Merge pull request 'Ensure Move endpoint does not overwrite an existing file' (#24) from feature/fix-file-move-overwrite into master

Reviewed-on: #24

src/files.rs

@@ -192,11 +192,21 @@ pub async fn move_file<FS: FileSystemAccess>(
     request: web::Json<MoveFileRequest>,
 ) -> HttpResponse {
     match is_valid_full_path(&app_state.base_path, &request.source, false)
+        .ok_or(ErrorKind::InvalidData)
         .and_then(|source| {
             is_valid_full_path(&app_state.base_path, &request.destination, true)
+                .ok_or(ErrorKind::InvalidData)
+                .and_then(|dest| {
+                    if dest.exists() {
+                        error!("Destination already exists, not moving file: {:?}", source);
+
+                        Err(ErrorKind::AlreadyExists)
+                    } else {
+                        Ok(dest)
+                    }
+                })
                 .map(|dest| (source, dest))
         })
-        .ok_or(ErrorKind::InvalidData)
         .map(|(source, dest)| file_system.move_file(source, dest))
     {
         Ok(_) => {