From 89a5ee4a8a9359bd82a154c16057c9f40ffec122 Mon Sep 17 00:00:00 2001
From: appflowy <annie@appflowy.io>
Date: Thu, 8 Sep 2022 17:47:53 +0800
Subject: [PATCH] fix: potential crash while calling apply_insert if the path
 is empty

---
 shared-lib/lib-ot/src/core/document/document.rs | 13 +++++++------
 shared-lib/lib-ot/src/core/document/position.rs |  6 ++++++
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/shared-lib/lib-ot/src/core/document/document.rs b/shared-lib/lib-ot/src/core/document/document.rs
index 95508237a4..a20457a656 100644
--- a/shared-lib/lib-ot/src/core/document/document.rs
+++ b/shared-lib/lib-ot/src/core/document/document.rs
@@ -121,14 +121,15 @@ impl DocumentTree {
     }
 
     fn apply_insert(&mut self, path: &Path, nodes: &[NodeSubTree]) -> Result<(), OTError> {
+        debug_assert!(!path.is_empty());
+        if path.is_empty() {
+            return Err(OTErrorCode::PathIsEmpty.into());
+        }
 
-
-        let parent_path = &path.0[0..(path.0.len() - 1)];
-        let last_index = path.0[path.0.len() - 1];
-
-
+        let (parent_path, last_path) = path.split_at(path.0.len() - 1);
+        let last_index = *last_path.first().unwrap();
         let parent_node = self
-            .node_at_path(&Path(parent_path.to_vec()))
+            .node_at_path(parent_path)
             .ok_or_else(|| ErrorBuilder::new(OTErrorCode::PathNotFound).build())?;
 
         self.insert_child_at_index(parent_node, last_index, nodes)
diff --git a/shared-lib/lib-ot/src/core/document/position.rs b/shared-lib/lib-ot/src/core/document/position.rs
index 697bde8177..e45c2556d6 100644
--- a/shared-lib/lib-ot/src/core/document/position.rs
+++ b/shared-lib/lib-ot/src/core/document/position.rs
@@ -39,6 +39,12 @@ impl From<&Vec<usize>> for Path {
     }
 }
 
+impl From<&[usize]> for Path {
+    fn from(values: &[usize]) -> Self {
+        Path(values.to_vec())
+    }
+}
+
 
 impl Path {
     // delta is default to be 1