Create example userspace scheme. Remove kernel duplication of syscalls, use syscall crate instead

schemes/example/src/main.rs

@@ -0,0 +1,38 @@
+extern crate syscall;
+
+use std::fs::File;
+use std::io::{Read, Write};
+use std::str;
+use std::thread;
+
+use syscall::{Packet, Result, Scheme};
+
+struct ExampleScheme;
+
+impl Scheme for ExampleScheme {
+    fn open(&self, path: &[u8], _flags: usize) -> Result<usize> {
+        println!("{}", unsafe { str::from_utf8_unchecked(path) });
+        Ok(0)
+    }
+
+    fn dup(&self, file: usize) -> Result<usize> {
+        Ok(file)
+    }
+
+    fn close(&self, _file: usize) -> Result<usize> {
+        Ok(0)
+    }
+}
+
+fn main(){
+    thread::spawn(move || {
+        let mut socket = File::create(":example").expect("example: failed to create example scheme");
+        let scheme = ExampleScheme;
+        loop {
+            let mut packet = Packet::default();
+            socket.read(&mut packet).expect("example: failed to read events from example scheme");
+            scheme.handle(&mut packet);
+            socket.write(&packet).expect("example: failed to write responses to example scheme");
+        }
+    });
+}