content: /*
   * 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.cassandra.distributed.shared;
  
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.lang.reflect.Method;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.net.URLConnection;
  import java.net.URLStreamHandler;
  import java.nio.charset.StandardCharsets;
  import java.security.CodeSigner;
  import java.security.CodeSource;
  import java.security.ProtectionDomain;
  import java.util.Arrays;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import com.google.common.base.StandardSystemProperty;
  import com.google.common.io.ByteStreams;
  import com.google.common.io.Files;
  import org.apache.cassandra.io.util.File;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.jboss.byteman.agent.Transformer;
  
  import static org.apache.cassandra.config.CassandraRelevantProperties.TEST_BYTEMAN_TRANSFORMATIONS_DEBUG;
  
  public final class Byteman
  {
      private static final Logger logger = LoggerFactory.getLogger(Byteman.class);
  
      private static final boolean DEBUG_TRANSFORMATIONS = TEST_BYTEMAN_TRANSFORMATIONS_DEBUG.getBoolean();
      private static final Method METHOD;
      private static final URL BYTEMAN;
  
      static
      {
          try
          {
              Method method = ClassLoader.class.getDeclaredMethod("defineClass",
                                                                  String.class, byte[].class, Integer.TYPE, Integer.TYPE,
                                                                  ProtectionDomain.class);
              method.setAccessible(true);
              METHOD = method;
          }
          catch (NoSuchMethodException e)
          {
              throw new AssertionError(e);
          }
  
          try
          {
              // this is just to make it more clear when you inspect a class that it was created by byteman
              // the code source will show it came from byteman:// which isn't a valid java URL (hence the stream handler
              // override)
              BYTEMAN = new URL(null, "byteman://", new URLStreamHandler() {
                  protected URLConnection openConnection(URL u)
                  {
                      throw new UnsupportedOperationException();
                  }
              });
          }
          catch (MalformedURLException e)
          {
              throw new AssertionError(e);
          }
      }
  
      private final Transformer transformer;
      private final List<KlassDetails> klasses;
  
      public static Byteman createFromScripts(String... scripts)
      {
          List<String> texts = Stream.of(scripts).map(p -> {
              try
              {
                  return Files.toString(new File(p).toJavaIOFile(), StandardCharsets.UTF_8);
              }
              catch (IOException e)
              {
                  throw new UncheckedIOException(e);
              }
          }).collect(Collectors.toList());
  
          return new Byteman(Arrays.asList(scripts), texts, extractClasses(texts));
      }
  
      public static Byteman createFromText(String text)
      {
          return new Byteman(Arrays.asList("invalid"), Arrays.asList(text), extractClasses(Arrays.asList(text)));
      }
  
      private Byteman(List<String> scripts, List<String> texts, Set<String> modifiedClassNames)
      {
          klasses = modifiedClassNames.stream().map(fullyQualifiedKlass -> {
              try
              {
                  Class<?> klass = Class.forName(fullyQualifiedKlass);
                  String klassPath = fullyQualifiedKlass.replace(".", "/");
                  byte[] bytes = ByteStreams.toByteArray(Thread.currentThread().getContextClassLoader().getResourceAsStream(klassPath + ".class"));
  
                  return new KlassDetails(klassPath, klass, klass.getProtectionDomain(), bytes);
              }
              catch (Exception e)
              {
                  throw new RuntimeException(e);
              }
          }).collect(Collectors.toList());
  
          try
          {
              this.transformer = new Transformer(null, null, scripts, texts, false);
          }
          catch (Exception e)
          {
              throw new RuntimeException(e);
          }
      }
  
      public void install(ClassLoader cl)
      {
          try
          {
              for (KlassDetails details : klasses)
              {
                  byte[] newBytes = transformer.transform(cl, details.klassPath, details.klass, details.protectionDomain, details.bytes);
                  if (newBytes == null)
                      throw new AssertionError("Unable to transform bytes for " + details.klassPath);
  
                  // inject the bytes into the classloader
                  METHOD.invoke(cl, null, newBytes, 0, newBytes.length,
                                new ProtectionDomain(new CodeSource(BYTEMAN, new CodeSigner[0]), details.protectionDomain.getPermissions()));
                  if (DEBUG_TRANSFORMATIONS)
                  {
                      File f = new File(StandardSystemProperty.JAVA_IO_TMPDIR.value(), "byteman/" + details.klassPath + ".class");
                      f.parent().tryCreateDirectories();
                      File original = new File(f.parent(), "original-" + f.name());
                      logger.info("Writing class file for {} to {}", details.klassPath, f.absolutePath());
                      Files.asByteSink(f.toJavaIOFile()).write(newBytes);
                      Files.asByteSink(original.toJavaIOFile()).write(details.bytes);
                  }
              }
          }
          catch (Exception e)
          {
              throw new RuntimeException(e);
          }
      }
  
      private static Set<String> extractClasses(List<String> texts)
      {
          Pattern pattern = Pattern.compile("^CLASS (.*)$");
          Set<String> modifiedClassNames = new HashSet<>();
          for (String text : texts)
          {
              for (String line : text.split("\n"))
              {
                  Matcher matcher = pattern.matcher(line);
                  if (!matcher.find())
                      continue;
                  modifiedClassNames.add(matcher.group(1));
              }
          }
          if (modifiedClassNames.isEmpty())
              throw new AssertionError("Unable to find any classes to modify");
          return modifiedClassNames;
      }
  
      private static final class KlassDetails
      {
          private final String klassPath;
          private final Class<?> klass;
          private final ProtectionDomain protectionDomain;
          private final byte[] bytes;
  
          public KlassDetails(String klassPath,
                              Class<?> klass, ProtectionDomain protectionDomain, byte[] bytes)
          {
              this.klassPath = klassPath;
              this.klass = klass;
              this.protectionDomain = protectionDomain;
              this.bytes = bytes;
          }
      }
  }
  