commit 895e23fb293d47e565f731d9c1c136aa2491a81b
author Sean Klein <smklein@google.com> Thu Feb 07 07:43:25 2019 -0800
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> Tue Feb 12 03:52:15 2019 +0000
tree aecd1ab18c127a19c48749d414d6df0ccc983475
parent 52059d0841223d5c3001d1204d37e511f747cb28

[fdio][ns] Reimplement local filesystem in safe C++

- Fix incorrect accounting of namespace refcounting (debug asserts
revealed that in the previous implementation, the refcount commonly
became negative). Utilize fbl::RefPtr to to automatically track
references.
- Alter API of |fdio_ns_destroy| to free the namespace when all strong
references go out of scope. All (known) clients within Fuchsia have
ignored the "in-use" error, which would have caused leaks.
- Alter API of |fdio_ns_bind| to close the supplied handle on failure.
- Encapsulate and isolate logic for local vnodes, connections, and
filesystems into distinct classes. Minimize surface area between
"safe C++" API and "raw C" API.
- Add reference counting to local vnodes, which will safely permit
usage of their remote objects, even if the node is unlinked.
- Reimplement "flat namespace" exporting logic to track a prefix string
in a single StringBuffer, populated once. This version is more
efficient, as it does not require re-constructing the path back to root
when each remote node is encountered.
- Add multiple tests for exporting, shadowing, re-binding, destruction, etc.

TEST=Multiple tests added in /boot/sys/namespace-test

Change-Id: I5f908e3837061c352dc4b749dd6892015e8a2969