add safe Ext2 wrapper struct

src/fs.rs

@@ -0,0 +1,26 @@
+use error::Error;
+use buffer::Buffer;
+use sys::superblock::Superblock;
+
+/// Safe wrapper for raw sys structs
+pub struct Ext2<B: Buffer<u8>> {
+    buffer: B,
+    superblock: Option<(Superblock, usize)>,
+}
+
+impl<B: Buffer<u8>> Ext2<B> {
+    pub fn new(buffer: B) -> Ext2<B> {
+        Ext2 {
+            buffer,
+            superblock: None,
+        }
+    }
+
+    pub fn init(&mut self) -> Result<(), Error> {
+        let superblock = Superblock::find(&self.buffer);
+        match superblock {
+            Ok(sb) => Ok(self.superblock = Some(sb)),
+            Err(err) => Err(err),
+        }
+    }
+}