| <!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/tokio-1.28.2/src/io/util/copy_buf.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>copy_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::{AsyncBufRead, AsyncWrite}; |
| <span class="kw">use </span>std::future::Future; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::pin::Pin; |
| <span class="kw">use </span>std::task::{Context, Poll}; |
| |
| <span class="macro">cfg_io_util! </span>{ |
| <span class="doccomment">/// A future that asynchronously copies the entire contents of a reader into a |
| /// writer. |
| /// |
| /// This struct is generally created by calling [`copy_buf`][copy_buf]. Please |
| /// see the documentation of `copy_buf()` for more details. |
| /// |
| /// [copy_buf]: copy_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">struct </span>CopyBuf<<span class="lifetime">'a</span>, R: <span class="question-mark">?</span>Sized, W: <span class="question-mark">?</span>Sized> { |
| reader: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, |
| writer: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>W, |
| amt: u64, |
| } |
| |
| <span class="doccomment">/// Asynchronously copies the entire contents of a reader into a writer. |
| /// |
| /// This function returns a future that will continuously read data from |
| /// `reader` and then write it into `writer` in a streaming fashion until |
| /// `reader` returns EOF or fails. |
| /// |
| /// On success, the total number of bytes that were copied from `reader` to |
| /// `writer` is returned. |
| /// |
| /// This is a [`tokio::io::copy`] alternative for [`AsyncBufRead`] readers |
| /// with no extra buffer allocation, since [`AsyncBufRead`] allow access |
| /// to the reader's inner buffer. |
| /// |
| /// [`tokio::io::copy`]: crate::io::copy |
| /// [`AsyncBufRead`]: crate::io::AsyncBufRead |
| /// |
| /// # Errors |
| /// |
| /// The returned future will finish with an error will return an error |
| /// immediately if any call to `poll_fill_buf` or `poll_write` returns an |
| /// error. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::io; |
| /// |
| /// # async fn dox() -> std::io::Result<()> { |
| /// let mut reader: &[u8] = b"hello"; |
| /// let mut writer: Vec<u8> = vec![]; |
| /// |
| /// io::copy_buf(&mut reader, &mut writer).await?; |
| /// |
| /// assert_eq!(b"hello", &writer[..]); |
| /// # Ok(()) |
| /// # } |
| /// ``` |
| </span><span class="kw">pub async fn </span>copy_buf<<span class="lifetime">'a</span>, R, W>(reader: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, writer: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>W) -> io::Result<u64> |
| <span class="kw">where |
| </span>R: AsyncBufRead + Unpin + <span class="question-mark">?</span>Sized, |
| W: AsyncWrite + Unpin + <span class="question-mark">?</span>Sized, |
| { |
| CopyBuf { |
| reader, |
| writer, |
| amt: <span class="number">0</span>, |
| }.<span class="kw">await |
| </span>} |
| } |
| |
| <span class="kw">impl</span><R, W> Future <span class="kw">for </span>CopyBuf<<span class="lifetime">'_</span>, R, W> |
| <span class="kw">where |
| </span>R: AsyncBufRead + Unpin + <span class="question-mark">?</span>Sized, |
| W: AsyncWrite + Unpin + <span class="question-mark">?</span>Sized, |
| { |
| <span class="kw">type </span>Output = io::Result<u64>; |
| |
| <span class="kw">fn </span>poll(<span class="kw-2">mut </span><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<<span class="self">Self</span>::Output> { |
| <span class="kw">loop </span>{ |
| <span class="kw">let </span>me = <span class="kw-2">&mut *</span><span class="self">self</span>; |
| <span class="kw">let </span>buffer = <span class="macro">ready!</span>(Pin::new(<span class="kw-2">&mut *</span>me.reader).poll_fill_buf(cx))<span class="question-mark">?</span>; |
| <span class="kw">if </span>buffer.is_empty() { |
| <span class="macro">ready!</span>(Pin::new(<span class="kw-2">&mut </span><span class="self">self</span>.writer).poll_flush(cx))<span class="question-mark">?</span>; |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Ok</span>(<span class="self">self</span>.amt)); |
| } |
| |
| <span class="kw">let </span>i = <span class="macro">ready!</span>(Pin::new(<span class="kw-2">&mut *</span>me.writer).poll_write(cx, buffer))<span class="question-mark">?</span>; |
| <span class="kw">if </span>i == <span class="number">0 </span>{ |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Err</span>(std::io::ErrorKind::WriteZero.into())); |
| } |
| <span class="self">self</span>.amt += i <span class="kw">as </span>u64; |
| Pin::new(<span class="kw-2">&mut *</span><span class="self">self</span>.reader).consume(i); |
| } |
| } |
| } |
| |
| <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>assert_unpin() { |
| <span class="kw">use </span>std::marker::PhantomPinned; |
| <span class="kw">crate</span>::is_unpin::<CopyBuf<<span class="lifetime">'_</span>, PhantomPinned, PhantomPinned>>(); |
| } |
| } |
| </code></pre></div> |
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