Renamed the file for Owen's gist for the gdal mailing list.

gtiff_test.cc

TEST_F(GTiffTest, CreateCopyPreservesMaskForBandInterleavedCog) {
  constexpr char kFilename[] = "/vsimem/create_copy_with_mask.tif";
  constexpr int kWidth = 2;
  constexpr int kHeight = 2;
  constexpr size_t kSize = kWidth * kHeight;
  constexpr int kNumBands = 1;

  GDALRegister_GTiff();
  GDALDriver* driver = GetGDALDriverManager()->GetDriverByName(GTiff);

  {
    char** options = nullptr;
    options = CSLSetNameValue(options, "COPY_SRC_OVERVIEWS", "YES");
    options = CSLSetNameValue(options, "INTERLEAVE", "BAND");
    auto dataset = absl::WrapUnique<GDALDataset>(driver->Create(
        kFilename, kWidth, kHeight, kNumBands, GDT_Byte, options));
    ASSERT_TRUE(dataset != nullptr);

    std::vector<unsigned char> raster_buf(kSize, 0);
    ASSERT_EQ(dataset->RasterIO(GF_Write, 0, 0, kWidth, kHeight, &raster_buf[0],
                                kWidth, kHeight, GDT_Byte, kNumBands, nullptr,
                                0, 0, 0),
              CE_None);
    {
      const CPLConfigOptionSetter internalMaskSetter("GDAL_TIFF_INTERNAL_MASK",
                                                     "YES", false);

      ASSERT_EQ(dataset->CreateMaskBand(GMF_PER_DATASET), CE_None);
      auto mask_band = dataset->GetRasterBand(1)->GetMaskBand();
      ASSERT_TRUE(mask_band != nullptr);
      std::vector<unsigned char> mask_buf = {0, 255, 255, 255};
      ASSERT_EQ(
          mask_band->RasterIO(GF_Write, 0, 0, kWidth, kHeight, &mask_buf[0],
                              kWidth, kHeight, GDT_Byte, 0, 0),
          CE_None);
    }

    auto copy_dataset = absl::WrapUnique<GDALDataset>(driver->CreateCopy(
        kFilename, dataset.get(), true, options, nullptr, nullptr));
    ASSERT_TRUE(copy_dataset != nullptr);

    CSLDestroy(options);
  }

  auto open_info = absl::make_unique<GDALOpenInfo>(filename.c_str(), GDAL_OF_READONLY, nullptr);
  auto dataset = absl::WrapUnique(driver->pfnOpen(open_info.get()));

  ASSERT_EQ(dataset->GetRasterCount(), kNumBands);
  ASSERT_EQ(dataset->GetRasterXSize(), kWidth);
  ASSERT_EQ(dataset->GetRasterYSize(), kHeight);

  auto band = dataset->GetRasterBand(1);
  ASSERT_NE(band->GetMaskFlags() & GMF_PER_DATASET, 0);
  auto mask_band = band->GetMaskBand();
  ASSERT_TRUE(mask_band != nullptr);
  std::vector<unsigned char> mask_buf(kSize, 0);
  ASSERT_EQ(mask_band->RasterIO(GF_Read, 0, 0, kWidth, kHeight, &mask_buf[0],
                                kWidth, kHeight, GDT_Byte, 0, 0),
            CE_None);
  EXPECT_EQ(mask_buf[0], 0);
  EXPECT_EQ(mask_buf[1], 255);  // This line fails.
  EXPECT_EQ(mask_buf[2], 255);
  EXPECT_EQ(mask_buf[3], 255);

  VSIUnlink(kFilename);
}
@schwehr
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