Trait ScmSocket

pub trait ScmSocket {
    // Required method
    fn socket_fd(&self) -> RawFd;

    // Provided methods
    fn send_with_fd<D: IntoIovec>(&self, buf: D, fd: RawFd) -> Result<usize> { ... }
    fn send_with_fds<D: IntoIovec>(
        &self,
        bufs: &[D],
        fds: &[RawFd],
    ) -> Result<usize> { ... }
    fn recv_with_fd(&self, buf: &mut [u8]) -> Result<(usize, Option<File>)> { ... }
    unsafe fn recv_with_fds(
        &self,
        iovecs: &mut [iovec],
        fds: &mut [RawFd],
    ) -> Result<(usize, usize)> { ... }
}

Trait for file descriptors can send and receive socket control messages via sendmsg and recvmsg.

Examples

extern crate vmm_sys_util;
use vmm_sys_util::sock_ctrl_msg::ScmSocket;


let (s1, s2) = UnixDatagram::pair().expect("failed to create socket pair");
let evt = EventFd::new(0).expect("failed to create eventfd");

let write_count = s1
    .send_with_fds(&[[237].as_ref()], &[evt.as_raw_fd()])
    .expect("failed to send fd");

let mut files = [0; 2];
let mut buf = [0u8];
let mut iovecs = [iovec {
    iov_base: buf.as_mut_ptr() as *mut c_void,
    iov_len: buf.len(),
}];
let (read_count, file_count) = unsafe {
    s2.recv_with_fds(&mut iovecs[..], &mut files)
        .expect("failed to recv fd")
};

let mut file = unsafe { File::from_raw_fd(files[0]) };
file.write(unsafe { from_raw_parts(&1203u64 as *const u64 as *const u8, 8) })
    .expect("failed to write to sent fd");
assert_eq!(evt.read().expect("failed to read from eventfd"), 1203);

Required Methods

fn socket_fd(&self) -> RawFd

Gets the file descriptor of this socket.

Provided Methods

fn send_with_fd<D: IntoIovec>(&self, buf: D, fd: RawFd) -> Result<usize>

Sends the given data and file descriptor over the socket.

On success, returns the number of bytes sent.

Arguments

• buf - A buffer of data to send on the socket.
• fd - A file descriptors to be sent.

fn send_with_fds<D: IntoIovec>( &self, bufs: &[D], fds: &[RawFd], ) -> Result<usize>

Sends the given data and file descriptors over the socket.

On success, returns the number of bytes sent.

Arguments

• bufs - A list of data buffer to send on the socket.
• fds - A list of file descriptors to be sent.

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

Receives data and potentially a file descriptor from the socket.

On success, returns the number of bytes and an optional file descriptor.

Arguments

• buf - A buffer to receive data from the socket.

unsafe fn recv_with_fds( &self, iovecs: &mut [iovec], fds: &mut [RawFd], ) -> Result<(usize, usize)>

Receives data and file descriptors from the socket.

On success, returns the number of bytes and file descriptors received as a tuple (bytes count, files count).

Arguments

• iovecs - A list of iovec to receive data from the socket.
• fds - A slice of RawFds to put the received file descriptors into. On success, the number of valid file descriptors is indicated by the second element of the returned tuple. The caller owns these file descriptors, but they will not be closed on drop like a File-like type would be. It is recommended that each valid file descriptor gets wrapped in a drop type that closes it after this returns.

Safety

It is the callers responsibility to ensure it is safe for arbitrary data to be written to the iovec pointers.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl ScmSocket for UnixDatagram

fn socket_fd(&self) -> RawFd

impl ScmSocket for UnixStream

fn socket_fd(&self) -> RawFd

Implementors