image_signing: strip_boot: support device node inputs

To speed things up, support stripping /boot from a rootfs block device.
This way we can mount an image via loopback and pass that in directly.

BRANCH=None
BUG=chromium:714598
TEST=strip_boot_from_image.sh on image files works, and on loopback partitions

Change-Id: Ie74d3f239ac29533f4325d0c1f75e3cce5fab7a5
Reviewed-on: https://chromium-review.googlesource.com/1152075
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: David Riley <davidriley@chromium.org>
Reviewed-by: Chris Ching <chingcodes@chromium.org>

2 files changed, 15 insertions, 10 deletions

diff --git a/scripts/image_signing/sign_official_build.sh b/scripts/image_signing/sign_official_build.sh
index 813a0210..8e9537d5 100755
--- a/scripts/image_signing/sign_official_build.sh
+++ b/scripts/image_signing/sign_official_build.sh
@@ -1023,6 +1023,7 @@ sign_image_file() {
 
   local loopdev=$(loopback_partscan "${output}")
   local loop_kern="${loopdev}p${dm_partno}"
+  local loop_rootfs="${loopdev}p3"
 
   resign_firmware_payload "${loopdev}"
   resign_android_image_if_exists "${loopdev}"
@@ -1039,7 +1040,7 @@ sign_image_file() {
   if [[ "${image_type}" != "factory_install" &&
         " ${kerna_config} " != *" cros_legacy "* &&
         " ${kerna_config} " != *" cros_efi "* ]]; then
-    "${SCRIPT_DIR}/strip_boot_from_image.sh" --image "${output}"
+    "${SCRIPT_DIR}/strip_boot_from_image.sh" --image "${loop_rootfs}"
   fi
   update_rootfs_hash "${loopdev}" "${loop_kern}" \
     "${kernA_keyblock}" "${kernA_privkey}" \
diff --git a/scripts/image_signing/strip_boot_from_image.sh b/scripts/image_signing/strip_boot_from_image.sh
index 2ff85e0a..1427d464 100755
--- a/scripts/image_signing/strip_boot_from_image.sh
+++ b/scripts/image_signing/strip_boot_from_image.sh
@@ -13,7 +13,7 @@
 load_shflags
 
 DEFINE_string image "chromiumos_image.bin" \
-  "Input file name of Chrome OS image to strip /boot from."
+  "Input file name of Chrome OS image to strip /boot from, or path to rootfs."
 
 # Parse command line.
 FLAGS "$@" || exit 1
@@ -22,10 +22,6 @@ eval set -- "${FLAGS_ARGV}"
 # Abort on error.
 set -e
 
-if [ -z "${FLAGS_image}" ] || [ ! -s "${FLAGS_image}" ] ; then
-  die "Error: need a valid file by --image"
-fi
-
 # Swiped/modifed from $SRC/src/scripts/base_library/base_image_util.sh.
 zero_free_space() {
   local rootfs="$1"
@@ -38,9 +34,15 @@ zero_free_space() {
 strip_boot() {
   local image=$1
 
-  # Mount image so we can modify it.
   local rootfs_dir=$(make_temp_dir)
-  mount_image_partition ${image} 3 ${rootfs_dir}
+  if [[ -b "${image}" ]]; then
+    enable_rw_mount "${image}"
+    sudo mount "${image}" "${rootfs_dir}"
+    tag_as_needs_to_be_resigned "${rootfs_dir}"
+  else
+    # Mount image so we can modify it.
+    mount_image_partition ${image} 3 ${rootfs_dir}
+  fi
 
   sudo rm -rf "${rootfs_dir}/boot" &&
     info "/boot directory was removed."
@@ -52,9 +54,11 @@ strip_boot() {
   zero_free_space "${rootfs_dir}"
 }
 
-
 IMAGE=$(readlink -f "${FLAGS_image}")
-if [[ -z "${IMAGE}" || ! -f "${IMAGE}" ]]; then
+if [[ ! -f "${IMAGE}" && ! -b "${IMAGE}" ]]; then
+  IMAGE=
+fi
+if [[ -z "${IMAGE}" ]]; then
   die "Missing required argument: --from (image to update)"
 fi