How do I properly create a Buffer object from a node native addon?

Question

I am using node 6.9.1 and I try to create a cpp addon that will create Node Buffer objects. After some research I came up with the following code:

#include <node.h>
#include <node_buffer.h>
#include <v8.h>

using v8::Local;
using v8::Object;
using v8::HandleScope;
using v8::Isolate;

Local<Object> create_buffer(Isolate* isolate, char* rawData, int length) {
  HandleScope scope(isolate);
  Local<Object> buf = node::Buffer::New(
    isolate,
    rawData,
    length).ToLocalChecked();
  return buf;
}

which I use as follows:

Local<Value> buff = create_buffer(isolate, rawData, length);
const unsigned argc = 1;
Local<Value> argv[argc] = { buff };
cb->Call(Null(isolate), argc, argv);

This code compiles just fine but causes an error when I access the .length property of the buffer I get through the callback:

Security context: 0x9d84c7cfb51 <JS Object>#0#

I found several tutorials but all of them use an earlier version of v8/node api and I cannot find any info what is a proper way to create buffer in the recent Node versions. Also it is possible that I have made a mistake somewhere. Thanks in advance if you can guide me in the right direction.

Answer 1

The best way is to use NAN's NewBuffer helper:

Nan::MaybeLocal<v8::Object> mybuffer = Nan::NewBuffer(size);
Nan::MaybeLocal<v8::Object> mybuffer = Nan::NewBuffer(mydata, size);

Node's node_buffer.h also has a public constructor, but it's not necessarily consistent across versions.

I'm not positive, but your error might be because you've freed the raw data used to construct the buffer?