pixel: Add shell script to download images from Google

Change-Id: I23ea5c3e8de675bf48ae2be93b83f24f7025f5c3

pixel/download.sh

@@ -0,0 +1,78 @@
+#!/bin/bash
+#
+# download:
+#
+#   Download Pixel factory images and OTA updates from Google
+#
+#
+##############################################################################
+
+
+### SET ###
+
+# use bash strict mode
+set -euo pipefail
+
+
+### TRAPS ###
+
+# trap signals for clean exit
+trap 'exit $?' EXIT
+trap 'error_m interrupted!' SIGINT
+
+### CONSTANTS ###
+readonly script_path="$(cd "$(dirname "$0")";pwd -P)"
+readonly vars_path="${script_path}/../vars/"
+
+readonly work_dir="${WORK_DIR:-/tmp/pixel}"
+
+source "${vars_path}/devices"
+
+readonly device="${1}"
+source "${vars_path}/${device}"
+
+## HELP MESSAGE (USAGE INFO)
+# TODO
+
+### FUNCTIONS ###
+
+download_factory_image() {
+  local factory_dir="${work_dir}/${device}/${build_id}"
+  mkdir -p "${factory_dir}"
+  local output="${factory_dir}/$(basename ${image_url})"
+  curl --http1.1 -C - -L -o "${output}" "${image_url}"
+  echo "${image_sha256} ${output}" | sha256sum --check --status
+}
+
+download_ota_zip() {
+  local ota_dir="${work_dir}/${device}/${build_id}"
+  mkdir -p "${ota_dir}"
+  local output="${ota_dir}/$(basename ${ota_url})"
+  curl --http1.1 -C - -L -o "${output}" "${ota_url}"
+  echo "${ota_sha256} ${output}" | sha256sum --check --status
+}
+
+# error message
+# ARG1: error message for STDERR
+# ARG2: error status
+error_m() {
+  echo "ERROR: ${1:-'failed.'}" 1>&2
+  return "${2:-1}"
+}
+
+# print help message.
+help_message() {
+  echo "${help_message:-'No help available.'}"
+}
+
+main() {
+  download_factory_image
+  download_ota_zip
+}
+
+### RUN PROGRAM ###
+
+main "${@}"
+
+
+##