GH-41016: [C++] Fix null count check in BooleanArray.true_count() (#4…

…1070) ### Rationale for this change Loading the `null_count` attribute doesn't take into account the possible value of -1, leading to a code path where the validity buffer is accessed, but which is not necessarily present in that case. ### What changes are included in this PR? Use `data->MayHaveNulls()` instead of `data->null_count.load()` ### Are these changes tested? Yes * GitHub Issue: #41016 Authored-by: Joris Van den Bossche <[email protected]> Signed-off-by: Antoine Pitrou <[email protected]>
apache · Apr 15, 2024 · 1e40252 · 1e40252
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commit 1e40252
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diff --git a/cpp/src/arrow/array/array_primitive.cc b/cpp/src/arrow/array/array_primitive.cc
@@ -56,7 +56,7 @@ int64_t BooleanArray::false_count() const {
 }
 
 int64_t BooleanArray::true_count() const {
-  if (data_->null_count.load() != 0) {
+  if (data_->MayHaveNulls()) {
     DCHECK(data_->buffers[0]);
     return internal::CountAndSetBits(data_->buffers[0]->data(), data_->offset,
                                      data_->buffers[1]->data(), data_->offset,

diff --git a/cpp/src/arrow/array/array_test.cc b/cpp/src/arrow/array/array_test.cc
@@ -1307,6 +1307,13 @@ TEST(TestBooleanArray, TrueCountFalseCount) {
   CheckArray(checked_cast<const BooleanArray&>(*arr));
   CheckArray(checked_cast<const BooleanArray&>(*arr->Slice(5)));
   CheckArray(checked_cast<const BooleanArray&>(*arr->Slice(0, 0)));
+
+  // GH-41016 true_count() with array without validity buffer with null_count of -1
+  auto arr_unknown_null_count = ArrayFromJSON(boolean(), "[true, false, true]");
+  arr_unknown_null_count->data()->null_count = kUnknownNullCount;
+  ASSERT_EQ(arr_unknown_null_count->data()->null_count.load(), -1);
+  ASSERT_EQ(arr_unknown_null_count->null_bitmap(), nullptr);
+  ASSERT_EQ(checked_pointer_cast<BooleanArray>(arr_unknown_null_count)->true_count(), 2);
 }
 
 TEST(TestPrimitiveAdHoc, TestType) {