Byte-array elements leak in `FromSchemaByteArray()`

Inizia in dataset/src/main/cpp/jni_util.cc, in FromSchemaByteArray(), e ispeziona il flusso di GetByteArrayElements, ReadSchema e ReleaseByteArrayElements. Verifica che il rilascio avvenga anche quando l’analisi non riesce, quindi esegui il percorso di uno schema malformato o incompatibile tramite createDataset(); il lavoro è completato quando gli elementi dell’array JNI acquisiti vengono rilasciati sia nei percorsi di successo sia in quelli di errore.

Describe the bug, including details regarding any error messages, version, and platform.

I found a possible JNI array leak in FromSchemaByteArray() when the serialized schema cannot be parsed.

File: dataset/src/main/cpp/jni_util.cc

Function: FromSchemaByteArray

Relevant code:

jbyte* schemaBytes_data =
    env->GetByteArrayElements(schemaBytes, nullptr);
auto serialized_schema = std::make_shared<arrow::Buffer>(
    reinterpret_cast<uint8_t*>(schemaBytes_data),
    schemaBytes_len);
arrow::io::BufferReader buf_reader(serialized_schema);

ARROW_ASSIGN_OR_RAISE(
    std::shared_ptr<arrow::Schema> schema,
    arrow::ipc::ReadSchema(&buf_reader, &in_memo))

env->ReleaseByteArrayElements(
    schemaBytes, schemaBytes_data, JNI_ABORT);
return schema;

GetByteArrayElements() returns a pointer that must be paired with
ReleaseByteArrayElements().

ARROW_ASSIGN_OR_RAISE returns immediately when ReadSchema() returns an
error. On that path, the release below the macro is skipped, so the acquired
array elements remain unreleased:

GetByteArrayElements succeeds
  -> ReadSchema returns an error
  -> ARROW_ASSIGN_OR_RAISE returns
  -> ReleaseByteArrayElements is skipped

The function is used by the public native createDataset() method:

schema = JniGetOrThrow(
    FromSchemaByteArray(env, schema_bytes));

Malformed, corrupted, or incompatible serialized schema bytes can therefore
reach this path. Repeated failed calls can retain copied array buffers or keep
Java arrays pinned, depending on the JVM implementation.

Suggested fix: release the elements before propagating the parse result, for
example:

auto schema_result =
    arrow::ipc::ReadSchema(&buf_reader, &in_memo);

env->ReleaseByteArrayElements(
    schemaBytes, schemaBytes_data, JNI_ABORT);

return schema_result;

An RAII guard for schemaBytes_data would also ensure release if additional
early returns are introduced later.