tc39 / proposal-limited-arraybuffer

Limited ArrayBuffer

Status

Champion(s): Jack Works

Author(s): Jack Works

Stage: 1

Presentations

• For stage 1 on 82th tc39 meeting (Apr 2021)
• TC39 meeting notes on 82th tc39 meeting

Problem to be resolved

All of the following are helpful to archive the minimal permission/information principle.

1. Cannot make an ArrayBuffer read-only.
2. Cannot give others a read-only view to the ArrayBuffer and keep the read-write permission internally.
3. Cannot give others a view that range limited (only a small area of the whole buffer is visible).

Design goal

1. Freeze the ArrayBuffer.
   1. Like Object.freeze, there is no way back once frozen.
   2. Any TypedArray/DataView to the freezed ArrayBuffer is read-only too.
   3. [Optional] Keep frozen when sent across Realm (HTML intergration).
2. Read-only TypedArray/DataView to a read-write ArrayBuffer.
   1. Must not be able to construct a read-write view from a read-only view.
3. [Optional] Range-limited TypedArray/DataView to a read-write ArrayBuffer (CrimsonCodes0's use case on WebAssembly).
   1. Must not be able to construct a bigger view range from a smaller view range.
4. Not adding too much complexity to the implementor.

Pros

1. Minimal permission/information principle works on ArrayBuffer.
2. Embedded JS engines can represent ROMs as read-only ArrayBuffer.

API design

See design.md