Implement Seek trait for File and rewind method in Dir.

src/dir.rs

@@ -1,12 +1,12 @@
 use std::ascii::AsciiExt;
 use std::io::prelude::*;
 use std::io;
-use std::io::ErrorKind;
+use std::io::{ErrorKind, SeekFrom};
 use std::str;
 use byteorder::{LittleEndian, ReadBytesExt};
 use chrono::{DateTime, Date, TimeZone, Local};
 
-use fs::FatSharedStateRef;
+use fs::{FatSharedStateRef, ReadSeek};
 use file::FatFile;
 
 bitflags! {
@@ -103,17 +103,18 @@ impl FatDirEntry {
 }
 
 pub struct FatDir {
-    rdr: Box<Read>,
+    rdr: Box<ReadSeek>,
     state: FatSharedStateRef,
 }
 
 impl FatDir {
     
-    pub(crate) fn new(rdr: Box<Read>, state: FatSharedStateRef) -> FatDir {
+    pub(crate) fn new(rdr: Box<ReadSeek>, state: FatSharedStateRef) -> FatDir {
         FatDir { rdr, state }
     }
     
     pub fn list(&mut self) -> io::Result<Vec<FatDirEntry>> {
+        self.rewind();
         let mut entries = Vec::new();
         loop {
             let entry = self.read_dir_entry()?;
@@ -132,6 +133,10 @@ impl FatDir {
         Ok(entries)
     }
     
+    pub fn rewind(&mut self) {
+        self.rdr.seek(SeekFrom::Start(0)).unwrap();
+    }
+    
     fn read_dir_entry(&mut self) -> io::Result<FatDirEntry> {
         let mut name = [0; 11];
         self.rdr.read(&mut name)?;
@@ -161,7 +166,6 @@ impl FatDir {
     }
     
     fn find_entry(&mut self, name: &str) -> io::Result<FatDirEntry> {
-        // FIXME: we should seek to beggining here
         let entries: Vec<FatDirEntry> = self.list()?;
         for e in entries {
             if e.get_name().eq_ignore_ascii_case(name) {

src/file.rs

@@ -1,6 +1,6 @@
 use std::cmp;
 use std::io::prelude::*;
-use std::io::SeekFrom;
+use std::io::{SeekFrom, ErrorKind};
 use std::io;
 
 use fs::FatSharedStateRef;
@@ -54,3 +54,26 @@ impl Read for FatFile {
         Ok(buf_offset)
     }
 }
+
+impl Seek for FatFile {
+    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
+        let new_offset = match pos {
+            SeekFrom::Current(x) => self.offset as i64 + x,
+            SeekFrom::Start(x) => x as i64,
+            SeekFrom::End(x) => self.size.unwrap() as i64 + x,
+        };
+        if new_offset < 0 || (self.size.is_some() && new_offset as u64 > self.size.unwrap() as u64) {
+            return Err(io::Error::new(ErrorKind::InvalidInput, "invalid seek"));
+        }
+        let cluster_size = self.state.borrow().get_cluster_size();
+        let cluster_count = (new_offset / cluster_size as i64) as usize;
+        let mut new_cluster = Some(self.first_cluster);
+        let state = self.state.borrow_mut();
+        for _ in 0..cluster_count {
+            new_cluster = state.table.get_next_cluster(new_cluster.unwrap());
+        }
+        self.offset = new_offset as u32;
+        self.current_cluster = new_cluster;
+        Ok(self.offset as u64)
+    }
+}

src/fs.rs

@@ -242,7 +242,7 @@ impl FatFileSystem {
     
     pub fn root_dir(&mut self) -> FatDir {
         let state = self.state.borrow();
-        let root_rdr: Box<Read> = match state.fat_type {
+        let root_rdr: Box<ReadSeek> = match state.fat_type {
             FatType::Fat12 | FatType::Fat16 => Box::new(FatSlice::from_sectors(
                 state.first_data_sector - state.root_dir_sectors, state.root_dir_sectors, self.state.clone())),
             _ => Box::new(FatFile::new(state.boot.bpb.root_cluster, None, self.state.clone())) // FIXME
@@ -280,3 +280,19 @@ impl Read for FatSlice {
         Ok(size)
     }
 }
+
+impl Seek for FatSlice {
+    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
+        let new_offset = match pos {
+            SeekFrom::Current(x) => self.offset as i64 + x,
+            SeekFrom::Start(x) => x as i64,
+            SeekFrom::End(x) => self.size as i64 + x,
+        };
+        if new_offset < 0 || new_offset as u64 > self.size {
+            Err(io::Error::new(ErrorKind::InvalidInput, "invalid seek"))
+        } else {
+            self.offset = new_offset as u64;
+            Ok(self.offset)
+        }
+    }
+}

tests/integration-test.rs

@@ -1,7 +1,7 @@
 extern crate rustfat;
 
 use std::fs::File;
-use std::io::BufReader;
+use std::io::{BufReader, SeekFrom};
 use std::io::prelude::*;
 use std::str;
 
@@ -15,16 +15,23 @@ fn test_img(name: &str) {
     let mut fs = FatFileSystem::new(Box::new(buf_rdr)).unwrap();
     let mut root_dir = fs.root_dir();
     let entries = root_dir.list().unwrap();
-    assert_eq!(entries.len(), 3);
-    assert_eq!(entries[0].get_name(), "LONG.TXT");
-    assert_eq!(entries[1].get_name(), "SHORT.TXT");
-    assert_eq!(entries[2].get_name(), "VERY");
+    let names = entries.iter().map(|e| e.get_name()).collect::<Vec<String>>();
+    assert_eq!(names, ["LONG.TXT", "SHORT.TXT", "VERY"]);
+    // Try read again
+    let entries = root_dir.list().unwrap();
+    let names2 = entries.iter().map(|e| e.get_name()).collect::<Vec<String>>();
+    assert_eq!(names2, names);
     
     {
         let mut short_file = entries[1].get_file();
         let mut buf = Vec::new();
         short_file.read_to_end(&mut buf).unwrap();
         assert_eq!(str::from_utf8(&buf).unwrap(), TEST_TEXT);
+        
+        short_file.seek(SeekFrom::Start(5)).unwrap();
+        buf.clear();
+        short_file.read_to_end(&mut buf).unwrap();
+        assert_eq!(str::from_utf8(&buf).unwrap(), &TEST_TEXT[5..]);
     }
     
     {