queryBitmapInfo in Java API returns no image address

[NorbiPeti]

I'm developing a Java frontend for VirtualBox machines and I managed to set it up to launch the machine inside the process and attach my framebuffer to it. It's receiving changes and updates, queryBitmapInfo returns all information correctly, except for the address out parameter.
The array I'm using to hold the value is large enough for the whole screen but all of the values in the array remain 0, even after the machine has booted up and is running the guest OS. VirtualBox also seems to freeze for longer periods while the machine is running inside my application.
(I'm also running my app as root as I was unable to set the setuid bit up correctly, but running VBox as root doesn't have any issues, so I don't think it's related.)

How can I receive images from the machine in Java?

VirtualBox version: 5.2.12 r122591 (Qt5.9.5)
VBox API: Java XPCOM 5.2
OS: Ubuntu 18.04 x64, Java 8

My code in notifyChange:

Code: Select all

display.querySourceBitmap(0L, holder);
byte[] arr = bb.array(); //640 * 480 * 4 bytes backing a ByteBuffer
long[] w = new long[1], h = new long[1], bpp = new long[1], bpl = new long[1], pf = new long[1];
holder.value.getTypedWrapped().queryBitmapInfo(arr, w, h, bpp, bpl, pf);
System.out.println("Arr0:" + arr[0]);
System.out.println("whbppbplpf: " + w[0] + " " + h[0] + " " + bpp[0] + " " + bpl[0] + " " + pf[0]);

Edit: Posted to the dev mailing list: https://www.virtualbox.org/pipermail/vb ... 15041.html

Update: Found how to solve this issue