fix(serde_v8): no panic on reading large text file (#15494)

Co-authored-by: Nayeem Rahman <nayeemrmn99@gmail.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/serde_v8/ser.rs b/serde_v8/ser.rs
index 31d3e3144..3f8ad3b32 100644
--- a/serde_v8/ser.rs
+++ b/serde_v8/ser.rs
@@ -447,11 +447,16 @@ impl<'a, 'b, 'c> ser::Serializer for Serializer<'a, 'b, 'c> {
   }
 
   fn serialize_str(self, v: &str) -> JsResult<'a> {
-    Ok(
-      v8::String::new(&mut self.scope.borrow_mut(), v)
-        .unwrap()
-        .into(),
-    )
+    let maybe_str = v8::String::new(&mut self.scope.borrow_mut(), v);
+
+    // v8 string can return 'None' if buffer length > kMaxLength.
+    if let Some(str) = maybe_str {
+      Ok(str.into())
+    } else {
+      Err(Error::Message(String::from(
+        "Cannot allocate String: buffer exceeds maximum length.",
+      )))
+    }
   }
 
   fn serialize_bytes(self, v: &[u8]) -> JsResult<'a> {