If we're asked to compute a hash of an image on a region of storage, we
may find that the region actually contains no image. In that case, we
need to compute a hash of zero bytes. Properly handle this case from
image size detection to hash computation to hash invalidation.
BUG=chrome-os-partner:49529
TEST=Manual on chell. `dd conv=notrunc if=/dev/zero of=ec.bin bs=131072
count=1`, then write ec.bin and verify SW sync occurs, RW hash is
computed correctly, and the system boots into dev mode.
BRANCH=glados, strago
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: Ie5a023d13d2521f9c224615666950aea8fbc22bb
Reviewed-on: https://chromium-review.googlesource.com/322750
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
17ffa6b1ab