Fix data corruption when reading ORC files with empty stripes

cpp/src/io/orc/reader_impl.cu

@@ -967,7 +967,6 @@ table_with_metadata reader::impl::read(size_type skip_rows,
     // Association between each ORC column and its cudf::column
     _col_meta.orc_col_map.emplace_back(_metadata.get_num_cols(), -1);
     std::vector<orc_column_meta> nested_col;
-    bool is_data_empty = false;
 
     // Get a list of column data types
     std::vector<data_type> column_types;
@@ -991,7 +990,6 @@ table_with_metadata reader::impl::read(size_type skip_rows,
 
       // Map each ORC column to its column
       _col_meta.orc_col_map[level][col.id] = column_types.size() - 1;
-      // TODO: Once MAP type is supported in cuDF, update this for MAP as well
       if (col_type == type_id::LIST or col_type == type_id::STRUCT) nested_col.emplace_back(col);
     }
 
@@ -1051,6 +1049,7 @@ table_with_metadata reader::impl::read(size_type skip_rows,
       size_t num_rowgroups    = 0;
       int stripe_idx          = 0;
 
+      bool is_level_data_empty = true;
       std::vector<std::pair<std::future<size_t>, size_t>> read_tasks;
       for (auto const& stripe_source_mapping : selected_stripes) {
         // Iterate through the source files selected stripes
@@ -1070,21 +1069,16 @@ table_with_metadata reader::impl::read(size_type skip_rows,
                                                           stream_info,
                                                           level == 0);
 
-          if (total_data_size == 0) {
-            CUDF_EXPECTS(stripe_info->indexLength == 0, "Invalid index rowgroup stream data");
-            // In case ROW GROUP INDEX is not present and all columns are structs with no null
-            // stream, there is nothing to read at this level.
-            auto fn_check_dtype = [](auto dtype) { return dtype.id() == type_id::STRUCT; };
-            CUDF_EXPECTS(std::all_of(column_types.begin(), column_types.end(), fn_check_dtype),
-                         "Expected streams data within stripe");
-            is_data_empty = true;
-          }
+          auto const is_stripe_data_empty = total_data_size == 0;
+          if (not is_stripe_data_empty) { is_level_data_empty = false; }
+          CUDF_EXPECTS(not is_stripe_data_empty or stripe_info->indexLength == 0,
+                       "Invalid index rowgroup stream data");
 
           stripe_data.emplace_back(total_data_size, stream);
           auto dst_base = static_cast<uint8_t*>(stripe_data.back().data());
 
           // Coalesce consecutive streams into one read
-          while (not is_data_empty and stream_count < stream_info.size()) {
+          while (not is_stripe_data_empty and stream_count < stream_info.size()) {
             const auto d_dst  = dst_base + stream_info[stream_count].dst_pos;
             const auto offset = stream_info[stream_count].offset;
             auto len          = stream_info[stream_count].length;
@@ -1162,7 +1156,7 @@ table_with_metadata reader::impl::read(size_type skip_rows,
             if (chunk.type_kind == orc::TIMESTAMP) {
               chunk.timestamp_type_id = _timestamp_type.id();
             }
-            if (not is_data_empty) {
+            if (not is_stripe_data_empty) {
               for (int k = 0; k < gpu::CI_NUM_STREAMS; k++) {
                 chunk.streams[k] = dst_base + stream_info[chunk.strm_id[k]].dst_pos;
               }
@@ -1199,7 +1193,8 @@ table_with_metadata reader::impl::read(size_type skip_rows,
                          });
         }
         // Setup row group descriptors if using indexes
-        if (_metadata.per_file_metadata[0].ps.compression != orc::NONE and not is_data_empty) {
+        if (_metadata.per_file_metadata[0].ps.compression != orc::NONE and
+            not is_level_data_empty) {
           auto decomp_data = decompress_stripe_data(chunks,
                                                     stripe_data,
                                                     *_metadata.per_file_metadata[0].decompressor,
@@ -1242,7 +1237,7 @@ table_with_metadata reader::impl::read(size_type skip_rows,
           out_buffers[level].emplace_back(column_types[i], n_rows, is_nullable, stream, _mr);
         }
 
-        if (not is_data_empty) {
+        if (not is_level_data_empty) {
           decode_stream_data(chunks,
                              num_dict_entries,
                              skip_rows,
@@ -1256,7 +1251,7 @@ table_with_metadata reader::impl::read(size_type skip_rows,
 
         // Extract information to process nested child columns
         if (nested_col.size()) {
-          if (not is_data_empty) {
+          if (not is_level_data_empty) {
             scan_null_counts(chunks, null_count_prefix_sums[level], stream);
           }
           row_groups.device_to_host(stream, true);

python/cudf/cudf/tests/test_orc.py

@@ -1815,3 +1815,22 @@ def test_statistics_string_sum():
 
     file_stats, stripe_stats = cudf.io.orc.read_orc_statistics([buff])
     assert_eq(file_stats[0]["str"].get("sum"), sum(len(s) for s in strings))
+
+
+@pytest.mark.parametrize(
+    "fname",
+    [
+        "TestOrcFile.Hive.OneEmptyMap.orc",
+        "TestOrcFile.Hive.OneEmptyList.orc",
+        "TestOrcFile.Hive.OneNullStruct.orc",
+        "TestOrcFile.Hive.EmptyListStripe.orc",
+        "TestOrcFile.Hive.NullStructStripe.orc",
+        "TestOrcFile.Hive.AllNulls.orc",
+    ],
+)
+def test_reader_empty_stripe(datadir, fname):
+    path = datadir / fname
+
+    expected = pd.read_orc(path)
+    got = cudf.read_orc(path)
+    assert_eq(expected, got)