Direct kernel input injection via Python uinput on Android (GPad2Mouse)

Many developers working with Android automation hit a wall when dealing with input latency. Standard accessibility overlays are too slow. The native solution is injecting events directly into /dev/uinput using Python, but it comes with a major hurdle: Kernel Struct Padding.

When using struct.unpack, 64-bit Android kernels expect a 24-byte event struct (llHHi). However, if you run the same Python script on older 32-bit devices (like Android TV Boxes), it expects a 16-byte struct (IIHHi). Failing to handle this dynamically using sys.maxsize causes instant crash errors.

I've implemented a full working architecture for this concept into an open-source project called GPad2Mouse.

Instead of just mapping keys, it uses Python's fcntl.ioctl to grab exclusive hardware control (EVIOCGRAB), reads VID:PID directly from /sys/class/input/, and dynamically calculates analog deadzones to prevent controller drift—all running as a daemon with 0% CPU overhead.

How to study the code? Due to sub rules against dropping external links, I won't post direct links here. But if you want to see the source code implementation or watch the video demonstration of how the kernel injection works in real-time:

👉 Just Google search: GPad2Mouse

Has anyone else here worked extensively with fcntl on Android? I’d love to hear your approach on handling sudden device disconnections gracefully without freezing the read loop. Cheers!