Cleanup, add node and header commands

src/filesystem.rs

@@ -1,50 +1,41 @@
 use alloc::boxed::Box;
 
-use collections::{BTreeMap, String};
-
-use core::cmp;
-
-use core::fmt::Display;
-
 use super::{Disk, Header, Node};
 
 /// A file system
 pub struct FileSystem<E> {
     pub disk: Box<Disk<E>>,
     pub header: Header,
-    pub nodes: BTreeMap<u64, Node>,
 }
 
-impl<E: Display> FileSystem<E> {
-    /// Create a file system from a disk
-    pub fn new(mut disk: Box<Disk<E>>) -> Result<Self, String> {
-        let mut header = Header::new();
-        try!(disk.read_at(1, &mut header).map_err(|err| format!("{}: could not read header: {}", disk.name(), err)));
+impl<E> FileSystem<E> {
+    /// Open a file system on a disk
+    pub fn open(mut disk: Box<Disk<E>>) -> Result<Option<Self>, E> {
+        let mut header = Header::default();
+        try!(disk.read_at(1, &mut header));
         if header.valid() {
-            let mut nodes = BTreeMap::new();
-            for extent in &header.extents {
-                if extent.block > 0 && extent.length > 0 {
-                    let current_sectors = (extent.length + 511) / 512;
-                    let max_size = current_sectors * 512;
-
-                    let size = cmp::min(extent.length, max_size);
-
-                    for i in 0..size / 512 {
-                        let node_block = extent.block + i;
-                        let mut node = Node::new();
-                        try!(disk.read_at(node_block, &mut node).map_err(|err| format!("{}: could not read node {}: {}", disk.name(), node_block, err)));
-                        nodes.insert(node_block, node);
-                    }
-                }
-            }
-
-            Ok(FileSystem {
+            Ok(Some(FileSystem {
                 disk: disk,
                 header: header,
-                nodes: nodes,
-            })
+            }))
         }else{
-            Err(format!("{}: invalid header", disk.name()))
+            Ok(None)
         }
     }
+
+    /// Create a file system on a disk
+    pub fn create(mut disk: Box<Disk<E>>) -> Result<Self, E> {
+        let header = Header::new();
+        try!(disk.write_at(1, &header));
+        Ok(FileSystem {
+            disk: disk,
+            header: header,
+        })
+    }
+
+    pub fn node(&mut self, block: u64) -> Result<Node, E> {
+        let mut node = Node::default();
+        try!(self.disk.read_at(block, &mut node));
+        Ok(node)
+    }
 }