tree 7efc140e60eefd3b46bca9d67b95970efd80321a
parent d2887b126ed307fff0e487a3786fed030353b0fa
author Sen Jiang <senj@google.com> 1459206875 -0700
committer Sen Jiang <senj@google.com> 1460407455 -0700

Stream the output to disk.

Now that update_engine no longer uses minor version 1, old file and
new file are always different in the device, so we can write the
output to disk right away to save memory.
The old behavior is still kept if the new file is overlapping with the
old file for paycheck.py usage.

Test: bsdiff_unittest
Test: apply a 3M patch overwriting old file, uses 25M memory.
Test: apply a 3M patch not overwriting old file, uses 9M memory.
Bug: 25773600

Change-Id: Ic289c9bcc6f1810d0f222a9a4241c05756084b1c