/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.codec.digest;
  
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assumptions.assumeTrue;
  
  import org.junit.jupiter.api.Test;
  
  public class XXHash32OverflowTest {
  
      /**
       * This test hits an edge case where a very large number of bytes is added to the incremental
       * hash. The data is constructed so that an integer counter of unprocessed bytes will
       * overflow. If this is not handled correctly then the code throws an exception when it
       * copies more data into the unprocessed bytes array.
       */
      @Test
      public void testIncrementalHashWithUnprocessedBytesAndHugeLengthArray() {
          // Assert the test precondition that a large array added to unprocessed bytes
          // will overflow an integer counter. We use the smallest hugeLength possible
          // as some VMs cannot allocate maximum length arrays.
          final int bufferSize = 16;
          final int unprocessedSize = bufferSize - 1;
          final int hugeLength = Integer.MAX_VALUE - (unprocessedSize - 1);
          assertTrue(unprocessedSize + hugeLength < bufferSize, "This should overflow to negative");
  
          // Check the test can be run
          byte[] bytes = null;
          try {
              bytes = new byte[hugeLength];
          } catch (final OutOfMemoryError ignore) {
              // Some VMs cannot allocate an array this large.
              // Some test environments may not have enough available memory for this.
          }
          assumeTrue(bytes != null, "Cannot allocate array of length " + hugeLength);
  
          final XXHash32 inc = new XXHash32();
          // Add bytes that should be unprocessed
          inc.update(bytes, 0, unprocessedSize);
          // Add a huge number of bytes to overflow an integer counter of unprocessed bytes.
          inc.update(bytes, 0, hugeLength);
      }
  }