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Commit bf3020b7 authored by David Anderson's avatar David Anderson
Browse files

libsnapshot: Fix CowWriter::Finalize() not restoring footer correctly. 

Bug: 173432386
Test: cow_api_test
Change-Id: If1b856fcdcd6b6ded5e00342037308c6b35d6fc0
parent d5bd5437

fs_mgr/libsnapshot/cow_api_test.cpp

+24 −0
Original line number Diff line number Diff line
@@ -757,6 +757,30 @@ TEST_F(CowTest, ClusterAppendTest) { 
    ASSERT_TRUE(iter->Done());

}



TEST_F(CowTest, AppendAfterFinalize) {

    CowOptions options;

    options.cluster_ops = 0;

    auto writer = std::make_unique<CowWriter>(options);

    ASSERT_TRUE(writer->Initialize(cow_->fd));



    std::string data = "This is some data, believe it";

    data.resize(options.block_size, '\0');

    ASSERT_TRUE(writer->AddRawBlocks(50, data.data(), data.size()));

    ASSERT_TRUE(writer->AddLabel(3));

    ASSERT_TRUE(writer->Finalize());



    std::string data2 = "More data!";

    data2.resize(options.block_size, '\0');

    ASSERT_TRUE(writer->AddRawBlocks(51, data2.data(), data2.size()));

    ASSERT_TRUE(writer->Finalize());



    ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);



    // COW should be valid.

    CowReader reader;

    ASSERT_TRUE(reader.Parse(cow_->fd));

}



}  // namespace snapshot

}  // namespace android

fs_mgr/libsnapshot/cow_reader.cpp

+2 −1
Original line number Diff line number Diff line
@@ -229,7 +229,8 @@ bool CowReader::ParseOps(std::optional<uint64_t> label) { 


    if (footer_) {

        if (ops_buffer->size() != footer_->op.num_ops) {

            LOG(ERROR) << "num ops does not match";

            LOG(ERROR) << "num ops does not match, expected " << footer_->op.num_ops << ", found "

                       << ops_buffer->size();

            return false;

        }

        if (ops_buffer->size() * sizeof(CowOperation) != footer_->op.ops_size) {

fs_mgr/libsnapshot/cow_writer.cpp

+2 −1
Original line number Diff line number Diff line
@@ -376,6 +376,7 @@ bool CowWriter::Finalize() { 
    auto continue_data_pos = next_data_pos_;

    auto continue_op_pos = next_op_pos_;

    auto continue_size = ops_.size();

    auto continue_num_ops = footer_.op.num_ops;

    bool extra_cluster = false;



    // Footer should be at the end of a file, so if there is data after the current block, end it
@@ -408,9 +409,9 @@ bool CowWriter::Finalize() { 
        current_data_size_ = continue_data_size;

        next_data_pos_ = continue_data_pos;

        next_op_pos_ = continue_op_pos;

        footer_.op.num_ops = continue_num_ops;

        ops_.resize(continue_size);

    }



    return Sync();

}