Improve code structure

src/dir.rs

@@ -120,7 +120,7 @@ impl <'a, 'b> Dir<'a, 'b> {
         let e = self.find_entry(name, None)?;
         match rest_opt {
             Some(rest) => e.to_dir().open_dir(rest),
-            None => Ok(e.to_dir())
+            None => Ok(e.to_dir()),
         }
     }
 
@@ -130,44 +130,46 @@ impl <'a, 'b> Dir<'a, 'b> {
         let e = self.find_entry(name, None)?;
         match rest_opt {
             Some(rest) => e.to_dir().open_file(rest),
-            None => Ok(e.to_file())
+            None => Ok(e.to_file()),
         }
     }
 
     /// Creates new file or opens existing without truncating.
     pub fn create_file(&mut self, path: &str) -> io::Result<File<'a, 'b>> {
+        // traverse path
         let (name, rest_opt) = split_path(path);
-        match rest_opt {
-            // path contains more than 1 component
-            Some(rest) => self.find_entry(name, None)?.to_dir().create_file(rest),
-            None => {
+        if let Some(rest) = rest_opt {
+            return self.find_entry(name, None)?.to_dir().create_file(rest);
+        }
         // this is final filename in the path
         let mut short_name_gen = ShortNameGenerator::new(name);
         let r = self.find_entry(name, Some(&mut short_name_gen));
         match r {
+            // file does not exist - create it
             Err(ref err) if err.kind() == ErrorKind::NotFound => {
                 let short_name = short_name_gen.generate()?;
                 let sfn_entry = self.create_sfn_entry(short_name, FileAttributes::from_bits_truncate(0), None);
                 Ok(self.write_entry(name, sfn_entry)?.to_file())
             },
+            // other error
             Err(err) => Err(err),
+            // file already exists - return it
             Ok(e) => Ok(e.to_file()),
         }
     }
-        }
-    }
 
     /// Creates new directory or opens existing.
     pub fn create_dir(&mut self, path: &str) -> io::Result<Self> {
+        // traverse path
         let (name, rest_opt) = split_path(path);
-        match rest_opt {
-            // path contains more than 1 component
-            Some(rest) => self.find_entry(name, None)?.to_dir().create_dir(rest),
-            None => {
+        if let Some(rest) = rest_opt {
+            return self.find_entry(name, None)?.to_dir().create_dir(rest);
+        }
         // this is final filename in the path
         let mut short_name_gen = ShortNameGenerator::new(name);
         let r = self.find_entry(name, Some(&mut short_name_gen));
         match r {
+            // directory does not exist - create it
             Err(ref err) if err.kind() == ErrorKind::NotFound => {
                 // alloc cluster for directory data
                 let cluster = self.fs.alloc_cluster(None)?;
@@ -185,12 +187,12 @@ impl <'a, 'b> Dir<'a, 'b> {
                 dir.write_entry("..", sfn_entry)?;
                 Ok(dir)
             },
+            // other error
             Err(err) => Err(err),
+            // directory already exists - return it
             Ok(e) => Ok(e.to_dir()),
         }
     }
-        }
-    }
 
     fn is_empty(&mut self) -> io::Result<bool> {
         // check if directory contains no files
@@ -210,17 +212,18 @@ impl <'a, 'b> Dir<'a, 'b> {
     /// Make sure there is no reference to this file (no File instance) or filesystem corruption
     /// can happen.
     pub fn remove(&mut self, path: &str) -> io::Result<()> {
+        // traverse path
         let (name, rest_opt) = split_path(path);
         let e = self.find_entry(name, None)?;
-        match rest_opt {
-            Some(rest) => e.to_dir().remove(rest),
-            None => {
+        if let Some(rest) = rest_opt {
+            return e.to_dir().remove(rest);
+        }
         trace!("removing {}", path);
         // in case of directory check if it is empty
         if e.is_dir() && !e.to_dir().is_empty()? {
             return Err(io::Error::new(ErrorKind::NotFound, "removing non-empty directory is denied"));
         }
-                // free directory data
+        // free data
         if let Some(n) = e.first_cluster() {
             self.fs.free_cluster_chain(n)?;
         }
@@ -237,8 +240,6 @@ impl <'a, 'b> Dir<'a, 'b> {
         }
         Ok(())
     }
-        }
-    }
 
     /// Renames or moves existing file or directory.
     ///
@@ -464,12 +465,14 @@ impl <'a, 'b> Iterator for DirIter<'a, 'b> {
 }
 
 fn validate_long_name(name: &str) -> io::Result<()> {
+    // check if length is valid
     if name.len() == 0 {
         return Err(io::Error::new(ErrorKind::InvalidInput, "filename cannot be empty"));
     }
     if name.len() > 255 {
         return Err(io::Error::new(ErrorKind::InvalidInput, "filename is too long"));
     }
+    // check if there are only valid characters
     for c in name.chars() {
         match c {
             'a'...'z' | 'A'...'Z' | '0'...'9' | '\u{80}'...'\u{FFFF}' |