[jsc-dev] Protect against modifying contents of `ArrayBuffer` in `JavaScriptCore`

[Saam barati]

Hi Karol,

What context are you running JavaScript code in?

Are you using the JavaScriptCore ObjC or C APIs? Something else?

- Saam

> On Oct 19, 2018, at 1:56 AM, Karol Szafranski <karolszafranski at gmail.com> wrote:
> 
> `ArrayBuffer` is created in JavaScript engine, and reference is passed to the "native side":
> 
> 
>    var myBuffer = new ArrayBuffer(32);
>    protectBufferMemory(myBuffer);
> 
> 
> Now I would like to hide the contents of the `ArrayBuffer` from the JavaScript engine. It would be best if `ArrayBuffer` could suddenly return 0 for `byteLength`, stay empty and nonresizable when looking at it with any `TypedArray`.
> 
> In the same time, I need to keep the contents of the `ArrayBuffer` in memory in the same place as it was. I do not want to copy those bytes.
> 
> Note: this is exactly how `ArrayBuffer` behaves in Chrome when you `postMessage` to a `Worker` with `ArrayBuffer` instance in the "transfer" array.
> 
> If there is no way of doing this, the following alternatives would also be acceptable:
> 
> 1. Removing the `ArrayBuffer` instance from the JavaScript engine, so that all variables pointing to it will return `undefined` would also be acceptable. As long as data will not be removed from memory.
> 
> 2. Keeping `ArrayBuffer` data visible inside JavaScript engine but disallow modification.
> 
> Thank you very much in advance.
> 
> Karol Szafrański
> 
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