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justjake / quickjs-emscripten

Safely execute untrusted Javascript in your Javascript, and execute synchronous code that uses async functions
https://www.npmjs.com/package/quickjs-emscripten
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Having troubles with ArrayBuffer #167

Open Tadeuchi opened 3 months ago

Tadeuchi commented 3 months ago

Hi,

I'm having troubles with passing array buffer. I followed the first example in the readme, but with additional code to handle array buffer. And then tried doing some modifications, but... every time the results are mostly undefined... That leads me to conclusion that I must be doing something wrong (very likely) or there may be an implementation issue?

Following code

import { getQuickJS } from "quickjs-emscripten"

async function main() {
    const QuickJS = await getQuickJS()
    const vm = QuickJS.newContext()

    const world = vm.newString("ArrayBuffer")
    const ab = new Uint8Array([1, 1])
    console.log(ab[0], ab.length)
    const ones = vm.newArrayBuffer(ab);
    vm.setProp(vm.global, "NAME", world)
    vm.setProp(vm.global, 'ones', ones)
    world.dispose()
    ones.dispose()

    const result = vm.evalCode(`"Hello " + NAME + ", why are you " + ones.length + "?"`)
    if (result.error) {
        console.log("Execution failed:", vm.dump(result.error))
        result.error.dispose()
    } else {
        console.log("Success:", vm.dump(result.value))
        result.value.dispose()
    }

    vm.dispose()
}

main().then(r => console.log('Finished'));

produces following result

1 2
Success: Hello ArrayBuffer, why are you undefined?
Finished
flawiddsouza commented 2 months ago

Hi, I'm also seeing the same thing. When I log the length of the arraybuffer created using vm.newArrayBuffer, it shows as undefined in the output of vm.evalCode.

It can be easily recreated in the browser like so:

<!doctype html>
<script type="module">
  import { getQuickJS } from "https://esm.sh/quickjs-emscripten@0.29.1"
  const QuickJS = await getQuickJS()

  const vm = QuickJS.newContext()

  const string = '12'
  const arrayBuffer = new Uint8Array([1, 2]).buffer

  console.log('string.length', string.length)
  console.log('arrayBuffer.length', arrayBuffer.byteLength)

  const vmString = vm.newString(string)
  const vmArrayBuffer = vm.newArrayBuffer(arrayBuffer)

  vm.setProp(vm.global, 'vmString', vmString)
  vm.setProp(vm.global, 'vmArrayBuffer', vmArrayBuffer)

  console.log('vmString.length', vm.dump(vm.evalCode('vmString.length').value))
  console.log('vmArrayBuffer.length', vm.dump(vm.evalCode('vmArrayBuffer.length').value))

  vmString.dispose()
  vmArrayBuffer.dispose()
  vm.dispose()
</script>

Output:

string.length 2
arrayBuffer.length 2
vmString.length 2
vmArrayBuffer.length undefined