Struct FileBackedDevice

pub struct FileBackedDevice { /* private fields */ }

FileBackedDevice is an implementation of Device backed by a std::fs::File. It is intended to be used for host tooling (to create or verify fxfs images), although it could also be used on Fuchsia builds if we wanted to do that for whatever reason.

Implementations

impl FileBackedDevice

pub fn new(file: File, block_size: u32) -> Self

Creates a new FileBackedDevice over |file|. The size of the file will be used as the size of the Device.

pub fn new_with_block_count( file: File, block_size: u32, block_count: u64, ) -> Self

Creates a new FileBackedDevice over |file| using an explicit size. The underlying file is not truncated to the target size, so the file size will be exactly as large as the filesystem ends up using within the file. With a sequential allocator, this makes the file as big as it needs to be and no more.

Trait Implementations

impl Device for FileBackedDevice

fn allocate_buffer(&self, size: usize) -> BufferFuture<'_>

Allocates a transfer buffer of at least |size| bytes for doing I/O with the device. The actual size of the buffer will be rounded up to a block-aligned size.

fn block_size(&self) -> u32

Returns the block size of the device. Buffers are aligned to block-aligned chunks.

fn block_count(&self) -> u64

Returns the number of blocks of the device.

fn read<'life0, 'life1, 'async_trait>( &'life0 self, offset: u64, buffer: MutableBufferRef<'life1>, ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Fills |buffer| with blocks read from |offset|.

fn write_with_opts<'life0, 'life1, 'async_trait>( &'life0 self, offset: u64, buffer: BufferRef<'life1>, _opts: WriteOptions, ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Writes the contents of |buffer| to the device at |offset|.

fn trim<'life0, 'async_trait>( &'life0 self, range: Range<u64>, ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Trims the given device |range|.

fn close<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Closes the block device. It is an error to continue using the device after this, but close itself is idempotent.

fn flush<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Flush the device.

fn is_read_only(&self) -> bool

Returns whether the device is read-only.

fn supports_trim(&self) -> bool

Returns whether the device supports trim.

fn size(&self) -> u64

Returns the size in bytes of the device.

fn write<'life0, 'life1, 'async_trait>( &'life0 self, offset: u64, buffer: BufferRef<'life1>, ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Writes the contents of |buffer| to the device at |offset|.

fn reopen(&self, _read_only: bool)

Reopens the device, making it usable again. (Only implemented for testing devices.)

fn snapshot(&self) -> Result<DeviceHolder, Error>

Returns a snapshot of the device.

fn discard_random_since_last_flush(&self) -> Result<(), Error>

Discards random blocks since the last flush.

fn poison(&self) -> Result<(), Error>

Poisons a device to panic on drop. Used to find hanging references.