buffer: fix UCS2 indexOf for odd buffer length

Fix `buffer.indexOf` for the case that the haystack has odd length
and the needle is not found in it. `StringSearch()` would return
the length of the buffer in multiples of `sizeof(uint16_t)`, but
checking that against `haystack_length` would not work if the latter
one was odd.

PR-URL: https://github.com/nodejs/node/pull/6511
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index 30618719d2..44020d91a1 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -994,7 +994,9 @@ void IndexOfString(const FunctionCallbackInfo<Value>& args) {
   bool is_forward = args[4]->IsTrue();
 
   const char* haystack = ts_obj_data;
-  const size_t haystack_length = ts_obj_length;
+  // Round down to the nearest multiple of 2 in case of UCS2.
+  const size_t haystack_length = (enc == UCS2) ?
+      ts_obj_length &~ 1 : ts_obj_length;  // NOLINT(whitespace/operators)
 
   const size_t needle_length =
       StringBytes::Size(args.GetIsolate(), needle, enc);