smol-rs
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async-fs
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async-fs/src/lib.rs

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//! Async filesystem primitives.
//!
//! This crate is an async version of [`std::fs`].
//!
//! # Implementation
//!
//! This crate uses [`blocking`] to offload blocking I/O onto a thread pool.
//!
//! [`blocking`]: https://docs.rs/blocking
//!
//! # Examples
//!
//! Create a new file and write some bytes to it:
//!
//! ```no_run
//! use async_fs::File;
//! use futures_lite::io::AsyncWriteExt;
//!
//! # futures_lite::future::block_on(async {
//! let mut file = File::create("a.txt").await?;
//! file.write_all(b"Hello, world!").await?;
//! file.flush().await?;
//! # std::io::Result::Ok(()) });
//! ```
#![forbid(unsafe_code)]
#![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)]
#![doc(
html_favicon_url = "https://raw.githubusercontent.com/smol-rs/smol/master/assets/images/logo_fullsize_transparent.png"
)]
#![doc(
html_logo_url = "https://raw.githubusercontent.com/smol-rs/smol/master/assets/images/logo_fullsize_transparent.png"
)]
use std::ffi::OsString;
use std::fmt;
use std::future::Future;
use std::io::{self, SeekFrom};
use std::path::{Path, PathBuf};
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};
#[cfg(unix)]
use std::os::unix::fs::{DirEntryExt as _, OpenOptionsExt as _};
#[cfg(windows)]
use std::os::windows::fs::OpenOptionsExt as _;
use async_lock::Mutex;
use blocking::{unblock, Unblock};
use futures_lite::future::FutureExt;
use futures_lite::io::{AsyncRead, AsyncSeek, AsyncWrite, AsyncWriteExt};
use futures_lite::ready;
use futures_lite::stream::Stream;
#[doc(no_inline)]
pub use std::fs::{FileType, Metadata, Permissions};
/// Returns the canonical form of a path.
///
/// The returned path is in absolute form with all intermediate components normalized and symbolic
/// links resolved.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file or directory.
/// * A non-final component in `path` is not a directory.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let path = async_fs::canonicalize(".").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn canonicalize<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::canonicalize(path)).await
}
/// Copies a file to a new location.
///
/// On success, the total number of bytes copied is returned and equals the length of the `dst`
/// file after this operation.
///
/// The old contents of `dst` will be overwritten. If `src` and `dst` both point to the same
/// file, then the file will likely get truncated as a result of this operation.
///
/// If you're working with open [`File`]s and want to copy contents through those types, use
/// [`futures_lite::io::copy()`] instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `src` does not point to an existing file.
/// * The current process lacks permissions to read `src` or write `dst`.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let num_bytes = async_fs::copy("a.txt", "b.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn copy<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<u64> {
let src = src.as_ref().to_owned();
let dst = dst.as_ref().to_owned();
unblock(move || std::fs::copy(&src, &dst)).await
}
/// Creates a directory.
///
/// Note that this function will only create the final directory in `path`. If you want to create
/// all of its missing parent directories too, use [`create_dir_all()`] instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` already points to an existing file or directory.
/// * A parent directory in `path` does not exist.
/// * The current process lacks permissions to create the directory.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::create_dir("./some/directory").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::create_dir(path)).await
}
/// Creates a directory and its parent directories if they are missing.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` already points to an existing file or directory.
/// * The current process lacks permissions to create the directory or its missing parents.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::create_dir_all("./some/directory").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn create_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::create_dir_all(path)).await
}
/// Creates a hard link on the filesystem.
///
/// The `dst` path will be a link pointing to the `src` path. Note that operating systems often
/// require these two paths to be located on the same filesystem.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `src` does not point to an existing file.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::hard_link("a.txt", "b.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn hard_link<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
let src = src.as_ref().to_owned();
let dst = dst.as_ref().to_owned();
unblock(move || std::fs::hard_link(&src, &dst)).await
}
/// Reads metadata for a path.
///
/// This function will traverse symbolic links to read metadata for the target file or directory.
/// If you want to read metadata without following symbolic links, use [`symlink_metadata()`]
/// instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file or directory.
/// * The current process lacks permissions to read metadata for the path.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let perm = async_fs::metadata("a.txt").await?.permissions();
/// # std::io::Result::Ok(()) });
/// ```
pub async fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::metadata(path)).await
}
/// Reads the entire contents of a file as raw bytes.
///
/// This is a convenience function for reading entire files. It pre-allocates a buffer based on the
/// file size when available, so it is typically faster than manually opening a file and reading
/// from it.
///
/// If you want to read the contents as a string, use [`read_to_string()`] instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file.
/// * The current process lacks permissions to read the file.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let contents = async_fs::read("a.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::read(path)).await
}
/// Returns a stream of entries in a directory.
///
/// The stream yields items of type [`io::Result`]`<`[`DirEntry`]`>`. Note that I/O errors can
/// occur while reading from the stream.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing directory.
/// * The current process lacks permissions to read the contents of the directory.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// use futures_lite::stream::StreamExt;
///
/// let mut entries = async_fs::read_dir(".").await?;
///
/// while let Some(entry) = entries.try_next().await? {
/// println!("{}", entry.file_name().to_string_lossy());
/// }
/// # std::io::Result::Ok(()) });
/// ```
pub async fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::read_dir(path).map(|inner| ReadDir(State::Idle(Some(inner))))).await
}
/// A stream of entries in a directory.
///
/// This stream is returned by [`read_dir()`] and yields items of type
/// [`io::Result`]`<`[`DirEntry`]`>`. Each [`DirEntry`] can then retrieve information like entry's
/// path or metadata.
pub struct ReadDir(State);
/// The state of an asynchronous `ReadDir`.
///
/// The `ReadDir` can be either idle or busy performing an asynchronous operation.
enum State {
Idle(Option<std::fs::ReadDir>),
Busy(blocking::Task<(std::fs::ReadDir, Option<io::Result<std::fs::DirEntry>>)>),
}
impl fmt::Debug for ReadDir {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("ReadDir").finish()
}
}
impl Stream for ReadDir {
type Item = io::Result<DirEntry>;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
loop {
match &mut self.0 {
State::Idle(opt) => {
let mut inner = opt.take().unwrap();
// Start the operation asynchronously.
self.0 = State::Busy(unblock(move || {
let next = inner.next();
(inner, next)
}));
}
// Poll the asynchronous operation the file is currently blocked on.
State::Busy(task) => {
let (inner, opt) = ready!(task.poll(cx));
self.0 = State::Idle(Some(inner));
return Poll::Ready(opt.map(|res| res.map(|inner| DirEntry(Arc::new(inner)))));
}
}
}
}
}
/// An entry in a directory.
///
/// A stream of entries in a directory is returned by [`read_dir()`].
///
/// For Unix-specific options, import the [`DirEntryExt`][`std::os::unix::fs::DirEntryExt`] trait.
pub struct DirEntry(Arc<std::fs::DirEntry>);
impl DirEntry {
/// Returns the full path to this entry.
///
/// The full path is created by joining the original path passed to [`read_dir()`] with the
/// name of this entry.
///
/// # Examples
///
/// ```no_run
/// use futures_lite::stream::StreamExt;
///
/// # futures_lite::future::block_on(async {
/// let mut dir = async_fs::read_dir(".").await?;
///
/// while let Some(entry) = dir.try_next().await? {
/// println!("{:?}", entry.path());
/// }
/// # std::io::Result::Ok(()) });
/// ```
pub fn path(&self) -> PathBuf {
self.0.path()
}
/// Reads the metadata for this entry.
///
/// This function will traverse symbolic links to read the metadata.
///
/// If you want to read metadata without following symbolic links, use [`symlink_metadata()`]
/// instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * This entry does not point to an existing file or directory anymore.
/// * The current process lacks permissions to read the metadata.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// use futures_lite::stream::StreamExt;
///
/// # futures_lite::future::block_on(async {
/// let mut dir = async_fs::read_dir(".").await?;
///
/// while let Some(entry) = dir.try_next().await? {
/// println!("{:?}", entry.metadata().await?);
/// }
/// # std::io::Result::Ok(()) });
/// ```
pub async fn metadata(&self) -> io::Result<Metadata> {
let inner = self.0.clone();
unblock(move || inner.metadata()).await
}
/// Reads the file type for this entry.
///
/// This function will not traverse symbolic links if this entry points at one.
///
/// If you want to read metadata with following symbolic links, use [`metadata()`] instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * This entry does not point to an existing file or directory anymore.
/// * The current process lacks permissions to read this entry's metadata.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// use futures_lite::stream::StreamExt;
///
/// # futures_lite::future::block_on(async {
/// let mut dir = async_fs::read_dir(".").await?;
///
/// while let Some(entry) = dir.try_next().await? {
/// println!("{:?}", entry.file_type().await?);
/// }
/// # std::io::Result::Ok(()) });
/// ```
pub async fn file_type(&self) -> io::Result<FileType> {
let inner = self.0.clone();
unblock(move || inner.file_type()).await
}
/// Returns the bare name of this entry without the leading path.
///
/// # Examples
///
/// ```no_run
/// use futures_lite::stream::StreamExt;
///
/// # futures_lite::future::block_on(async {
/// let mut dir = async_fs::read_dir(".").await?;
///
/// while let Some(entry) = dir.try_next().await? {
/// println!("{}", entry.file_name().to_string_lossy());
/// }
/// # std::io::Result::Ok(()) });
/// ```
pub fn file_name(&self) -> OsString {
self.0.file_name()
}
}
impl fmt::Debug for DirEntry {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("DirEntry").field(&self.path()).finish()
}
}
impl Clone for DirEntry {
fn clone(&self) -> Self {
DirEntry(self.0.clone())
}
}
#[cfg(unix)]
impl unix::DirEntryExt for DirEntry {
fn ino(&self) -> u64 {
self.0.ino()
}
}
/// Reads a symbolic link and returns the path it points to.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing link.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let path = async_fs::read_link("a.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn read_link<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::read_link(path)).await
}
/// Reads the entire contents of a file as a string.
///
/// This is a convenience function for reading entire files. It pre-allocates a string based on the
/// file size when available, so it is typically faster than manually opening a file and reading
/// from it.
///
/// If you want to read the contents as raw bytes, use [`read()`] instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file.
/// * The current process lacks permissions to read the file.
/// * The contents of the file cannot be read as a UTF-8 string.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let contents = async_fs::read_to_string("a.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::read_to_string(path)).await
}
/// Removes an empty directory.
///
/// Note that this function can only delete an empty directory. If you want to delete a directory
/// and all of its contents, use [`remove_dir_all()`] instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` is not an existing and empty directory.
/// * The current process lacks permissions to remove the directory.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::remove_dir("./some/directory").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::remove_dir(path)).await
}
/// Removes a directory and all of its contents.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` is not an existing directory.
/// * The current process lacks permissions to remove the directory.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::remove_dir_all("./some/directory").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::remove_dir_all(path)).await
}
/// Removes a file.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file.
/// * The current process lacks permissions to remove the file.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::remove_file("a.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn remove_file<P: AsRef<Path>>(path: P) -> io::Result<()> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::remove_file(path)).await
}
/// Renames a file or directory to a new location.
///
/// If a file or directory already exists at the target location, it will be overwritten by this
/// operation.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `src` does not point to an existing file or directory.
/// * `src` and `dst` are on different filesystems.
/// * The current process lacks permissions to do the rename operation.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::rename("a.txt", "b.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn rename<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
let src = src.as_ref().to_owned();
let dst = dst.as_ref().to_owned();
unblock(move || std::fs::rename(&src, &dst)).await
}
/// Changes the permissions of a file or directory.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file or directory.
/// * The current process lacks permissions to change attributes on the file or directory.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let mut perm = async_fs::metadata("a.txt").await?.permissions();
/// perm.set_readonly(true);
/// async_fs::set_permissions("a.txt", perm).await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result<()> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::set_permissions(path, perm)).await
}
/// Reads metadata for a path without following symbolic links.
///
/// If you want to follow symbolic links before reading metadata of the target file or directory,
/// use [`metadata()`] instead.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file or directory.
/// * The current process lacks permissions to read metadata for the path.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// let perm = async_fs::symlink_metadata("a.txt").await?.permissions();
/// # std::io::Result::Ok(()) });
/// ```
pub async fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
let path = path.as_ref().to_owned();
unblock(move || std::fs::symlink_metadata(path)).await
}
/// Writes a slice of bytes as the new contents of a file.
///
/// This function will create a file if it does not exist, and will entirely replace its contents
/// if it does.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * The file's parent directory does not exist.
/// * The current process lacks permissions to write to the file.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::write("a.txt", b"Hello world!").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
let path = path.as_ref().to_owned();
let contents = contents.as_ref().to_owned();
unblock(move || std::fs::write(&path, contents)).await
}
/// A builder for creating directories with configurable options.
///
/// For Unix-specific options, import the [`DirBuilderExt`][`std::os::unix::fs::DirBuilderExt`]
/// trait.
#[derive(Debug, Default)]
pub struct DirBuilder {
/// Set to `true` if non-existent parent directories should be created.
recursive: bool,
/// Unix mode for newly created directories.
#[cfg(unix)]
mode: Option<u32>,
}
impl DirBuilder {
/// Creates a blank set of options.
///
/// The [`recursive()`][`DirBuilder::recursive()`] option is initially set to `false`.
///
/// # Examples
///
/// ```
/// use async_fs::DirBuilder;
///
/// let builder = DirBuilder::new();
/// ```
pub fn new() -> DirBuilder {
#[cfg(not(unix))]
let builder = DirBuilder { recursive: false };
#[cfg(unix)]
let builder = DirBuilder {
recursive: false,
mode: None,
};
builder
}
/// Sets the option for recursive mode.
///
/// When set to `true`, this option means all parent directories should be created recursively
/// if they don't exist. Parents are created with the same permissions as the final directory.
///
/// This option is initially set to `false`.
///
/// # Examples
///
/// ```
/// use async_fs::DirBuilder;
///
/// let mut builder = DirBuilder::new();
/// builder.recursive(true);
/// ```
pub fn recursive(&mut self, recursive: bool) -> &mut Self {
self.recursive = recursive;
self
}
/// Creates a directory with the configured options.
///
/// It is considered an error if the directory already exists unless recursive mode is enabled.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` already points to an existing file or directory.
/// * The current process lacks permissions to create the directory or its missing parents.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// use async_fs::DirBuilder;
///
/// # futures_lite::future::block_on(async {
/// DirBuilder::new()
/// .recursive(true)
/// .create("./some/directory")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn create<P: AsRef<Path>>(&self, path: P) -> impl Future<Output = io::Result<()>> {
let mut builder = std::fs::DirBuilder::new();
builder.recursive(self.recursive);
#[cfg(unix)]
{
if let Some(mode) = self.mode {
std::os::unix::fs::DirBuilderExt::mode(&mut builder, mode);
}
}
let path = path.as_ref().to_owned();
unblock(move || builder.create(path))
}
}
#[cfg(unix)]
impl unix::DirBuilderExt for DirBuilder {
fn mode(&mut self, mode: u32) -> &mut Self {
self.mode = Some(mode);
self
}
}
/// An open file on the filesystem.
///
/// Depending on what options the file was opened with, this type can be used for reading and/or
/// writing.
///
/// Files are automatically closed when they get dropped and any errors detected on closing are
/// ignored. Use the [`sync_all()`][`File::sync_all()`] method before dropping a file if such
/// errors need to be handled.
///
/// **NOTE:** If writing to a file, make sure to call
/// [`flush()`][`futures_lite::io::AsyncWriteExt::flush()`], [`sync_data()`][`File::sync_data()`],
/// or [`sync_all()`][`File::sync_all()`] before dropping the file or else some written data
/// might get lost!
///
/// # Examples
///
/// Create a new file and write some bytes to it:
///
/// ```no_run
/// use async_fs::File;
/// use futures_lite::io::AsyncWriteExt;
///
/// # futures_lite::future::block_on(async {
/// let mut file = File::create("a.txt").await?;
///
/// file.write_all(b"Hello, world!").await?;
/// file.flush().await?;
/// # std::io::Result::Ok(()) });
/// ```
///
/// Read the contents of a file into a vector of bytes:
///
/// ```no_run
/// use async_fs::File;
/// use futures_lite::io::AsyncReadExt;
///
/// # futures_lite::future::block_on(async {
/// let mut file = File::open("a.txt").await?;
///
/// let mut contents = Vec::new();
/// file.read_to_end(&mut contents).await?;
/// # std::io::Result::Ok(()) });
/// ```
pub struct File {
/// Always accessible reference to the file.
file: Arc<std::fs::File>,
/// Performs blocking I/O operations on a thread pool.
unblock: Mutex<Unblock<ArcFile>>,
/// Logical file cursor, tracked when reading from the file.
///
/// This will be set to an error if the file is not seekable.
read_pos: Option<io::Result<u64>>,
/// Set to `true` if the file needs flushing.
is_dirty: bool,
}
impl File {
/// Creates an async file from a blocking file.
fn new(inner: std::fs::File, is_dirty: bool) -> File {
let file = Arc::new(inner);
let unblock = Mutex::new(Unblock::new(ArcFile(file.clone())));
let read_pos = None;
File {
file,
unblock,
read_pos,
is_dirty,
}
}
/// Opens a file in read-only mode.
///
/// See the [`OpenOptions::open()`] function for more options.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * `path` does not point to an existing file.
/// * The current process lacks permissions to read the file.
/// * Some other I/O error occurred.
///
/// For more details, see the list of errors documented by [`OpenOptions::open()`].
///
/// # Examples
///
/// ```no_run
/// use async_fs::File;
///
/// # futures_lite::future::block_on(async {
/// let file = File::open("a.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn open<P: AsRef<Path>>(path: P) -> io::Result<File> {
let path = path.as_ref().to_owned();
let file = unblock(move || std::fs::File::open(path)).await?;
Ok(File::new(file, false))
}
/// Opens a file in write-only mode.
///
/// This method will create a file if it does not exist, and will truncate it if it does.
///
/// See the [`OpenOptions::open`] function for more options.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * The file's parent directory does not exist.
/// * The current process lacks permissions to write to the file.
/// * Some other I/O error occurred.
///
/// For more details, see the list of errors documented by [`OpenOptions::open()`].
///
/// # Examples
///
/// ```no_run
/// use async_fs::File;
///
/// # futures_lite::future::block_on(async {
/// let file = File::create("a.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn create<P: AsRef<Path>>(path: P) -> io::Result<File> {
let path = path.as_ref().to_owned();
let file = unblock(move || std::fs::File::create(path)).await?;
Ok(File::new(file, false))
}
/// Synchronizes OS-internal buffered contents and metadata to disk.
///
/// This function will ensure that all in-memory data reaches the filesystem.
///
/// This can be used to handle errors that would otherwise only be caught by closing the file.
/// When a file is dropped, errors in synchronizing this in-memory data are ignored.
///
/// # Examples
///
/// ```no_run
/// use async_fs::File;
/// use futures_lite::io::AsyncWriteExt;
///
/// # futures_lite::future::block_on(async {
/// let mut file = File::create("a.txt").await?;
///
/// file.write_all(b"Hello, world!").await?;
/// file.sync_all().await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn sync_all(&self) -> io::Result<()> {
let mut inner = self.unblock.lock().await;
inner.flush().await?;
let file = self.file.clone();
unblock(move || file.sync_all()).await
}
/// Synchronizes OS-internal buffered contents to disk.
///
/// This is similar to [`sync_all()`][`File::sync_data()`], except that file metadata may not
/// be synchronized.
///
/// This is intended for use cases that must synchronize the contents of the file, but don't
/// need the file metadata synchronized to disk.
///
/// Note that some platforms may simply implement this in terms of
/// [`sync_all()`][`File::sync_data()`].
///
/// # Examples
///
/// ```no_run
/// use async_fs::File;
/// use futures_lite::io::AsyncWriteExt;
///
/// # futures_lite::future::block_on(async {
/// let mut file = File::create("a.txt").await?;
///
/// file.write_all(b"Hello, world!").await?;
/// file.sync_data().await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn sync_data(&self) -> io::Result<()> {
let mut inner = self.unblock.lock().await;
inner.flush().await?;
let file = self.file.clone();
unblock(move || file.sync_data()).await
}
/// Truncates or extends the file.
///
/// If `size` is less than the current file size, then the file will be truncated. If it is
/// greater than the current file size, then the file will be extended to `size` and have all
/// intermediate data filled with zeros.
///
/// The file's cursor stays at the same position, even if the cursor ends up being past the end
/// of the file after this operation.
///
/// # Examples
///
/// ```no_run
/// use async_fs::File;
///
/// # futures_lite::future::block_on(async {
/// let mut file = File::create("a.txt").await?;
/// file.set_len(10).await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn set_len(&self, size: u64) -> io::Result<()> {
let mut inner = self.unblock.lock().await;
inner.flush().await?;
let file = self.file.clone();
unblock(move || file.set_len(size)).await
}
/// Reads the file's metadata.
///
/// # Examples
///
/// ```no_run
/// use async_fs::File;
///
/// # futures_lite::future::block_on(async {
/// let file = File::open("a.txt").await?;
/// let metadata = file.metadata().await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn metadata(&self) -> io::Result<Metadata> {
let file = self.file.clone();
unblock(move || file.metadata()).await
}
/// Changes the permissions on the file.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * The current process lacks permissions to change attributes on the file.
/// * Some other I/O error occurred.
///
/// # Examples
///
/// ```no_run
/// use async_fs::File;
///
/// # futures_lite::future::block_on(async {
/// let file = File::create("a.txt").await?;
///
/// let mut perms = file.metadata().await?.permissions();
/// perms.set_readonly(true);
/// file.set_permissions(perms).await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
let file = self.file.clone();
unblock(move || file.set_permissions(perm)).await
}
/// Repositions the cursor after reading.
///
/// When reading from a file, actual file reads run asynchronously in the background, which
/// means the real file cursor is usually ahead of the logical cursor, and the data between
/// them is buffered in memory. This kind of buffering is an important optimization.
///
/// After reading ends, if we decide to perform a write or a seek operation, the real file
/// cursor must first be repositioned back to the correct logical position.
fn poll_reposition(&mut self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
if let Some(Ok(read_pos)) = self.read_pos {
ready!(Pin::new(self.unblock.get_mut()).poll_seek(cx, SeekFrom::Start(read_pos)))?;
}
self.read_pos = None;
Poll::Ready(Ok(()))
}
}
impl fmt::Debug for File {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.file.fmt(f)
}
}
impl From<std::fs::File> for File {
fn from(inner: std::fs::File) -> File {
File::new(inner, true)
}
}
#[cfg(unix)]
impl std::os::unix::io::AsRawFd for File {
fn as_raw_fd(&self) -> std::os::unix::io::RawFd {
self.file.as_raw_fd()
}
}
#[cfg(windows)]
impl std::os::windows::io::AsRawHandle for File {
fn as_raw_handle(&self) -> std::os::windows::io::RawHandle {
self.file.as_raw_handle()
}
}
#[cfg(unix)]
impl From<std::os::unix::io::OwnedFd> for File {
fn from(fd: std::os::unix::io::OwnedFd) -> Self {
File::from(std::fs::File::from(fd))
}
}
#[cfg(windows)]
impl From<std::os::windows::io::OwnedHandle> for File {
fn from(fd: std::os::windows::io::OwnedHandle) -> Self {
File::from(std::fs::File::from(fd))
}
}
#[cfg(unix)]
impl std::os::unix::io::AsFd for File {
fn as_fd(&self) -> std::os::unix::io::BorrowedFd<'_> {
self.file.as_fd()
}
}
#[cfg(windows)]
impl std::os::windows::io::AsHandle for File {
fn as_handle(&self) -> std::os::windows::io::BorrowedHandle<'_> {
self.file.as_handle()
}
}
impl AsyncRead for File {
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
// Before reading begins, remember the current cursor position.
if self.read_pos.is_none() {
// Initialize the logical cursor to the current position in the file.
self.read_pos = Some(ready!(self.as_mut().poll_seek(cx, SeekFrom::Current(0))));
}
let n = ready!(Pin::new(self.unblock.get_mut()).poll_read(cx, buf))?;
// Update the logical cursor if the file is seekable.
if let Some(Ok(pos)) = self.read_pos.as_mut() {
*pos += n as u64;
}
Poll::Ready(Ok(n))
}
}
impl AsyncWrite for File {
fn poll_write(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
ready!(self.poll_reposition(cx))?;
self.is_dirty = true;
Pin::new(self.unblock.get_mut()).poll_write(cx, buf)
}
fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
if self.is_dirty {
ready!(Pin::new(self.unblock.get_mut()).poll_flush(cx))?;
self.is_dirty = false;
}
Poll::Ready(Ok(()))
}
fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
Pin::new(self.unblock.get_mut()).poll_close(cx)
}
}
impl AsyncSeek for File {
fn poll_seek(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom,
) -> Poll<io::Result<u64>> {
ready!(self.poll_reposition(cx))?;
Pin::new(self.unblock.get_mut()).poll_seek(cx, pos)
}
}
/// A wrapper around `Arc<std::fs::File>` that implements `Read`, `Write`, and `Seek`.
struct ArcFile(Arc<std::fs::File>);
impl io::Read for ArcFile {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(&*self.0).read(buf)
}
}
impl io::Write for ArcFile {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(&*self.0).write(buf)
}
fn flush(&mut self) -> io::Result<()> {
(&*self.0).flush()
}
}
impl io::Seek for ArcFile {
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(&*self.0).seek(pos)
}
}
/// A builder for opening files with configurable options.
///
/// Files can be opened in [`read`][`OpenOptions::read()`] and/or
/// [`write`][`OpenOptions::write()`] mode.
///
/// The [`append`][`OpenOptions::append()`] option opens files in a special writing mode that
/// moves the file cursor to the end of file before every write operation.
///
/// It is also possible to [`truncate`][`OpenOptions::truncate()`] the file right after opening,
/// to [`create`][`OpenOptions::create()`] a file if it doesn't exist yet, or to always create a
/// new file with [`create_new`][`OpenOptions::create_new()`].
///
/// # Examples
///
/// Open a file for reading:
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
///
/// Open a file for both reading and writing, and create it if it doesn't exist yet:
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .read(true)
/// .write(true)
/// .create(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
#[derive(Clone, Debug)]
pub struct OpenOptions(std::fs::OpenOptions);
impl OpenOptions {
/// Creates a blank set of options.
///
/// All options are initially set to `false`.
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn new() -> OpenOptions {
OpenOptions(std::fs::OpenOptions::new())
}
/// Configures the option for read mode.
///
/// When set to `true`, this option means the file will be readable after opening.
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn read(&mut self, read: bool) -> &mut OpenOptions {
self.0.read(read);
self
}
/// Configures the option for write mode.
///
/// When set to `true`, this option means the file will be writable after opening.
///
/// If the file already exists, write calls on it will overwrite the previous contents without
/// truncating it.
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .write(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn write(&mut self, write: bool) -> &mut OpenOptions {
self.0.write(write);
self
}
/// Configures the option for append mode.
///
/// When set to `true`, this option means the file will be writable after opening and the file
/// cursor will be moved to the end of file before every write operaiton.
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .append(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn append(&mut self, append: bool) -> &mut OpenOptions {
self.0.append(append);
self
}
/// Configures the option for truncating the previous file.
///
/// When set to `true`, the file will be truncated to the length of 0 bytes.
///
/// The file must be opened in [`write`][`OpenOptions::write()`] or
/// [`append`][`OpenOptions::append()`] mode for truncation to work.
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .write(true)
/// .truncate(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions {
self.0.truncate(truncate);
self
}
/// Configures the option for creating a new file if it doesn't exist.
///
/// When set to `true`, this option means a new file will be created if it doesn't exist.
///
/// The file must be opened in [`write`][`OpenOptions::write()`] or
/// [`append`][`OpenOptions::append()`] mode for file creation to work.
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .write(true)
/// .create(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn create(&mut self, create: bool) -> &mut OpenOptions {
self.0.create(create);
self
}
/// Configures the option for creating a new file or failing if it already exists.
///
/// When set to `true`, this option means a new file will be created, or the open operation
/// will fail if the file already exists.
///
/// The file must be opened in [`write`][`OpenOptions::write()`] or
/// [`append`][`OpenOptions::append()`] mode for file creation to work.
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .write(true)
/// .create_new(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions {
self.0.create_new(create_new);
self
}
/// Opens a file with the configured options.
///
/// # Errors
///
/// An error will be returned in the following situations:
///
/// * The file does not exist and neither [`create`] nor [`create_new`] were set.
/// * The file's parent directory does not exist.
/// * The current process lacks permissions to open the file in the configured mode.
/// * The file already exists and [`create_new`] was set.
/// * Invalid combination of options was used, like [`truncate`] was set but [`write`] wasn't,
/// or none of [`read`], [`write`], and [`append`] modes was set.
/// * An OS-level occurred, like too many files are open or the file name is too long.
/// * Some other I/O error occurred.
///
/// [`read`]: `OpenOptions::read()`
/// [`write`]: `OpenOptions::write()`
/// [`append`]: `OpenOptions::append()`
/// [`truncate`]: `OpenOptions::truncate()`
/// [`create`]: `OpenOptions::create()`
/// [`create_new`]: `OpenOptions::create_new()`
///
/// # Examples
///
/// ```no_run
/// use async_fs::OpenOptions;
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .read(true)
/// .open("a.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
pub fn open<P: AsRef<Path>>(&self, path: P) -> impl Future<Output = io::Result<File>> {
let path = path.as_ref().to_owned();
let options = self.0.clone();
async move {
let file = unblock(move || options.open(path)).await?;
Ok(File::new(file, false))
}
}
}
impl Default for OpenOptions {
fn default() -> Self {
Self::new()
}
}
#[cfg(unix)]
impl unix::OpenOptionsExt for OpenOptions {
fn mode(&mut self, mode: u32) -> &mut Self {
self.0.mode(mode);
self
}
fn custom_flags(&mut self, flags: i32) -> &mut Self {
self.0.custom_flags(flags);
self
}
}
#[cfg(windows)]
impl windows::OpenOptionsExt for OpenOptions {
fn access_mode(&mut self, access: u32) -> &mut Self {
self.0.access_mode(access);
self
}
fn share_mode(&mut self, val: u32) -> &mut Self {
self.0.share_mode(val);
self
}
fn custom_flags(&mut self, flags: u32) -> &mut Self {
self.0.custom_flags(flags);
self
}
fn attributes(&mut self, val: u32) -> &mut Self {
self.0.attributes(val);
self
}
fn security_qos_flags(&mut self, flags: u32) -> &mut Self {
self.0.security_qos_flags(flags);
self
}
}
mod __private {
#[doc(hidden)]
pub trait Sealed {}
impl Sealed for super::OpenOptions {}
impl Sealed for super::File {}
impl Sealed for super::DirBuilder {}
impl Sealed for super::DirEntry {}
}
/// Unix-specific extensions.
#[cfg(unix)]
pub mod unix {
use super::__private::Sealed;
use super::*;
#[doc(no_inline)]
pub use std::os::unix::fs::{FileTypeExt, MetadataExt, PermissionsExt};
/// Creates a new symbolic link on the filesystem.
///
/// The `dst` path will be a symbolic link pointing to the `src` path.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::unix::symlink("a.txt", "b.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn symlink<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
let src = src.as_ref().to_owned();
let dst = dst.as_ref().to_owned();
unblock(move || std::os::unix::fs::symlink(&src, &dst)).await
}
/// Unix-specific extensions to [`DirBuilder`].
pub trait DirBuilderExt: Sealed {
/// Sets the mode to create new directories with.
///
/// This option defaults to `0o777`.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{DirBuilder, unix::DirBuilderExt};
///
/// let mut builder = DirBuilder::new();
/// builder.mode(0o755);
/// ```
fn mode(&mut self, mode: u32) -> &mut Self;
}
/// Unix-specific extension methods for [`DirEntry`].
pub trait DirEntryExt: Sealed {
/// Returns the underlying `d_ino` field in the contained `dirent` structure.
///
/// # Examples
///
/// ```no_run
/// use async_fs::unix::DirEntryExt;
/// use futures_lite::stream::StreamExt;
///
/// # futures_lite::future::block_on(async {
/// let mut entries = async_fs::read_dir(".").await?;
///
/// while let Some(entry) = entries.try_next().await? {
/// println!("{:?}: {}", entry.file_name(), entry.ino());
/// }
/// # std::io::Result::Ok(()) });
/// ```
fn ino(&self) -> u64;
}
/// Unix-specific extensions to [`OpenOptions`].
pub trait OpenOptionsExt: Sealed {
/// Sets the mode bits that a new file will be created with.
///
/// If a new file is created as part of an [`OpenOptions::open()`] call then this
/// specified `mode` will be used as the permission bits for the new file.
///
/// If no `mode` is set, the default of `0o666` will be used.
/// The operating system masks out bits with the system's `umask`, to produce
/// the final permissions.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{OpenOptions, unix::OpenOptionsExt};
///
/// # futures_lite::future::block_on(async {
/// let mut options = OpenOptions::new();
/// // Read/write permissions for owner and read permissions for others.
/// options.mode(0o644);
/// let file = options.open("foo.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
fn mode(&mut self, mode: u32) -> &mut Self;
/// Passes custom flags to the `flags` argument of `open`.
///
/// The bits that define the access mode are masked out with `O_ACCMODE`, to
/// ensure they do not interfere with the access mode set by Rust's options.
///
/// Custom flags can only set flags, not remove flags set by Rust's options.
/// This options overwrites any previously set custom flags.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{OpenOptions, unix::OpenOptionsExt};
///
/// # futures_lite::future::block_on(async {
/// let mut options = OpenOptions::new();
/// options.write(true);
/// options.custom_flags(libc::O_NOFOLLOW);
/// let file = options.open("foo.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
fn custom_flags(&mut self, flags: i32) -> &mut Self;
}
}
/// Windows-specific extensions.
#[cfg(windows)]
pub mod windows {
use super::__private::Sealed;
use super::*;
#[doc(no_inline)]
pub use std::os::windows::fs::MetadataExt;
/// Creates a new directory symbolic link on the filesystem.
///
/// The `dst` path will be a directory symbolic link pointing to the `src` path.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::windows::symlink_dir("a", "b").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn symlink_dir<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
let src = src.as_ref().to_owned();
let dst = dst.as_ref().to_owned();
unblock(move || std::os::windows::fs::symlink_dir(&src, &dst)).await
}
/// Creates a new file symbolic link on the filesystem.
///
/// The `dst` path will be a file symbolic link pointing to the `src` path.
///
/// # Examples
///
/// ```no_run
/// # futures_lite::future::block_on(async {
/// async_fs::windows::symlink_file("a.txt", "b.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
pub async fn symlink_file<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
let src = src.as_ref().to_owned();
let dst = dst.as_ref().to_owned();
unblock(move || std::os::windows::fs::symlink_file(&src, &dst)).await
}
/// Windows-specific extensions to [`OpenOptions`].
pub trait OpenOptionsExt: Sealed {
/// Overrides the `dwDesiredAccess` argument to the call to [`CreateFile`]
/// with the specified value.
///
/// This will override the `read`, `write`, and `append` flags on the
/// [`OpenOptions`] structure. This method provides fine-grained control over
/// the permissions to read, write and append data, attributes (like hidden
/// and system), and extended attributes.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{OpenOptions, windows::OpenOptionsExt};
///
/// # futures_lite::future::block_on(async {
/// // Open without read and write permission, for example if you only need
/// // to call `stat` on the file
/// let file = OpenOptions::new().access_mode(0).open("foo.txt").await?;
/// # std::io::Result::Ok(()) });
/// ```
///
/// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
fn access_mode(&mut self, access: u32) -> &mut Self;
/// Overrides the `dwShareMode` argument to the call to [`CreateFile`] with
/// the specified value.
///
/// By default `share_mode` is set to
/// `FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE`. This allows
/// other processes to read, write, and delete/rename the same file
/// while it is open. Removing any of the flags will prevent other
/// processes from performing the corresponding operation until the file
/// handle is closed.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{OpenOptions, windows::OpenOptionsExt};
///
/// # futures_lite::future::block_on(async {
/// // Do not allow others to read or modify this file while we have it open
/// // for writing.
/// let file = OpenOptions::new()
/// .write(true)
/// .share_mode(0)
/// .open("foo.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
///
/// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
fn share_mode(&mut self, val: u32) -> &mut Self;
/// Sets extra flags for the `dwFileFlags` argument to the call to
/// [`CreateFile2`] to the specified value (or combines it with
/// `attributes` and `security_qos_flags` to set the `dwFlagsAndAttributes`
/// for [`CreateFile`]).
///
/// Custom flags can only set flags, not remove flags set by Rust's options.
/// This option overwrites any previously set custom flags.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{OpenOptions, windows::OpenOptionsExt};
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .create(true)
/// .write(true)
/// .custom_flags(windows_sys::Win32::Storage::FileSystem::FILE_FLAG_DELETE_ON_CLOSE)
/// .open("foo.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
///
/// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
/// [`CreateFile2`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfile2
fn custom_flags(&mut self, flags: u32) -> &mut Self;
/// Sets the `dwFileAttributes` argument to the call to [`CreateFile2`] to
/// the specified value (or combines it with `custom_flags` and
/// `security_qos_flags` to set the `dwFlagsAndAttributes` for
/// [`CreateFile`]).
///
/// If a _new_ file is created because it does not yet exist and
/// `.create(true)` or `.create_new(true)` are specified, the new file is
/// given the attributes declared with `.attributes()`.
///
/// If an _existing_ file is opened with `.create(true).truncate(true)`, its
/// existing attributes are preserved and combined with the ones declared
/// with `.attributes()`.
///
/// In all other cases the attributes get ignored.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{OpenOptions, windows::OpenOptionsExt};
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .write(true)
/// .create(true)
/// .attributes(windows_sys::Win32::Storage::FileSystem::FILE_ATTRIBUTE_HIDDEN)
/// .open("foo.txt")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
///
/// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
/// [`CreateFile2`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfile2
fn attributes(&mut self, val: u32) -> &mut Self;
/// Sets the `dwSecurityQosFlags` argument to the call to [`CreateFile2`] to
/// the specified value (or combines it with `custom_flags` and `attributes`
/// to set the `dwFlagsAndAttributes` for [`CreateFile`]).
///
/// By default `security_qos_flags` is not set. It should be specified when
/// opening a named pipe, to control to which degree a server process can
/// act on behalf of a client process (security impersonation level).
///
/// When `security_qos_flags` is not set, a malicious program can gain the
/// elevated privileges of a privileged Rust process when it allows opening
/// user-specified paths, by tricking it into opening a named pipe. So
/// arguably `security_qos_flags` should also be set when opening arbitrary
/// paths. However the bits can then conflict with other flags, specifically
/// `FILE_FLAG_OPEN_NO_RECALL`.
///
/// For information about possible values, see [Impersonation Levels] on the
/// Windows Dev Center site. The `SECURITY_SQOS_PRESENT` flag is set
/// automatically when using this method.
///
/// # Examples
///
/// ```no_run
/// use async_fs::{OpenOptions, windows::OpenOptionsExt};
///
/// # futures_lite::future::block_on(async {
/// let file = OpenOptions::new()
/// .write(true)
/// .create(true)
/// .security_qos_flags(windows_sys::Win32::Storage::FileSystem::SECURITY_IDENTIFICATION)
/// .open(r"\\.\pipe\MyPipe")
/// .await?;
/// # std::io::Result::Ok(()) });
/// ```
///
/// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
/// [`CreateFile2`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfile2
/// [Impersonation Levels]: https://docs.microsoft.com/en-us/windows/win32/api/winnt/ne-winnt-security_impersonation_level
fn security_qos_flags(&mut self, flags: u32) -> &mut Self;
}
}
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