Buffer.buffer in iojs 3.0

[Nibbler999]

Buffers have picked up a new .buffer property in 3.0 that seems to be a side effect of the Uint8Array stuff but is breaking code.

2.5

> new Buffer("test").buffer;
undefined

3.1

> new Buffer("test").buffer;
ArrayBuffer {}

Can you remove this new property or do I need to file PR against the modules this breaks?

[bnoordhuis]

I don't think it's a property we want to remove (or even can.) I'm curious though, how is it breaking code?

[Nibbler999]

Slightly simplified example from engine.io:

var packets = exports.packets = {
    message:  4
};

var packet = {
    data: new Buffer("hello"),
    type: 'message'
};

encodePacket = function (packet, supportsBinary, callback) {

  var data = (packet.data === undefined)
    ? undefined
    : packet.data.buffer || packet.data;

  if (Buffer.isBuffer(data)) {
    return encodeBuffer(packet, supportsBinary, callback);
  } else if (data instanceof ArrayBuffer) {
    return encodeArrayBuffer(packet, supportsBinary, callback);
  }

};

function encodeBuffer(packet, supportsBinary, callback) {
  var data = packet.data;
  var typeBuffer = new Buffer(1);
  typeBuffer[0] = packets[packet.type];
  return callback(Buffer.concat([typeBuffer, data]));
}

function encodeArrayBuffer(packet, supportsBinary, callback) {
  var data = (packet.data === undefined)
    ? undefined
    : packet.data.buffer || packet.data;

  var contentArray = new Uint8Array(data);
  var resultBuffer = new Buffer(1 + data.byteLength);

  resultBuffer[0] = packets[packet.type];
  for (var i = 0; i < contentArray.length; i++){
    resultBuffer[i+1] = contentArray[i];
  }

  return callback(resultBuffer);
}

encodePacket(packet, true, function (message) {
    console.log(message.toString());
});

In 2.5 this will send the message "hello" to your client. In 3.0 it will send them 8kb of what looks like random memory contents.

[bnoordhuis]

Thanks, I see what you mean. It's regrettable but I think we'll have to chalk this one up to the price of progress.

Even if we could remove the .buffer property (which from a technical POV is undesirable for a number of reasons), it couldn't land in v3.x because it's an API change. You'd end up having to fix engine.io for v3.x anyway.

[Nibbler999]

Understood, thanks.