commit 02144a9ae25b7a0ea765c800e1c6ac75fc3703d7
author Hung-Te Lin <hungte@chromium.org> Fri Feb 10 10:22:21 2017
committer chrome-bot <chrome-bot@chromium.org> Fri Feb 10 16:32:48 2017
tree 17b081ae2d76669eaec8659a48a43d3c45cdb45b
parent dca771d0d82480f60419da97e5de4f3c2bc10387

vpd_get_value: Allow ignoring cache by environment VPD_IGNORE_CACHE.

Some programs may want to read current VPD values, or from the
dump_vpd_log cache files (usually for testing, or factory provisioning).

Add two environment variables to control how vpd_get_value retrieves VPD
values:

 VPD_IGNORE_CACHE: Ignore any caches (read directly by 'vpd -g').
 VPD_IGNORE_SYS_CACHE: Ignore cache from /sys/firmware.

BRANCH=None
BUG=None
TEST=vpd_get_value customization_id # A-B
     vpd -s customization_id=C-D
     vpd_get_value customization_id # A-B
     VPD_IGNORE_CACHE=1 vpd_get_value customization_id # C-D
     VPD_IGNORE_SYS_CACH=1 vpd_get_value customization_id # A-B
     dump_vpd_log --force
     VPD_IGNORE_CACHE=1 vpd_get_value customization_id # C-D
     VPD_IGNORE_SYS_CACH=1 vpd_get_value customization_id # C-D

Change-Id: Id2e1be9596cdff1ff8b4810d89d2b1f91e29ba87
Reviewed-on: https://chromium-review.googlesource.com/440713
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Ting Shen <phoenixshen@chromium.org>

util/vpd_get_value

diff --git a/util/vpd_get_value b/util/vpd_get_value
index a695244..99de55e 100755
--- a/util/vpd_get_value
+++ b/util/vpd_get_value
@@ -12,6 +12,9 @@
 CACHE_FILE=/mnt/stateful_partition/unencrypted/cache/vpd/full-v2.txt
 SYS_VPD=/sys/firmware/vpd
 
+: "${VPD_IGNORE_CACHE:=}"
+: "${VPD_IGNORE_SYS_CACHE}"
+
 cat_if_exists() {
   local file="$1"
   if [ -f "${file}" ]; then
@@ -28,9 +31,13 @@
   fi
   local key="$1"
 
+  if [ -n "${VPD_IGNORE_CACHE}" ]; then
+    exec vpd -g "${key}"
+  fi
+
   # Reading from /sys (works on ARM 3.18+, x86 4.4+) is most efficient;
   # otherwise we have to parse from VPD cache (maintained by dump_vpd_log).
-  if [ -d "${SYS_VPD}/ro" ]; then
+  if [ -z "${VPD_IGNORE_SYS_CACHE}" ] && [ -d "${SYS_VPD}/ro" ]; then
     cat_if_exists "${SYS_VPD}/ro/${key}" ||
       cat_if_exists "${SYS_VPD}/rw/${key}"
   else