Struct OpenOptions

pub struct OpenOptions { /* private fields */ }

Options and flags which can be used to configure how a file is opened.

Implementations

impl OpenOptions

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.

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.

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).

For most filesystems, the operating system guarantees that all writes are atomic: no writes get mangled because another process writes at the same time.

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

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.

Only take effect if OpenOptions::create is set to true.

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

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

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.

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.

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

Cancel Safety

This function is cancel safe.

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.