futility: vbutil_kernel should check the kernel a bit more

Trying to repack an invalid kernel blob should notice and
complain that the blob is invalid instead of just segfaulting.

BUG=chromium:452353
BRANCH=ToT
TEST=manual

See the bug report for an example test case. Many more tests are
being added as futility development continues.

Change-Id: I2bbfb8ab41a0f596b25a76f76f74d7b47b7e4a17
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/243583
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
1 file changed