fix(ops): fallback when FastApiOneByteString is not utf8 (#18518)

Fixes https://github.com/denoland/deno/issues/18255

1 files changed, 9 insertions, 2 deletions

diff --git a/ops/optimizer_tests/strings.out b/ops/optimizer_tests/strings.out
index 8a72c8cab..3238bfc42 100644
--- a/ops/optimizer_tests/strings.out
+++ b/ops/optimizer_tests/strings.out
@@ -31,7 +31,7 @@ impl op_string_length {
                 use deno_core::v8::fast_api::CType;
                 Some(
                     deno_core::v8::fast_api::FastFunction::new(
-                        &[V8Value, SeqOneByteString],
+                        &[V8Value, SeqOneByteString, CallbackOptions],
                         CType::Uint32,
                         op_string_length_fast_fn as *const ::std::ffi::c_void,
                     ),
@@ -90,10 +90,17 @@ impl op_string_length {
 fn op_string_length_fast_fn<'scope>(
     _: deno_core::v8::Local<deno_core::v8::Object>,
     string: *const deno_core::v8::fast_api::FastApiOneByteString,
+    fast_api_callback_options: *mut deno_core::v8::fast_api::FastApiCallbackOptions,
 ) -> u32 {
     use deno_core::v8;
     use deno_core::_ops;
-    let string = unsafe { &*string }.as_str();
+    let string = match ::std::str::from_utf8(unsafe { &*string }.as_bytes()) {
+        Ok(v) => v,
+        Err(_) => {
+            unsafe { &mut *fast_api_callback_options }.fallback = true;
+            return Default::default();
+        }
+    };
     let result = op_string_length::call(string);
     result
 }