From 3158f9c7c0ff4fa7f6969d3f76fdc5177ef9e2eb Mon Sep 17 00:00:00 2001
From: Alex Lyon <arcterus@mail.com>
Date: Fri, 15 Dec 2017 19:59:14 -0800
Subject: [PATCH] Move zero scheme from kernel space to user space

---
 .gitignore    |  3 +++
 Cargo.toml    |  7 ++++++
 src/main.rs   | 28 ++++++++++++++++++++++++
 src/scheme.rs | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 98 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.toml
 create mode 100644 src/main.rs
 create mode 100644 src/scheme.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000..0196246bdd
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+
+/target/
+**/*.rs.bk
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000000..ab09cc3f00
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "zerod"
+version = "0.1.0"
+authors = ["Alex Lyon <arcterus@mail.com>"]
+
+[dependencies]
+redox_syscall = "*"
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000000..88589ea7f9
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,28 @@
+extern crate syscall;
+
+use syscall::data::Packet;
+use syscall::scheme::Scheme;
+use std::fs::File;
+use std::io::{Read, Write};
+use std::mem::size_of;
+use scheme::ZeroScheme;
+
+mod scheme;
+
+fn main() {
+    if unsafe { syscall::clone(0).unwrap() } == 0 {
+        let mut socket = File::create(":zero").expect("zerod: failed to create zero scheme");
+        let scheme = ZeroScheme;
+
+        syscall::setrens(0, 0).expect("zerod: failed to enter null namespace");
+
+        loop {
+            let mut packet = Packet::default();
+            socket.read(&mut packet).expect("zerod: failed to read events from zero scheme");
+
+            scheme.handle(&mut packet);
+
+            socket.write(&packet).expect("zerod: failed to write responses to zero scheme");
+        }
+    }
+}
diff --git a/src/scheme.rs b/src/scheme.rs
new file mode 100644
index 0000000000..91f5871460
--- /dev/null
+++ b/src/scheme.rs
@@ -0,0 +1,60 @@
+use syscall::error::*;
+use syscall::scheme::Scheme;
+
+use std::cmp;
+
+pub struct ZeroScheme;
+
+impl Scheme for ZeroScheme {
+    fn open(&self, _path: &[u8], _flags: usize, _uid: u32, _gid: u32) -> Result<usize> {
+        Ok(0)
+    }
+
+    fn dup(&self, _file: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(EINVAL));
+        }
+
+        Ok(0)
+    }
+
+    /// Read the file `number` into the `buffer`
+    ///
+    /// Returns the number of bytes read
+    fn read(&self, _file: usize, buf: &mut [u8]) -> Result<usize> {
+        let size = buf.len();
+
+        buf[..size].iter_mut().for_each(|val| *val = 0);
+
+        Ok(size)
+    }
+
+    /// Write the `buffer` to the `file`
+    ///
+    /// Returns the number of bytes written
+    fn write(&self, _file: usize, buffer: &[u8]) -> Result<usize> {
+        Ok(buffer.len())
+    }
+
+    fn fcntl(&self, _id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        Ok(0)
+    }
+
+    fn fpath(&self, _id: usize, buf: &mut [u8]) -> Result<usize> {
+        let scheme_path = b"zero:";
+        let size = cmp::min(buf.len(), scheme_path.len());
+
+        buf[..size].copy_from_slice(&scheme_path[..size]);
+
+        Ok(size)
+    }
+
+    fn fsync(&self, _file: usize) -> Result<usize> {
+        Ok(0)
+    }
+
+    /// Close the file `number`
+    fn close(&self, _file: usize) -> Result<usize> {
+        Ok(0)
+    }
+}