use crate::fs::{asyncify, File};
use std::io;
use std::path::Path;
/// Options and flags which can be used to configure how a file is opened.
///
/// This builder exposes the ability to configure how a [`File`] is opened and
/// what operations are permitted on the open file. The [`File::open`] and
/// [`File::create`] methods are aliases for commonly used options using this
/// builder.
///
/// Generally speaking, when using `OpenOptions`, you'll first call [`new`],
/// then chain calls to methods to set each option, then call [`open`], passing
/// the path of the file you're trying to open. This will give you a
/// [`io::Result`][result] with a [`File`] inside that you can further operate
/// on.
///
/// This is a specialized version of [`std::fs::OpenOptions`] for usage from
/// the Tokio runtime.
///
/// `From<std::fs::OpenOptions>` is implemented for more advanced configuration
/// than the methods provided here.
///
/// [`new`]: OpenOptions::new
/// [`open`]: OpenOptions::open
/// [result]: std::io::Result
/// [`File`]: File
/// [`File::open`]: File::open
/// [`File::create`]: File::create
/// [`std::fs::OpenOptions`]: std::fs::OpenOptions
///
/// # Examples
///
/// Opening a file to read:
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .read(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
///
/// Opening a file for both reading and writing, as well as creating it if it
/// doesn't exist:
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .read(true)
/// .write(true)
/// .create(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
#[derive(Clone, Debug)]
pub struct OpenOptions(std::fs::OpenOptions);
impl OpenOptions {
/// Creates a blank new set of options ready for configuration.
///
/// All options are initially set to `false`.
///
/// This is an async version of [`std::fs::OpenOptions::new`][std]
///
/// [std]: std::fs::OpenOptions::new
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
///
/// let mut options = OpenOptions::new();
/// let future = options.read(true).open("foo.txt");
/// ```
pub fn new() -> OpenOptions {
OpenOptions(std::fs::OpenOptions::new())
}
/// Sets the option for read access.
///
/// This option, when true, will indicate that the file should be
/// `read`-able if opened.
///
/// This is an async version of [`std::fs::OpenOptions::read`][std]
///
/// [std]: std::fs::OpenOptions::read
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .read(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
pub fn read(&mut self, read: bool) -> &mut OpenOptions {
self.0.read(read);
self
}
/// Sets the option for write access.
///
/// This option, when true, will indicate that the file should be
/// `write`-able if opened.
///
/// This is an async version of [`std::fs::OpenOptions::write`][std]
///
/// [std]: std::fs::OpenOptions::write
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .write(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
pub fn write(&mut self, write: bool) -> &mut OpenOptions {
self.0.write(write);
self
}
/// Sets the option for the append mode.
///
/// This option, when true, means that writes will append to a file instead
/// of overwriting previous contents. Note that setting
/// `.write(true).append(true)` has the same effect as setting only
/// `.append(true)`.
///
/// For most filesystems, the operating system guarantees that all writes are
/// atomic: no writes get mangled because another process writes at the same
/// time.
///
/// One maybe obvious note when using append-mode: make sure that all data
/// that belongs together is written to the file in one operation. This
/// can be done by concatenating strings before passing them to [`write()`],
/// or using a buffered writer (with a buffer of adequate size),
/// and calling [`flush()`] when the message is complete.
///
/// If a file is opened with both read and append access, beware that after
/// opening, and after every write, the position for reading may be set at the
/// end of the file. So, before writing, save the current position (using
/// [`seek`]`(`[`SeekFrom`]`::`[`Current`]`(0))`), and restore it before the next read.
///
/// This is an async version of [`std::fs::OpenOptions::append`][std]
///
/// [std]: std::fs::OpenOptions::append
///
/// ## Note
///
/// This function doesn't create the file if it doesn't exist. Use the [`create`]
/// method to do so.
///
/// [`write()`]: crate::io::AsyncWriteExt::write
/// [`flush()`]: crate::io::AsyncWriteExt::flush
/// [`seek`]: crate::io::AsyncSeekExt::seek
/// [`SeekFrom`]: std::io::SeekFrom
/// [`Current`]: std::io::SeekFrom::Current
/// [`create`]: OpenOptions::create
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .append(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
pub fn append(&mut self, append: bool) -> &mut OpenOptions {
self.0.append(append);
self
}
/// Sets the option for truncating a previous file.
///
/// If a file is successfully opened with this option set it will truncate
/// the file to 0 length if it already exists.
///
/// The file must be opened with write access for truncate to work.
///
/// This is an async version of [`std::fs::OpenOptions::truncate`][std]
///
/// [std]: std::fs::OpenOptions::truncate
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .write(true)
/// .truncate(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
pub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions {
self.0.truncate(truncate);
self
}
/// Sets the option for creating a new file.
///
/// This option indicates whether a new file will be created if the file
/// does not yet already exist.
///
/// In order for the file to be created, [`write`] or [`append`] access must
/// be used.
///
/// This is an async version of [`std::fs::OpenOptions::create`][std]
///
/// [std]: std::fs::OpenOptions::create
/// [`write`]: OpenOptions::write
/// [`append`]: OpenOptions::append
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .write(true)
/// .create(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
pub fn create(&mut self, create: bool) -> &mut OpenOptions {
self.0.create(create);
self
}
/// Sets the option to always create a new file.
///
/// This option indicates whether a new file will be created. No file is
/// allowed to exist at the target location, also no (dangling) symlink.
///
/// This option is useful because it is atomic. Otherwise between checking
/// whether a file exists and creating a new one, the file may have been
/// created by another process (a TOCTOU race condition / attack).
///
/// If `.create_new(true)` is set, [`.create()`] and [`.truncate()`] are
/// ignored.
///
/// The file must be opened with write or append access in order to create a
/// new file.
///
/// This is an async version of [`std::fs::OpenOptions::create_new`][std]
///
/// [std]: std::fs::OpenOptions::create_new
/// [`.create()`]: OpenOptions::create
/// [`.truncate()`]: OpenOptions::truncate
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new()
/// .write(true)
/// .create_new(true)
/// .open("foo.txt")
/// .await?;
///
/// Ok(())
/// }
/// ```
pub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions {
self.0.create_new(create_new);
self
}
/// Opens a file at `path` with the options specified by `self`.
///
/// This is an async version of [`std::fs::OpenOptions::open`][std]
///
/// [std]: std::fs::OpenOptions::open
///
/// # Errors
///
/// This function will return an error under a number of different
/// circumstances. Some of these error conditions are listed here, together
/// with their [`ErrorKind`]. The mapping to [`ErrorKind`]s is not part of
/// the compatibility contract of the function, especially the `Other` kind
/// might change to more specific kinds in the future.
///
/// * [`NotFound`]: The specified file does not exist and neither `create`
/// or `create_new` is set.
/// * [`NotFound`]: One of the directory components of the file path does
/// not exist.
/// * [`PermissionDenied`]: The user lacks permission to get the specified
/// access rights for the file.
/// * [`PermissionDenied`]: The user lacks permission to open one of the
/// directory components of the specified path.
/// * [`AlreadyExists`]: `create_new` was specified and the file already
/// exists.
/// * [`InvalidInput`]: Invalid combinations of open options (truncate
/// without write access, no access mode set, etc.).
/// * [`Other`]: One of the directory components of the specified file path
/// was not, in fact, a directory.
/// * [`Other`]: Filesystem-level errors: full disk, write permission
/// requested on a read-only file system, exceeded disk quota, too many
/// open files, too long filename, too many symbolic links in the
/// specified path (Unix-like systems only), etc.
///
/// # Examples
///
/// ```no_run
/// use tokio::fs::OpenOptions;
/// use std::io;
///
/// #[tokio::main]
/// async fn main() -> io::Result<()> {
/// let file = OpenOptions::new().open("foo.txt").await?;
/// Ok(())
/// }
/// ```
///
/// [`ErrorKind`]: std::io::ErrorKind
/// [`AlreadyExists`]: std::io::ErrorKind::AlreadyExists
/// [`InvalidInput`]: std::io::ErrorKind::InvalidInput
/// [`NotFound`]: std::io::ErrorKind::NotFound
/// [`Other`]: std::io::ErrorKind::Other
/// [`PermissionDenied`]: std::io::ErrorKind::PermissionDenied
pub async fn open(&self, path: impl AsRef<Path>) -> io::Result<File> {
let path = path.as_ref().to_owned();
let opts = self.0.clone();
let std = asyncify(move || opts.open(path)).await?;
Ok(File::from_std(std))
}
}
impl From<std::fs::OpenOptions> for OpenOptions {
fn from(options: std::fs::OpenOptions) -> OpenOptions {
OpenOptions(options)
}
}
impl Default for OpenOptions {
fn default() -> Self {
Self::new()
}
}