genusb

#!/bin/sh
set -eu

dev="$1"
iso="${2:-$PWD/image.iso}"

devp="$dev"
if [ "${dev%[0-9]}" != "$dev" ]; then
    devp="${dev}p"
fi

cat << 'EOF' | sfdisk "$dev"
label: gpt
type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, size=131072
type=0FC63DAF-8483-4772-8E79-3D69D8477DE4
EOF
partprobe "$dev"
mkfs.vfat -F32 "$devp"1
mkfs.ext4 -O '^has_journal' -E lazy_itable_init=0 -F "$devp"2

tmp="$(mktemp -d -t genusb.XXXXXXXXXX)"
mkdir "$tmp/iso" "$tmp/efi" "$tmp/dev"
mount -o ro "$iso" "$tmp/iso"
mount "$devp"1 "$tmp/efi"
mount "$devp"2 "$tmp/dev"

# Copy the base files
rsync -avP "$tmp/iso/LiveOS/" "$tmp/dev/LiveOS"

# Install grub
grub-install --target=x86_64-efi --removable --boot-directory="$tmp/dev/boot" --efi-directory="$tmp/efi"

label="$(blkid -o value -s LABEL "$devp"2)"
uuid="$(blkid -o value -s UUID "$devp"2)"

# Create persistent overlay
mkdir -p "$tmp/dev/LiveOS/ovlwork" "$tmp/dev/LiveOS/overlay-$label-$uuid"

# Create grub configuration
cat > "$tmp/dev/boot/grub/grub.cfg" << 'EOF'
set timeout=1
set gfxpayload=keep
insmod all_video
menuentry 'boot' {
    linux /LiveOS/bzImage root=live:UUID=$uuid rd.live.overlay=UUID=$uuid mitigations=off loglevel=0
    initrd /LiveOS/initramfs.img
}
EOF

echo 'Unmounting...'
umount "$tmp/iso" "$tmp/efi" "$tmp/dev"
rm -r "$tmp"