Struct virtio_queue::Reader

pub struct Reader<'a, B = ()> { /* private fields */ }

Provides high-level interface over the sequence of memory regions defined by readable descriptors in the descriptor chain.

Note that virtio spec requires driver to place any device-writable descriptors after any device-readable descriptors (2.6.4.2 in Virtio Spec v1.1). Reader will skip iterating over descriptor chain when first writable descriptor is encountered.

Implementations

impl<'a, B: BitmapSlice> Reader<'a, B>

pub fn new<M, T>( mem: &'a M, desc_chain: DescriptorChain<T> ) -> Result<Reader<'a, B>, Error>

where M: GuestMemory, <<M as GuestMemory>::R as GuestMemoryRegion>::B: WithBitmapSlice<'a, S = B>, T: Deref, T::Target: GuestMemory + Sized,

Construct a new Reader wrapper over desc_chain.

pub fn read_obj<T: ByteValued>(&mut self) -> Result<T>

Reads an object from the descriptor chain buffer.

pub fn available_bytes(&self) -> usize

Returns number of bytes available for reading. May return an error if the combined lengths of all the buffers in the DescriptorChain would cause an integer overflow.

pub fn bytes_read(&self) -> usize

Returns number of bytes already read from the descriptor chain buffer.

pub fn split_at(&mut self, offset: usize) -> Result<Reader<'a, B>, Error>

Splits this Reader into two at the given offset in the DescriptorChain buffer. After the split, self will be able to read up to offset bytes while the returned Reader can read up to available_bytes() - offset bytes. Returns an error if offset > self.available_bytes().

Trait Implementations

impl<'a, B: Clone> Clone for Reader<'a, B>

fn clone(&self) -> Reader<'a, B>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'a, B: BitmapSlice> Read for Reader<'a, B>

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

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Read the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R>

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.