canonicalize path when opening MmapDirectory (#1231)

* canonicalize path when opening `MmapDirectory`
fixes #1229

src/directory/error.rs

@@ -39,6 +39,16 @@ pub enum OpenDirectoryError {
     },
 }
 
+impl OpenDirectoryError {
+    /// Wraps an io error.
+    pub fn wrap_io_error(io_error: io::Error, directory_path: PathBuf) -> Self {
+        Self::IoError {
+            io_error,
+            directory_path,
+        }
+    }
+}
+
 /// Error that may occur when starting to write in a file
 #[derive(Debug, Error)]
 pub enum OpenWriteError {

src/directory/mmap_directory.rs

@@ -193,16 +193,19 @@ impl MmapDirectory {
     pub fn open<P: AsRef<Path>>(directory_path: P) -> Result<MmapDirectory, OpenDirectoryError> {
         let directory_path: &Path = directory_path.as_ref();
         if !directory_path.exists() {
-            Err(OpenDirectoryError::DoesNotExist(PathBuf::from(
+            return Err(OpenDirectoryError::DoesNotExist(PathBuf::from(
                 directory_path,
-            )))
-        } else if !directory_path.is_dir() {
-            Err(OpenDirectoryError::NotADirectory(PathBuf::from(
+            )));
+        }
+        let canonical_path: PathBuf = directory_path.canonicalize().map_err(|io_err| {
+            OpenDirectoryError::wrap_io_error(io_err, PathBuf::from(directory_path))
+        })?;
+        if !canonical_path.is_dir() {
+            return Err(OpenDirectoryError::NotADirectory(PathBuf::from(
                 directory_path,
-            )))
-        } else {
-            Ok(MmapDirectory::new(PathBuf::from(directory_path), None))
+            )));
         }
+        Ok(MmapDirectory::new(canonical_path, None))
     }
 
     /// Joins a relative_path to the directory `root_path`