feat: Update linux header fetching script

build/init/fetch-linux-headers.sh

@@ -1,120 +1,126 @@
 #!/bin/bash
 
-set -x
+set -ex
 
 LSB_FILE="/etc/lsb-release.host"
 OS_RELEASE_FILE="/etc/os-release.host"
 TARGET_DIR="/usr/src"
 HOST_MODULES_DIR="/lib/modules.host"
 
+KERNEL_VERSION="${KERNEL_VERSION:-$(uname -r)}"
+
 generate_headers()
 {
   echo "Generating kernel headers"
-  cd ${BUILD_DIR}
+
+  cd "${BUILD_DIR}"
   zcat /proc/config.gz > .config
   make ARCH=x86 oldconfig > /dev/null
   make ARCH=x86 prepare > /dev/null
 
   # Clean up abundant non-header files to speed-up copying
-  find ${BUILD_DIR} -regex '.*\.c\|.*\.txt\|.*Makefile\|.*Build\|.*Kconfig' -type f -delete
+  find "${BUILD_DIR}" -regex '.*\.c\|.*\.txt\|.*Makefile\|.*Build\|.*Kconfig' -type f -delete
 }
 
 fetch_cos_linux_sources()
 {
   echo "Fetching upstream kernel sources."
-  mkdir -p ${BUILD_DIR}
-  curl -s "https://storage.googleapis.com/cos-tools/${BUILD_ID}/kernel-src.tar.gz" | tar -xzf - -C ${BUILD_DIR}
+  mkdir -p "${BUILD_DIR}"
+  curl -s "https://storage.googleapis.com/cos-tools/${BUILD_ID}/kernel-src.tar.gz" \
+    | tar -xzf - -C "${BUILD_DIR}"
 }
 
 fetch_generic_linux_sources()
 {
-  kernel_version=$(uname -r | tr -d '+')
-  major_version=$(echo ${kernel_version} | cut -d . -f 1)
-  echo "Fetching upstream kernel sources for ${kernel_version}."
-  mkdir -p ${BUILD_DIR}
-  curl -sL https://www.kernel.org/pub/linux/kernel/v${major_version}.x/linux-$kernel_version.tar.gz | tar --strip-components=1 -xzf - -C ${BUILD_DIR}
+  kernel_version="$(echo "${KERNEL_VERSION}" | awk -vFS=+ '{ print $1 }')"
+  major_version="$(echo "${KERNEL_VERSION}" | awk -vFS=. '{ print $1 }')"
 
+  echo "Fetching upstream kernel sources for ${kernel_version}."
+  mkdir -p "${BUILD_DIR}"
+  curl -sL "https://www.kernel.org/pub/linux/kernel/v${major_version}.x/linux-$kernel_version.tar.gz" \
+    | tar --strip-components=1 -xzf - -C "${BUILD_DIR}"
 }
 
 install_cos_linux_headers()
 {
-  if grep -q CHROMEOS_RELEASE_VERSION ${LSB_FILE};then
-    BUILD_ID=$(grep CHROMEOS_RELEASE_VERSION ${LSB_FILE} | cut -d = -f 2)
+  if grep -q CHROMEOS_RELEASE_VERSION "${LSB_FILE}" >/dev/null; then
+    BUILD_ID=$(awk '/CHROMEOS_RELEASE_VERSION =/ { print $3 }' "${LSB_FILE}")
     BUILD_DIR="/linux-lakitu-${BUILD_ID}"
     SOURCES_DIR="${TARGET_DIR}/linux-lakitu-${BUILD_ID}"
 
-    if [ ! -e "${SOURCES_DIR}/.installed" ];then
+    if [[ ! -e "${SOURCES_DIR}/.installed" ]]; then
       echo "Installing kernel headers for COS build ${BUILD_ID}"
       time fetch_cos_linux_sources
       time generate_headers
-      time mv ${BUILD_DIR} ${TARGET_DIR}
+      time rm -rf "${TARGET_DIR}${BUILD_DIR}"
+      time mv "${BUILD_DIR}" "${TARGET_DIR}"
       touch "${SOURCES_DIR}/.installed"
     fi
   fi
 }
 
 install_generic_linux_headers()
 {
-  BUILD_DIR="/linux-generic-$(uname -r)"
-  SOURCES_DIR="${TARGET_DIR}/linux-generic-$(uname -r)"
+  BUILD_DIR="/linux-generic-${KERNEL_VERSION}"
+  SOURCES_DIR="${TARGET_DIR}/linux-generic-${KERNEL_VERSION}"
 
-  if [ ! -e "${SOURCES_DIR}/.installed" ];then
+  if [[ ! -e "${SOURCES_DIR}/.installed" ]];then
     echo "Installing kernel headers for generic kernel"
     time fetch_generic_linux_sources
     time generate_headers
-    time mv ${BUILD_DIR} ${TARGET_DIR}
+    time rm -rf "${TARGET_DIR}${BUILD_DIR}"
+    time mv "${BUILD_DIR}" "${TARGET_DIR}"
     touch "${SOURCES_DIR}/.installed"
   fi
 }
 
 install_headers()
 {
-  distro=$(grep ^NAME ${OS_RELEASE_FILE} | cut -d = -f 2)
+  distro="$(awk '/^NAME =/ { print $3 }' "${OS_RELEASE_FILE}")"
 
   case $distro in
     *"Container-Optimized OS"*)
       install_cos_linux_headers
-      HEADERS_TARGET=${SOURCES_DIR}
+      HEADERS_TARGET="${SOURCES_DIR}"
       ;;
     *)
       echo "WARNING: Cannot find distro-specific headers for ${distro}. Fetching generic headers."
       install_generic_linux_headers
-      HEADERS_TARGET=${SOURCES_DIR}
+      HEADERS_TARGET="${SOURCES_DIR}"
       ;;
   esac
 }
 
 check_headers()
 {
-  modules_path=$1
-  utsname=$(uname -r)
-  arch=$(uname -m)
-  kdir="${modules_path}/${utsname}"
+  modules_path="$1"
+  arch="$(uname -m)"
+  kdir="${modules_path}/${KERNEL_VERSION}"
 
-  [ "${arch}" == "x86_64" ] && arch="x86"
+  [[ "${arch}" == "x86_64" ]] && arch="x86"
 
-  [ ! -e ${kdir} ] && return 1
-  [ ! -e "${kdir}/source" ] && [ ! -e "${kdir}/build" ] && return 1
+  [[ ! -e "${kdir}" ]] && return 1
+  [[ ! -e "${kdir}/source" ]] && [[ ! -e "${kdir}/build" ]] && return 1
 
-  header_dir=$([ -e "${kdir}/source" ] && echo "${kdir}/source" || echo "${kdir}/build")
+  header_dir="$([[ -e "${kdir}/source" ]] && echo "${kdir}/source" || echo "${kdir}/build")"
 
-  [ ! -e "${header_dir}/include/linux/kconfig.h" ] && return 1
-  [ ! -e "${header_dir}/include/generated/uapi" ] && return 1
-  [ ! -e "${header_dir}/arch/${arch}/include/generated/uapi" ] && return 1
+  [[ ! -e "${header_dir}/include/linux/kconfig.h" ]] && return 1
+  [[ ! -e "${header_dir}/include/generated/uapi" ]] && return 1
+  [[ ! -e "${header_dir}/arch/${arch}/include/generated/uapi" ]] && return 1
 
   return 0
 }
 
-if [ ! -e /lib/modules/.installed ];then
-  if ! check_headers ${HOST_MODULES_DIR}; then
-    install_headers
+if [[ ! -e /lib/modules/.installed ]]; then
+  if check_headers "${HOST_MODULES_DIR}"; then
+    HEADERS_TARGET="${HOST_MODULES_DIR}/source"
   else
-    HEADERS_TARGET=${HOST_MODULES_DIR}/source
+    install_headers
   fi
 
-  mkdir -p "/lib/modules/$(uname -r)"
-  ln -sf ${HEADERS_TARGET} "/lib/modules/$(uname -r)/source"
-  ln -sf ${HEADERS_TARGET} "/lib/modules/$(uname -r)/build"
+  mkdir -p "/lib/modules/${KERNEL_VERSION}"
+  ln -sf "${HEADERS_TARGET}" "/lib/modules/${KERNEL_VERSION}/source"
+  ln -sf "${HEADERS_TARGET}" "/lib/modules/${KERNEL_VERSION}/build"
   touch /lib/modules/.installed
   exit 0
 else