fs_mgr/libsnapshot/partition_cow_creator_test.cpp

// Copyright (C) 2018 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <liblp/builder.h>
#include <liblp/property_fetcher.h>

#include "dm_snapshot_internals.h"
#include "partition_cow_creator.h"
#include "test_helpers.h"

using namespace android::fs_mgr;

namespace android {
namespace snapshot {

class PartitionCowCreatorTest : public ::testing::Test {
  public:
    void SetUp() override { SnapshotTestPropertyFetcher::SetUp(); }
    void TearDown() override { SnapshotTestPropertyFetcher::TearDown(); }
};

TEST_F(PartitionCowCreatorTest, IntersectSelf) {
    constexpr uint64_t initial_size = 1_MiB;
    constexpr uint64_t final_size = 40_KiB;

    auto builder_a = MetadataBuilder::New(initial_size, 1_KiB, 2);
    ASSERT_NE(builder_a, nullptr);
    auto system_a = builder_a->AddPartition("system_a", LP_PARTITION_ATTR_READONLY);
    ASSERT_NE(system_a, nullptr);
    ASSERT_TRUE(builder_a->ResizePartition(system_a, final_size));

    auto builder_b = MetadataBuilder::New(initial_size, 1_KiB, 2);
    ASSERT_NE(builder_b, nullptr);
    auto system_b = builder_b->AddPartition("system_b", LP_PARTITION_ATTR_READONLY);
    ASSERT_NE(system_b, nullptr);
    ASSERT_TRUE(builder_b->ResizePartition(system_b, final_size));

    PartitionCowCreator creator{.target_metadata = builder_b.get(),
                                .target_suffix = "_b",
                                .target_partition = system_b,
                                .current_metadata = builder_a.get(),
                                .current_suffix = "_a"};
    auto ret = creator.Run();
    ASSERT_TRUE(ret.has_value());
    ASSERT_EQ(final_size, ret->snapshot_status.device_size());
    ASSERT_EQ(final_size, ret->snapshot_status.snapshot_size());
}

TEST_F(PartitionCowCreatorTest, Holes) {
    const auto& opener = test_device->GetPartitionOpener();

    constexpr auto slack_space = 1_MiB;
    constexpr auto big_size = (kSuperSize - slack_space) / 2;
    constexpr auto small_size = big_size / 2;

    BlockDeviceInfo super_device("super", kSuperSize, 0, 0, 4_KiB);
    std::vector<BlockDeviceInfo> devices = {super_device};
    auto source = MetadataBuilder::New(devices, "super", 1_KiB, 2);
    auto system = source->AddPartition("system_a", 0);
    ASSERT_NE(nullptr, system);
    ASSERT_TRUE(source->ResizePartition(system, big_size));
    auto vendor = source->AddPartition("vendor_a", 0);
    ASSERT_NE(nullptr, vendor);
    ASSERT_TRUE(source->ResizePartition(vendor, big_size));
    // Create a hole between system and vendor
    ASSERT_TRUE(source->ResizePartition(system, small_size));
    auto source_metadata = source->Export();
    ASSERT_NE(nullptr, source_metadata);
    ASSERT_TRUE(FlashPartitionTable(opener, fake_super, *source_metadata.get()));

    auto target = MetadataBuilder::NewForUpdate(opener, "super", 0, 1);
    // Shrink vendor
    vendor = target->FindPartition("vendor_b");
    ASSERT_NE(nullptr, vendor);
    ASSERT_TRUE(target->ResizePartition(vendor, small_size));
    // Grow system to take hole & saved space from vendor
    system = target->FindPartition("system_b");
    ASSERT_NE(nullptr, system);
    ASSERT_TRUE(target->ResizePartition(system, big_size * 2 - small_size));

    PartitionCowCreator creator{.target_metadata = target.get(),
                                .target_suffix = "_b",
                                .target_partition = system,
                                .current_metadata = source.get(),
                                .current_suffix = "_a"};
    auto ret = creator.Run();
    ASSERT_TRUE(ret.has_value());
}

TEST(DmSnapshotInternals, CowSizeCalculator) {
    DmSnapCowSizeCalculator cc(512, 8);
    unsigned long int b;

    // Empty COW
    ASSERT_EQ(cc.cow_size_sectors(), 16);

    // First chunk written
    for (b = 0; b < 4_KiB; ++b) {
        cc.WriteByte(b);
        ASSERT_EQ(cc.cow_size_sectors(), 24);
    }

    // Second chunk written
    for (b = 4_KiB; b < 8_KiB; ++b) {
        cc.WriteByte(b);
        ASSERT_EQ(cc.cow_size_sectors(), 32);
    }

    // Leave a hole and write 5th chunk
    for (b = 16_KiB; b < 20_KiB; ++b) {
        cc.WriteByte(b);
        ASSERT_EQ(cc.cow_size_sectors(), 40);
    }
}

}  // namespace snapshot
}  // namespace android