1 use crate::fs::asyncify;
2
3 use std::{io, path::Path};
4
5 /// Reads the entire contents of a file into a bytes vector.
6 ///
7 /// This is an async version of [`std::fs::read`].
8 ///
9 /// This is a convenience function for using [`File::open`] and [`read_to_end`]
10 /// with fewer imports and without an intermediate variable. It pre-allocates a
11 /// buffer based on the file size when available, so it is generally faster than
12 /// reading into a vector created with `Vec::new()`.
13 ///
14 /// This operation is implemented by running the equivalent blocking operation
15 /// on a separate thread pool using [`spawn_blocking`].
16 ///
17 /// [`File::open`]: super::File::open
18 /// [`read_to_end`]: crate::io::AsyncReadExt::read_to_end
19 /// [`spawn_blocking`]: crate::task::spawn_blocking
20 ///
21 /// # Errors
22 ///
23 /// This function will return an error if `path` does not already exist.
24 /// Other errors may also be returned according to [`OpenOptions::open`].
25 ///
26 /// [`OpenOptions::open`]: super::OpenOptions::open
27 ///
28 /// It will also return an error if it encounters while reading an error
29 /// of a kind other than [`ErrorKind::Interrupted`].
30 ///
31 /// [`ErrorKind::Interrupted`]: std::io::ErrorKind::Interrupted
32 ///
33 /// # Examples
34 ///
35 /// ```no_run
36 /// use tokio::fs;
37 /// use std::net::SocketAddr;
38 ///
39 /// #[tokio::main]
40 /// async fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
41 /// let contents = fs::read("address.txt").await?;
42 /// let foo: SocketAddr = String::from_utf8_lossy(&contents).parse()?;
43 /// Ok(())
44 /// }
45 /// ```
read(path: impl AsRef<Path>) -> io::Result<Vec<u8>>46 pub async fn read(path: impl AsRef<Path>) -> io::Result<Vec<u8>> {
47 let path = path.as_ref().to_owned();
48 asyncify(move || std::fs::read(path)).await
49 }
50