Struct Descriptor

#[repr(C)]
pub struct Descriptor { /* private fields */ }

A virtio descriptor constraints with C representation.

Example

use virtio_queue::{desc::{split::Descriptor as SplitDescriptor, RawDescriptor}, Queue, QueueOwnedT};
use vm_memory::{GuestAddress, GuestMemoryMmap};

let m = &GuestMemoryMmap::<()>::from_ranges(&[(GuestAddress(0), 0x10000)]).unwrap();
// Populate the queue with descriptor chains and update the available ring accordingly.
let mut queue = populate_queue(m);
let mut i = queue.iter(m).unwrap();
let mut c = i.next().unwrap();

// Get the first descriptor and access its fields.
let desc = c.next().unwrap();
let _addr = desc.addr();
let _len = desc.len();
let _flags = desc.flags();
let _next = desc.next();
let _is_write_only = desc.is_write_only();
let _has_next = desc.has_next();
let _refers_to_ind_table = desc.refers_to_indirect_table();

A virtio split descriptor constraints with C representation.

Implementations

impl Descriptor

pub fn new(addr: u64, len: u32, flags: u16, next: u16) -> Self

Create a new descriptor.

Arguments

• addr - the guest physical address of the descriptor buffer.
• len - the length of the descriptor buffer.
• flags - the flags for the descriptor.
• next - the next field of the descriptor.

pub fn addr(&self) -> GuestAddress

Return the guest physical address of the descriptor buffer.

pub fn len(&self) -> u32

Return the length of the descriptor buffer.

pub fn flags(&self) -> u16

Return the flags for this descriptor, including next, write and indirect bits.

pub fn next(&self) -> u16

Return the value stored in the next field of the descriptor.

pub fn refers_to_indirect_table(&self) -> bool

Check whether this descriptor refers to a buffer containing an indirect descriptor table.

pub fn has_next(&self) -> bool

Check whether the VIRTQ_DESC_F_NEXT is set for the descriptor.

pub fn is_write_only(&self) -> bool

Check if the driver designated this as a write only descriptor.

If this is false, this descriptor is read only. Write only means the the emulated device can write and the driver can read.

Trait Implementations

impl ByteValued for Descriptor

fn from_slice(data: &[u8]) -> Option<&Self>

Converts a slice of raw data into a reference of Self.

fn from_mut_slice(data: &mut [u8]) -> Option<&mut Self>

Converts a mutable slice of raw data into a mutable reference of Self.

fn as_slice(&self) -> &[u8]

Converts a reference to self into a slice of bytes.

fn as_mut_slice(&mut self) -> &mut [u8]

Converts a mutable reference to self into a mutable slice of bytes.

fn as_bytes(&mut self) -> VolatileSlice<'_>

Converts a mutable reference to self into a VolatileSlice. This is useful because VolatileSlice provides a Bytes<usize> implementation.

impl Clone for Descriptor

fn clone(&self) -> Descriptor

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Descriptor

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

Formats the value using the given formatter.

impl Default for Descriptor

fn default() -> Descriptor

Returns the “default value” for a type.

impl From<Descriptor> for RawDescriptor

fn from(desc: Descriptor) -> Self

Converts to this type from the input type.

impl From<RawDescriptor> for Descriptor

fn from(desc: RawDescriptor) -> Descriptor

Converts to this type from the input type.

impl Copy for Descriptor