Add fsync. Add env scheme, currently hardcoded to get ion to launch. Make serial IRQ send data to debug scheme

kernel/scheme/debug.rs

@@ -1,8 +1,25 @@
+use collections::VecDeque;
 use core::str;
+use spin::{Mutex, MutexGuard, Once};
 
+use context;
 use syscall::Result;
 use super::Scheme;
 
+/// Input
+static INPUT: Once<Mutex<VecDeque<u8>>> = Once::new();
+
+/// Initialize contexts, called if needed
+fn init_input() -> Mutex<VecDeque<u8>> {
+    Mutex::new(VecDeque::new())
+}
+
+/// Get the global schemes list, const
+#[no_mangle]
+pub extern fn debug_input(b: u8) {
+    INPUT.call_once(init_input).lock().push_back(b)
+}
+
 pub struct DebugScheme;
 
 impl Scheme for DebugScheme {
@@ -17,8 +34,23 @@ impl Scheme for DebugScheme {
     /// Read the file `number` into the `buffer`
     ///
     /// Returns the number of bytes read
-    fn read(&mut self, _file: usize, _buffer: &mut [u8]) -> Result<usize> {
-        Ok(0)
+    fn read(&mut self, _file: usize, buf: &mut [u8]) -> Result<usize> {
+        loop {
+            let mut i = 0;
+            {
+                let mut input = INPUT.call_once(init_input).lock();
+                while i < buf.len() && ! input.is_empty() {
+                    buf[i] = input.pop_front().expect("debug_input lost byte");
+                    i += 1;
+                }
+            }
+
+            if i > 0 {
+                return Ok(i);
+            } else {
+                unsafe { context::switch(); }
+            }
+        }
     }
 
     /// Write the `buffer` to the `file`
@@ -30,6 +62,10 @@ impl Scheme for DebugScheme {
         Ok(buffer.len())
     }
 
+    fn fsync(&mut self, file: usize) -> Result<()> {
+        Ok(())
+    }
+
     /// Close the file `number`
     fn close(&mut self, _file: usize) -> Result<()> {
         Ok(())