Struct File

pub struct File { /* private fields */ }

A reference to an open file on the host system.

Depending on the options that it was opened with, files can be read and/or written.

Files are auromatically closed when they are dropped. If an error occurs while dropping, the error is silently swallowed. Use close if these errors should be explicitly handled.

Because all semihosting operations are very slow, buffering reads and writes might be beneficial.

As the semihosting operations don’t return a specific error when they fail, most methods just return a Result<_, ()>.

Implementations

impl File

pub fn open(path: &CStr, mode: FileOpenMode) -> Result<File, ()>

Opens the file with the given mode.

pub fn write(&mut self, buf: &[u8]) -> Result<usize, ()>

Tries to write all of buffers bytes into the file, and returns the number of bytes that were actually written.

pub fn close(self) -> Result<(), File>

Closes the file.

The file is also closed when it the file is dropped. However this method is more explicit and allows to check if an error happenend while closing the file.

If an error occured, the unclosed file is returned.

pub fn len(&self) -> Result<usize, ()>

Retrieves the total number of bytes of the file

pub fn read(&mut self, buf: &mut [u8]) -> Result<usize, ()>

Tries to read buf.len() bytes from the file and returns the number of bytes that was read into the buffer.

The result Ok(0usize) suggests that EOF has been reached.

pub fn seek(&mut self, from: SeekFrom) -> Result<(), SeekError>

Sets the read/write-cursor to the specified position This actually consists of two semihosting operations: One to get the length, and another to set the cursor

If you want to set the cursor to the beginning of the file, use rewind instead.

see also: seek_unchecked

pub unsafe fn seek_unchecked(&mut self, pos: usize) -> Result<(), ()>

Sets the position of the cursor.

The position is specified relative to the beginning of the file.

See also seek for a safe, and slightly more ergonomic way to set the cursor.

Safety

The position must lie inside the extend of the file. Otherwise, the behaviour is undefined.

pub fn rewind(&mut self) -> Result<(), ()>

Sets the cursor to the beginning of the file.

In comparison to seek, this method does not need to check the length of the file or the provided index.

Trait Implementations

impl Debug for File

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

Formats the value using the given formatter.

impl Drop for File

fn drop(&mut self)

Executes the destructor for this type.

impl Hash for File

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for File

fn eq(&self, other: &File) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for File

impl StructuralPartialEq for File