Use --usepkgonly in build_image to ensure no accidental builds of packages.

build_image

 #!/bin/bash
 
 # Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Script to build a bootable keyfob-based chromeos system image from within
 # a chromiumos setup. This assumes that all needed packages have been built into
 # the given target's root with binary packages turned on. This script will
 # build the Chrome OS image using only pre-built binary packages.
@@ skipping 12 matching lines @@
 
 # Flags.
 DEFINE_string board "${DEFAULT_BOARD}" \
   "The board to build an image for."
 DEFINE_string build_root "/build" \
   "The root location for board sysroots."
 DEFINE_integer build_attempt 1 \
   "The build attempt for this image build."
 DEFINE_string output_root "${DEFAULT_BUILD_ROOT}/images" \
   "Directory in which to place image result directories (named by version)"
+DEFINE_boolean eclean ${FLAGS_TRUE} \
+  "Perform eclean-<board> -d as part of this script to remove obsolete packages"
 DEFINE_boolean replace ${FLAGS_FALSE} \
   "Overwrite existing output, if any."
 DEFINE_boolean withdev ${FLAGS_TRUE} \
   "Include useful developer friendly utilities in the image."
 DEFINE_boolean installmask ${FLAGS_TRUE} \
   "Use INSTALL_MASK to shrink the resulting image."
 DEFINE_integer jobs -1 \
   "How many packages to build in parallel at maximum."
 DEFINE_boolean statefuldev ${FLAGS_TRUE} \
   "Install development packages on stateful partition rather than the rootfs"
@@ skipping 334 matching lines @@
     -s "${STATEFUL_FS_DIR}" -e "${ESP_FS_DIR}"
 
   # Determine the root dir for developer packages.
   local root_dev_dir="${ROOT_FS_DIR}"
   [ ${FLAGS_statefuldev} -eq ${FLAGS_TRUE} ] && \
     root_dev_dir="${ROOT_FS_DIR}/usr/local"
 
   # Install developer packages described in chromeos-dev.
   sudo INSTALL_MASK="${INSTALL_MASK}" ${EMERGE_BOARD_CMD} \
       --root="${root_dev_dir}" --root-deps=rdeps \
-      --usepkg -uDNv chromeos-dev ${EMERGE_JOBS}
+      --usepkgonly -uDNv chromeos-dev ${EMERGE_JOBS}
 
   if [[ $FLAGS_preserve -eq ${FLAGS_TRUE} ]] ; then
     # Clean out unused packages
     sudo INSTALL_MASK="${INSTALL_MASK}" ${EMERGE_BOARD_CMD} \
       --root="${ROOT_FS_DIR}" --root-deps=rdeps \
-      --usepkg --depclean ${EMERGE_JOBS}
+      --usepkgonly --depclean ${EMERGE_JOBS}
   fi
 
   # Re-run ldconfig to fix /etc/ldconfig.so.cache.
   sudo /sbin/ldconfig -r "${ROOT_FS_DIR}"
 
   # Mark the image as a developer image (input to chromeos_startup).
   sudo mkdir -p "${ROOT_FS_DIR}/root"
   sudo touch "${ROOT_FS_DIR}/root/.dev_mode"
 
   # Additional changes to developer image.
@@ skipping 42 matching lines @@
   # Create stateful partition of the same size as the rootfs.
   trap "mount_gpt_cleanup" EXIT
 
   ${SCRIPTS_DIR}/mount_gpt_image.sh --from "${OUTPUT_DIR}" \
     --image "${image_name}" -r "${ROOT_FS_DIR}" \
     -s "${STATEFUL_FS_DIR}" -e "${ESP_FS_DIR}"
 
   # Emerge updated packages, exactly like when creating base image
   sudo USE="${EXTRA_USE}" INSTALL_MASK="${INSTALL_MASK}" ${EMERGE_BOARD_CMD} \
     --root="${ROOT_FS_DIR}" --root-deps=rdeps \
-    --usepkg -uDNv chromeos ${EXTRA_PACKAGES} ${EMERGE_JOBS}
+    --usepkgonly -uDNv chromeos ${EXTRA_PACKAGES} ${EMERGE_JOBS}
 
   # Clean out unused packages
   sudo INSTALL_MASK="${INSTALL_MASK}" ${EMERGE_BOARD_CMD} \
     --root="${ROOT_FS_DIR}" --root-deps=rdeps \
-    --usepkg --depclean ${EMERGE_JOBS}
+    --usepkgonly --depclean ${EMERGE_JOBS}
 
   trap - EXIT
   ${SCRIPTS_DIR}/mount_gpt_image.sh -u -r "${ROOT_FS_DIR}" \
     -s "${STATEFUL_FS_DIR}" -e "${ESP_FS_DIR}"
 }
 
 create_base_image() {
   local image_name=$1
 
   trap "cleanup && delete_prompt" EXIT
@@ skipping 106 matching lines @@
 
   # Perform binding rather than symlinking because directories must exist
   # on rootfs so that we can bind at run-time since rootfs is read-only.
   echo "Binding directories from stateful partition onto the rootfs"
   sudo mkdir -p "${ROOT_FS_DIR}/usr/local"
   sudo mount --bind "${DEV_IMAGE_ROOT}" "${ROOT_FS_DIR}/usr/local"
   sudo mkdir -p "${ROOT_FS_DIR}/var"
   sudo mount --bind "${STATEFUL_FS_DIR}/var" "${ROOT_FS_DIR}/var"
   sudo mkdir -p "${ROOT_FS_DIR}/dev"
 
-  # We "emerge --root=${ROOT_FS_DIR} --root-deps=rdeps --usepkg" all of the
+  # We "emerge --root=${ROOT_FS_DIR} --root-deps=rdeps --usepkgonly" all of the
   # runtime packages for chrome os. This builds up a chrome os image from
   # binary packages with runtime dependencies only.  We use INSTALL_MASK to
   # trim the image size as much as possible.
   sudo USE="${EXTRA_USE}" INSTALL_MASK="${INSTALL_MASK}" ${EMERGE_BOARD_CMD} \
     --root="${ROOT_FS_DIR}" --root-deps=rdeps \
-    --usepkg chromeos ${EXTRA_PACKAGES} ${EMERGE_JOBS}
+    --usepkgonly chromeos ${EXTRA_PACKAGES} ${EMERGE_JOBS}
 
   # Perform any customizations on the root file system that are needed.
   "${SCRIPTS_DIR}/customize_rootfs" \
     --root="${ROOT_FS_DIR}" \
     --target="${ARCH}" \
     --board="${BOARD}"
 
   # Populates the root filesystem with legacy bootloader templates
   # appropriate for the platform.  The autoupdater and installer will
   # use those templates to update the legacy boot partition (12/ESP)
@@ skipping 68 matching lines @@
     cp ${PREVIOUS_DIR}/${PRISTINE_IMAGE_NAME} ${OUTPUT_DIR}
 
     # Copy forward the developer image, if we already copied forward the base.
     if [[ ${FLAGS_withdev} -eq ${FLAGS_TRUE} ]] && \
        [[ -f ${PREVIOUS_DIR}/${DEVELOPER_IMAGE_NAME} ]] ; then
       cp ${PREVIOUS_DIR}/${DEVELOPER_IMAGE_NAME} ${OUTPUT_DIR}
     fi
   fi
 fi
 
+# Perform an eclean to remove packages which are not installed
+if [[ "${FLAGS_eclean}" -eq "${FLAGS_TRUE}" ]]; then
+  eclean-${FLAGS_board} -d packages
+fi
+
 # Create the boot.desc file which stores the build-time configuration
 # information needed for making the image bootable after creation with
 # cros_make_image_bootable.
 create_boot_desc
 
 if [[ -f ${PRISTINE_IMG} ]] ; then
   update_base_packages ${PRISTINE_IMAGE_NAME}
 else
   create_base_image ${PRISTINE_IMAGE_NAME}
 fi
@@ skipping 50 matching lines @@
   echo "Developer image created as ${DEVELOPER_IMAGE_NAME}"
 fi
 
 print_time_elapsed
 
 echo "To copy to USB keyfob, OUTSIDE the chroot, do something like:"
 echo "  ./image_to_usb.sh --from=${OUTSIDE_OUTPUT_DIR} --to=/dev/sdX"
 echo "To convert to VMWare image, INSIDE the chroot, do something like:"
 echo "  ./image_to_vm.sh --from=${OUTSIDE_OUTPUT_DIR} --board=${BOARD}"
 echo "from the scripts directory where you entered the chroot."