# Nadir Kernel CI. Runs on every pull request and every push to main.
#
# Builds os.img with make, verifies the image, then boots it headless in
# QEMU and asserts the kernel's welcome message reaches the screen.

name: CI

on:
  push:
    branches: [main]
  pull_request:

permissions:
  contents: read

jobs:
  build-and-boot:
    name: Build and boot in QEMU
    runs-on: ubuntu-latest
    steps:
      - name: Check out repository
        uses: actions/checkout@v4

      - name: Install toolchain
        # gcc, make and binutils ship with the runner; nasm and qemu do not.
        run: sudo apt-get update && sudo apt-get install -y nasm qemu-system-x86

      - name: Build image
        run: make

      - name: Verify image
        run: |
          set -euo pipefail
          test -f os.img
          size=$(stat -c %s os.img)
          test "$size" -ge 1024
          test $(( (size - 512) % 512 )) -eq 0
          sig=$(dd if=os.img bs=1 skip=510 count=2 2>/dev/null | od -A n -t x1 | tr -d ' \n')
          test "$sig" = "55aa" || { echo "missing 0xAA55 boot signature"; exit 1; }
          grep -q "Nadir" os.img || { echo "kernel payload missing from os.img"; exit 1; }
          echo "os.img: $size bytes, boot signature and payload present"

      - name: Boot and check welcome message in QEMU
        run: python3 .github/scripts/check_boot.py os.img