patch_rootfs.sh

#!/bin/bash

#patch the target rootfs to add any needed drivers

. ./common.sh
. ./image_utils.sh

print_help() {
  echo "Usage: ./patch_rootfs.sh shim_path reco_path rootfs_dir"
}

assert_root
assert_deps "git gunzip depmod"
assert_args "$3"

copy_modules() {
  local shim_rootfs=$(realpath -m $1)
  local reco_rootfs=$(realpath -m $2)
  local target_rootfs=$(realpath -m $3)

  rm -rf "${target_rootfs}/lib/modules"
  cp -r "${shim_rootfs}/lib/modules" "${target_rootfs}/lib/modules"

  mkdir -p "${target_rootfs}/lib/firmware"
  cp -r --remove-destination "${shim_rootfs}/lib/firmware/"* "${target_rootfs}/lib/firmware/"
  cp -r --remove-destination "${reco_rootfs}/lib/firmware/"* "${target_rootfs}/lib/firmware/"

  mkdir -p "${target_rootfs}/lib/modprobe.d/"
  mkdir -p "${target_rootfs}/etc/modprobe.d/"
  cp -r "${reco_rootfs}/lib/modprobe.d/"* "${target_rootfs}/lib/modprobe.d/"
  cp -r "${reco_rootfs}/etc/modprobe.d/"* "${target_rootfs}/etc/modprobe.d/"

  #decompress kernel modules if necessary - debian won't recognize these otherwise
  local compressed_files="$(find "${target_rootfs}/lib/modules" -name '*.gz')"
  if [ "$compressed_files" ]; then
    echo "$compressed_files" | xargs gunzip
    for kernel_dir in "$target_rootfs/lib/modules/"*; do
      local version="$(basename "$kernel_dir")"
      depmod -b "$target_rootfs" "$version"
    done
  fi
}

copy_firmware() {
  local firmware_path="/tmp/chromium-firmware"
  local target_rootfs=$(realpath -m $1)

  if [ ! -e "$firmware_path" ]; then
    download_firmware $firmware_path
  fi

  cp -r --remove-destination "${firmware_path}/"* "${target_rootfs}/lib/firmware/"
}

download_firmware() {
  local firmware_url="https://chromium.googlesource.com/chromiumos/third_party/linux-firmware"
  local firmware_path=$(realpath -m $1)

  git clone --branch master --depth=1 "${firmware_url}" $firmware_path
}

shim_path=$(realpath -m $1)
reco_path=$(realpath -m $2)
target_rootfs=$(realpath -m $3)
shim_rootfs="/tmp/shim_rootfs"
reco_rootfs="/tmp/reco_rootfs"

echo "mounting shim"
shim_loop=$(create_loop "${shim_path}")
safe_mount "${shim_loop}p3" $shim_rootfs ro

echo "mounting recovery image"
reco_loop=$(create_loop "${reco_path}")
safe_mount "${reco_loop}p3" $reco_rootfs ro

echo "copying modules to rootfs"
copy_modules $shim_rootfs $reco_rootfs $target_rootfs

echo "downloading misc firmware"
copy_firmware $target_rootfs

echo "unmounting and cleaning up"
umount $shim_rootfs
umount $reco_rootfs
losetup -d $shim_loop
losetup -d $reco_loop

echo "done"