[GitHub] [lucene-solr] jpountz commented on a change in pull request #1569: LUCENE-9356: Add a test that verifies that Lucene catches bit flips.

[GitBox <gi...@apache.org>]

jpountz commented on a change in pull request #1569:
URL: https://github.com/apache/lucene-solr/pull/1569#discussion_r438754619



##########
File path: lucene/core/src/test/org/apache/lucene/index/TestAllFilesDetectBitFlips.java
##########
@@ -0,0 +1,139 @@
+/*
+ * 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.lucene.index;
+
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collections;
+
+import org.apache.lucene.analysis.MockAnalyzer;
+import org.apache.lucene.codecs.CodecUtil;
+import org.apache.lucene.store.BaseDirectoryWrapper;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.store.IOContext;
+import org.apache.lucene.store.IndexInput;
+import org.apache.lucene.store.IndexOutput;
+import org.apache.lucene.util.LineFileDocs;
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.util.LuceneTestCase.SuppressFileSystems;
+import org.apache.lucene.util.TestUtil;
+
+/**
+ * Test that the default codec detects bit flips at open or checkIntegrity time.
+ */
+@SuppressFileSystems("ExtrasFS")
+public class TestAllFilesDetectBitFlips extends LuceneTestCase {
+
+  public void test() throws Exception {
+    doTest(false);
+  }
+
+  public void testCFS() throws Exception {
+    doTest(true);
+  }
+
+  public void doTest(boolean cfs) throws Exception {
+    Directory dir = newDirectory();
+
+    IndexWriterConfig conf = newIndexWriterConfig(new MockAnalyzer(random()));
+    conf.setCodec(TestUtil.getDefaultCodec());
+
+    if (cfs == false) {
+      conf.setUseCompoundFile(false);
+      conf.getMergePolicy().setNoCFSRatio(0.0);
+    }
+
+    RandomIndexWriter riw = new RandomIndexWriter(random(), dir, conf);
+    // Use LineFileDocs so we (hopefully) get most Lucene features
+    // tested, e.g. IntPoint was recently added to it:
+    LineFileDocs docs = new LineFileDocs(random());
+    for (int i = 0; i < 100; i++) {
+      riw.addDocument(docs.nextDoc());
+      if (random().nextInt(7) == 0) {
+        riw.commit();
+      }
+      if (random().nextInt(20) == 0) {
+        riw.deleteDocuments(new Term("docid", Integer.toString(i)));
+      }
+      if (random().nextInt(15) == 0) {
+        riw.updateNumericDocValue(new Term("docid", Integer.toString(i)), "docid_intDV", Long.valueOf(i));
+      }
+    }
+    if (TEST_NIGHTLY == false) {
+      riw.forceMerge(1);
+    }
+    riw.close();
+    checkBitFlips(dir);
+    dir.close();
+  }
+  
+  private void checkBitFlips(Directory dir) throws IOException {
+    for(String name : dir.listAll()) {
+      if (name.equals(IndexWriter.WRITE_LOCK_NAME) == false) {
+        corruptFile(dir, name);
+      }
+    }
+  }
+  
+  private void corruptFile(Directory dir, String victim) throws IOException {
+    try (BaseDirectoryWrapper dirCopy = newDirectory()) {
+      dirCopy.setCheckIndexOnClose(false);
+
+      long victimLength = dir.fileLength(victim);
+      long flipOffset = TestUtil.nextLong(random(), 0, victimLength - 1);
+
+      if (VERBOSE) {
+        System.out.println("TEST: now corrupt file " + victim + " by changing byte at offset " + flipOffset + " (length= " + victimLength + ")");
+      }
+
+      for(String name : dir.listAll()) {
+        if (name.equals(victim) == false) {
+          dirCopy.copyFrom(dir, name, name, IOContext.DEFAULT);
+        } else {
+          try (IndexOutput out = dirCopy.createOutput(name, IOContext.DEFAULT);
+              IndexInput in = dir.openInput(name, IOContext.DEFAULT)) {
+              out.copyBytes(in, flipOffset);
+              out.writeByte((byte) (in.readByte() + TestUtil.nextInt(random(), 0x01, 0xFF)));
+              out.copyBytes(in, victimLength - flipOffset - 1);
+          }
+          try (IndexInput in = dirCopy.openInput(name, IOContext.DEFAULT)) {
+            try {
+              CodecUtil.checksumEntireFile(in);
+              System.out.println("TEST: changing a byte in " + victim + " did not update the checksum)");

Review comment:
       I haven't seen a single occurrence of it (fortunately! :) )




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