Struct OpenOptions

Source

pub struct OpenOptions { /* private fields */ }

Implementations§

Source §

impl OpenOptions

Source

pub fn new() -> Self

Creates a blank new set of options ready for configuration.

All options are initially set to false.

§Examples

use tauri_plugin_fs::OpenOptions;

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

Source

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

Sets the option for read access.

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

§Examples

use tauri_plugin_fs::OpenOptions;

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

Source

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

Sets the option for write access.

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

If the file already exists, any write calls on it will overwrite its contents, without truncating it.

§Examples

use tauri_plugin_fs::OpenOptions;

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

Source

pub fn append(&mut self, append: bool) -> &mut 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).

Append mode guarantees that writes will be positioned at the current end of file, even when there are other processes or threads appending to the same file. This is unlike seek([SeekFrom]::End(0)) followed by write(), which has a race between seeking and writing during which another writer can write, with our write() overwriting their data.

Keep in mind that this does not necessarily guarantee that data appended by different processes or threads does not interleave. The amount of data accepted a single write() call depends on the operating system and file system. A successful write() is allowed to write only part of the given data, so even if you’re careful to provide the whole message in a single call to write(), there is no guarantee that it will be written out in full. If you rely on the filesystem accepting the message in a single write, make sure that all data that belongs together is written in one operation. This can be done by concatenating strings before passing them to write().

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::stream_position), and restore it before the next read.

§Note

This function doesn’t create the file if it doesn’t exist. Use the OpenOptions::create method to do so.

§Examples

use tauri_plugin_fs::OpenOptions;

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

Source

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

§Examples

use tauri_plugin_fs::OpenOptions;

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

Source

pub fn create(&mut self, create: bool) -> &mut 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 or OpenOptions::append access must be used.

§Examples

use tauri_plugin_fs::OpenOptions;

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

Source

pub fn create_new(&mut self, create_new: bool) -> &mut 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. If a file exists at the target location, creating a new file will fail with AlreadyExists or another error based on the situation. See [OpenOptions::open] for a non-exhaustive list of likely errors.

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.

§Examples

use tauri_plugin_fs::OpenOptions;

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