| <!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/git/checkouts/tokio-377c595163f99a10/dfe252d/tokio/src/io/util/read_buf.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>read_buf.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="../../../../tokio/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="../../../../tokio/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="kw">use </span><span class="kw">crate</span>::io::AsyncRead; |
| |
| <span class="kw">use </span>bytes::BufMut; |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| <span class="kw">use </span>std::future::Future; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::marker::PhantomPinned; |
| <span class="kw">use </span>std::pin::Pin; |
| <span class="kw">use </span>std::task::{Context, Poll}; |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>read_buf<<span class="lifetime">'a</span>, R, B>(reader: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, buf: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>B) -> ReadBuf<<span class="lifetime">'a</span>, R, B> |
| <span class="kw">where |
| </span>R: AsyncRead + Unpin, |
| B: BufMut, |
| { |
| ReadBuf { |
| reader, |
| buf, |
| _pin: PhantomPinned, |
| } |
| } |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future returned by [`read_buf`](crate::io::AsyncReadExt::read_buf). |
| </span><span class="attribute">#[derive(Debug)] |
| #[must_use = <span class="string">"futures do nothing unless you `.await` or poll them"</span>] |
| </span><span class="kw">pub struct </span>ReadBuf<<span class="lifetime">'a</span>, R, B> { |
| reader: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, |
| buf: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>B, |
| <span class="attribute">#[pin] |
| </span>_pin: PhantomPinned, |
| } |
| } |
| |
| <span class="kw">impl</span><R, B> Future <span class="kw">for </span>ReadBuf<<span class="lifetime">'_</span>, R, B> |
| <span class="kw">where |
| </span>R: AsyncRead + Unpin, |
| B: BufMut, |
| { |
| <span class="kw">type </span>Output = io::Result<usize>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<io::Result<usize>> { |
| <span class="kw">use </span><span class="kw">crate</span>::io::ReadBuf; |
| <span class="kw">use </span>std::mem::MaybeUninit; |
| |
| <span class="kw">let </span>me = <span class="self">self</span>.project(); |
| |
| <span class="kw">if </span>!me.buf.has_remaining_mut() { |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Ok</span>(<span class="number">0</span>)); |
| } |
| |
| <span class="kw">let </span>n = { |
| <span class="kw">let </span>dst = me.buf.chunk_mut(); |
| <span class="kw">let </span>dst = <span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span>(dst <span class="kw">as </span><span class="kw-2">*mut </span><span class="kw">_ as </span><span class="kw-2">*mut </span>[MaybeUninit<u8>]) }; |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = ReadBuf::uninit(dst); |
| <span class="kw">let </span>ptr = buf.filled().as_ptr(); |
| <span class="macro">ready!</span>(Pin::new(me.reader).poll_read(cx, <span class="kw-2">&mut </span>buf)<span class="question-mark">?</span>); |
| |
| <span class="comment">// Ensure the pointer does not change from under us |
| </span><span class="macro">assert_eq!</span>(ptr, buf.filled().as_ptr()); |
| buf.filled().len() |
| }; |
| |
| <span class="comment">// Safety: This is guaranteed to be the number of initialized (and read) |
| // bytes due to the invariants provided by `ReadBuf::filled`. |
| </span><span class="kw">unsafe </span>{ |
| me.buf.advance_mut(n); |
| } |
| |
| Poll::Ready(<span class="prelude-val">Ok</span>(n)) |
| } |
| } |
| </code></pre></div> |
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