<a href=#125 id=125 data-nosnippet>125</a></span><span class="kw">struct </span>ActionId(u128);
<a href=#126 id=126 data-nosnippet>126</a>
<a href=#127 id=127 data-nosnippet>127</a><span class="doccomment">/// An ID of registered action.
<a href=#128 id=128 data-nosnippet>128</a>///
<a href=#129 id=129 data-nosnippet>129</a>/// This is returned by all the registration routines and can be used to remove the action later on
<a href=#130 id=130 data-nosnippet>130</a>/// with a call to [`unregister`].
<a href=#131 id=131 data-nosnippet>131</a></span><span class="attr">#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
<a href=#132 id=132 data-nosnippet>132</a></span><span class="kw">pub struct </span>SigId {
<a href=#133 id=133 data-nosnippet>133</a> signal: c_int,
<a href=#134 id=134 data-nosnippet>134</a> action: ActionId,
<a href=#135 id=135 data-nosnippet>135</a>}
<a href=#136 id=136 data-nosnippet>136</a>
<a href=#137 id=137 data-nosnippet>137</a><span class="comment">// This should be dyn Fn(...), but we want to support Rust 1.26.0 and that one doesn't allow dyn
<a href=#138 id=138 data-nosnippet>138</a>// yet.
<a href=#139 id=139 data-nosnippet>139</a></span><span class="attr">#[allow(unknown_lints, bare_trait_objects)]
<a href=#140 id=140 data-nosnippet>140</a></span><span class="kw">type </span>Action = Fn(<span class="kw-2">&amp;</span>siginfo_t) + Send + Sync;
<a href=#141 id=141 data-nosnippet>141</a>
<a href=#142 id=142 data-nosnippet>142</a><span class="attr">#[derive(Clone)]
<a href=#143 id=143 data-nosnippet>143</a></span><span class="kw">struct </span>Slot {
<a href=#144 id=144 data-nosnippet>144</a> prev: Prev,
<a href=#145 id=145 data-nosnippet>145</a> <span class="comment">// Actions are stored and executed in the order they were registered.
<a href=#146 id=146 data-nosnippet>146</a> </span>actions: VecMap&lt;ActionId, Arc&lt;Action&gt;&gt;,
<a href=#147 id=147 data-nosnippet>147</a>}
<a href=#148 id=148 data-nosnippet>148</a>
<a href=#149 id=149 data-nosnippet>149</a><span class="kw">impl </span>Slot {
<a href=#150 id=150 data-nosnippet>150</a> <span class="attr">#[cfg(windows)]
<a href=#151 id=151 data-nosnippet>151</a> </span><span class="kw">fn </span>new(signal: libc::c_int) -&gt; <span class="prelude-ty">Result</span>&lt;<span class="self">Self</span>, Error&gt; {
<a href=#152 id=152 data-nosnippet>152</a> <span class="kw">let </span>old = <span class="kw">unsafe </span>{ libc::signal(signal, handler <span class="kw">as </span><span class="kw-2">*const </span>() <span class="kw">as </span>sighandler_t) };
<a href=#153 id=153 data-nosnippet>153</a> <span class="kw">if </span>old == SIG_ERR {
<a href=#154 id=154 data-nosnippet>154</a> <span class="kw">return </span><span class="prelude-val">Err</span>(Error::last_os_error());
<a href=#155 id=155 data-nosnippet>155</a> }
<a href=#156 id=156 data-nosnippet>156</a> <span class="prelude-val">Ok</span>(Slot {
<a href=#157 id=157 data-nosnippet>157</a> prev: Prev { signal, info: old },
<a href=#158 id=158 data-nosnippet>158</a> actions: VecMap::new(),
<a href=#159 id=159 data-nosnippet>159</a> })
<a href=#160 id=160 data-nosnippet>160</a> }
<a href=#161 id=161 data-nosnippet>161</a>
<a href=#162 id=162 data-nosnippet>162</a> <span class="attr">#[cfg(not(windows))]
<a href=#163 id=163 data-nosnippet>163</a> </span><span class="kw">fn </span>new(signal: libc::c_int) -&gt; <span class="prelude-ty">Result</span>&lt;<span class="self">Self</span>, Error&gt; {
<a href=#164 id=164 data-nosnippet>164</a> <span class="comment">// C data structure, expected to be zeroed out.
<a href=#165 id=165 data-nosnippet>165</a> </span><span class="kw">let </span><span class="kw-2">mut </span>new: libc::sigaction = <span class="kw">unsafe </span>{ mem::zeroed() };
<a href=#166 id=166 data-nosnippet>166</a>
<a href=#167 id=167 data-nosnippet>167</a> <span class="comment">// Note: AIX fixed their naming in libc 0.2.171.
<a href=#168 id=168 data-nosnippet>168</a> //
<a href=#169 id=169 data-nosnippet>169</a> // However, if we mandate that _for everyone_, other systems fail to compile on old Rust
<a href=#170 id=170 data-nosnippet>170</a> // versions (eg. 1.26.0), because they are no longer able to compile this new libc.
<a href=#171 id=171 data-nosnippet>171</a> //
<a href=#172 id=172 data-nosnippet>172</a> // There doesn't seem to be a way to make Cargo force the dependency for only one target
<a href=#173 id=173 data-nosnippet>173</a> // (it doesn't compile the ones it doesn't need, but it stills considers the other targets
<a href=#174 id=174 data-nosnippet>174</a> // for version resolution).
<a href=#175 id=175 data-nosnippet>175</a> //
<a href=#176 id=176 data-nosnippet>176</a> // Therefore, we let the user have freedom - if they want AIX, they can upgrade to new
<a href=#177 id=177 data-nosnippet>177</a> // enough libc. If they want ancient rustc, they can force older versions of libc.
<a href=#178 id=178 data-nosnippet>178</a> //
<a href=#179 id=179 data-nosnippet>179</a> // See #169.
<a href=#180 id=180 data-nosnippet>180</a>
<a href=#181 id=181 data-nosnippet>181</a> </span>new.sa_sigaction = handler <span class="kw">as </span><span class="kw-2">*const </span>() <span class="kw">as </span>usize; <span class="comment">// If it doesn't compile on AIX, upgrade the libc dependency
<a href=#182 id=182 data-nosnippet>182</a>
<a href=#183 id=183 data-nosnippet>183</a> </span><span class="attr">#[cfg(target_os = <span class="string">"nto"</span>)]
<a href=#184 id=184 data-nosnippet>184</a> </span><span class="kw">let </span>flags = <span class="number">0</span>;
<a href=#185 id=185 data-nosnippet>185</a> <span class="comment">// SA_RESTART is not supported by qnx https://www.qnx.com/support/knowledgebase.html?id=50130000000SmiD
<a href=#186 id=186 data-nosnippet>186</a> </span><span class="attr">#[cfg(not(target_os = <span class="string">"nto"</span>))]
<a href=#187 id=187 data-nosnippet>187</a> </span><span class="kw">let </span>flags = libc::SA_RESTART;
<a href=#188 id=188 data-nosnippet>188</a> <span class="comment">// Android is broken and uses different int types than the rest (and different depending on
<a href=#189 id=189 data-nosnippet>189</a> // the pointer width). This converts the flags to the proper type no matter what it is on
<a href=#190 id=190 data-nosnippet>190</a> // the given platform.
<a href=#191 id=191 data-nosnippet>191</a> </span><span class="attr">#[allow(unused_assignments)]
<a href=#192 id=192 data-nosnippet>192</a> </span><span class="kw">let </span><span class="kw-2">mut </span>siginfo = flags;
<a href=#193 id=193 data-nosnippet>193</a> siginfo = libc::SA_SIGINFO <span class="kw">as _</span>;
<a href=#194 id=194 data-nosnippet>194</a> <span class="kw">let </span>flags = flags | siginfo;
<a href=#195 id=195 data-nosnippet>195</a> new.sa_flags = flags <span class="kw">as _</span>;
<a href=#196 id=196 data-nosnippet>196</a> <span class="comment">// C data structure, expected to be zeroed out.
<a href=#197 id=197 data-nosnippet>197</a> </span><span class="kw">let </span><span class="kw-2">mut </span>old: libc::sigaction = <span class="kw">unsafe </span>{ mem::zeroed() };
<a href=#198 id=198 data-nosnippet>198</a> <span class="comment">// FFI pointers are valid, it doesn't take ownership.
<a href=#199 id=199 data-nosnippet>199</a> </span><span class="kw">if unsafe </span>{ libc::sigaction(signal, <span class="kw-2">&amp;</span>new, <span class="kw-2">&amp;mut </span>old) } != <span class="number">0 </span>{
<a href=#200 id=200 data-nosnippet>200</a> <span class="kw">return </span><span class="prelude-val">Err</span>(Error::last_os_error());
<a href=#201 id=201 data-nosnippet>201</a> }
<a href=#202 id=202 data-nosnippet>202</a> <span class="prelude-val">Ok</span>(Slot {
<a href=#203 id=203 data-nosnippet>203</a> prev: Prev { signal, info: old },
<a href=#204 id=204 data-nosnippet>204</a> actions: VecMap::new(),
<a href=#205 id=205 data-nosnippet>205</a> })
<a href=#206 id=206 data-nosnippet>206</a> }
<a href=#207 id=207 data-nosnippet>207</a>}
<a href=#208 id=208 data-nosnippet>208</a>
<a href=#209 id=209 data-nosnippet>209</a><span class="attr">#[derive(Clone)]
<a href=#210 id=210 data-nosnippet>210</a></span><span class="kw">struct </span>SignalData {
<a href=#211 id=211 data-nosnippet>211</a> signals: VecMap&lt;c_int, Slot&gt;,
<a href=#212 id=212 data-nosnippet>212</a> next_id: u128,
<a href=#213 id=213 data-nosnippet>213</a>}
<a href=#214 id=214 data-nosnippet>214</a>
<a href=#215 id=215 data-nosnippet>215</a><span class="attr">#[derive(Clone)]
<a href=#216 id=216 data-nosnippet>216</a></span><span class="kw">struct </span>Prev {
<a href=#217 id=217 data-nosnippet>217</a> signal: c_int,
<a href=#218 id=218 data-nosnippet>218</a> <span class="attr">#[cfg(windows)]
<a href=#219 id=219 data-nosnippet>219</a> </span>info: sighandler_t,
<a href=#220 id=220 data-nosnippet>220</a> <span class="attr">#[cfg(not(windows))]
<a href=#221 id=221 data-nosnippet>221</a> </span>info: sigaction,
<a href=#222 id=222 data-nosnippet>222</a>}
<a href=#223 id=223 data-nosnippet>223</a>
<a href=#224 id=224 data-nosnippet>224</a><span class="kw">impl </span>Prev {
<a href=#225 id=225 data-nosnippet>225</a> <span class="attr">#[cfg(windows)]
<a href=#226 id=226 data-nosnippet>226</a> </span><span class="kw">fn </span>detect(signal: c_int) -&gt; <span class="prelude-ty">Result</span>&lt;<span class="self">Self</span>, Error&gt; {
<a href=#227 id=227 data-nosnippet>227</a> <span class="kw">let </span>old = <span class="kw">unsafe </span>{ libc::signal(signal, SIG_GET) };
<a href=#228 id=228 data-nosnippet>228</a> <span class="kw">if </span>old == SIG_ERR {
<a href=#229 id=229 data-nosnippet>229</a> <span class="kw">return </span><span class="prelude-val">Err</span>(Error::last_os_error());
<a href=#230 id=230 data-nosnippet>230</a> }
<a href=#231 id=231 data-nosnippet>231</a> <span class="prelude-val">Ok</span>(Prev { signal, info: old })
<a href=#232 id=232 data-nosnippet>232</a> }
<a href=#233 id=233 data-nosnippet>233</a>
<a href=#234 id=234 data-nosnippet>234</a> <span class="attr">#[cfg(not(windows))]
<a href=#235 id=235 data-nosnippet>235</a> </span><span class="kw">fn </span>detect(signal: c_int) -&gt; <span class="prelude-ty">Result</span>&lt;<span class="self">Self</span>, Error&gt; {
<a href=#236 id=236 data-nosnippet>236</a> <span class="comment">// C data structure, expected to be zeroed out.
<a href=#237 id=237 data-nosnippet>237</a> </span><span class="kw">let </span><span class="kw-2">mut </span>old: libc::sigaction = <span class="kw">unsafe </span>{ mem::zeroed() };
<a href=#238 id=238 data-nosnippet>238</a> <span class="comment">// FFI pointers are valid, it doesn't take ownership.
<a href=#239 id=239 data-nosnippet>239</a> </span><span class="kw">if unsafe </span>{ libc::sigaction(signal, ptr::null(), <span class="kw-2">&amp;mut </span>old) } != <span class="number">0 </span>{
<a href=#240 id=240 data-nosnippet>240</a> <span class="kw">return </span><span class="prelude-val">Err</span>(Error::last_os_error());
<a href=#241 id=241 data-nosnippet>241</a> }
<a href=#242 id=242 data-nosnippet>242</a>
<a href=#243 id=243 data-nosnippet>243</a> <span class="prelude-val">Ok</span>(Prev { signal, info: old })
<a href=#244 id=244 data-nosnippet>244</a> }
<a href=#245 id=245 data-nosnippet>245</a>
<a href=#246 id=246 data-nosnippet>246</a> <span class="attr">#[cfg(windows)]
<a href=#247 id=247 data-nosnippet>247</a> </span><span class="kw">fn </span>execute(<span class="kw-2">&amp;</span><span class="self">self</span>, sig: c_int) {
<a href=#248 id=248 data-nosnippet>248</a> <span class="kw">let </span>fptr = <span class="self">self</span>.info;
<a href=#249 id=249 data-nosnippet>249</a> <span class="kw">if </span><span class="macro">fptr !</span>= <span class="number">0 </span>&amp;&amp; <span class="macro">fptr !</span>= SIG_DFL &amp;&amp; <span class="macro">fptr !</span>= SIG_IGN {
<a href=#250 id=250 data-nosnippet>250</a> <span class="comment">// `sighandler_t` is an integer type. Transmuting it directly from an integer to a
<a href=#251 id=251 data-nosnippet>251</a> // function pointer seems dubious w.r.t. pointer provenance -- at least Miri complains
<a href=#252 id=252 data-nosnippet>252</a> // about it. Casting to a raw pointer first side-steps the issue.
<a href=#253 id=253 data-nosnippet>253</a> </span><span class="kw">let </span>fptr = fptr <span class="kw">as </span><span class="kw-2">*mut </span>();
<a href=#254 id=254 data-nosnippet>254</a> <span class="comment">// FFI calling the original signal handler.
<a href=#255 id=255 data-nosnippet>255</a> </span><span class="kw">unsafe </span>{
<a href=#256 id=256 data-nosnippet>256</a> <span class="kw">let </span>action = mem::transmute::&lt;<span class="kw-2">*mut </span>(), <span class="kw">extern </span><span class="string">"C" </span><span class="kw">fn</span>(c_int)&gt;(fptr);
<a href=#257 id=257 data-nosnippet>257</a> action(sig);
<a href=#258 id=258 data-nosnippet>258</a> }
<a href=#259 id=259 data-nosnippet>259</a> }
<a href=#260 id=260 data-nosnippet>260</a> }
<a href=#261 id=261 data-nosnippet>261</a>
<a href=#262 id=262 data-nosnippet>262</a> <span class="attr">#[cfg(not(windows))]
<a href=#263 id=263 data-nosnippet>263</a> </span><span class="comment">// libc re-exports the core::ffi::c_void on rustc &gt;= 1.30, else defines its own type
<a href=#264 id=264 data-nosnippet>264</a> // cfg_attr is needed because the `allow(clippy::lint)` syntax was added in Rust 1.31
<a href=#265 id=265 data-nosnippet>265</a> </span><span class="attr">#[cfg_attr(clippy, allow(clippy::incompatible_msrv))]
<a href=#266 id=266 data-nosnippet>266</a> </span><span class="kw">unsafe fn </span>execute(<span class="kw-2">&amp;</span><span class="self">self</span>, sig: c_int, info: <span class="kw-2">*mut </span>siginfo_t, data: <span class="kw-2">*mut </span>c_void) {
<a href=#267 id=267 data-nosnippet>267</a> <span class="kw">let </span>fptr = <span class="self">self</span>.info.sa_sigaction;
<a href=#268 id=268 data-nosnippet>268</a> <span class="kw">if </span><span class="macro">fptr !</span>= <span class="number">0 </span>&amp;&amp; <span class="macro">fptr !</span>= libc::SIG_DFL &amp;&amp; <span class="macro">fptr !</span>= libc::SIG_IGN {
<a href=#269 id=269 data-nosnippet>269</a> <span class="comment">// `sa_sigaction` is usually stored as integer type. Transmuting it directly from an
<a href=#270 id=270 data-nosnippet>270</a> // integer to a function pointer seems dubious w.r.t. pointer provenance -- at least
<a href=#271 id=271 data-nosnippet>271</a> // Miri complains about it. Casting to a raw pointer first side-steps the issue.
<a href=#272 id=272 data-nosnippet>272</a> </span><span class="kw">let </span>fptr = fptr <span class="kw">as </span><span class="kw-2">*mut </span>();
<a href=#273 id=273 data-nosnippet>273</a> <span class="comment">// Android is broken and uses different int types than the rest (and different
<a href=#274 id=274 data-nosnippet>274</a> // depending on the pointer width). This converts the flags to the proper type no
<a href=#275 id=275 data-nosnippet>275</a> // matter what it is on the given platform.
<a href=#276 id=276 data-nosnippet>276</a> //
<a href=#277 id=277 data-nosnippet>277</a> // The trick is to create the same-typed variable as the sa_flags first and then
<a href=#278 id=278 data-nosnippet>278</a> // set it to the proper value (does Rust have a way to copy a type in a different
<a href=#279 id=279 data-nosnippet>279</a> // way?)
<a href=#280 id=280 data-nosnippet>280</a> </span><span class="attr">#[allow(unused_assignments)]
<a href=#281 id=281 data-nosnippet>281</a> </span><span class="kw">let </span><span class="kw-2">mut </span>siginfo = <span class="self">self</span>.info.sa_flags;
<a href=#282 id=282 data-nosnippet>282</a> siginfo = libc::SA_SIGINFO <span class="kw">as _</span>;
<a href=#283 id=283 data-nosnippet>283</a> <span class="kw">if </span><span class="self">self</span>.info.sa_flags &amp; siginfo == <span class="number">0 </span>{
<a href=#284 id=284 data-nosnippet>284</a> <span class="kw">let </span>action = mem::transmute::&lt;<span class="kw-2">*mut </span>(), <span class="kw">extern </span><span class="string">"C" </span><span class="kw">fn</span>(c_int)&gt;(fptr);
<a href=#285 id=285 data-nosnippet>285</a> action(sig);
<a href=#286 id=286 data-nosnippet>286</a> } <span class="kw">else </span>{
<a href=#287 id=287 data-nosnippet>287</a> <span class="kw">type </span>SigAction = <span class="kw">extern </span><span class="string">"C" </span><span class="kw">fn</span>(c_int, <span class="kw-2">*mut </span>siginfo_t, <span class="kw-2">*mut </span>c_void);
<a href=#288 id=288 data-nosnippet>288</a> <span class="kw">let </span>action = mem::transmute::&lt;<span class="kw-2">*mut </span>(), SigAction&gt;(fptr);
<a href=#289 id=289 data-nosnippet>289</a> action(sig, info, data);
<a href=#290 id=290 data-nosnippet>290</a> }
<a href=#291 id=291 data-nosnippet>291</a> }
<a href=#292 id=292 data-nosnippet>292</a> }
<a href=#293 id=293 data-nosnippet>293</a>}
<a href=#294 id=294 data-nosnippet>294</a>
<a href=#295 id=295 data-nosnippet>295</a><span class="doccomment">/// Lazy-initiated data structure with our global variables.
<a href=#296 id=296 data-nosnippet>296</a>///
<a href=#297 id=297 data-nosnippet>297</a>/// Used inside a structure to cut down on boilerplate code to lazy-initialize stuff. We don't dare
<a href=#298 id=298 data-nosnippet>298</a>/// use anything fancy like lazy-static or once-cell, since we are not sure they are
<a href=#299 id=299 data-nosnippet>299</a>/// async-signal-safe in their access. Our code uses the [Once], but only on the write end outside
<a href=#300 id=300 data-nosnippet>300</a>/// of signal handler. The handler assumes it has already been initialized.
<a href=#301 id=301 data-nosnippet>301</a></span><span class="kw">struct </span>GlobalData {
<a href=#302 id=302 data-nosnippet>302</a> <span class="doccomment">/// The data structure describing what needs to be run for each signal.
<a href=#303 id=303 data-nosnippet>303</a> </span>data: HalfLock&lt;SignalData&gt;,
<a href=#304 id=304 data-nosnippet>304</a>
<a href=#305 id=305 data-nosnippet>305</a> <span class="doccomment">/// A fallback to fight/minimize a race condition during signal initialization.
<a href=#306 id=306 data-nosnippet>306</a> ///
<a href=#307 id=307 data-nosnippet>307</a> /// See the comment inside [`register_unchecked_impl`].
<a href=#308 id=308 data-nosnippet>308</a> </span>race_fallback: HalfLock&lt;<span class="prelude-ty">Option</span>&lt;Prev&gt;&gt;,
<a href=#309 id=309 data-nosnippet>309</a>}
<a href=#310 id=310 data-nosnippet>310</a>
<a href=#311 id=311 data-nosnippet>311</a><span class="kw">static </span>GLOBAL_DATA: AtomicPtr&lt;GlobalData&gt; = AtomicPtr::new(ptr::null_mut());
<a href=#312 id=312 data-nosnippet>312</a><span class="attr">#[allow(deprecated)]
<a href=#313 id=313 data-nosnippet>313</a></span><span class="kw">static </span>GLOBAL_INIT: Once = ONCE_INIT;
<a href=#314 id=314 data-nosnippet>314</a>
<a href=#315 id=315 data-nosnippet>315</a><span class="kw">impl </span>GlobalData {
<a href=#316 id=316 data-nosnippet>316</a> <span class="kw">fn </span>get() -&gt; <span class="kw-2">&amp;</span><span class="lifetime">'static </span><span class="self">Self </span>{
<a href=#317 id=317 data-nosnippet>317</a> <span class="kw">let </span>data = GLOBAL_DATA.load(Ordering::Acquire);
<a href=#318 id=318 data-nosnippet>318</a> <span class="comment">// # Safety
<a href=#319 id=319 data-nosnippet>319</a> //
<a href=#320 id=320 data-nosnippet>320</a> // * The data actually does live forever - created by Box::into_raw.
<a href=#321 id=321 data-nosnippet>321</a> // * It is _never_ modified (apart for interior mutability, but that one is fine).
<a href=#322 id=322 data-nosnippet>322</a> </span><span class="kw">unsafe </span>{ data.as_ref().expect(<span class="string">"We shall be set up already"</span>) }
<a href=#323 id=323 data-nosnippet>323</a> }
<a href=#324 id=324 data-nosnippet>324</a> <span class="kw">fn </span>ensure() -&gt; <span class="kw-2">&amp;</span><span class="lifetime">'static </span><span class="self">Self </span>{
<a href=#325 id=325 data-nosnippet>325</a> GLOBAL_INIT.call_once(|| {
<a href=#326 id=326 data-nosnippet>326</a> <span class="kw">let </span>data = Box::into_raw(Box::new(GlobalData {
<a href=#327 id=327 data-nosnippet>327</a> data: HalfLock::new(SignalData {
<a href=#328 id=328 data-nosnippet>328</a> signals: VecMap::new(),
<a href=#329 id=329 data-nosnippet>329</a> next_id: <span class="number">1</span>,
<a href=#330 id=330 data-nosnippet>330</a> }),
<a href=#331 id=331 data-nosnippet>331</a> race_fallback: HalfLock::new(<span class="prelude-val">None</span>),
<a href=#332 id=332 data-nosnippet>332</a> }));
<a href=#333 id=333 data-nosnippet>333</a> <span class="kw">let </span>old = GLOBAL_DATA.swap(data, Ordering::Release);
<a href=#334 id=334 data-nosnippet>334</a> <span class="macro">assert!</span>(old.is_null());
<a href=#335 id=335 data-nosnippet>335</a> });
<a href=#336 id=336 data-nosnippet>336</a> <span class="self">Self</span>::get()
<a href=#337 id=337 data-nosnippet>337</a> }
<a href=#338 id=338 data-nosnippet>338</a>}
<a href=#339 id=339 data-nosnippet>339</a>
<a href=#340 id=340 data-nosnippet>340</a><span class="attr">#[cfg(windows)]
<a href=#341 id=341 data-nosnippet>341</a></span><span class="kw">extern </span><span class="string">"C" </span><span class="kw">fn </span>handler(sig: c_int) {
<a href=#342 id=342 data-nosnippet>342</a> <span class="kw">let </span>_errno = ErrnoGuard::new();
<a href=#343 id=343 data-nosnippet>343</a>
<a href=#344 id=344 data-nosnippet>344</a> <span class="kw">if </span><span class="macro">sig !</span>= SIGFPE {
<a href=#345 id=345 data-nosnippet>345</a> <span class="comment">// Windows CRT `signal` resets handler every time, unless for SIGFPE.
<a href=#346 id=346 data-nosnippet>346</a> // Reregister the handler to retain maximal compatibility.
<a href=#347 id=347 data-nosnippet>347</a> // Problems:
<a href=#348 id=348 data-nosnippet>348</a> // - It's racy. But this is inevitably racy in Windows.
<a href=#349 id=349 data-nosnippet>349</a> // - Interacts poorly with handlers outside signal-hook-registry.
<a href=#350 id=350 data-nosnippet>350</a> </span><span class="kw">let </span>old = <span class="kw">unsafe </span>{ libc::signal(sig, handler <span class="kw">as </span><span class="kw-2">*const </span>() <span class="kw">as </span>sighandler_t) };
<a href=#351 id=351 data-nosnippet>351</a> <span class="kw">if </span>old == SIG_ERR {
<a href=#352 id=352 data-nosnippet>352</a> <span class="comment">// MSDN doesn't describe which errors might occur,
<a href=#353 id=353 data-nosnippet>353</a> // but we can tell from the Linux manpage that
<a href=#354 id=354 data-nosnippet>354</a> // EINVAL (invalid signal number) is mostly the only case.
<a href=#355 id=355 data-nosnippet>355</a> // Therefore, this branch must not occur.
<a href=#356 id=356 data-nosnippet>356</a> // In any case we can do nothing useful in the signal handler,
<a href=#357 id=357 data-nosnippet>357</a> // so we're going to abort silently.
<a href=#358 id=358 data-nosnippet>358</a> </span><span class="kw">unsafe </span>{
<a href=#359 id=359 data-nosnippet>359</a> libc::abort();
<a href=#360 id=360 data-nosnippet>360</a> }
<a href=#361 id=361 data-nosnippet>361</a> }
<a href=#362 id=362 data-nosnippet>362</a> }
<a href=#363 id=363 data-nosnippet>363</a>
<a href=#364 id=364 data-nosnippet>364</a> <span class="kw">let </span>globals = GlobalData::get();
<a href=#365 id=365 data-nosnippet>365</a> <span class="kw">let </span>fallback = globals.race_fallback.read();
<a href=#366 id=366 data-nosnippet>366</a> <span class="kw">let </span>sigdata = globals.data.read();
<a href=#367 id=367 data-nosnippet>367</a>
<a href=#368 id=368 data-nosnippet>368</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>slot) = sigdata.signals.get(<span class="kw-2">&amp;</span>sig) {
<a href=#369 id=369 data-nosnippet>369</a> slot.prev.execute(sig);
<a href=#370 id=370 data-nosnippet>370</a>
<a href=#371 id=371 data-nosnippet>371</a> <span class="kw">for </span>action <span class="kw">in </span>slot.actions.values() {
<a href=#372 id=372 data-nosnippet>372</a> action(<span class="kw-2">&amp;</span>siginfo_t);
<a href=#373 id=373 data-nosnippet>373</a> }
<a href=#374 id=374 data-nosnippet>374</a> } <span class="kw">else if let </span><span class="prelude-val">Some</span>(prev) = fallback.as_ref() {
<a href=#375 id=375 data-nosnippet>375</a> <span class="comment">// In case we get called but don't have the slot for this signal set up yet, we are under
<a href=#376 id=376 data-nosnippet>376</a> // the race condition. We may have the old signal handler stored in the fallback
<a href=#377 id=377 data-nosnippet>377</a> // temporarily.
<a href=#378 id=378 data-nosnippet>378</a> </span><span class="kw">if </span>sig == prev.signal {
<a href=#379 id=379 data-nosnippet>379</a> prev.execute(sig);
<a href=#380 id=380 data-nosnippet>380</a> }
<a href=#381 id=381 data-nosnippet>381</a> <span class="comment">// else -&gt; probably should not happen, but races with other threads are possible so
<a href=#382 id=382 data-nosnippet>382</a> // better safe
<a href=#383 id=383 data-nosnippet>383</a> </span>}
<a href=#384 id=384 data-nosnippet>384</a>}
<a href=#385 id=385 data-nosnippet>385</a>
<a href=#386 id=386 data-nosnippet>386</a><span class="attr">#[cfg(not(windows))]
<a href=#387 id=387 data-nosnippet>387</a></span><span class="comment">// libc re-exports the core::ffi::c_void on rustc &gt;= 1.30, else defines its own type
<a href=#388 id=388 data-nosnippet>388</a>// cfg_attr is needed because the `allow(clippy::lint)` syntax was added in Rust 1.31
<a href=#389 id=389 data-nosnippet>389</a></span><span class="attr">#[cfg_attr(clippy, allow(clippy::incompatible_msrv))]
<a href=#390 id=390 data-nosnippet>390</a></span><span class="kw">extern </span><span class="string">"C" </span><span class="kw">fn </span>handler(sig: c_int, info: <span class="kw-2">*mut </span>siginfo_t, data: <span class="kw-2">*mut </span>c_void) {
<a href=#391 id=391 data-nosnippet>391</a> <span class="kw">let </span>_errno = ErrnoGuard::new();
<a href=#392 id=392 data-nosnippet>392</a>
<a href=#393 id=393 data-nosnippet>393</a> <span class="kw">let </span>globals = GlobalData::get();
<a href=#394 id=394 data-nosnippet>394</a> <span class="kw">let </span>fallback = globals.race_fallback.read();
<a href=#395 id=395 data-nosnippet>395</a> <span class="kw">let </span>sigdata = globals.data.read();
<a href=#396 id=396 data-nosnippet>396</a>
<a href=#397 id=397 data-nosnippet>397</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(slot) = sigdata.signals.get(<span class="kw-2">&amp;</span>sig) {
<a href=#398 id=398 data-nosnippet>398</a> <span class="kw">unsafe </span>{ slot.prev.execute(sig, info, data) };
<a href=#399 id=399 data-nosnippet>399</a>
<a href=#400 id=400 data-nosnippet>400</a> <span class="kw">let </span>info = <span class="kw">unsafe </span>{ info.as_ref() };
<a href=#401 id=401 data-nosnippet>401</a> <span class="kw">let </span>info = info.unwrap_or_else(|| {
<a href=#402 id=402 data-nosnippet>402</a> <span class="comment">// The info being null seems to be illegal according to POSIX, but has been observed on
<a href=#403 id=403 data-nosnippet>403</a> // some probably broken platform. We can't do anything about that, that is just broken,
<a href=#404 id=404 data-nosnippet>404</a> // but we are not allowed to panic in a signal handler, so we are left only with simply
<a href=#405 id=405 data-nosnippet>405</a> // aborting. We try to write a message what happens, but using the libc stuff
<a href=#406 id=406 data-nosnippet>406</a> // (`eprintln` is not guaranteed to be async-signal-safe).
<a href=#407 id=407 data-nosnippet>407</a> </span><span class="kw">unsafe </span>{
<a href=#408 id=408 data-nosnippet>408</a> <span class="kw">const </span>MSG: <span class="kw-2">&amp;</span>[u8] =
<a href=#409 id=409 data-nosnippet>409</a> <span class="string">b"Platform broken, got NULL as siginfo to signal handler. Aborting"</span>;
<a href=#410 id=410 data-nosnippet>410</a> libc::write(<span class="number">2</span>, MSG.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span><span class="kw">_</span>, MSG.len());
<a href=#411 id=411 data-nosnippet>411</a> libc::abort();
<a href=#412 id=412 data-nosnippet>412</a> }
<a href=#413 id=413 data-nosnippet>413</a> });
<a href=#414 id=414 data-nosnippet>414</a>
<a href=#415 id=415 data-nosnippet>415</a> <span class="kw">for </span>action <span class="kw">in </span>slot.actions.values() {
<a href=#416 id=416 data-nosnippet>416</a> action(info);
<a href=#417 id=417 data-nosnippet>417</a> }
<a href=#418 id=418 data-nosnippet>418</a> } <span class="kw">else if let </span><span class="prelude-val">Some</span>(prev) = fallback.as_ref() {
<a href=#419 id=419 data-nosnippet>419</a> <span class="comment">// In case we get called but don't have the slot for this signal set up yet, we are under
<a href=#420 id=420 data-nosnippet>420</a> // the race condition. We may have the old signal handler stored in the fallback
<a href=#421 id=421 data-nosnippet>421</a> // temporarily.
<a href=#422 id=422 data-nosnippet>422</a> </span><span class="kw">if </span>prev.signal == sig {
<a href=#423 id=423 data-nosnippet>423</a> <span class="kw">unsafe </span>{ prev.execute(sig, info, data) };
<a href=#424 id=424 data-nosnippet>424</a> }
<a href=#425 id=425 data-nosnippet>425</a> <span class="comment">// else -&gt; probably should not happen, but races with other threads are possible so
<a href=#426 id=426 data-nosnippet>426</a> // better safe
<a href=#427 id=427 data-nosnippet>427</a> </span>}
<a href=#428 id=428 data-nosnippet>428</a>}
<a href=#429 id=429 data-nosnippet>429</a>
<a href=#430 id=430 data-nosnippet>430</a><span class="kw">struct </span>ErrnoGuard(Errno);
<a href=#431 id=431 data-nosnippet>431</a>
<a href=#432 id=432 data-nosnippet>432</a><span class="kw">impl </span>ErrnoGuard {
<a href=#433 id=433 data-nosnippet>433</a> <span class="kw">fn </span>new() -&gt; <span class="self">Self </span>{
<a href=#434 id=434 data-nosnippet>434</a> ErrnoGuard(errno::errno())
<a href=#435 id=435 data-nosnippet>435</a> }
<a href=#436 id=436 data-nosnippet>436</a>}
<a href=#437 id=437 data-nosnippet>437</a>
<a href=#438 id=438 data-nosnippet>438</a><span class="kw">impl </span>Drop <span class="kw">for </span>ErrnoGuard {
<a href=#439 id=439 data-nosnippet>439</a> <span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<a href=#440 id=440 data-nosnippet>440</a> errno::set_errno(<span class="self">self</span>.<span class="number">0</span>);
<a href=#441 id=441 data-nosnippet>441</a> }
<a href=#442 id=442 data-nosnippet>442</a>}
<a href=#443 id=443 data-nosnippet>443</a>
<a href=#444 id=444 data-nosnippet>444</a><span class="doccomment">/// List of forbidden signals.
<a href=#445 id=445 data-nosnippet>445</a>///
<a href=#446 id=446 data-nosnippet>446</a>/// Some signals are impossible to replace according to POSIX and some are so special that this
<a href=#447 id=447 data-nosnippet>447</a>/// library refuses to handle them (eg. SIGSEGV). The routines panic in case registering one of
<a href=#448 id=448 data-nosnippet>448</a>/// these signals is attempted.
<a href=#449 id=449 data-nosnippet>449</a>///
<a href=#450 id=450 data-nosnippet>450</a>/// See [`register`].
<a href=#451 id=451 data-nosnippet>451</a></span><span class="kw">pub const </span>FORBIDDEN: <span class="kw-2">&amp;</span>[c_int] = FORBIDDEN_IMPL;
<a href=#452 id=452 data-nosnippet>452</a>
<a href=#453 id=453 data-nosnippet>453</a><span class="attr">#[cfg(windows)]
<a href=#454 id=454 data-nosnippet>454</a></span><span class="kw">const </span>FORBIDDEN_IMPL: <span class="kw-2">&amp;</span>[c_int] = <span class="kw-2">&amp;</span>[SIGILL, SIGFPE, SIGSEGV];
<a href=#455 id=455 data-nosnippet>455</a><span class="attr">#[cfg(not(windows))]
<a href=#456 id=456 data-nosnippet>456</a></span><span class="kw">const </span>FORBIDDEN_IMPL: <span class="kw-2">&amp;</span>[c_int] = <span class="kw-2">&amp;</span>[SIGKILL, SIGSTOP, SIGILL, SIGFPE, SIGSEGV];
<a href=#457 id=457 data-nosnippet>457</a>
<a href=#458 id=458 data-nosnippet>458</a><span class="doccomment">/// Registers an arbitrary action for the given signal.
<a href=#459 id=459 data-nosnippet>459</a>///
<a href=#460 id=460 data-nosnippet>460</a>/// This makes sure there's a signal handler for the given signal. It then adds the action to the
<a href=#461 id=461 data-nosnippet>461</a>/// ones called each time the signal is delivered. If multiple actions are set for the same signal,
<a href=#462 id=462 data-nosnippet>462</a>/// all are called, in the order of registration.
<a href=#463 id=463 data-nosnippet>463</a>///
<a href=#464 id=464 data-nosnippet>464</a>/// If there was a previous signal handler for the given signal, it is chained it will be called
<a href=#465 id=465 data-nosnippet>465</a>/// as part of this library's signal handler, before any actions set through this function.
<a href=#466 id=466 data-nosnippet>466</a>///
<a href=#467 id=467 data-nosnippet>467</a>/// On success, the function returns an ID that can be used to remove the action again with
<a href=#468 id=468 data-nosnippet>468</a>/// [`unregister`].
<a href=#469 id=469 data-nosnippet>469</a>///
<a href=#470 id=470 data-nosnippet>470</a>/// # Panics
<a href=#471 id=471 data-nosnippet>471</a>///
<a href=#472 id=472 data-nosnippet>472</a>/// If the signal is one of (see [`FORBIDDEN`]):
<a href=#473 id=473 data-nosnippet>473</a>///
<a href=#474 id=474 data-nosnippet>474</a>/// * `SIGKILL`
<a href=#475 id=475 data-nosnippet>475</a>/// * `SIGSTOP`
<a href=#476 id=476 data-nosnippet>476</a>/// * `SIGILL`
<a href=#477 id=477 data-nosnippet>477</a>/// * `SIGFPE`
<a href=#478 id=478 data-nosnippet>478</a>/// * `SIGSEGV`
<a href=#479 id=479 data-nosnippet>479</a>///
<a href=#480 id=480 data-nosnippet>480</a>/// The first two are not possible to override (and the underlying C functions simply ignore all
<a href=#481 id=481 data-nosnippet>481</a>/// requests to do so, which smells of possible bugs, or return errors). The rest can be set, but
<a href=#482 id=482 data-nosnippet>482</a>/// generally needs very special handling to do so correctly (direct manipulation of the
<a href=#483 id=483 data-nosnippet>483</a>/// application's address space, `longjmp` and similar). Unless you know very well what you're
<a href=#484 id=484 data-nosnippet>484</a>/// doing, you'll shoot yourself into the foot and this library won't help you with that.
<a href=#485 id=485 data-nosnippet>485</a>///
<a href=#486 id=486 data-nosnippet>486</a>/// # Errors
<a href=#487 id=487 data-nosnippet>487</a>///
<a href=#488 id=488 data-nosnippet>488</a>/// Since the library manipulates signals using the low-level C functions, all these can return
<a href=#489 id=489 data-nosnippet>489</a>/// errors. Generally, the errors mean something like the specified signal does not exist on the
<a href=#490 id=490 data-nosnippet>490</a>/// given platform after a program is debugged and tested on a given OS, it should never return
<a href=#491 id=491 data-nosnippet>491</a>/// an error.
<a href=#492 id=492 data-nosnippet>492</a>///
<a href=#493 id=493 data-nosnippet>493</a>/// However, if an error *is* returned, there are no guarantees if the given action was registered
<a href=#494 id=494 data-nosnippet>494</a>/// or not.
<a href=#495 id=495 data-nosnippet>495</a>///
<a href=#496 id=496 data-nosnippet>496</a>/// # Safety
<a href=#497 id=497 data-nosnippet>497</a>///
<a href=#498 id=498 data-nosnippet>498</a>/// This function is unsafe, because the `action` is run inside a signal handler. While Rust is
<a href=#499 id=499 data-nosnippet>499</a>/// somewhat vague about the consequences of such, it is reasonably to assume that similar
<a href=#500 id=500 data-nosnippet>500</a>/// restrictions as specified in C or C++ apply.
<a href=#501 id=501 data-nosnippet>501</a>///
<a href=#502 id=502 data-nosnippet>502</a>/// In particular:
<a href=#503 id=503 data-nosnippet>503</a>///
<a href=#504 id=504 data-nosnippet>504</a>/// * Calling any OS functions that are not async-signal-safe as specified as POSIX is not allowed.
<a href=#505 id=505 data-nosnippet>505</a>/// * Accessing globals or thread-locals without synchronization is not allowed (however, mutexes
<a href=#506 id=506 data-nosnippet>506</a>/// are not within the async-signal-safe functions, therefore the synchronization is limited to
<a href=#507 id=507 data-nosnippet>507</a>/// using atomics).
<a href=#508 id=508 data-nosnippet>508</a>///
<a href=#509 id=509 data-nosnippet>509</a>/// The underlying reason is, signals are asynchronous (they can happen at arbitrary time) and are
<a href=#510 id=510 data-nosnippet>510</a>/// run in context of arbitrary thread (with some limited control of at which thread they can run).
<a href=#511 id=511 data-nosnippet>511</a>/// As a consequence, things like mutexes are prone to deadlocks, memory allocators can likely
<a href=#512 id=512 data-nosnippet>512</a>/// contain mutexes and the compiler doesn't expect the interruption during optimizations.
<a href=#513 id=513 data-nosnippet>513</a>///
<a href=#514 id=514 data-nosnippet>514</a>/// Things that generally are part of the async-signal-safe set (though check specifically) are
<a href=#515 id=515 data-nosnippet>515</a>/// routines to terminate the program, to further manipulate signals (by the low-level functions,
<a href=#516 id=516 data-nosnippet>516</a>/// not by this library) and to read and write file descriptors. The async-signal-safety is
<a href=#517 id=517 data-nosnippet>517</a>/// transitive - that is, a function composed only from computations (with local variables or with
<a href=#518 id=518 data-nosnippet>518</a>/// variables accessed with proper synchronizations) and other async-signal-safe functions is also
<a href=#519 id=519 data-nosnippet>519</a>/// safe.
<a href=#520 id=520 data-nosnippet>520</a>///
<a href=#521 id=521 data-nosnippet>521</a>/// As panicking from within a signal handler would be a panic across FFI boundary (which is
<a href=#522 id=522 data-nosnippet>522</a>/// undefined behavior), the passed handler must not panic.
<a href=#523 id=523 data-nosnippet>523</a>///
<a href=#524 id=524 data-nosnippet>524</a>/// Note that many innocently-looking functions do contain some of the forbidden routines (a lot of
<a href=#525 id=525 data-nosnippet>525</a>/// things lock or allocate).
<a href=#526 id=526 data-nosnippet>526</a>///
<a href=#527 id=527 data-nosnippet>527</a>/// If you find these limitations hard to satisfy, choose from the helper functions in the
<a href=#528 id=528 data-nosnippet>528</a>/// [signal-hook](https://docs.rs/signal-hook) crate these provide safe interface to use some
<a href=#529 id=529 data-nosnippet>529</a>/// common signal handling patters.
<a href=#530 id=530 data-nosnippet>530</a>///
<a href=#531 id=531 data-nosnippet>531</a>/// # Race condition
<a href=#532 id=532 data-nosnippet>532</a>///
<a href=#533 id=533 data-nosnippet>533</a>/// Upon registering the first hook for a given signal into this library, there's a short race
<a href=#534 id=534 data-nosnippet>534</a>/// condition under the following circumstances:
<a href=#535 id=535 data-nosnippet>535</a>///
<a href=#536 id=536 data-nosnippet>536</a>/// * The program already has a signal handler installed for this particular signal (through some
<a href=#537 id=537 data-nosnippet>537</a>/// other library, possibly).
<a href=#538 id=538 data-nosnippet>538</a>/// * Concurrently, some other thread installs a different signal handler while it is being
<a href=#539 id=539 data-nosnippet>539</a>/// installed by this library.
<a href=#540 id=540 data-nosnippet>540</a>/// * At the same time, the signal is delivered.
<a href=#541 id=541 data-nosnippet>541</a>///
<a href=#542 id=542 data-nosnippet>542</a>/// Under such conditions signal-hook might wrongly "chain" to the older signal handler for a short
<a href=#543 id=543 data-nosnippet>543</a>/// while (until the registration is fully complete).
<a href=#544 id=544 data-nosnippet>544</a>///
<a href=#545 id=545 data-nosnippet>545</a>/// Note that the exact conditions of the race condition might change in future versions of the
<a href=#546 id=546 data-nosnippet>546</a>/// library. The recommended way to avoid it is to register signals before starting any additional
<a href=#547 id=547 data-nosnippet>547</a>/// threads, or at least not to register signals concurrently.
<a href=#548 id=548 data-nosnippet>548</a>///
<a href=#549 id=549 data-nosnippet>549</a>/// Alternatively, make sure all signals are handled through this library.
<a href=#550 id=550 data-nosnippet>550</a>///
<a href=#551 id=551 data-nosnippet>551</a>/// # Performance
<a href=#552 id=552 data-nosnippet>552</a>///
<a href=#553 id=553 data-nosnippet>553</a>/// Even when it is possible to repeatedly install and remove actions during the lifetime of a
<a href=#554 id=554 data-nosnippet>554</a>/// program, the installation and removal is considered a slow operation and should not be done
<a href=#555 id=555 data-nosnippet>555</a>/// very often. Also, there's limited (though huge) amount of distinct IDs (they are `u128`).
<a href=#556 id=556 data-nosnippet>556</a>///
<a href=#557 id=557 data-nosnippet>557</a>/// # Examples
<a href=#558 id=558 data-nosnippet>558</a>///
<a href=#559 id=559 data-nosnippet>559</a>/// ```rust
<a href=#560 id=560 data-nosnippet>560</a>/// extern crate signal_hook_registry;
<a href=#561 id=561 data-nosnippet>561</a>///
<a href=#562 id=562 data-nosnippet>562</a>/// use std::io::Error;
<a href=#563 id=563 data-nosnippet>563</a>/// use std::process;
<a href=#564 id=564 data-nosnippet>564</a>///
<a href=#565 id=565 data-nosnippet>565</a>/// fn main() -&gt; Result&lt;(), Error&gt; {
<a href=#566 id=566 data-nosnippet>566</a>/// let signal = unsafe {
<a href=#567 id=567 data-nosnippet>567</a>/// signal_hook_registry::register(signal_hook::consts::SIGTERM, || process::abort())
<a href=#568 id=568 data-nosnippet>568</a>/// }?;
<a href=#569 id=569 data-nosnippet>569</a>/// // Stuff here...
<a href=#570 id=570 data-nosnippet>570</a>/// signal_hook_registry::unregister(signal); // Not really necessary.
<a href=#571 id=571 data-nosnippet>571</a>/// Ok(())
<a href=#572 id=572 data-nosnippet>572</a>/// }
<a href=#573 id=573 data-nosnippet>573</a>/// ```
<a href=#574 id=574 data-nosnippet>574</a></span><span class="kw">pub unsafe fn </span>register&lt;F&gt;(signal: c_int, action: F) -&gt; <span class="prelude-ty">Result</span>&lt;SigId, Error&gt;
<a href=#575 id=575 data-nosnippet>575</a><span class="kw">where
<a href=#576 id=576 data-nosnippet>576</a> </span>F: Fn() + Sync + Send + <span class="lifetime">'static</span>,
<a href=#577 id=577 data-nosnippet>577</a>{
<a href=#578 id=578 data-nosnippet>578</a> register_sigaction_impl(signal, Arc::new(<span class="kw">move </span>|<span class="kw">_</span>: <span class="kw-2">&amp;</span><span class="kw">_</span>| action()))
<a href=#579 id=579 data-nosnippet>579</a>}
<a href=#580 id=580 data-nosnippet>580</a>
<a href=#581 id=581 data-nosnippet>581</a><span class="doccomment">/// Register a signal action.
<a href=#582 id=582 data-nosnippet>582</a>///
<a href=#583 id=583 data-nosnippet>583</a>/// This acts in the same way as [`register`], including the drawbacks, panics and performance
<a href=#584 id=584 data-nosnippet>584</a>/// characteristics. The only difference is the provided action accepts a [`siginfo_t`] argument,
<a href=#585 id=585 data-nosnippet>585</a>/// providing information about the received signal.
<a href=#586 id=586 data-nosnippet>586</a>///
<a href=#587 id=587 data-nosnippet>587</a>/// # Safety
<a href=#588 id=588 data-nosnippet>588</a>///
<a href=#589 id=589 data-nosnippet>589</a>/// See the details of [`register`].
<a href=#590 id=590 data-nosnippet>590</a></span><span class="attr">#[cfg(not(windows))]
<a href=#591 id=591 data-nosnippet>591</a></span><span class="kw">pub unsafe fn </span>register_sigaction&lt;F&gt;(signal: c_int, action: F) -&gt; <span class="prelude-ty">Result</span>&lt;SigId, Error&gt;
<a href=#592 id=592 data-nosnippet>592</a><span class="kw">where
<a href=#593 id=593 data-nosnippet>593</a> </span>F: Fn(<span class="kw-2">&amp;</span>siginfo_t) + Sync + Send + <span class="lifetime">'static</span>,
<a href=#594 id=594 data-nosnippet>594</a>{
<a href=#595 id=595 data-nosnippet>595</a> register_sigaction_impl(signal, Arc::new(action))
<a href=#596 id=596 data-nosnippet>596</a>}
<a href=#597 id=597 data-nosnippet>597</a>
<a href=#598 id=598 data-nosnippet>598</a><span class="kw">unsafe fn </span>register_sigaction_impl(signal: c_int, action: Arc&lt;Action&gt;) -&gt; <span class="prelude-ty">Result</span>&lt;SigId, Error&gt; {
<a href=#599 id=599 data-nosnippet>599</a> <span class="macro">assert!</span>(
<a href=#600 id=600 data-nosnippet>600</a> !FORBIDDEN.contains(<span class="kw-2">&amp;</span>signal),
<a href=#601 id=601 data-nosnippet>601</a> <span class="string">"Attempted to register forbidden signal {}"</span>,
<a href=#602 id=602 data-nosnippet>602</a> signal,
<a href=#603 id=603 data-nosnippet>603</a> );
<a href=#604 id=604 data-nosnippet>604</a> register_unchecked_impl(signal, action)
<a href=#605 id=605 data-nosnippet>605</a>}
<a href=#606 id=606 data-nosnippet>606</a>
<a href=#607 id=607 data-nosnippet>607</a><span class="doccomment">/// Register a signal action without checking for forbidden signals.
<a href=#608 id=608 data-nosnippet>608</a>///
<a href=#609 id=609 data-nosnippet>609</a>/// This acts in the same way as [`register_unchecked`], including the drawbacks, panics and
<a href=#610 id=610 data-nosnippet>610</a>/// performance characteristics. The only difference is the provided action doesn't accept a
<a href=#611 id=611 data-nosnippet>611</a>/// [`siginfo_t`] argument.
<a href=#612 id=612 data-nosnippet>612</a>///
<a href=#613 id=613 data-nosnippet>613</a>/// # Safety
<a href=#614 id=614 data-nosnippet>614</a>///
<a href=#615 id=615 data-nosnippet>615</a>/// See the details of [`register`].
<a href=#616 id=616 data-nosnippet>616</a></span><span class="kw">pub unsafe fn </span>register_signal_unchecked&lt;F&gt;(signal: c_int, action: F) -&gt; <span class="prelude-ty">Result</span>&lt;SigId, Error&gt;
<a href=#617 id=617 data-nosnippet>617</a><span class="kw">where
<a href=#618 id=618 data-nosnippet>618</a> </span>F: Fn() + Sync + Send + <span class="lifetime">'static</span>,
<a href=#619 id=619 data-nosnippet>619</a>{
<a href=#620 id=620 data-nosnippet>620</a> register_unchecked_impl(signal, Arc::new(<span class="kw">move </span>|<span class="kw">_</span>: <span class="kw-2">&amp;</span><span class="kw">_</span>| action()))
<a href=#621 id=621 data-nosnippet>621</a>}
<a href=#622 id=622 data-nosnippet>622</a>
<a href=#623 id=623 data-nosnippet>623</a><span class="doccomment">/// Register a signal action without checking for forbidden signals.
<a href=#624 id=624 data-nosnippet>624</a>///
<a href=#625 id=625 data-nosnippet>625</a>/// This acts the same way as [`register_sigaction`], but without checking for the [`FORBIDDEN`]
<a href=#626 id=626 data-nosnippet>626</a>/// signals. All the signals passed are registered and it is up to the caller to make some sense of
<a href=#627 id=627 data-nosnippet>627</a>/// them.
<a href=#628 id=628 data-nosnippet>628</a>///
<a href=#629 id=629 data-nosnippet>629</a>/// Note that you really need to know what you're doing if you change eg. the `SIGSEGV` signal
<a href=#630 id=630 data-nosnippet>630</a>/// handler. Generally, you don't want to do that. But unlike the other functions here, this
<a href=#631 id=631 data-nosnippet>631</a>/// function still allows you to do it.
<a href=#632 id=632 data-nosnippet>632</a>///
<a href=#633 id=633 data-nosnippet>633</a>/// # Safety
<a href=#634 id=634 data-nosnippet>634</a>///
<a href=#635 id=635 data-nosnippet>635</a>/// See the details of [`register`].
<a href=#636 id=636 data-nosnippet>636</a></span><span class="attr">#[cfg(not(windows))]
<a href=#637 id=637 data-nosnippet>637</a></span><span class="kw">pub unsafe fn </span>register_unchecked&lt;F&gt;(signal: c_int, action: F) -&gt; <span class="prelude-ty">Result</span>&lt;SigId, Error&gt;
<a href=#638 id=638 data-nosnippet>638</a><span class="kw">where
<a href=#639 id=639 data-nosnippet>639</a> </span>F: Fn(<span class="kw-2">&amp;</span>siginfo_t) + Sync + Send + <span class="lifetime">'static</span>,
<a href=#640 id=640 data-nosnippet>640</a>{
<a href=#641 id=641 data-nosnippet>641</a> register_unchecked_impl(signal, Arc::new(action))
<a href=#642 id=642 data-nosnippet>642</a>}
<a href=#643 id=643 data-nosnippet>643</a>
<a href=#644 id=644 data-nosnippet>644</a><span class="kw">unsafe fn </span>register_unchecked_impl(signal: c_int, action: Arc&lt;Action&gt;) -&gt; <span class="prelude-ty">Result</span>&lt;SigId, Error&gt; {
<a href=#645 id=645 data-nosnippet>645</a> <span class="kw">let </span>globals = GlobalData::ensure();
<a href=#646 id=646 data-nosnippet>646</a>
<a href=#647 id=647 data-nosnippet>647</a> <span class="kw">let </span><span class="kw-2">mut </span>lock = globals.data.write();
<a href=#648 id=648 data-nosnippet>648</a>
<a href=#649 id=649 data-nosnippet>649</a> <span class="kw">let </span><span class="kw-2">mut </span>sigdata = SignalData::clone(<span class="kw-2">&amp;</span>lock);
<a href=#650 id=650 data-nosnippet>650</a> <span class="kw">let </span>id = ActionId(sigdata.next_id);
<a href=#651 id=651 data-nosnippet>651</a> sigdata.next_id += <span class="number">1</span>;
<a href=#652 id=652 data-nosnippet>652</a>
<a href=#653 id=653 data-nosnippet>653</a> <span class="kw">if </span>sigdata.signals.contains(<span class="kw-2">&amp;</span>signal) {
<a href=#654 id=654 data-nosnippet>654</a> <span class="kw">let </span>slot = sigdata.signals.get_mut(<span class="kw-2">&amp;</span>signal).unwrap();
<a href=#655 id=655 data-nosnippet>655</a> <span class="macro">assert!</span>(slot.actions.insert(id, action).is_none());
<a href=#656 id=656 data-nosnippet>656</a> } <span class="kw">else </span>{
<a href=#657 id=657 data-nosnippet>657</a> <span class="comment">// While the sigaction/signal exchanges the old one atomically, we are not able to
<a href=#658 id=658 data-nosnippet>658</a> // atomically store it somewhere a signal handler could read it. That poses a race
<a href=#659 id=659 data-nosnippet>659</a> // condition where we could lose some signals delivered in between changing it and
<a href=#660 id=660 data-nosnippet>660</a> // storing it.
<a href=#661 id=661 data-nosnippet>661</a> //
<a href=#662 id=662 data-nosnippet>662</a> // Therefore we first store the old one in the fallback storage. The fallback only
<a href=#663 id=663 data-nosnippet>663</a> // covers the cases where the slot is not yet active and becomes "inert" after that,
<a href=#664 id=664 data-nosnippet>664</a> // even if not removed (it may get overwritten by some other signal, but for that the
<a href=#665 id=665 data-nosnippet>665</a> // mutex in globals.data must be unlocked here - and by that time we already stored the
<a href=#666 id=666 data-nosnippet>666</a> // slot.
<a href=#667 id=667 data-nosnippet>667</a> //
<a href=#668 id=668 data-nosnippet>668</a> // And yes, this still leaves a short race condition when some other thread could
<a href=#669 id=669 data-nosnippet>669</a> // replace the signal handler and we would be calling the outdated one for a short
<a href=#670 id=670 data-nosnippet>670</a> // time, until we install the slot.
<a href=#671 id=671 data-nosnippet>671</a> </span>globals
<a href=#672 id=672 data-nosnippet>672</a> .race_fallback
<a href=#673 id=673 data-nosnippet>673</a> .write()
<a href=#674 id=674 data-nosnippet>674</a> .store(<span class="prelude-val">Some</span>(Prev::detect(signal)<span class="question-mark">?</span>));
<a href=#675 id=675 data-nosnippet>675</a>
<a href=#676 id=676 data-nosnippet>676</a> <span class="kw">let </span><span class="kw-2">mut </span>slot = Slot::new(signal)<span class="question-mark">?</span>;
<a href=#677 id=677 data-nosnippet>677</a> slot.actions.insert(id, action);
<a href=#678 id=678 data-nosnippet>678</a> sigdata.signals.insert(signal, slot);
<a href=#679 id=679 data-nosnippet>679</a> }
<a href=#680 id=680 data-nosnippet>680</a>
<a href=#681 id=681 data-nosnippet>681</a> lock.store(sigdata);
<a href=#682 id=682 data-nosnippet>682</a>
<a href=#683 id=683 data-nosnippet>683</a> <span class="prelude-val">Ok</span>(SigId { signal, action: id })
<a href=#684 id=684 data-nosnippet>684</a>}
<a href=#685 id=685 data-nosnippet>685</a>
<a href=#686 id=686 data-nosnippet>686</a><span class="doccomment">/// Removes a previously installed action.
<a href=#687 id=687 data-nosnippet>687</a>///
<a href=#688 id=688 data-nosnippet>688</a>/// This function does nothing if the action was already removed. It returns true if it was removed
<a href=#689 id=689 data-nosnippet>689</a>/// and false if the action wasn't found.
<a href=#690 id=690 data-nosnippet>690</a>///
<a href=#691 id=691 data-nosnippet>691</a>/// It can unregister all the actions installed by [`register`] as well as the ones from downstream
<a href=#692 id=692 data-nosnippet>692</a>/// crates (like [`signal-hook`](https://docs.rs/signal-hook)).
<a href=#693 id=693 data-nosnippet>693</a>///
<a href=#694 id=694 data-nosnippet>694</a>/// # Warning
<a href=#695 id=695 data-nosnippet>695</a>///
<a href=#696 id=696 data-nosnippet>696</a>/// This does *not* currently return the default/previous signal handler if the last action for a
<a href=#697 id=697 data-nosnippet>697</a>/// signal was just unregistered. That means that if you replaced for example `SIGTERM` and then
<a href=#698 id=698 data-nosnippet>698</a>/// removed the action, the program will effectively ignore `SIGTERM` signals from now on, not
<a href=#699 id=699 data-nosnippet>699</a>/// terminate on them as is the default action. This is OK if you remove it as part of a shutdown,
<a href=#700 id=700 data-nosnippet>700</a>/// but it is not recommended to remove termination actions during the normal runtime of
<a href=#701 id=701 data-nosnippet>701</a>/// application (unless the desired effect is to create something that can be terminated only by
<a href=#702 id=702 data-nosnippet>702</a>/// SIGKILL).
<a href=#703 id=703 data-nosnippet>703</a></span><span class="kw">pub fn </span>unregister(id: SigId) -&gt; bool {
<a href=#704 id=704 data-nosnippet>704</a> <span class="kw">let </span>globals = GlobalData::ensure();
<a href=#705 id=705 data-nosnippet>705</a> <span class="kw">let </span><span class="kw-2">mut </span>replace = <span class="bool-val">false</span>;
<a href=#706 id=706 data-nosnippet>706</a> <span class="kw">let </span><span class="kw-2">mut </span>lock = globals.data.write();
<a href=#707 id=707 data-nosnippet>707</a> <span class="kw">let </span><span class="kw-2">mut </span>sigdata = SignalData::clone(<span class="kw-2">&amp;</span>lock);
<a href=#708 id=708 data-nosnippet>708</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(slot) = sigdata.signals.get_mut(<span class="kw-2">&amp;</span>id.signal) {
<a href=#709 id=709 data-nosnippet>709</a> replace = slot.actions.remove(<span class="kw-2">&amp;</span>id.action).is_some();
<a href=#710 id=710 data-nosnippet>710</a> }
<a href=#711 id=711 data-nosnippet>711</a> <span class="kw">if </span>replace {
<a href=#712 id=712 data-nosnippet>712</a> lock.store(sigdata);
<a href=#713 id=713 data-nosnippet>713</a> }
<a href=#714 id=714 data-nosnippet>714</a> replace
<a href=#715 id=715 data-nosnippet>715</a>}
<a href=#716 id=716 data-nosnippet>716</a>
<a href=#717 id=717 data-nosnippet>717</a><span class="comment">// We keep this one here for strict backwards compatibility, but the API is kind of bad. One can
<a href=#718 id=718 data-nosnippet>718</a>// delete actions that don't belong to them, which is kind of against the whole idea of not
<a href=#719 id=719 data-nosnippet>719</a>// breaking stuff for others.
<a href=#720 id=720 data-nosnippet>720</a></span><span class="attr">#[deprecated(
<a href=#721 id=721 data-nosnippet>721</a> since = <span class="string">"1.3.0"</span>,
<a href=#722 id=722 data-nosnippet>722</a> note = <span class="string">"Don't use. Can influence unrelated parts of program / unknown actions"
<a href=#723 id=723 data-nosnippet>723</a></span>)]
<a href=#724 id=724 data-nosnippet>724</a>#[doc(hidden)]
<a href=#725 id=725 data-nosnippet>725</a></span><span class="kw">pub fn </span>unregister_signal(signal: c_int) -&gt; bool {
<a href=#726 id=726 data-nosnippet>726</a> <span class="kw">let </span>globals = GlobalData::ensure();
<a href=#727 id=727 data-nosnippet>727</a> <span class="kw">let </span><span class="kw-2">mut </span>replace = <span class="bool-val">false</span>;
<a href=#728 id=728 data-nosnippet>728</a> <span class="kw">let </span><span class="kw-2">mut </span>lock = globals.data.write();
<a href=#729 id=729 data-nosnippet>729</a> <span class="kw">let </span><span class="kw-2">mut </span>sigdata = SignalData::clone(<span class="kw-2">&amp;</span>lock);
<a href=#730 id=730 data-nosnippet>730</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(slot) = sigdata.signals.get_mut(<span class="kw-2">&amp;</span>signal) {
<a href=#731 id=731 data-nosnippet>731</a> <span class="kw">if </span>!slot.actions.is_empty() {
<a href=#732 id=732 data-nosnippet>732</a> slot.actions.clear();
<a href=#733 id=733 data-nosnippet>733</a> replace = <span class="bool-val">true</span>;
<a href=#734 id=734 data-nosnippet>734</a> }
<a href=#735 id=735 data-nosnippet>735</a> }
<a href=#736 id=736 data-nosnippet>736</a> <span class="kw">if </span>replace {
<a href=#737 id=737 data-nosnippet>737</a> lock.store(sigdata);
<a href=#738 id=738 data-nosnippet>738</a> }
<a href=#739 id=739 data-nosnippet>739</a> replace
<a href=#740 id=740 data-nosnippet>740</a>}
<a href=#741 id=741 data-nosnippet>741</a>
<a href=#742 id=742 data-nosnippet>742</a><span class="attr">#[cfg(test)]
<a href=#743 id=743 data-nosnippet>743</a></span><span class="kw">mod </span>tests {
<a href=#744 id=744 data-nosnippet>744</a> <span class="kw">use </span>std::sync::atomic::{AtomicUsize, Ordering};
<a href=#745 id=745 data-nosnippet>745</a> <span class="kw">use </span>std::sync::Arc;
<a href=#746 id=746 data-nosnippet>746</a> <span class="kw">use </span>std::thread;
<a href=#747 id=747 data-nosnippet>747</a> <span class="kw">use </span>std::time::Duration;
<a href=#748 id=748 data-nosnippet>748</a>
<a href=#749 id=749 data-nosnippet>749</a> <span class="attr">#[cfg(not(windows))]
<a href=#750 id=750 data-nosnippet>750</a> </span><span class="kw">use </span>libc::{pid_t, SIGUSR1, SIGUSR2};
<a href=#751 id=751 data-nosnippet>751</a>
<a href=#752 id=752 data-nosnippet>752</a> <span class="attr">#[cfg(windows)]
<a href=#753 id=753 data-nosnippet>753</a> </span><span class="kw">use </span>libc::SIGTERM <span class="kw">as </span>SIGUSR1;
<a href=#754 id=754 data-nosnippet>754</a> <span class="attr">#[cfg(windows)]
<a href=#755 id=755 data-nosnippet>755</a> </span><span class="kw">use </span>libc::SIGTERM <span class="kw">as </span>SIGUSR2;
<a href=#756 id=756 data-nosnippet>756</a>
<a href=#757 id=757 data-nosnippet>757</a> <span class="kw">use super</span>::<span class="kw-2">*</span>;
<a href=#758 id=758 data-nosnippet>758</a>
<a href=#759 id=759 data-nosnippet>759</a> <span class="attr">#[test]
<a href=#760 id=760 data-nosnippet>760</a> #[should_panic]
<a href=#761 id=761 data-nosnippet>761</a> </span><span class="kw">fn </span>panic_forbidden() {
<a href=#762 id=762 data-nosnippet>762</a> <span class="kw">let _ </span>= <span class="kw">unsafe </span>{ register(SIGILL, || ()) };
<a href=#763 id=763 data-nosnippet>763</a> }
<a href=#764 id=764 data-nosnippet>764</a>
<a href=#765 id=765 data-nosnippet>765</a> <span class="doccomment">/// Registering the forbidden signals is allowed in the _unchecked version.
<a href=#766 id=766 data-nosnippet>766</a> </span><span class="attr">#[test]
<a href=#767 id=767 data-nosnippet>767</a> #[allow(clippy::redundant_closure)] </span><span class="comment">// Clippy, you're wrong. Because it changes the return value.
<a href=#768 id=768 data-nosnippet>768</a> </span><span class="kw">fn </span>forbidden_raw() {
<a href=#769 id=769 data-nosnippet>769</a> <span class="kw">unsafe </span>{ register_signal_unchecked(SIGFPE, || std::process::abort()).unwrap() };
<a href=#770 id=770 data-nosnippet>770</a> }
<a href=#771 id=771 data-nosnippet>771</a>
<a href=#772 id=772 data-nosnippet>772</a> <span class="attr">#[test]
<a href=#773 id=773 data-nosnippet>773</a> </span><span class="kw">fn </span>signal_without_pid() {
<a href=#774 id=774 data-nosnippet>774</a> <span class="kw">let </span>status = Arc::new(AtomicUsize::new(<span class="number">0</span>));
<a href=#775 id=775 data-nosnippet>775</a> <span class="kw">let </span>action = {
<a href=#776 id=776 data-nosnippet>776</a> <span class="kw">let </span>status = Arc::clone(<span class="kw-2">&amp;</span>status);
<a href=#777 id=777 data-nosnippet>777</a> <span class="kw">move </span>|| {
<a href=#778 id=778 data-nosnippet>778</a> status.store(<span class="number">1</span>, Ordering::Relaxed);
<a href=#779 id=779 data-nosnippet>779</a> }
<a href=#780 id=780 data-nosnippet>780</a> };
<a href=#781 id=781 data-nosnippet>781</a> <span class="kw">unsafe </span>{
<a href=#782 id=782 data-nosnippet>782</a> register(SIGUSR2, action).unwrap();
<a href=#783 id=783 data-nosnippet>783</a> libc::raise(SIGUSR2);
<a href=#784 id=784 data-nosnippet>784</a> }
<a href=#785 id=785 data-nosnippet>785</a> <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">10 </span>{
<a href=#786 id=786 data-nosnippet>786</a> thread::sleep(Duration::from_millis(<span class="number">100</span>));
<a href=#787 id=787 data-nosnippet>787</a> <span class="kw">let </span>current = status.load(Ordering::Relaxed);
<a href=#788 id=788 data-nosnippet>788</a> <span class="kw">match </span>current {
<a href=#789 id=789 data-nosnippet>789</a> <span class="comment">// Not yet
<a href=#790 id=790 data-nosnippet>790</a> </span><span class="number">0 </span>=&gt; <span class="kw">continue</span>,
<a href=#791 id=791 data-nosnippet>791</a> <span class="comment">// Good, we are done with the correct result
<a href=#792 id=792 data-nosnippet>792</a> </span><span class="kw">_ if </span>current == <span class="number">1 </span>=&gt; <span class="kw">return</span>,
<a href=#793 id=793 data-nosnippet>793</a> <span class="kw">_ </span>=&gt; <span class="macro">panic!</span>(<span class="string">"Wrong result value {}"</span>, current),
<a href=#794 id=794 data-nosnippet>794</a> }
<a href=#795 id=795 data-nosnippet>795</a> }
<a href=#796 id=796 data-nosnippet>796</a> <span class="macro">panic!</span>(<span class="string">"Timed out waiting for the signal"</span>);
<a href=#797 id=797 data-nosnippet>797</a> }
<a href=#798 id=798 data-nosnippet>798</a>
<a href=#799 id=799 data-nosnippet>799</a> <span class="attr">#[test]
<a href=#800 id=800 data-nosnippet>800</a> #[cfg(not(windows))]
<a href=#801 id=801 data-nosnippet>801</a> </span><span class="kw">fn </span>signal_with_pid() {
<a href=#802 id=802 data-nosnippet>802</a> <span class="kw">let </span>status = Arc::new(AtomicUsize::new(<span class="number">0</span>));
<a href=#803 id=803 data-nosnippet>803</a> <span class="kw">let </span>action = {
<a href=#804 id=804 data-nosnippet>804</a> <span class="kw">let </span>status = Arc::clone(<span class="kw-2">&amp;</span>status);
<a href=#805 id=805 data-nosnippet>805</a> <span class="kw">move </span>|siginfo: <span class="kw-2">&amp;</span>siginfo_t| {
<a href=#806 id=806 data-nosnippet>806</a> <span class="comment">// Hack: currently, libc exposes only the first 3 fields of siginfo_t. The pid
<a href=#807 id=807 data-nosnippet>807</a> // comes somewhat later on. Therefore, we do a Really Ugly Hack and define our
<a href=#808 id=808 data-nosnippet>808</a> // own structure (and hope it is correct on all platforms). But hey, this is
<a href=#809 id=809 data-nosnippet>809</a> // only the tests, so we are going to get away with this.
<a href=#810 id=810 data-nosnippet>810</a> </span><span class="attr">#[repr(C)]
<a href=#811 id=811 data-nosnippet>811</a> </span><span class="kw">struct </span>SigInfo {
<a href=#812 id=812 data-nosnippet>812</a> _fields: [c_int; <span class="number">3</span>],
<a href=#813 id=813 data-nosnippet>813</a> <span class="attr">#[cfg(all(target_pointer_width = <span class="string">"64"</span>, target_os = <span class="string">"linux"</span>))]
<a href=#814 id=814 data-nosnippet>814</a> </span>_pad: c_int,
<a href=#815 id=815 data-nosnippet>815</a> pid: pid_t,
<a href=#816 id=816 data-nosnippet>816</a> }
<a href=#817 id=817 data-nosnippet>817</a> <span class="kw">let </span>s: <span class="kw-2">&amp;</span>SigInfo = <span class="kw">unsafe </span>{
<a href=#818 id=818 data-nosnippet>818</a> (siginfo <span class="kw">as </span><span class="kw-2">*const </span><span class="kw">_ as </span>usize <span class="kw">as </span><span class="kw-2">*const </span>SigInfo)
<a href=#819 id=819 data-nosnippet>819</a> .as_ref()
<a href=#820 id=820 data-nosnippet>820</a> .unwrap()
<a href=#821 id=821 data-nosnippet>821</a> };
<a href=#822 id=822 data-nosnippet>822</a> status.store(s.pid <span class="kw">as </span>usize, Ordering::Relaxed);
<a href=#823 id=823 data-nosnippet>823</a> }
<a href=#824 id=824 data-nosnippet>824</a> };
<a href=#825 id=825 data-nosnippet>825</a> <span class="kw">let </span>pid;
<a href=#826 id=826 data-nosnippet>826</a> <span class="kw">unsafe </span>{
<a href=#827 id=827 data-nosnippet>827</a> pid = libc::getpid();
<a href=#828 id=828 data-nosnippet>828</a> register_sigaction(SIGUSR2, action).unwrap();
<a href=#829 id=829 data-nosnippet>829</a> libc::raise(SIGUSR2);
<a href=#830 id=830 data-nosnippet>830</a> }
<a href=#831 id=831 data-nosnippet>831</a> <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">10 </span>{
<a href=#832 id=832 data-nosnippet>832</a> thread::sleep(Duration::from_millis(<span class="number">100</span>));
<a href=#833 id=833 data-nosnippet>833</a> <span class="kw">let </span>current = status.load(Ordering::Relaxed);
<a href=#834 id=834 data-nosnippet>834</a> <span class="kw">match </span>current {
<a href=#835 id=835 data-nosnippet>835</a> <span class="comment">// Not yet (PID == 0 doesn't happen)
<a href=#836 id=836 data-nosnippet>836</a> </span><span class="number">0 </span>=&gt; <span class="kw">continue</span>,
<a href=#837 id=837 data-nosnippet>837</a> <span class="comment">// Good, we are done with the correct result
<a href=#838 id=838 data-nosnippet>838</a> </span><span class="kw">_ if </span>current == pid <span class="kw">as </span>usize =&gt; <span class="kw">return</span>,
<a href=#839 id=839 data-nosnippet>839</a> <span class="kw">_ </span>=&gt; <span class="macro">panic!</span>(<span class="string">"Wrong status value {}"</span>, current),
<a href=#840 id=840 data-nosnippet>840</a> }
<a href=#841 id=841 data-nosnippet>841</a> }
<a href=#842 id=842 data-nosnippet>842</a> <span class="macro">panic!</span>(<span class="string">"Timed out waiting for the signal"</span>);
<a href=#843 id=843 data-nosnippet>843</a> }
<a href=#844 id=844 data-nosnippet>844</a>
<a href=#845 id=845 data-nosnippet>845</a> <span class="doccomment">/// Check that registration works as expected and that unregister tells if it did or not.
<a href=#846 id=846 data-nosnippet>846</a> </span><span class="attr">#[test]
<a href=#847 id=847 data-nosnippet>847</a> </span><span class="kw">fn </span>register_unregister() {
<a href=#848 id=848 data-nosnippet>848</a> <span class="kw">let </span>signal = <span class="kw">unsafe </span>{ register(SIGUSR1, || ()).unwrap() };
<a href=#849 id=849 data-nosnippet>849</a> <span class="comment">// It was there now, so we can unregister
<a href=#850 id=850 data-nosnippet>850</a> </span><span class="macro">assert!</span>(unregister(signal));
<a href=#851 id=851 data-nosnippet>851</a> <span class="comment">// The next time unregistering does nothing and tells us so.
<a href=#852 id=852 data-nosnippet>852</a> </span><span class="macro">assert!</span>(!unregister(signal));
<a href=#853 id=853 data-nosnippet>853</a> }
<a href=#854 id=854 data-nosnippet>854</a>
<a href=#855 id=855 data-nosnippet>855</a> <span class="doccomment">/// Check that errno is not clobbered by the signal handler.
<a href=#856 id=856 data-nosnippet>856</a> </span><span class="attr">#[test]
<a href=#857 id=857 data-nosnippet>857</a> </span><span class="kw">fn </span>save_restore_errno() {
<a href=#858 id=858 data-nosnippet>858</a> <span class="kw">const </span>MAGIC_ERRNO: i32 = <span class="number">123456</span>;
<a href=#859 id=859 data-nosnippet>859</a> <span class="kw">let </span>action = <span class="kw">move </span>|| {
<a href=#860 id=860 data-nosnippet>860</a> errno::set_errno(Errno(MAGIC_ERRNO));
<a href=#861 id=861 data-nosnippet>861</a> };
<a href=#862 id=862 data-nosnippet>862</a> <span class="kw">unsafe </span>{
<a href=#863 id=863 data-nosnippet>863</a> register(SIGUSR1, action).unwrap();
<a href=#864 id=864 data-nosnippet>864</a> libc::raise(SIGUSR1);
<a href=#865 id=865 data-nosnippet>865</a> }
<a href=#866 id=866 data-nosnippet>866</a> <span class="comment">// NB: raise() might clobber errno on some platforms, so this test isn't waterproof. But it
<a href=#867 id=867 data-nosnippet>867</a> // fails at least sometimes on some platforms if the errno save/restore is removed.
<a href=#868 id=868 data-nosnippet>868</a> </span><span class="macro">assert!</span>(errno::errno().<span class="number">0 </span>!= MAGIC_ERRNO);
<a href=#869 id=869 data-nosnippet>869</a> }
<a href=#870 id=870 data-nosnippet>870</a>}
</code></pre></div></section></main></body></html>

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<!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/newkirk/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/signal-hook-registry-1.4.8/src/vec_map.rs`."><title>vec_map.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="signal_hook_registry" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../../static.files/src-script-813739b1.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc src"><!--[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="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">signal_hook_registry/</div>vec_map.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap digits-3"><pre class="rust"><code><a href=#1 id=1 data-nosnippet>1</a><span class="kw">use </span>std::mem;
<a href=#2 id=2 data-nosnippet>2</a>
<a href=#3 id=3 data-nosnippet>3</a><span class="doccomment">/// A small map backed by an unsorted vector.
<a href=#4 id=4 data-nosnippet>4</a>///
<a href=#5 id=5 data-nosnippet>5</a>/// Maintains key uniqueness at cost of O(n) lookup/insert/remove. Maintains insertion order
<a href=#6 id=6 data-nosnippet>6</a>/// (`insert` calls that overwrite an existing value don't change order).
<a href=#7 id=7 data-nosnippet>7</a></span><span class="attr">#[derive(Clone, Default)]
<a href=#8 id=8 data-nosnippet>8</a></span><span class="kw">pub struct </span>VecMap&lt;K, V&gt;(Vec&lt;(K, V)&gt;);
<a href=#9 id=9 data-nosnippet>9</a>
<a href=#10 id=10 data-nosnippet>10</a><span class="kw">impl</span>&lt;K: Eq, V&gt; VecMap&lt;K, V&gt; {
<a href=#11 id=11 data-nosnippet>11</a> <span class="kw">pub fn </span>new() -&gt; <span class="self">Self </span>{
<a href=#12 id=12 data-nosnippet>12</a> VecMap(Vec::new())
<a href=#13 id=13 data-nosnippet>13</a> }
<a href=#14 id=14 data-nosnippet>14</a>
<a href=#15 id=15 data-nosnippet>15</a> <span class="kw">pub fn </span>is_empty(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; bool {
<a href=#16 id=16 data-nosnippet>16</a> <span class="self">self</span>.<span class="number">0</span>.is_empty()
<a href=#17 id=17 data-nosnippet>17</a> }
<a href=#18 id=18 data-nosnippet>18</a>
<a href=#19 id=19 data-nosnippet>19</a> <span class="kw">pub fn </span>clear(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<a href=#20 id=20 data-nosnippet>20</a> <span class="self">self</span>.<span class="number">0</span>.clear();
<a href=#21 id=21 data-nosnippet>21</a> }
<a href=#22 id=22 data-nosnippet>22</a>
<a href=#23 id=23 data-nosnippet>23</a> <span class="kw">fn </span>find(<span class="kw-2">&amp;</span><span class="self">self</span>, key: <span class="kw-2">&amp;</span>K) -&gt; <span class="prelude-ty">Option</span>&lt;usize&gt; {
<a href=#24 id=24 data-nosnippet>24</a> <span class="kw">for </span>(i, (k, <span class="kw">_</span>)) <span class="kw">in </span><span class="self">self</span>.<span class="number">0</span>.iter().enumerate() {
<a href=#25 id=25 data-nosnippet>25</a> <span class="kw">if </span>k == key {
<a href=#26 id=26 data-nosnippet>26</a> <span class="kw">return </span><span class="prelude-val">Some</span>(i);
<a href=#27 id=27 data-nosnippet>27</a> }
<a href=#28 id=28 data-nosnippet>28</a> }
<a href=#29 id=29 data-nosnippet>29</a> <span class="prelude-val">None
<a href=#30 id=30 data-nosnippet>30</a> </span>}
<a href=#31 id=31 data-nosnippet>31</a>
<a href=#32 id=32 data-nosnippet>32</a> <span class="kw">pub fn </span>contains(<span class="kw-2">&amp;</span><span class="self">self</span>, key: <span class="kw-2">&amp;</span>K) -&gt; bool {
<a href=#33 id=33 data-nosnippet>33</a> <span class="self">self</span>.find(key).is_some()
<a href=#34 id=34 data-nosnippet>34</a> }
<a href=#35 id=35 data-nosnippet>35</a>
<a href=#36 id=36 data-nosnippet>36</a> <span class="kw">pub fn </span>get(<span class="kw-2">&amp;</span><span class="self">self</span>, key: <span class="kw-2">&amp;</span>K) -&gt; <span class="prelude-ty">Option</span>&lt;<span class="kw-2">&amp;</span>V&gt; {
<a href=#37 id=37 data-nosnippet>37</a> <span class="kw">match </span><span class="self">self</span>.find(key) {
<a href=#38 id=38 data-nosnippet>38</a> <span class="prelude-val">Some</span>(i) =&gt; <span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="number">0</span>[i].<span class="number">1</span>),
<a href=#39 id=39 data-nosnippet>39</a> <span class="prelude-val">None </span>=&gt; <span class="prelude-val">None</span>,
<a href=#40 id=40 data-nosnippet>40</a> }
<a href=#41 id=41 data-nosnippet>41</a> }
<a href=#42 id=42 data-nosnippet>42</a>
<a href=#43 id=43 data-nosnippet>43</a> <span class="kw">pub fn </span>get_mut(<span class="kw-2">&amp;mut </span><span class="self">self</span>, key: <span class="kw-2">&amp;</span>K) -&gt; <span class="prelude-ty">Option</span>&lt;<span class="kw-2">&amp;mut </span>V&gt; {
<a href=#44 id=44 data-nosnippet>44</a> <span class="kw">match </span><span class="self">self</span>.find(key) {
<a href=#45 id=45 data-nosnippet>45</a> <span class="prelude-val">Some</span>(i) =&gt; <span class="prelude-val">Some</span>(<span class="kw-2">&amp;mut </span><span class="self">self</span>.<span class="number">0</span>[i].<span class="number">1</span>),
<a href=#46 id=46 data-nosnippet>46</a> <span class="prelude-val">None </span>=&gt; <span class="prelude-val">None</span>,
<a href=#47 id=47 data-nosnippet>47</a> }
<a href=#48 id=48 data-nosnippet>48</a> }
<a href=#49 id=49 data-nosnippet>49</a>
<a href=#50 id=50 data-nosnippet>50</a> <span class="kw">pub fn </span>insert(<span class="kw-2">&amp;mut </span><span class="self">self</span>, key: K, value: V) -&gt; <span class="prelude-ty">Option</span>&lt;V&gt; {
<a href=#51 id=51 data-nosnippet>51</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(old) = <span class="self">self</span>.get_mut(<span class="kw-2">&amp;</span>key) {
<a href=#52 id=52 data-nosnippet>52</a> <span class="kw">return </span><span class="prelude-val">Some</span>(mem::replace(old, value));
<a href=#53 id=53 data-nosnippet>53</a> }
<a href=#54 id=54 data-nosnippet>54</a> <span class="self">self</span>.<span class="number">0</span>.push((key, value));
<a href=#55 id=55 data-nosnippet>55</a> <span class="prelude-val">None
<a href=#56 id=56 data-nosnippet>56</a> </span>}
<a href=#57 id=57 data-nosnippet>57</a>
<a href=#58 id=58 data-nosnippet>58</a> <span class="kw">pub fn </span>remove(<span class="kw-2">&amp;mut </span><span class="self">self</span>, key: <span class="kw-2">&amp;</span>K) -&gt; <span class="prelude-ty">Option</span>&lt;V&gt; {
<a href=#59 id=59 data-nosnippet>59</a> <span class="kw">match </span><span class="self">self</span>.find(key) {
<a href=#60 id=60 data-nosnippet>60</a> <span class="prelude-val">Some</span>(i) =&gt; <span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="number">0</span>.remove(i).<span class="number">1</span>),
<a href=#61 id=61 data-nosnippet>61</a> <span class="prelude-val">None </span>=&gt; <span class="prelude-val">None</span>,
<a href=#62 id=62 data-nosnippet>62</a> }
<a href=#63 id=63 data-nosnippet>63</a> }
<a href=#64 id=64 data-nosnippet>64</a>
<a href=#65 id=65 data-nosnippet>65</a> <span class="kw">pub fn </span>values(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw">impl </span>Iterator&lt;Item = <span class="kw-2">&amp;</span>V&gt; {
<a href=#66 id=66 data-nosnippet>66</a> <span class="self">self</span>.<span class="number">0</span>.iter().map(|kv| <span class="kw-2">&amp;</span>kv.<span class="number">1</span>)
<a href=#67 id=67 data-nosnippet>67</a> }
<a href=#68 id=68 data-nosnippet>68</a>}
<a href=#69 id=69 data-nosnippet>69</a>
<a href=#70 id=70 data-nosnippet>70</a><span class="attr">#[cfg(test)]
<a href=#71 id=71 data-nosnippet>71</a></span><span class="kw">mod </span>tests {
<a href=#72 id=72 data-nosnippet>72</a> <span class="kw">use super</span>::<span class="kw-2">*</span>;
<a href=#73 id=73 data-nosnippet>73</a>
<a href=#74 id=74 data-nosnippet>74</a> <span class="attr">#[test]
<a href=#75 id=75 data-nosnippet>75</a> </span><span class="kw">fn </span>empty() {
<a href=#76 id=76 data-nosnippet>76</a> <span class="kw">let </span>m: VecMap&lt;char, u32&gt; = VecMap::new();
<a href=#77 id=77 data-nosnippet>77</a> <span class="macro">assert!</span>(m.is_empty());
<a href=#78 id=78 data-nosnippet>78</a> <span class="macro">assert!</span>(!m.contains(<span class="kw-2">&amp;</span><span class="string">'a'</span>));
<a href=#79 id=79 data-nosnippet>79</a> <span class="macro">assert!</span>(m.values().next().is_none());
<a href=#80 id=80 data-nosnippet>80</a> }
<a href=#81 id=81 data-nosnippet>81</a>
<a href=#82 id=82 data-nosnippet>82</a> <span class="attr">#[test]
<a href=#83 id=83 data-nosnippet>83</a> </span><span class="kw">fn </span>insert_update_get() {
<a href=#84 id=84 data-nosnippet>84</a> <span class="kw">let </span><span class="kw-2">mut </span>m: VecMap&lt;char, u32&gt; = VecMap::new();
<a href=#85 id=85 data-nosnippet>85</a> <span class="macro">assert!</span>(m.insert(<span class="string">'a'</span>, <span class="number">1</span>).is_none());
<a href=#86 id=86 data-nosnippet>86</a> <span class="macro">assert!</span>(m.insert(<span class="string">'b'</span>, <span class="number">2</span>).is_none());
<a href=#87 id=87 data-nosnippet>87</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'a'</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span><span class="number">1</span>));
<a href=#88 id=88 data-nosnippet>88</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'b'</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span><span class="number">2</span>));
<a href=#89 id=89 data-nosnippet>89</a> <span class="kw-2">*</span>m.get_mut(<span class="kw-2">&amp;</span><span class="string">'a'</span>).unwrap() += <span class="number">10</span>;
<a href=#90 id=90 data-nosnippet>90</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'a'</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span><span class="number">11</span>));
<a href=#91 id=91 data-nosnippet>91</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'b'</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span><span class="number">2</span>));
<a href=#92 id=92 data-nosnippet>92</a> }
<a href=#93 id=93 data-nosnippet>93</a>
<a href=#94 id=94 data-nosnippet>94</a> <span class="attr">#[test]
<a href=#95 id=95 data-nosnippet>95</a> </span><span class="kw">fn </span>insert_overwrite() {
<a href=#96 id=96 data-nosnippet>96</a> <span class="kw">let </span><span class="kw-2">mut </span>m = VecMap::new();
<a href=#97 id=97 data-nosnippet>97</a> <span class="macro">assert_eq!</span>(m.insert(<span class="string">'a'</span>, <span class="number">1</span>), <span class="prelude-val">None</span>);
<a href=#98 id=98 data-nosnippet>98</a> <span class="macro">assert_eq!</span>(m.insert(<span class="string">'b'</span>, <span class="number">2</span>), <span class="prelude-val">None</span>);
<a href=#99 id=99 data-nosnippet>99</a> <span class="macro">assert_eq!</span>(m.insert(<span class="string">'a'</span>, <span class="number">3</span>), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<a href=#100 id=100 data-nosnippet>100</a> <span class="macro">assert_eq!</span>(m.insert(<span class="string">'a'</span>, <span class="number">4</span>), <span class="prelude-val">Some</span>(<span class="number">3</span>));
<a href=#101 id=101 data-nosnippet>101</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'a'</span>).copied(), <span class="prelude-val">Some</span>(<span class="number">4</span>));
<a href=#102 id=102 data-nosnippet>102</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'b'</span>).copied(), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<a href=#103 id=103 data-nosnippet>103</a> <span class="macro">assert_eq!</span>(m.insert(<span class="string">'b'</span>, <span class="number">5</span>), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<a href=#104 id=104 data-nosnippet>104</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'a'</span>).copied(), <span class="prelude-val">Some</span>(<span class="number">4</span>));
<a href=#105 id=105 data-nosnippet>105</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span><span class="string">'b'</span>).copied(), <span class="prelude-val">Some</span>(<span class="number">5</span>));
<a href=#106 id=106 data-nosnippet>106</a> }
<a href=#107 id=107 data-nosnippet>107</a>
<a href=#108 id=108 data-nosnippet>108</a> <span class="attr">#[test]
<a href=#109 id=109 data-nosnippet>109</a> </span><span class="kw">fn </span>insert_remove() {
<a href=#110 id=110 data-nosnippet>110</a> <span class="kw">let </span><span class="kw-2">mut </span>m: VecMap&lt;char, u32&gt; = VecMap::new();
<a href=#111 id=111 data-nosnippet>111</a> <span class="macro">assert_eq!</span>(m.remove(<span class="kw-2">&amp;</span><span class="string">'a'</span>), <span class="prelude-val">None</span>);
<a href=#112 id=112 data-nosnippet>112</a> m.insert(<span class="string">'a'</span>, <span class="number">1</span>);
<a href=#113 id=113 data-nosnippet>113</a> m.insert(<span class="string">'b'</span>, <span class="number">2</span>);
<a href=#114 id=114 data-nosnippet>114</a> <span class="macro">assert_eq!</span>(m.remove(<span class="kw-2">&amp;</span><span class="string">'a'</span>), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<a href=#115 id=115 data-nosnippet>115</a> <span class="macro">assert_eq!</span>(m.remove(<span class="kw-2">&amp;</span><span class="string">'a'</span>), <span class="prelude-val">None</span>);
<a href=#116 id=116 data-nosnippet>116</a> <span class="macro">assert_eq!</span>(m.remove(<span class="kw-2">&amp;</span><span class="string">'b'</span>), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<a href=#117 id=117 data-nosnippet>117</a> <span class="macro">assert!</span>(m.is_empty());
<a href=#118 id=118 data-nosnippet>118</a> }
<a href=#119 id=119 data-nosnippet>119</a>
<a href=#120 id=120 data-nosnippet>120</a> <span class="attr">#[test]
<a href=#121 id=121 data-nosnippet>121</a> </span><span class="kw">fn </span>insertion_order() {
<a href=#122 id=122 data-nosnippet>122</a> <span class="kw">let </span><span class="kw-2">mut </span>m: VecMap&lt;char, u32&gt; = VecMap::new();
<a href=#123 id=123 data-nosnippet>123</a> <span class="kw">let </span>values = |m: <span class="kw-2">&amp;</span>VecMap&lt;char, u32&gt;| -&gt; Vec&lt;u32&gt; { m.values().copied().collect() };
<a href=#124 id=124 data-nosnippet>124</a> m.insert(<span class="string">'b'</span>, <span class="number">2</span>);
<a href=#125 id=125 data-nosnippet>125</a> m.insert(<span class="string">'a'</span>, <span class="number">1</span>);
<a href=#126 id=126 data-nosnippet>126</a> m.insert(<span class="string">'c'</span>, <span class="number">3</span>);
<a href=#127 id=127 data-nosnippet>127</a> <span class="macro">assert_eq!</span>(values(<span class="kw-2">&amp;</span>m), <span class="macro">vec!</span>[<span class="number">2</span>, <span class="number">1</span>, <span class="number">3</span>]);
<a href=#128 id=128 data-nosnippet>128</a> m.insert(<span class="string">'a'</span>, <span class="number">11</span>);
<a href=#129 id=129 data-nosnippet>129</a> m.remove(<span class="kw-2">&amp;</span><span class="string">'b'</span>);
<a href=#130 id=130 data-nosnippet>130</a> <span class="macro">assert_eq!</span>(values(<span class="kw-2">&amp;</span>m), <span class="macro">vec!</span>[<span class="number">11</span>, <span class="number">3</span>]);
<a href=#131 id=131 data-nosnippet>131</a> m.insert(<span class="string">'b'</span>, <span class="number">2</span>);
<a href=#132 id=132 data-nosnippet>132</a> <span class="macro">assert_eq!</span>(values(<span class="kw-2">&amp;</span>m), <span class="macro">vec!</span>[<span class="number">11</span>, <span class="number">3</span>, <span class="number">2</span>]);
<a href=#133 id=133 data-nosnippet>133</a> }
<a href=#134 id=134 data-nosnippet>134</a>
<a href=#135 id=135 data-nosnippet>135</a> <span class="attr">#[test]
<a href=#136 id=136 data-nosnippet>136</a> </span><span class="kw">fn </span>containment_equivalences() {
<a href=#137 id=137 data-nosnippet>137</a> <span class="kw">let </span><span class="kw-2">mut </span>m = VecMap::new();
<a href=#138 id=138 data-nosnippet>138</a> <span class="kw">for </span>i <span class="kw">in </span><span class="number">0u8</span>..=<span class="number">255 </span>{
<a href=#139 id=139 data-nosnippet>139</a> <span class="kw">if </span>i % <span class="number">10 </span>&lt; <span class="number">3 </span>{
<a href=#140 id=140 data-nosnippet>140</a> m.insert(i, i);
<a href=#141 id=141 data-nosnippet>141</a> }
<a href=#142 id=142 data-nosnippet>142</a> }
<a href=#143 id=143 data-nosnippet>143</a> <span class="kw">for </span>i <span class="kw">in </span><span class="number">0u8</span>..=<span class="number">255 </span>{
<a href=#144 id=144 data-nosnippet>144</a> <span class="kw">if </span>m.contains(<span class="kw-2">&amp;</span>i) {
<a href=#145 id=145 data-nosnippet>145</a> <span class="macro">assert_eq!</span>(m.get(<span class="kw-2">&amp;</span>i).copied(), <span class="prelude-val">Some</span>(i));
<a href=#146 id=146 data-nosnippet>146</a> <span class="macro">assert_eq!</span>(m.get_mut(<span class="kw-2">&amp;</span>i).copied(), <span class="prelude-val">Some</span>(i));
<a href=#147 id=147 data-nosnippet>147</a> <span class="macro">assert_eq!</span>(m.insert(i, i), <span class="prelude-val">Some</span>(i));
<a href=#148 id=148 data-nosnippet>148</a> <span class="macro">assert_eq!</span>(m.remove(<span class="kw-2">&amp;</span>i), <span class="prelude-val">Some</span>(i));
<a href=#149 id=149 data-nosnippet>149</a> } <span class="kw">else </span>{
<a href=#150 id=150 data-nosnippet>150</a> <span class="macro">assert!</span>(m.get(<span class="kw-2">&amp;</span>i).is_none());
<a href=#151 id=151 data-nosnippet>151</a> <span class="macro">assert!</span>(m.get_mut(<span class="kw-2">&amp;</span>i).is_none());
<a href=#152 id=152 data-nosnippet>152</a> <span class="macro">assert!</span>(m.remove(<span class="kw-2">&amp;</span>i).is_none());
<a href=#153 id=153 data-nosnippet>153</a> <span class="macro">assert!</span>(m.insert(i, i).is_none());
<a href=#154 id=154 data-nosnippet>154</a> }
<a href=#155 id=155 data-nosnippet>155</a> }
<a href=#156 id=156 data-nosnippet>156</a> }
<a href=#157 id=157 data-nosnippet>157</a>
<a href=#158 id=158 data-nosnippet>158</a> <span class="attr">#[test]
<a href=#159 id=159 data-nosnippet>159</a> </span><span class="kw">fn </span>clear() {
<a href=#160 id=160 data-nosnippet>160</a> <span class="kw">let </span><span class="kw-2">mut </span>m = VecMap::new();
<a href=#161 id=161 data-nosnippet>161</a> m.clear();
<a href=#162 id=162 data-nosnippet>162</a> <span class="macro">assert!</span>(m.is_empty());
<a href=#163 id=163 data-nosnippet>163</a> m.insert(<span class="string">'a'</span>, <span class="number">1</span>);
<a href=#164 id=164 data-nosnippet>164</a> m.insert(<span class="string">'b'</span>, <span class="number">2</span>);
<a href=#165 id=165 data-nosnippet>165</a> <span class="macro">assert!</span>(!m.is_empty());
<a href=#166 id=166 data-nosnippet>166</a> m.clear();
<a href=#167 id=167 data-nosnippet>167</a> <span class="macro">assert!</span>(m.is_empty());
<a href=#168 id=168 data-nosnippet>168</a> m.insert(<span class="string">'c'</span>, <span class="number">3</span>);
<a href=#169 id=169 data-nosnippet>169</a> <span class="macro">assert!</span>(!m.is_empty());
<a href=#170 id=170 data-nosnippet>170</a> }
<a href=#171 id=171 data-nosnippet>171</a>}
</code></pre></div></section></main></body></html>