Struct compio_fs::OpenOptions

pub struct OpenOptions(/* private fields */);

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 OpenOptions::new, then chain calls to methods to set each option, then call OpenOptions::open, passing the path of the file you’re trying to open. This will give you a std::io::Result with a File inside that you can further operate on.

Examples

Opening a file to read:

use compio_fs::OpenOptions;

let file = OpenOptions::new().read(true).open("foo.txt").unwrap();

Opening a file for both reading and writing, as well as creating it if it doesn’t exist:

use compio_fs::OpenOptions;

let file = OpenOptions::new()
    .read(true)
    .write(true)
    .create(true)
    .open("foo.txt")
    .unwrap();

Implementations

impl OpenOptions

pub fn new() -> Self

Creates a blank new set of options ready for configuration.

pub fn read(self, read: bool) -> Self

Sets the option for read access.

This option, when true, will indicate that the file should be read-able if opened.

pub fn write(self, write: bool) -> Self

Sets the option for write access.

This option, when true, will indicate that the file should be write-able if opened.

pub fn truncate(self, truncate: bool) -> 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.

pub fn create(self, create: bool) -> Self

Sets the option to create a new file, or open it if it already exists.

In order for the file to be created, OpenOptions::write access must be used.

pub fn create_new(self, create_new: bool) -> Self

Sets the option to create a new file, failing if it already exists.

No file is allowed to exist at the target location, also no (dangling) symlink. In this way, if the call succeeds, the file returned is guaranteed to be new.

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.

pub fn open(self, path: impl AsRef<Path>) -> Result<File>

Opens a file at path with the options specified by self.

See std::fs::OpenOptions::open.

Trait Implementations

impl Clone for OpenOptions

fn clone(&self) -> OpenOptions

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for OpenOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.