exchange TypedArray or Buffer between host and vm

[Lyoko-Jeremie]

can i exchange TypedArray or Buffer between host and vm ?

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i want to use libsodium-wrapper in vm, but it need crypto.getRandomValues function,

so when i try to impl the crypto.getRandomValues in vm, i notice that this function is a node impl and the web polyfill use randombytes to wrap browser crypto.randomBytes function to impl crypto.getRandomValues function.

but the randomBytes and getRandomValues all process the Buffer or TypedArray .

    // crypto.randomBytes  define in nodejs crypto
    function randomBytes(size: number): Buffer;
    function randomBytes(size: number, callback: (err: Error | null, buf: Buffer) => void): void;
    function pseudoRandomBytes(size: number): Buffer;
    function pseudoRandomBytes(size: number, callback: (err: Error | null, buf: Buffer) => void): void;

    // crypto.getRandomValues  define in `lib.dom.d.ts`
    getRandomValues<T extends ArrayBufferView | null>(array: T): T;

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so , i think it can impl like :

vm request some random -> tell the host -> host generate crypto random Buffer -> pass random Buffer to vm -> get the crypto random Buffer 

vm.randomBytes() call -> host.randomBytes() call -> host return random buffer -> vm.randomBytes() return

can i pass TypedArray or Buffer from host to vm ?

[justjake]

Currently you cannot directly pass a ArrayBuffer or similar to the VM, although it’s an interesting use-case, because we might be able to expose raw data like this directly to the VM without copying in the future.

For now, I suggest converting your random bytes to an Array of number on the host, sending to the vm, and converting from array of number to TypedArray inside the guest.

[justjake]

This was released in v0.24.0: https://github.com/justjake/quickjs-emscripten/blob/main/CHANGELOG.md#v0240

Docs: https://github.com/justjake/quickjs-emscripten/blob/main/doc/quickjs-emscripten/classes/QuickJSContext.md#newarraybuffer