tests/signature/api-check/src/java/android/signature/cts/api/BootClassPathClassesProvider.java

/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed 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 android.signature.cts.api;

import android.os.Debug;
import android.signature.cts.ClassProvider;
import android.signature.cts.DexField;
import android.signature.cts.DexMethod;
import android.signature.cts.DexMember;
import dalvik.system.BaseDexClassLoader;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.stream.Stream;

@SuppressWarnings("deprecation")
public class BootClassPathClassesProvider extends ClassProvider {
    private static boolean sJvmtiAttached = false;

    @Override
    public Stream<Class<?>> getAllClasses() {
        maybeAttachJvmtiAgent();
        return Arrays.stream(getClassloaderDescriptors(Object.class.getClassLoader()))
                .map(descriptor -> {
                    String classname = descriptor.replace('/', '.');
                    // omit L and ; at the front and at the end
                    return classname.substring(1, classname.length() - 1);
                })
                .map(classname -> {
                    try {
                        return getClass(classname);
                    } catch (ClassNotFoundException e) {
                        throw new RuntimeException("Cannot load " + classname, e);
                    }
                });
    }

    @Override
    public Stream<DexMember> getAllMembers(Class<?> klass) {
        maybeAttachJvmtiAgent();

        String[][] field_infos = getClassMemberNamesAndTypes(klass, /* fields */ true);
        String[][] method_infos = getClassMemberNamesAndTypes(klass, /* fields */ false);
        if (field_infos.length != 2 || field_infos[0].length != field_infos[1].length ||
            method_infos.length != 2 || method_infos[0].length != method_infos[1].length) {
          throw new RuntimeException("Invalid result from getClassMemberNamesAndTypes");
        }

        String klass_desc = "L" + klass.getName().replace('.', '/') + ";";
        DexMember[] members = new DexMember[field_infos[0].length + method_infos[0].length];
        for (int i = 0; i < field_infos[0].length; i++) {
            members[i] = new DexField(klass_desc, field_infos[0][i], field_infos[1][i], null);
        }
        for (int i = 0; i < method_infos[0].length; i++) {
            members[i + field_infos[0].length] =
                new DexMethod(klass_desc, method_infos[0][i], method_infos[1][i], null);
        }
        return Arrays.stream(members);
    }

    private static void maybeAttachJvmtiAgent() {
      if (!sJvmtiAttached) {
          try {
              Debug.attachJvmtiAgent(copyAgentToFile("classdescriptors").getAbsolutePath(), null,
                      BootClassPathClassesProvider.class.getClassLoader());
              sJvmtiAttached = true;
              initialize();
          } catch (Exception e) {
              throw new RuntimeException("Error while attaching JVMTI agent", e);
          }
      }
    }

    private static File copyAgentToFile(String lib) throws Exception {
        ClassLoader cl = BootClassPathClassesProvider.class.getClassLoader();

        File copiedAgent = File.createTempFile("agent", ".so");
        try (InputStream is = new FileInputStream(
                ((BaseDexClassLoader) cl).findLibrary(lib))) {
            try (OutputStream os = new FileOutputStream(copiedAgent)) {
                byte[] buffer = new byte[64 * 1024];

                while (true) {
                    int numRead = is.read(buffer);
                    if (numRead == -1) {
                        break;
                    }
                    os.write(buffer, 0, numRead);
                }
            }
        }
        return copiedAgent;
    }

    private static native void initialize();

    private static native String[] getClassloaderDescriptors(ClassLoader loader);
    private static native String[][] getClassMemberNamesAndTypes(Class<?> klass, boolean getFields);
}