| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.26.2/src/sys/signalfd.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>signalfd.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../nix/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../nix/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Interface for the `signalfd` syscall. |
| //! |
| //! # Signal discarding |
| //! When a signal can't be delivered to a process (or thread), it will become a pending signal. |
| //! Failure to deliver could happen if the signal is blocked by every thread in the process or if |
| //! the signal handler is still handling a previous signal. |
| //! |
| //! If a signal is sent to a process (or thread) that already has a pending signal of the same |
| //! type, it will be discarded. This means that if signals of the same type are received faster than |
| //! they are processed, some of those signals will be dropped. Because of this limitation, |
| //! `signalfd` in itself cannot be used for reliable communication between processes or threads. |
| //! |
| //! Once the signal is unblocked, or the signal handler is finished, and a signal is still pending |
| //! (ie. not consumed from a signalfd) it will be delivered to the signal handler. |
| //! |
| //! Please note that signal discarding is not specific to `signalfd`, but also happens with regular |
| //! signal handlers. |
| </span><span class="kw">use </span><span class="kw">crate</span>::errno::Errno; |
| <span class="kw">pub use </span><span class="kw">crate</span>::sys::signal::{<span class="self">self</span>, SigSet}; |
| <span class="kw">use </span><span class="kw">crate</span>::unistd; |
| <span class="kw">use </span><span class="kw">crate</span>::Result; |
| <span class="kw">pub use </span>libc::signalfd_siginfo <span class="kw">as </span>siginfo; |
| |
| <span class="kw">use </span>std::mem; |
| <span class="kw">use </span>std::os::unix::io::{AsRawFd, RawFd}; |
| |
| <span class="macro">libc_bitflags! </span>{ |
| <span class="kw">pub struct </span>SfdFlags: libc::c_int { |
| SFD_NONBLOCK; |
| SFD_CLOEXEC; |
| } |
| } |
| |
| <span class="kw">pub const </span>SIGNALFD_NEW: RawFd = -<span class="number">1</span>; |
| <span class="attribute">#[deprecated(since = <span class="string">"0.23.0"</span>, note = <span class="string">"use mem::size_of::<siginfo>() instead"</span>)] |
| </span><span class="kw">pub const </span>SIGNALFD_SIGINFO_SIZE: usize = mem::size_of::<siginfo>(); |
| |
| <span class="doccomment">/// Creates a new file descriptor for reading signals. |
| /// |
| /// **Important:** please read the module level documentation about signal discarding before using |
| /// this function! |
| /// |
| /// The `mask` parameter specifies the set of signals that can be accepted via this file descriptor. |
| /// |
| /// A signal must be blocked on every thread in a process, otherwise it won't be visible from |
| /// signalfd (the default handler will be invoked instead). |
| /// |
| /// See [the signalfd man page for more information](https://man7.org/linux/man-pages/man2/signalfd.2.html) |
| </span><span class="kw">pub fn </span>signalfd(fd: RawFd, mask: <span class="kw-2">&</span>SigSet, flags: SfdFlags) -> <span class="prelude-ty">Result</span><RawFd> { |
| <span class="kw">unsafe </span>{ |
| Errno::result(libc::signalfd( |
| fd <span class="kw">as </span>libc::c_int, |
| mask.as_ref(), |
| flags.bits(), |
| )) |
| } |
| } |
| |
| <span class="doccomment">/// A helper struct for creating, reading and closing a `signalfd` instance. |
| /// |
| /// **Important:** please read the module level documentation about signal discarding before using |
| /// this struct! |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use nix::sys::signalfd::*; |
| /// // Set the thread to block the SIGUSR1 signal, otherwise the default handler will be used |
| /// let mut mask = SigSet::empty(); |
| /// mask.add(signal::SIGUSR1); |
| /// mask.thread_block().unwrap(); |
| /// |
| /// // Signals are queued up on the file descriptor |
| /// let mut sfd = SignalFd::with_flags(&mask, SfdFlags::SFD_NONBLOCK).unwrap(); |
| /// |
| /// match sfd.read_signal() { |
| /// // we caught a signal |
| /// Ok(Some(sig)) => (), |
| /// // there were no signals waiting (only happens when the SFD_NONBLOCK flag is set, |
| /// // otherwise the read_signal call blocks) |
| /// Ok(None) => (), |
| /// Err(err) => (), // some error happend |
| /// } |
| /// ``` |
| </span><span class="attribute">#[derive(Debug, Eq, Hash, PartialEq)] |
| </span><span class="kw">pub struct </span>SignalFd(RawFd); |
| |
| <span class="kw">impl </span>SignalFd { |
| <span class="kw">pub fn </span>new(mask: <span class="kw-2">&</span>SigSet) -> <span class="prelude-ty">Result</span><SignalFd> { |
| <span class="self">Self</span>::with_flags(mask, SfdFlags::empty()) |
| } |
| |
| <span class="kw">pub fn </span>with_flags(mask: <span class="kw-2">&</span>SigSet, flags: SfdFlags) -> <span class="prelude-ty">Result</span><SignalFd> { |
| <span class="kw">let </span>fd = signalfd(SIGNALFD_NEW, mask, flags)<span class="question-mark">?</span>; |
| |
| <span class="prelude-val">Ok</span>(SignalFd(fd)) |
| } |
| |
| <span class="kw">pub fn </span>set_mask(<span class="kw-2">&mut </span><span class="self">self</span>, mask: <span class="kw-2">&</span>SigSet) -> <span class="prelude-ty">Result</span><()> { |
| signalfd(<span class="self">self</span>.<span class="number">0</span>, mask, SfdFlags::empty()).map(drop) |
| } |
| |
| <span class="kw">pub fn </span>read_signal(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Result</span><<span class="prelude-ty">Option</span><siginfo>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = mem::MaybeUninit::<siginfo>::uninit(); |
| |
| <span class="kw">let </span>size = mem::size_of_val(<span class="kw-2">&</span>buffer); |
| <span class="kw">let </span>res = Errno::result(<span class="kw">unsafe </span>{ |
| libc::read(<span class="self">self</span>.<span class="number">0</span>, buffer.as_mut_ptr() <span class="kw">as </span><span class="kw-2">*mut </span>libc::c_void, size) |
| }) |
| .map(|r| r <span class="kw">as </span>usize); |
| <span class="kw">match </span>res { |
| <span class="prelude-val">Ok</span>(x) <span class="kw">if </span>x == size => <span class="prelude-val">Ok</span>(<span class="prelude-val">Some</span>(<span class="kw">unsafe </span>{ buffer.assume_init() })), |
| <span class="prelude-val">Ok</span>(<span class="kw">_</span>) => <span class="macro">unreachable!</span>(<span class="string">"partial read on signalfd"</span>), |
| <span class="prelude-val">Err</span>(Errno::EAGAIN) => <span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>), |
| <span class="prelude-val">Err</span>(error) => <span class="prelude-val">Err</span>(error), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>Drop <span class="kw">for </span>SignalFd { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">let </span>e = unistd::close(<span class="self">self</span>.<span class="number">0</span>); |
| <span class="kw">if </span>!std::thread::panicking() && e == <span class="prelude-val">Err</span>(Errno::EBADF) { |
| <span class="macro">panic!</span>(<span class="string">"Closing an invalid file descriptor!"</span>); |
| }; |
| } |
| } |
| |
| <span class="kw">impl </span>AsRawFd <span class="kw">for </span>SignalFd { |
| <span class="kw">fn </span>as_raw_fd(<span class="kw-2">&</span><span class="self">self</span>) -> RawFd { |
| <span class="self">self</span>.<span class="number">0 |
| </span>} |
| } |
| |
| <span class="kw">impl </span>Iterator <span class="kw">for </span>SignalFd { |
| <span class="kw">type </span>Item = siginfo; |
| |
| <span class="kw">fn </span>next(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="self">Self</span>::Item> { |
| <span class="kw">match </span><span class="self">self</span>.read_signal() { |
| <span class="prelude-val">Ok</span>(<span class="prelude-val">Some</span>(sig)) => <span class="prelude-val">Some</span>(sig), |
| <span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>) | <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="prelude-val">None</span>, |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>create_signalfd() { |
| <span class="kw">let </span>mask = SigSet::empty(); |
| SignalFd::new(<span class="kw-2">&</span>mask).unwrap(); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>create_signalfd_with_opts() { |
| <span class="kw">let </span>mask = SigSet::empty(); |
| SignalFd::with_flags( |
| <span class="kw-2">&</span>mask, |
| SfdFlags::SFD_CLOEXEC | SfdFlags::SFD_NONBLOCK, |
| ) |
| .unwrap(); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>read_empty_signalfd() { |
| <span class="kw">let </span>mask = SigSet::empty(); |
| <span class="kw">let </span><span class="kw-2">mut </span>fd = |
| SignalFd::with_flags(<span class="kw-2">&</span>mask, SfdFlags::SFD_NONBLOCK).unwrap(); |
| |
| <span class="kw">let </span>res = fd.read_signal(); |
| <span class="macro">assert!</span>(res.unwrap().is_none()); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="nix" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
