src: allow not materializing ArrayBuffers from C++

Where appropriate, use a helper that wraps around
`ArrayBufferView::Buffer()` or `ArrayBufferView::CopyContents()`
rather than `Buffer::Data()`, as that may help to avoid materializing
the underlying `ArrayBuffer` when reading small typed arrays from C++.
This allows keeping the performance benefits of the faster creation of
heap-allocated small typed arrays in many cases.

PR-URL: https://github.com/nodejs/node/pull/26301
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/util.cc b/src/util.cc
index 3cdc222a96..223e0e8772 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -29,6 +29,7 @@
 
 namespace node {
 
+using v8::ArrayBufferView;
 using v8::Isolate;
 using v8::Local;
 using v8::String;
@@ -89,11 +90,11 @@ BufferValue::BufferValue(Isolate* isolate, Local<Value> value) {
 
   if (value->IsString()) {
     MakeUtf8String(isolate, value, this);
-  } else if (Buffer::HasInstance(value)) {
-    const size_t len = Buffer::Length(value);
+  } else if (value->IsArrayBufferView()) {
+    const size_t len = value.As<ArrayBufferView>()->ByteLength();
     // Leave place for the terminating '\0' byte.
     AllocateSufficientStorage(len + 1);
-    memcpy(out(), Buffer::Data(value), len);
+    value.As<ArrayBufferView>()->CopyContents(out(), len);
     SetLengthAndZeroTerminate(len);
   } else {
     Invalidate();