Allow read of filesystem names

src/filesystem.rs

@@ -0,0 +1,45 @@
+use std::cmp;
+use std::collections::BTreeMap;
+
+use super::{Disk, Header, Node};
+
+/// A file system
+pub struct FileSystem {
+    pub disk: Box<Disk>,
+    pub header: Header,
+    pub nodes: BTreeMap<u64, Node>,
+}
+
+impl FileSystem {
+    /// Create a file system from a disk
+    pub fn new(mut disk: Box<Disk>) -> 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)));
+        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 {
+                disk: disk,
+                header: header,
+                nodes: nodes,
+            })
+        }else{
+            Err(format!("{}: invalid header", disk.name()))
+        }
+    }
+}