tree 1f4a8e32dae11e6fb392d249cbe9e20b8a4cf117
parent 79ffca0eec59ce48514af7a3ef8ba13abb3ea4a3
author Sen Jiang <senj@google.com> 1460416083 -0700
committer Sen Jiang <senj@google.com> 1461359650 -0700

Fix infinite loop when using extents.

Clearing |buffer_| still actually makes sense because MemoryFile::Close()
is called twice: once explicitly from bspatch to check if Close()
succeeded, once from destructor to ensure that everything is closed. And
if we don't clear |buffer_|, on the second Close(), it will try to write
|buffer_| to |file_| again, and if |file_| is an ExtentsFile, it will
simply return true and set |bytes_written| to 0 on Write() because all
the extents are already written, now WriteAll() became an infinite
loop.
Although returning false if written is 0 in WriteAll() will fix this, but
I think we should not write the same buffer again in the first place.

Test: call bspatch with extents
Bug: 28345972

Change-Id: If3bddcc6e8ca6751c422c066e5b8b02f91086ed5
(cherry picked from commit b14bb55294132466913a07e2c0a54b8765c9240b)