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

kernel/scheme/env.rs

@@ -0,0 +1,88 @@
+use collections::BTreeMap;
+
+use syscall::{Error, Result};
+use super::Scheme;
+
+struct Handle {
+    data: &'static [u8],
+    seek: usize
+}
+
+pub struct EnvScheme {
+    next_id: usize,
+    files: BTreeMap<&'static [u8], &'static [u8]>,
+    handles: BTreeMap<usize, Handle>
+}
+
+impl EnvScheme {
+    pub fn new() -> EnvScheme {
+        let mut files: BTreeMap<&'static [u8], &'static [u8]> = BTreeMap::new();
+
+        files.insert(b"HOME", b"initfs:");
+        files.insert(b"PWD", b"initfs:");
+        files.insert(b"COLUMNS", b"80");
+        files.insert(b"LINES", b"30");
+
+        EnvScheme {
+            next_id: 0,
+            files: files,
+            handles: BTreeMap::new()
+        }
+    }
+}
+
+impl Scheme for EnvScheme {
+    fn open(&mut self, path: &[u8], _flags: usize) -> Result<usize> {
+        let data = self.files.get(path).ok_or(Error::NoEntry)?;
+
+        let id = self.next_id;
+        self.next_id += 1;
+        self.handles.insert(id, Handle {
+            data: data,
+            seek: 0
+        });
+
+        Ok(id)
+    }
+
+    fn dup(&mut self, file: usize) -> Result<usize> {
+        let (data, seek) = {
+            let handle = self.handles.get(&file).ok_or(Error::BadFile)?;
+            (handle.data, handle.seek)
+        };
+
+        let id = self.next_id;
+        self.next_id += 1;
+        self.handles.insert(id, Handle {
+            data: data,
+            seek: seek
+        });
+
+        Ok(id)
+    }
+
+    fn read(&mut self, file: usize, buffer: &mut [u8]) -> Result<usize> {
+        let mut handle = self.handles.get_mut(&file).ok_or(Error::BadFile)?;
+
+        let mut i = 0;
+        while i < buffer.len() && handle.seek < handle.data.len() {
+            buffer[i] = handle.data[handle.seek];
+            i += 1;
+            handle.seek += 1;
+        }
+
+        Ok(i)
+    }
+
+    fn write(&mut self, _file: usize, _buffer: &[u8]) -> Result<usize> {
+        Err(Error::NotPermitted)
+    }
+
+    fn fsync(&mut self, file: usize) -> Result<()> {
+        Ok(())
+    }
+
+    fn close(&mut self, file: usize) -> Result<()> {
+        self.handles.remove(&file).ok_or(Error::BadFile).and(Ok(()))
+    }
+}