1use crate::io;
2use crate::path::Path;
3use crate::task::spawn_blocking;
4use crate::utils::Context as _;
5
6/// Reads the entire contents of a file as raw bytes.
7///
8/// This is a convenience function for reading entire files. It pre-allocates a buffer based on the
9/// file size when available, so it is typically faster than manually opening a file and reading
10/// from it.
11///
12/// If you want to read the contents as a string, use [`read_to_string`] instead.
13///
14/// This function is an async version of [`std::fs::read`].
15///
16/// [`read_to_string`]: fn.read_to_string.html
17/// [`std::fs::read`]: https://doc.rust-lang.org/std/fs/fn.read.html
18///
19/// # Errors
20///
21/// An error will be returned in the following situations:
22///
23/// * `path` does not point to an existing file.
24/// * The current process lacks permissions to read the file.
25/// * Some other I/O error occurred.
26///
27/// # Examples
28///
29/// ```no_run
30/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
31/// #
32/// use async_std::fs;
33///
34/// let contents = fs::read("a.txt").await?;
35/// #
36/// # Ok(()) }) }
37/// ```
38pub async fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
39 let path: PathBuf = path.as_ref().to_owned();
40 spawn_blockingJoinHandle, …>>(move || {
41 std::fs::read(&path).context(|| format!("could not read file `{}`", path.display()))
42 })
43 .await
44}
45