Add hello example

examples/hello.rs

@@ -0,0 +1,22 @@
+extern crate syscall;
+
+use std::{
+    fs::File,
+    io::{self, prelude::*},
+    os::unix::io::{AsRawFd, FromRawFd}
+};
+
+fn from_syscall_error(error: syscall::Error) -> io::Error {
+    io::Error::from_raw_os_error(error.errno as i32)
+}
+
+fn main() -> io::Result<()> {
+    let server = File::create("chan:hello")?;
+
+    loop {
+        let stream = syscall::dup(server.as_raw_fd(), b"listen").map_err(from_syscall_error)?;
+        let mut stream = unsafe { File::from_raw_fd(stream) };
+
+        stream.write(b"Hello World!\n")?;
+    }
+}