passfd allows passing file descriptors between unrelated processes using Unix sockets.

Both tokio 0.1 and 0.2 are supported with tokio_01 and tokio_02 features. Please note that these features rely on internal representation of UnixStream and are unsafe.

Example usage

Process 1 (sender)

use passfd::FdPassingExt;
use std::fs::File;
use std::os::unix::io::AsRawFd;
use std::os::unix::net::UnixListener;

let file = File::open("/etc/passwd").unwrap();
let listener = UnixListener::bind("/tmp/test.sock").unwrap();
let (stream, _) = listener.accept().unwrap();
stream.send_fd(file.as_raw_fd()).unwrap();

Process 2 (receiver)

use passfd::FdPassingExt;
use std::fs::File;
use std::io::Read;
use std::os::unix::io::FromRawFd;
use std::os::unix::net::UnixStream;

let stream = UnixStream::connect("/tmp/test.sock").unwrap();
let fd = stream.recv_fd().unwrap();
let mut file = unsafe { File::from_raw_fd(fd) };
let mut buf = String::new();
file.read_to_string(&mut buf).unwrap();
println!("{}", buf);

passfd

Unix sockets possess magic ability to transfer file descriptors from one process to another (unrelated) process using obscure SCM_RIGHTS API. This little crate adds extension methods to UnixStream to use it.

Links

• fd-passing same thing, different API
• Good article on fd passing