Allow renaming to the same name

src/dir.rs

@@ -302,6 +302,10 @@ impl <'a, T: ReadWriteSeek + 'a> Dir<'a, T> {
         let mut short_name_gen = ShortNameGenerator::new(dst_name);
         let r = dst_dir.find_entry(dst_name, None, Some(&mut short_name_gen));
         if r.is_ok() {
+            // check if source and destination entry is the same
+            if e.is_same_entry(&r.unwrap()) {
+                return Ok(());
+            }
             return Err(io::Error::new(ErrorKind::AlreadyExists, "destination file already exists"))
         }
         // free long and short name entries

src/dir_entry.rs

@@ -666,6 +666,10 @@ impl <'a, T: ReadWriteSeek> DirEntry<'a, T> {
         DirEntryEditor::new(self.data.clone(), self.entry_pos)
     }
 
+    pub(crate) fn is_same_entry(&self, other: &DirEntry<T>) -> bool {
+        self.entry_pos == other.entry_pos
+    }
+
     /// Returns `File` struct for this entry.
     ///
     /// Panics if this is not a file.

tests/write.rs

@@ -276,6 +276,8 @@ fn test_rename_file(fs: FileSystem) {
     let names = entries.iter().map(|r| r.file_name()).collect::<Vec<_>>();
     assert_eq!(names, ["long.txt", "short.txt", "very", "very-long-dir-name", "moved-file.txt"]);
 
+    assert!(root_dir.rename("moved-file.txt", &root_dir, "moved-file.txt").is_ok());
+
     let new_stats = fs.stats().unwrap();
     assert_eq!(new_stats.free_clusters(), stats.free_clusters());
 }