Dont assume cluster iterator always succeeds.

src/file.rs

@@ -50,7 +50,11 @@ impl <'a, 'b> Read for FatFile<'a, 'b> {
             self.offset += read_bytes as u32;
             buf_offset += read_bytes;
             if self.offset % cluster_size == 0 {
-                self.current_cluster = self.fs.cluster_iter(current_cluster).skip(1).next();
+                match self.fs.cluster_iter(current_cluster).skip(1).next() {
+                    Some(Err(err)) => return Err(err),
+                    Some(Ok(n)) => self.current_cluster = Some(n),
+                    None => self.current_cluster = None,
+                }
             }
         }
         Ok(buf_offset)
@@ -71,7 +75,11 @@ impl <'a, 'b> Seek for FatFile<'a, 'b> {
         let cluster_count = (new_offset / cluster_size as i64) as usize;
         let mut new_cluster = Some(self.first_cluster);
         if cluster_count > 0 {
-            new_cluster = self.fs.cluster_iter(new_cluster.unwrap()).skip(cluster_count).next();
+            match self.fs.cluster_iter(new_cluster.unwrap()).skip(cluster_count).next() {
+                Some(Err(err)) => return Err(err),
+                Some(Ok(n)) => new_cluster = Some(n),
+                None => new_cluster = None,
+            }
         }
         self.offset = new_offset as u32;
         self.current_cluster = new_cluster;

src/fs.rs

@@ -214,7 +214,7 @@ impl <'a> FatFileSystem<'a> {
         self.offset_from_sector(self.sector_from_cluster(cluser))
     }
     
-    pub(crate) fn cluster_iter<'b>(&'b self, cluster: u32) -> iter::Chain<iter::Once<u32>, FatClusterIterator<'b, 'a>> {
+    pub(crate) fn cluster_iter<'b>(&'b self, cluster: u32) -> iter::Chain<iter::Once<io::Result<u32>>, FatClusterIterator<'b, 'a>> {
         let bytes_per_sector = self.boot.bpb.bytes_per_sector as u64;
         let fat_offset = self.boot.bpb.reserved_sectors as u64 * bytes_per_sector;
         let sectors_per_fat =

src/table.rs

@@ -51,27 +51,47 @@ fn get_next_cluster_32(rdr: &mut ReadSeek, cluster: u32) -> io::Result<Option<u3
 }
 
 pub(crate) struct FatClusterIterator<'a, 'b: 'a> {
-    part: FatSlice<'a, 'b>,
+    rdr: FatSlice<'a, 'b>,
     fat_type: FatType,
     cluster: Option<u32>,
+    err: bool,
 }
 
 impl <'a, 'b> FatClusterIterator<'a, 'b> {
-    pub(crate) fn new(part: FatSlice<'a, 'b>, fat_type: FatType, cluster: u32) -> iter::Chain<iter::Once<u32>, FatClusterIterator<'a, 'b>> {
+    pub(crate) fn new(rdr: FatSlice<'a, 'b>, fat_type: FatType, cluster: u32)
+    -> iter::Chain<iter::Once<io::Result<u32>>, FatClusterIterator<'a, 'b>> {
         let iter = FatClusterIterator {
-            part: part,
+            rdr: rdr,
             fat_type: fat_type,
             cluster: Some(cluster),
+            err: false,
         };
-        iter::once(cluster).chain(iter)
+        iter::once(Ok(cluster)).chain(iter)
     }
 }
 
 impl <'a, 'b> Iterator for FatClusterIterator<'a, 'b> {
-    type Item = u32;
+    type Item = io::Result<u32>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        self.cluster = get_next_cluster(&mut self.part, self.fat_type, self.cluster.unwrap()).unwrap(); // FIXME: unwrap!
-        self.cluster
+        if self.err {
+            return None;
+        }
+        match self.cluster {
+            Some(current_cluster) => {
+                self.cluster = match get_next_cluster(&mut self.rdr, self.fat_type, current_cluster) {
+                    Ok(next_cluster) => next_cluster,
+                    Err(err) => {
+                        self.err = true;
+                        return Some(Err(err));
+                    },
+                }
+            },
+            None => {},
+        };
+        match self.cluster {
+            Some(n) => Some(Ok(n)),
+            None => None,
+        }
     }
 }