tree d0aa461244112ab00aced60cc9d5e7ccd3b53785
parent db1d5a6204ead78024bcfc854cbf084cc53f1734
author Gilad Arnold <garnold@chromium.org> 1431061506 -0700
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> 1431113594 +0000

update_engine: Delta generator should not read past old image size.

This fixes a problem that was introduced by CL:246670 and caused the
delta generator to fail when generating deltas from a source image
that's smaller than the target image.

The bug is fixed by ensuring that the reading and comparing of unused
blocks is not attempted for block indexes that exceed the size of the
old image. Instead, these blocks are assumed to be new and their content
packaged into the payload.

BUG=chromium:477876
TEST=Unit tests
TEST=delta_generator successfully applied to FSI version 2913.331.0

Change-Id: Icc3163cca25ebeaefe05c2ba852664b6f0504053
Reviewed-on: https://chromium-review.googlesource.com/270075
Trybot-Ready: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>