tree 67d72459130fc9e23d08e553a2c07b9553db4771
parent 015ca93e1ae41d3d1f6ee7dffe3be847e56bb493
author Jeff Sharkey <jsharkey@android.com> 1481655319 -0700
committer Jeff Sharkey <jsharkey@android.com> 1481660888 -0700

Define range of GIDs for cached app data.

To support upcoming disk usage calculation optimizations, this change
creates a new GID for each app that will be used to mark its cached
data.  We're allocating these unique GIDs so that we can use
quotactl() to track cached data on a per-app basis.

This change also tightens up the implementation of both the cache
and shared GID calculation to ensure that they stay inside the valid
ranges, and includes tests to verify.

Test: builds, boots, tests pass
Bug: 27948817
Change-Id: Ie4377e5aae267f2da39a165888139228995987cb