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Commit 92b29e19 authored by David Anderson's avatar David Anderson
Browse files

libsnapshot: Add a test case for recent decompress regression. 

The attached test data is a 4096 length byte run that gz compresses to
exactly 4096 bytes. This exposes an edge case in CowReader::ReadData
with v2 snapshot files.

Bug: 310191184
Test: cow_api_test
Change-Id: I35e8d7e939d607d1dc118285ebc2f636c2291a20
parent 0ac91e1f

fs_mgr/libsnapshot/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -420,6 +420,7 @@ cc_test { 
    },

    data: [

        "tools/testdata/cow_v2",

        "tools/testdata/incompressible_block",

    ],

    auto_gen_config: true,

    require_root: false,

fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp

+31 −0
Original line number Diff line number Diff line
@@ -1522,6 +1522,37 @@ TEST_F(CowTest, CompatibilityTest) { 
    ASSERT_TRUE(reader.GetFooter(&footer));

}



TEST_F(CowTest, DecompressIncompressibleBlock) {

    auto fd = OpenTestFile("incompressible_block", O_RDONLY);

    ASSERT_GE(fd, 0);



    std::string original;

    ASSERT_TRUE(android::base::ReadFdToString(fd, &original)) << strerror(errno);

    ASSERT_EQ(original.size(), 4096);



    CowOptions options;

    options.compression = "gz";

    auto writer = CreateCowWriter(2, options, GetCowFd());

    ASSERT_NE(writer, nullptr);

    ASSERT_TRUE(writer->AddRawBlocks(0, original.data(), original.size()));

    ASSERT_TRUE(writer->Finalize());



    CowReader reader;

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



    auto iter = reader.GetOpIter();

    ASSERT_NE(iter, nullptr);

    ASSERT_FALSE(iter->AtEnd());



    std::string block(original.size(), '\0');

    ASSERT_EQ(iter->Get()->data_length, 4096);

    ASSERT_TRUE(ReadData(reader, iter->Get(), block.data(), block.size()));



    for (size_t i = 0; i < block.size(); i++) {

        ASSERT_EQ(block[i], original[i]) << "mismatch at byte " << i;

    }

}



}  // namespace snapshot

}  // namespace android

fs_mgr/libsnapshot/tools/testdata/incompressible_block

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+4 KiB

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