zircon/system/ulib/fs/test/tracked-remote-dir-tests.cpp

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <lib/async-loop/cpp/loop.h>
#include <fs/tracked-remote-dir.h>

#include <unittest/unittest.h>

#include <utility>

namespace {

// A Remote Directory which shuts down a dispatch loop when it is destroyed.
// This may be utilized to synchronize destruction of the remote directory
// with a test's dispatch loop.
class TestRemoteDir final : public fs::TrackedRemoteDir {
public:
    TestRemoteDir(zx::channel remote, async::Loop* loop)
        : TrackedRemoteDir(std::move(remote)), loop_(loop) {}
    ~TestRemoteDir() {
        loop_->Shutdown();
    }
private:
    async::Loop* loop_;
};

bool TestAddingTrackedDirectory() {
    BEGIN_TEST;

    async::Loop loop(&kAsyncLoopConfigNoAttachToThread);
    zx::channel server, client;
    ASSERT_EQ(ZX_OK, zx::channel::create(0u, &server, &client));

    fbl::String name = "remote-directory";
    auto dir = fbl::AdoptRef<fs::PseudoDir>(new fs::PseudoDir());

    // Get attributes.
    vnattr_t attr;
    EXPECT_EQ(ZX_OK, dir->Getattr(&attr));
    EXPECT_EQ(V_TYPE_DIR | V_IRUSR, attr.mode);
    EXPECT_EQ(1, attr.nlink);

    // "name" should not yet exist within the directory.
    fbl::RefPtr<fs::Vnode> node;
    EXPECT_EQ(ZX_ERR_NOT_FOUND, dir->Lookup(&node, name));

    // Add a remote directory, observe that it can be looked up.
    auto remote = fbl::AdoptRef<TestRemoteDir>(new TestRemoteDir(std::move(client), &loop));
    EXPECT_EQ(ZX_OK, remote->AddAsTrackedEntry(loop.dispatcher(), dir.get(), name));
    remote.reset();
    EXPECT_EQ(ZX_OK, dir->Lookup(&node, name));
    node.reset();

    // Forcing the remote connection to become "peer closed" causes the entry to be removed.
    server.reset();
    EXPECT_EQ(ZX_ERR_BAD_STATE, loop.Run());
    EXPECT_EQ(ZX_ERR_NOT_FOUND, dir->Lookup(&node, name));

    END_TEST;
}

bool TestAddingTrackedDirectoryMultiple() {
    BEGIN_TEST;

    async::Loop loop(&kAsyncLoopConfigNoAttachToThread);
    zx::channel server, client;
    ASSERT_EQ(ZX_OK, zx::channel::create(0u, &server, &client));

    fbl::String name = "remote-directory";
    auto dir = fbl::AdoptRef<fs::PseudoDir>(new fs::PseudoDir());

    auto remote = fbl::AdoptRef<TestRemoteDir>(new TestRemoteDir(std::move(client), &loop));
    EXPECT_EQ(ZX_OK, remote->AddAsTrackedEntry(loop.dispatcher(), dir.get(), name));

    // Observe that we cannot track the remote object multiple times.
    EXPECT_EQ(ZX_ERR_BAD_STATE, remote->AddAsTrackedEntry(loop.dispatcher(), dir.get(), name));

    // Observe that we cannot track the remote directory in a different
    // container.
    auto dir2 = fbl::AdoptRef<fs::PseudoDir>(new fs::PseudoDir());
    EXPECT_EQ(ZX_ERR_BAD_STATE, remote->AddAsTrackedEntry(loop.dispatcher(), dir2.get(), name));

    remote.reset();

    // Forcing the remote connection to become "peer closed" causes the entry to be removed.
    server.reset();
    EXPECT_EQ(ZX_ERR_BAD_STATE, loop.Run());
    fbl::RefPtr<fs::Vnode> node;
    EXPECT_EQ(ZX_ERR_NOT_FOUND, dir->Lookup(&node, name));

    END_TEST;
}

bool TestTrackAddingDifferentVnode() {
    BEGIN_TEST;

    async::Loop loop(&kAsyncLoopConfigNoAttachToThread);
    zx::channel server, client;
    ASSERT_EQ(ZX_OK, zx::channel::create(0u, &server, &client));

    auto dir = fbl::AdoptRef<fs::PseudoDir>(new fs::PseudoDir());

    auto remote = fbl::AdoptRef<TestRemoteDir>(new TestRemoteDir(std::move(client), &loop));
    auto not_remote = fbl::AdoptRef<fs::PseudoDir>(new fs::PseudoDir());

    // Test a subtle behavior:
    // - Add |remote| to |dir|, begin tracking the remote handle.
    // - Remove |remote| from |dir| (while still tracking).
    // - Add a different Vnode to |dir| with the same name.
    // - Close the remote connection for the still-tracked, but already-removed
    // vnode.
    //
    // This tests that when |remote| is closed, we don't accidentally remove the
    // "wrong" Vnode from the containing pseudodirectory.
    fbl::String name = "remote-directory";
    EXPECT_EQ(ZX_OK, remote->AddAsTrackedEntry(loop.dispatcher(), dir.get(), name));
    EXPECT_EQ(ZX_OK, dir->RemoveEntry(name));
    EXPECT_EQ(ZX_OK, dir->AddEntry(name, not_remote));
    remote.reset();
    server.reset();

    EXPECT_EQ(ZX_ERR_BAD_STATE, loop.Run());
    fbl::RefPtr<fs::Vnode> node;

    // The underlying entry should NOT have been removed.
    EXPECT_EQ(ZX_OK, dir->Lookup(&node, name));

    END_TEST;
}

} // namespace

BEGIN_TEST_CASE(tracked_remote_dir_tests)
RUN_TEST(TestAddingTrackedDirectory)
RUN_TEST(TestAddingTrackedDirectoryMultiple)
RUN_TEST(TestTrackAddingDifferentVnode)
END_TEST_CASE(tracked_remote_dir_tests)