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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="Emulates the behaviour of a default handler for the provided signal."><title>emulate_default_handler in signal_hook::low_level - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-ac92e1bbe349e143.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="signal_hook" data-themes="" data-resource-suffix="" data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../signal_hook/index.html">signal_hook</a><span class="version">0.3.17</span></h2></div><div class="sidebar-elems"><h2><a href="index.html">In signal_hook::low_level</a></h2></div></nav><div class="sidebar-resizer"></div>
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<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../../signal_hook/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Function <a href="../index.html">signal_hook</a>::<wbr><a href="index.html">low_level</a>::<wbr><a class="fn" href="#">emulate_default_handler</a><button id="copy-path" title="Copy item path to clipboard"><img src="../../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../../src/signal_hook/low_level/signal_details.rs.html#174-240">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><pre class="rust item-decl"><code>pub fn emulate_default_handler(signal: <a class="type" href="../../libc/unix/type.c_int.html" title="type libc::unix::c_int">c_int</a>) -> <a class="enum" href="https://doc.rust-lang.org/1.76.0/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/1.76.0/std/primitive.unit.html">()</a>, <a class="struct" href="https://doc.rust-lang.org/1.76.0/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Emulates the behaviour of a default handler for the provided signal.</p>
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<p>This function does its best to provide the same action as the default handler would do, without
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disrupting the rest of the handling of such signal in the application. It is also
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async-signal-safe.</p>
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<p>This function necessarily looks up the appropriate action in a table. That means it is possible
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your system has a signal that is not known to this function. In such case an error is returned
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(equivalent of <code>EINVAL</code>).</p>
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<p>See also the <a href="../flag/fn.register_conditional_default.html" title="fn signal_hook::flag::register_conditional_default"><code>register_conditional_default</code></a>.</p>
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<h2 id="warning"><a href="#warning">Warning</a></h2>
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<p>There’s a short race condition in case of signals that terminate (either with or without a core
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dump). The emulation first resets the signal handler back to default (as the application is
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going to end, it’s not a problem) and invokes it. But if some other thread installs a signal
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handler in the meantime (without assistance from <code>signal-hook</code>), it can happen this will be
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invoked by the re-raised signal.</p>
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<p>This function will still terminate the application (there’s a fallback on <code>abort</code>), the risk is
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invoking the newly installed signal handler. Note that manipulating the low-level signals is
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always racy in a multi-threaded program, therefore the described situation is already
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discouraged.</p>
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<p>If you are uneasy about such race condition, the recommendation is to run relevant termination
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routine manually (<a href="fn.exit.html" title="fn signal_hook::low_level::exit"><code>exit</code></a> or <a href="fn.abort.html" title="fn signal_hook::low_level::abort"><code>abort</code></a>); they always do what they
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say, but slightly differ in externally observable behaviour from termination by a signal (the
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exit code will specify that the application exited, not that it terminated with a signal in the
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first case, and <code>abort</code> terminates on <code>SIGABRT</code>, so the detected termination signal may be
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different).</p>
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</div></details></section></div></main></body></html> |