[ARROW-7559] [Rust] Possibly incorrect index check assertion in StringArray and BinaryArray

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.16.0
• Fix Version/s: 0.16.0
• Component/s: Rust
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/23818
• Assignee: Paddy Horan
• Reporter: Jörn Horstmann
• Created: 13/Jan/20 10:41
• Updated: 11/Jan/23 07:54
• Resolved: 14/Jan/20 04:36

Description

The following code tries to build a list array based on an underlying string array and panics on master (commit acfcdee75acb4b1814f2e727c150a7403d618e8f)

 #[test]
fn nested_string_array() {
    let strarray = StringArray::from(vec!["foo", "bar", "foobar"]);

    let nestedData = ArrayData::builder(DataType::List(Box::new(DataType::Utf8)))
        .len(2)
        .add_buffer(Buffer::from(&[0, 2, 3].to_byte_slice()))
        .add_child_data(ArrayData::builder(DataType::Utf8)
            .len(strarray.len())
            .add_buffer(strarray.value_offsets())
            .add_buffer(strarray.value_data())
            .build())
        .build();
    let nestedArray = ListArray::from(nestedData);

    dbg!(nestedArray);
}

My guess is that the index check in StringArray.value is incorrect, instead of

    pub fn value(&self, i: usize) -> &str {
        assert!(
            i + self.offset() < self.data.len(),
            "StringArray out of bounds access"
        );

it should probably compare i without adding the offset. The same check is also done in BinaryArray. Changing this results in the expected output of

[arrow/src/array/array.rs:2460] nestedArray = ListArray
[
  StringArray
[
  "foo",
  "bar",
],
  StringArray
[
  "foobar",
],
]
 

Issue Links

• links to: GitHub Pull Request #6180